Human Physiology Flashcards
What does human physiology study?
how functions in the human body occur/regulate
What does homeostasis mean?
maintenance of relatively stable internal environment
What does dynamic disequilibrium mean?
gradients are maintained even though there is still movement
What does phenotypic plasticity mean?
changes in phenotype
What is one of the unifying themes of human physiology?
1. physiological phenomena are manifestations of chemical and physical properties
What is the second unifying theme of human physiology?
2. physiological processes are regulated to maintain homeostasis
What is the third unifying theme of human physiology?
3. physiological phenotype = genotype and environment
What is the last unifying theme of human physiology?
4. physiological processes are products of evolution
What is one characteristic of membranes to allow for transport across it?
membranes are semipermeable
What does semipermeable mean?
small, nonpolar solutes can cross the membrane on their own
What are some examples of nonpolar solutes?
dissolved gasses, fatty acids, steroid hormones
What is necessary to transport other types of solutes?
protein-mediated transport
What does a channel protein do?
form a solute-specific pore in the membrane
What are some characteristics of channel proteins?
some are always opensome are gated
What are examples of channel proteins that are always open?
aquaporins, ion leak channels
What are some examples of gated channel proteins?
ligand-gatedvoltage-gatedmechanically-gated
What must carrier proteins have?
a conformational change each time they transport a solute
What is a uniporter?
carrier protein that transports a single solute at a time
What is a symporter?
a carrier protein that transports multiple solutes in the same direction
What is an antiporter?
a carrier protein that transports multiple solutes in opposite direction
What do some carrier proteins use?
active transport to move solutes against their gradients
What does gradient mean?
difference between two points in concentration, charge, pressure, temp
How does stuff move across a gradient?
down (high to low)
What is Fick's Law?
net flux = gradient X ease of movement X area
What is the driving force in this equation?
the gradient
What does osmolarity mean?
the total concentration of solutes in a solution
What are cells generally in?
osmotic equilibrium with the ECF
What are the three osmotic labels?
hyposmotic, isosmotic, and hyperosmotic
What does tonicity refer to?
the change in cell volume
What does hypotonic mean?
water diffuses in, the cell swells
What does isotonic mean?
no net water movement, no cell volume change
What does hypertonic mean?
water diffuses out, the cell shrinks
What do penetrating solutes do?
equilibrate across the membrane
What do non-penetrating solutes do?
do not equilibrate
What is cell communication necessary for?
coordinating physiological processes
What does the signalling cell do?
send a signal (chemical or electrical)
What receives the signal?
the target cell
What does direct signaling use?
gap junctions between cellssignal never goes into ECF
What does indirect signaling use?
a chemical signal that goes into the extracellular environment
How does this chemical signal enter the ECF?
exocytosis
What does the target cell have?
receptors that only bind to a specific ligand
What is signal strength modified by?
target cell (receptor number)signaling cell (amount of signaling molecules released)
What is the faster method to strengthen a signal?
create more signal cells
What is a longer lasting method to strengthen a signal?
add more receptors on target cell
What are the 5 characteristics of hormones?
1. carried in blood2. made by endocrine tissue3. can be peptides, derived from single amino acids, or cholesterol 4. function at low concentrations5. broken down or excreted by our bodies to limit duration of their effect
What are some examples of endocrine tissue?
thyroidpituitary glandadrenal gland
What are the types of feedback regulation?
positive feedbacknegative feedback
What does positive feedback mean?
regulated variable is pushed away from a set point
Explain how this uses positive feedback
increase in uterine pressure --> posterior pituitary gland --> oxytocin (hormone) -->uterine smooth muscle -->uterine contractions --> increase in uterine pressure
What is negative feedback?
regulated variable is pushed back towards set point
Explain an example of negative feedback
high blood glucose --> Beta cells in pancreas --> insulin (hormone) --> storage of glucose in muscle and adipose
What is it called when two opposing negative feedback loops are used for precise control of a variable?
Antagonistic regulation
What does antagonistic regulation do?
uses two opposing negative feedback loops for precise control of a variable
What is an example of antagonistic regulation?
negative feed back loop with high blood glucose ANDlow blood glucose --> alpha cells in pancreas --> glucagon (hormone) --> liver --> releases glucose
What are the two different effects hormones can have?
an additive effecta synergistic effect
What does the posterior pituitary do?
releases oxytocin and vasopressin
What does anterior pituitary do?
releases several hormones in response to trophic hormones released by hypothalamus
What do trophic hormones do?
influence the release of other hormones
How do hypothalamic trophic hormones travel?
directly to the anterior pituitary via portal veins
What is membrane potential?
a difference in charge across the membrane
Explain the concentrations of Na and K inside and outside the cell
low Na inside, high Na outsidehigh K inside, low K outside
When does an ion's equilibrium potential occur?
at the membrane potential where the electrical gradient exactly opposes the concentration gradient
What is resting potential around?
-70 because more K leak channels than Na
What do neurons send?
signals rapidly and precisely
What do neurons allow for?
us to sense and respond to our environment
What is information in neurons coded as?
changes in membrane potential
What is our nervous system split into?
a central nervous system and peripheral nervous system
What structures are found on a neuron?
dendrites, cell body, trigger zone, axon, axon terminus
Explain the order of a signal
signal reception, signal integration, signal conduction, signal transmission
What can signal transmission be?
electrical to chemical
In a neuron, what does a chemical signal bind to?
a receptor on the dendrites or cell body causing an ion channel to open/close
What does ion movement cause?
local graded membrane potential
What happens if a dendrite reaches threshold potential?
nothing, unless the signal is strong enough for the trigger zone to reach threshold potential
What does the trigger zone integrate multiple signals through?
temporal summation
What is temporal summation?
integration of signals coming in at a quick succession
What is spatial summation?
integration of multiple simultaneous signals
What does an excitatory signal do?
brings trigger zone membrane potential closer to threshold potential
What does an inhibitory signal do?
brings trigger zone membrane potential farther away from threshold potential
What is an action potential?
an abrupt change in membrane potential in an axon
What is an action potential triggered by?
threshold potential at the trigger zone
What are three characteristics of action potentials?
all or nonedo not degrade along the axonuse voltage gated Na and voltage gated K channels
Explain the first step of action potentials
1. at threshold potential, V-G Na channels open
Explain the second step of action potentials
2. after a short time, the inactivation gate closes on the V-G Na channels
Explain the third step of action potentials
3. at this point, V-G K channels responding to threshold potential open
Explain the fourth step of action potentials
4. V-G K channels stay open long enough for membrane potential to go below resting potential
Explain the fifth step of action potentials
5. positive charges from the depolarization phase brings the adjacent section of the axon to threshold potential
Explain the sixth step of action potentials
6. action potentials are not back-propagated because the inactivation gate is refractory to threshold potential
When is the depolarization phase?
from when the V-G Na channels open to when the V-G Na channels close
When is the repolarization phase?
from when the V-G K channels open to when the V-G K channels close
When is the hyperpolarization phase?
when the V-G K channels close and MP goes back to resting
What occurs at the axon terminal?
the electrical signal is turned into a chemical signal
What does an action potential cause? The seventh step:
V-G Ca channels to open and Ca to diffuse in
What does Ca influx cause?
neurotransmitter release
What can action potential frequency modify?
the signal strength
What is action potential frequency limited by?
the duration of the inactivation gate being closed
What is occurring when the inactivation gate is closed?
absolute refractory period
What is occurring during hyperpolarization?
relative refractory period
What can the signal cause membrane potential changes in?
the post synaptic cell
What happens if the membrane potential increases?
it is an excitatory post synaptic potential
What happens if the membrane potential decreases?
it is an inhibitory post synaptic potential
What are the five types of glial cells?
oligodendrocytesSchwann cellsastrocytemicrogliaependymal cells
Explain oligodendrocytes
myelinate axons in CNS
Explain Schwann cells
myelinate axons in PNS
Explain astrocytes
transfer nutrients to neurons (especially in CNS)
Explain microglia
clean up waste and cellular detritus
Explain ependymal cells
lines cavities and circulate CSF
When is action potential conduction fast?
when the ratio of intracellular resistance/membrane resistance is low
When is action potential conduction slow?
when the ratio of intracellular resistance/membrane resistance is high
What happens when axon diameter increases?
both intracellular resistance and membrane resistance decreaseintracellular resistance decreases a lot more
What greatly increases membrane resistance?
if the axons are myelinated
G was a:
Node of ranvier
What does saltatory conduction mean?
Action potential jumps from node to node
What does the nervous system break into?
an afferent and efferent system
what does the efferent pathway break into?
somatic and autonomic
What is the somatic system responsible for?
innervating muscles
What does the autonomic system break into?
parasympathetic and sympathetic pathways
What is a simple definition of the parasympathetic pathway?
rest and digest
What is a simple definition of the sympathetic pathway?
fight or flight
What occurs in the sympathetic pathway?
increased heart rateincreased breathing ratepupils dilateincreased blood glucoseredistribution of blood flow to skeletal muscles, liver, and heart
What occurs in the parasympathetic pathway?
decreased heart ratedecreased breathing rategut motility increases
What does the autonomic pathway consist of?
a pre-ganglionic neuron, a post-ganglionic neuron, and a target cell
What does the autonomic division often (but not always) use?
antagonistic regulation
Nicotinic Ach receptor is what kind of channel?
ligand-gated Na channel
Muscarinic Ach receptor is what kind of receptor?
G-protein coupled receptor
Parasympathetic:
Pre-ganglionic: Gives off Acetylcholine. Post-ganglionic: Nicotinic Ach receptor. Na diffuses in. Gives off Acetylcholine.Target Cell: Muscarinic Ach receptor.
Muscarinic Ach Receptor can do what?
Can cause changes in gene expression and enzyme activity
Muscarinic Ach Receptor is an example of what type of receptor?
A metabolic receptor
Nicotinic Ach Receptor is an example of what type of receptor?
An ionotropic receptor
Sympathetic:
Pre-ganglionic: Gives off Acetylcholine.Post-ganglionic: Nicotinic Ach receptor. Na diffuses in. Gives off Norepinephrine.Target Cell: Alpha or Beta Adrenergic receptor.
Alpha and Beta Adrenergic receptors are what type of receptors?
G-protein coupled receptors
Adrenal Medulla is made of:
Chromaffin cells
Chromaffin cells are:
Axon-less post-ganglionic neurons
What do chromaffin cells do?
They release the neurohormone epinephrine
What does epinephrine do?
Epinephrine binds to alpha and beta adrenergic receptors
What is myosin?
The motor protein that pulls on actin
First step of the sliding filament model:
ATP binds to myosin causing myosin to release actin
Second step of the sliding filament model:
Myosin hydrolyzes ATP to ADP and Pi causing myosin head to extend and re-bind farther down
Third step of the sliding filament model:
Myosin releases Pi causing a power stroke (force generation)
Last step of the sliding filament model:
Myosin releases ADP making room for another ATP to bind (and start cycle again)
What is repetition of the steps to the sliding filament model called?
Cross-bridge cycling
What type of muscle cell is myofiber?
a skeletal muscle cell
What are some characteristics of skeletal muscle cells?
Long, cylindrical, multi-nucleated cells
What is the cell membrane of a skeletal muscle cell called?
The sarcolemma
What is the E.R. in a skeletal muscle cell called?
The sarcoplasmic reticulum
How are actin and myosin arranged?
They are arranged in sarcomeres.
What are the parts in a sarcomere?
Z-disk, actin, myosin
Why are skeletal muscles not always contracted?
The myosin-binding sites on actin are normally blocked by tropomyosin
High intracellular [Ca++] causes what?
Contraction
Low intracellular [Ca++] causes what?
Relaxation
Calcium binds to what?
Troponin
What does troponin do?
Troponin moves tropomyosin off of myosin-binding sites on actin
Excitation Contraction Coupling:Each motor neuron synapses with what?
Multiple myofibers
Excitation Contraction Coupling:An action potential in the motor neuron causes what?
Acetylcholine to be released
Excitation Contraction Coupling:Acetylcholine binds to what?
Acetylcholine binds to Nicotinic Ach receptors on the myofiber
Excitation Contraction Coupling:Acetylcholine binding to Nicotinic Ach receptors causes what?
Na to diffuse in, which brings the myofiber to threshold potential
During excitation and contraction coupling, what happens?
Ca++ channels open and close when Na channels do
Excitation Contraction Coupling:A myofiber action potential is propagated down a t-tubule and causes:
The Dihydropyridine (DHP) receptor to change conformation
Excitation Contraction Coupling:What happens as a result of the DHP receptor's conformational change?
The DHP receptor pulls open the gate on the Ryanodine receptor (RyR)
Excitation Contraction Coupling:What happens after the gate on the RyR is opened?
Ca++ diffuses out of the S.R. into the myofiber
Excitation Contraction Coupling:Contraction speed depends in part upon what?
How quickly intracellular [Ca++] increases
Excitation Contraction Coupling:Relaxation occurs when...?
The sarcolemmal Ca++ ATPase and SERCA remove Ca++ from the myofiber
Excitation Contraction Coupling:Relaxation speed depends in part upon what?
How quickly intracellular [Ca++] decreases
Excitation Contraction Coupling:What do parvalbumin do?
They bind to Ca++ in the myofiber and speed up relaxation (because Ca++ can't bind to troponin when bound to parvalbumin)
What is threshold potential determined by?
The voltage at which voltage-gated channels open
Muscle Fatigue is caused by:
ATP depletion in the muscle
What happens when ATP concentration in the muscle decreases enough?
K+ ATP channels open which hyperpolarizes the myofiber making an action potential less likely
What are the types of muscle fibers?
Slow-twitch oxidative and Fast-twitch glycolitic
ATP generation of slow-twitch oxidative muscle fibers:Mitochondria (few/many):Myoglobin content (high/low):Fatigue Resistance (high/low):Substrate use:
Many mitochondria, high myoglobin content, high fatigue resistance, and uses carbs, lipids, and amino acids as substrates (slower)
Speed of slow-twitch oxidative muscle fibers:Speed (fast/slow):SERCA (fast/slow):Myosin ATPase (fast/slow):Sarcoplasmic Reticulum (big/small):Force Generation (high/low):
Have slow contraction & relaxation speeds, slow SERCA isoform, slow myosin ATPase isoform, small sarcoplasmic reticulum, and low force generation
ATP generation of fast-twitch oxidative muscle fibers:Mitochondria (few/many):Myoglobin content (high/low):Fatigue Resistance (high/low):Substrate use:
Few mitochondria, low myoglobin content, low fatigue resistance, and uses only carbs as a substrate (faster)
Speed of fast-twitch oxidative muscle fibers:Speed (fast/slow):SERCA (fast/slow):Myosin ATPase (fast/slow):Sarcoplasmic Reticulum (big/small):Force Generation (high/low):
Have high contraction & relaxation speeds, fast SERCA isoform, fast myosin ATPase isoform, large sarcoplasmic reticulum, and high force generation
Muscle fiber type can change due to what?
Usage patterns
Myofibers are what?
Specialized for their function
Contraction strength depends on:
Recruitment of myofibers (# activated), Increasing intracellular [Ca++], and the length of the muscle affects force
Recruitment:What is a motor unit made of?
A motor neuron and the myofibers it innervates
Recruitment:What is asynchronous recruitment?
When different motor neurons alternate
Recruitment:What does asynchronous recruitment do?
Helps avoid fatigue
Increasing intracellular [Ca++]:
Summation and Tetanus
What is mechanical summation?
When more force is generated, because there is more Ca++ in cytoplasm (occurs when twitches are higher in frequency--second twitch starts before the first ended)
What is tetanus?
When the frequency of twitches is so high, that the force is maintained (no relaxation).
Length of the muscle affects force. This is called the:
Length-tension relationship
Length of the muscle:Short length:
Can't shorten anymore
Length of the muscle:Long length:
Too physically separated; not enough overlap; can't bind
Where do you typically find smooth muscle?
Around tubes and cavities. Ex) digestive tract
What are some characteristics of smooth muscle cells?
They are mono-nucleated, change from elongate to globular (when contracted), are fatigue resistant, and have actin and myosin (but not in sarcomeres).
What causes smooth muscle cells to contract?
High intracellular [Ca++] BUT is NOT regulated by troponin and tropomyosin
What are the mechanisms of smooth muscle contraction?
Ca++ binds to calmodulin---> calmodulin activates myosin light chain kinase (MLCK)---> MLCK phosphorylates myosin which makes it active---> cross-bridge cycling occurs
What are the mechanisms of smooth muscle relaxation?
Intracellular [Ca++] decreasesMyosin phosphatase dephosphorylates myosin---> myosin becomes inactive---> no more cross-bridge cycling
The circulatory system transports:
O2 & CO2NutrientsHormonesWaste (urea, uric acid, ammonia)Immune Cells and MoleculesHeat
The circulatory system is composed of:
Heart (pump)Blood Vessels (tubes: arteries, veins, capillaries)Blood (fluid)
Blood is made of:
PlasmaWhite Blood CellsRed Blood CellsPlatelets
Plasma
the liquid extracellular matrix
White Blood Cells
Immune Cells
Red Blood Cells
transport oxygen (O2)
Platelets
important in blood clotting they are not really cells
What is Hypocythemia?
abnormally low hematocrit
What does abnormally low hematocrit do?
It compromises oxygen (O2) acquisition and transport
What is Hypercythemia?
abnormally high hematocrit
What does abnormally high hematocrit do?
It increases blood viscocity
What do we use bulk flow for?
to circulate blood
What happens when the heart exerts pressure on the blood?
The blood flows down the pressure gradient
What can constrain this blood flow?
a series of one-way valves
What are the significant parts of a heart?
SA nodeAV nodethe bundle of HisPurkinje fibersventriclesatria
Pacemaker cells have what?
Action potentials
1. On a heart, where does the action potential begin?
At the SA node
2. Pacemaker cells are connected to neighboring cardiomyocytes how?
via gap junctions
3. Atria do what?
they contract
4. What happens to the action potential?
It pauses at the AV node
What are the valves in the heart?
TricuspidPulmonary Semi-lunarMitral (bicuspid)Aortic Semi-lunar
1. Right Side of the Heart Blood:
Blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart.
2. Right Side of the Heart Blood:
As the atrium contracts, blood flows from your right atrium into your right ventricle through the open tricuspid valve.
3. Right Side of the Heart Blood:
When the ventricle is full, the tricuspid valve shuts. This prevents blood from flowing backward into the atria while the ventricle contracts.
4. Right Side of the Heart
As the ventricle contracts, blood leaves the heart through the pulmonary semi-lunar valve, into the pulmonary arteries and to the lungs where it is oxygenated.
5. Left Side of the HeartBlood:
The pulmonary veins empty oxygen-rich blood from the lungs into the left atrium of the heart.
6. Left Side of the HeartBlood:
As the atrium contracts, blood flows from your left atrium into your left ventricle through the open mitral valve.
7. Left Side of the HeartBlood:
When the ventricle is full, the mitral (bicuspid) valve shuts. This prevents blood from flowing backward into the atrium while the ventricle contracts.
8. Left Side of the HeartBlood:
As the ventricle contracts, blood leaves the heart through the aortic semi-lunar valve, into the aorta and to the body.
The first step of the cardiac cycle is:
Ventricular Diastole (passive filling)
The second step of the cardiac cycle is:
Atrial Systole
The third step of the cardiac cycle is:
Ventricular Systole (isovolumetric contraction)
The fourth step of the cardiac cycle is:
Ventricular Systole (ventricular ejection)
The fifth step of the cardiac cycle is:
Ventricular Diastole (isovolumetric relaxation)
Diastole typically means:
Relaxation
Systole typically means:
Contraction
What occurs during Ventricular Diastole (passive filling)?
Ventricular pressure is lower than atrial pressure and blood passively fills the ventricles (~80% filling)
What occurs during Atrial Systole?
Atrial pressure increases and forces blood into the ventricles (~20% filling)
What occurs during Ventricular Systole (isovolumetric contraction)?
Ventricular pressure increases up to the pressure in the pulmonary artery (right ventricle) and aorta (left ventricle)
What occurs during Ventricular Systole (ventricular ejection)?
Ventricular pressure increasing above that in the pulmonary artery (right ventricle) and aorta (left ventricle)
What occurs during Ventricular Diastole (isovolumetric relaxation)?
Ventricular pressure is decreasing, but not yet lower than that in the atria
What is the systemic circuit?
A high-pressure, high-flow circuit that is powered by the left ventricle
What is the systemic circuit powered by?
the left ventricle
What is the pulmonary circuit?
A low-pressure, high-flow circuit that is powered by the right ventricle
What is the pulmonary circuit powered by?
the right ventricle
Cardiomyocytes have:
actin and myosin arranged in sarcomeres
Cardiomyocytes are regulated by:
Troponin and Tropomyosin
Cardiomyocytes are:
mononucleated
Cardiomyocytes are connected together by:
Intercalated disks - they fortify their connections
Because cardiomyocytes function like slow-twitch fibers, they are:
fatigue resistanthave lots of mitochondriause lipidshave many myoglobinhave a small sarcoplasmic reticulumetc.
What are the membrane potential values of a pacemaker cell?
-60 mV, -40 mV, and +20 mV
What are the steps that affect membrane potential in a pacemaker cell?
1. At -40 mV V-G Ca++ channels open2. At 20 mV Ca++ channels close3. At 20 mV K+ channels open4. At -60 mV K+ channels close
What is the funny current?
The unstable "resting" membrane potential in pacemaker cells that creeps up from -60 mV to -40 mV
What are funny channels?
Voltage-gated channels that open at about -60 mV and allow sodium (Na+) to slowly diffuse in
What is the sympathetic input?
Norepinephrine binds to beta adrenergic receptors which increases Na+ permeability of the funny channels
What occurs due to the increased Na+ permeability of the funny channels?
Increased heart rate (cuz reaches -40 mV faster)
What is the parasympathetic input?
Acetylcholine binds to muscarinic ach receptors which increases K+ permeability of the pacemaker cells
What occurs due to the increased K+ permeability of the pacemaker cells?
Decreased heart rate (cuz starts below -60 mV)
What are the steps of an action potential in contractile cardiomyocytes?
1. At threshold, V-G Na+ channels open2. V-G Na+ channels close and "fast" V-G K+ channels open3. V-G Ca++ channels open and most "fast" V-G K+ channels close4. V-G Ca++ channels close and "slow" V-G K+ channels open5. "Slow" V-G K+ channels closeresting = -90 mVpeak = -20 mV
What allows cardiomyocytes to prevent cardiac tetanus?
prolonged action potentials (pump doesn't work if always contracted)
What is cardiac output?
volume of blood per minute that is pumped out of the ventricle
What does cardiac output equal?
cardiac output = heart rate (autonomic regulation) x stroke volume
What is end-diastolic volume?
Total blood in chamber before it is ejected
What is stroke volume?
The volume of blood ejected per contraction
Frank Starling Law:
As end-diastolic volume increases, stroke volume increases
What is the Frank Starling Law due to?
The length-tension relationship of sarcomeres
What is end-diastolic volume determined by?
Venous return
Sympathetic input increases what?
stroke volume
How does sympathetic input increase stroke volume?
By increasing the contractility of the cardiomyocytes
How does the sympathetic input increase the contractility of the cardiomyocytes?
By increasing intracellular [Ca++] in the cell
What is the path that blood takes through the body?
Heart --> Arteries --> Arterioles --> Capillaries (exchange with tissues) --> Venules --> Veins --> Heart
What does blood velocity depend upon?
flow rate and total cross-sectional area
What happens to pressure as blood moves through a circuit?
blood pressure decreases as it moves further through a circuit
What affects resistance?
The length of blood vessels, the viscosity of blood, and the radius of vessels
Which of the things that affects resistance is the regulator?
The radius of the vessels
What does vasoconstriction do?
It reduces blood flow by increasing resistance
What does vasodilation do?
It increases blood flow by decreasing resistance
What regulates the radius of blood vessels?
smooth muscle
What type of blood vessels don't change in diameter?
Capillaries and Venules
How are blood vessels structured?
differently for their different functions
What do arterioles do?
they regulate blood distribution via vasoconstriction and vasodilation
What do pre-capillary sphincters do?
they give us fine control of blood distribution
What regulates vasoconstriction and vasodilation?
Autonomic (sympathetic)EndocrineLocal control - arterioles dilate in response to low O2 or high CO2 and matches perfusion to metabolism
Arterial pressure is affected by:
blood volumeblood viscositycardiac outputperipheral resistance
What is peripheral resistance?
An index of overall vasoconstriction
What does arterial pressure equal?
arterial pressure = cardiac output x peripheral resistance
Again, what does cardiac output equal?
cardiac output = heart rate x stroke volume
What is pressure sensed by?
Aortic and Corotid Baroreceptors
Baroreceptor Reflex:If pressure is too high, then:
cause vasodilationdecrease heart ratedecrease stroke volume
Baroreceptor Reflex:If pressure is too low, then:
cause vasoconstrictionincrease heart rateincrease stroke volume
How do the baroreceptors cause vasodilation?
they decrease sympathetic input to blood vessels
How do the baroreceptors decrease heart rate?
they increase parasympathetic input and decrease sympathetic input to the pacemaker cells
How do the baroreceptors decrease stroke volume?
they decrease sympathetic input to ventricular cardiomyocytes
How do the baroreceptors cause vasoconstriction?
they increase sympathetic input to blood vessels
How do the baroreceptors increase heart rate?
they increase sympathetic input and decrease parasympathetic input to the pacemaker cells
How do the baroreceptors increase stroke volume?
they increase sympathetic input to ventricular cardiomyocytes
What aids venous return from the legs?
skeletal muscle contractions and one-way valves in the veins
The aorta has highest pressure except during what?
ventricular ejection
What occurs when blood is coming in?
pressure is slowly increasing
When doesn't aortic pressure slowly decrease?
when it is receiving blood
The aorta's pressure during the cardiac cycle:
Ventricular filling: decreasesAtrial systole: decreasesIsovolumic contraction: decreasesVentricular ejection: increasesIsovolumic relaxation: decreases
The left atrium's pressure during the cardiac cycle:
Ventricular filling: increasesAtrial systole: increasesIsovolumic contraction: decreasesVentricular ejection: increasesIsovolumic relaxation: decreases
The left ventricle's pressure during the cardiac cycle:
Ventricular filling: increasesAtrial systole: increasesIsovolumic contraction: increases a lotVentricular ejection: ^^ v increases&decreasesIsovolumic relaxation: decreases a lot
Ventricular filling: Pressure scale of aorta, left atrium, & left ventricle
aorta > left atrium > left ventricle
Atrial systole: Pressure scale of aorta, left atrium, & left ventricle
aorta > left atrium > left ventricle
Isovolumic contraction: Pressure scale of aorta, left atrium, & left ventricle
aorta > left ventricle > left atrium
Ventricular ejection: Pressure scale of aorta, left atrium, & left ventricle
left ventricle > aorta > left atrium
Isovolumic relaxation: Pressure scale of aorta, left atrium, & left ventricle
aorta > left ventricle > left atrium
AFTER QUIZ 2BEGINNING OF INFO FOR QUIZ 3
AFTER QUIZ 2BEGINNING OF INFO FOR QUIZ 3
Fetal Heart:
A lot of blood from inferior vena cava (from body & placenta)A little blood from pulmonary veins most blood bypasses the pulmonary circuit and goes through the systemic circuit
What is the Foramen Ovale?
a hole between the right and left atrium
What is the Ductus Arteriosus?
a connection between the aorta and the pulmonary arteries
Which is the systolic pressure?
highest100-140
Which is the diastolic pressure?
lowest60-100
How do you calculate mean arterial pressure?
diastolic + 1/3(systolic-diastolic)
What are the three things the respiratory system does?
acquires and distributes O2dumps excess CO2regulating acid-base balance
How does the respiratory system regulate acid-base balance?
CO2 + H20 <---> H2CO3 <---> HCO3- + H+
What is H2CO3?
carbonic acid
What else is H2CO3 called and what does it do?
carbonic anhydraseit drives the reaction
What is HCO3-?
bicarbonate
What does the hydrogen ion do to the equation?
makes it more acidic
What is our respiratory epithelium?
an invagination
How is our respiratory system structured?
openings --> tubes --> gas-exchange surface (respiratory epithelium)
What are the openings?
mouth and nares (nostrils)
What are the tubes?
trachea, primary bronchi, smaller bronchi, bronchioles
Describe the structures air goes through in the respiratory system?
mouth and nares/nostrils --> trachea --> primary bronchi --> smaller bronchi --> bronchioles --> alveoli
What is net flux?
gradient X ease of movement X area
What occurs if there is a larger area?
higher net flux
What are alveoli wrapped in?
elastic connective tissue
What do Type I alveolar cells do?
allow for easy gas exchange with blood
What do Type II alveolar cells do?
make lung surfactant
What does lung surfactant do?
it keeps the alveolar surface moist
What other structures exist in the respiratory system?
lungsdiaphragmribs/costalsexternal intercostal musclesinternal intercostal musclespleural sac
What does the pleural sac do?
lubricates lungs
What occurs during inhalation?
diaphragm contracts (passive)deep inhalation uses external intercostal muscles
What occurs during exhalation?
diaphragm relaxes (passive)deep exhalation uses internal intercostal muscles
What are two words that describe lungs?
lungs are elastic and compliant
What does elastic connective tissue do?
It increases thoracic cavity pressure during exhalation
What does emphysema do?
destroys the elastic connective tissue
What is compliance (stretchability) important for?
inhalation, which is increased by lung surfactant
What does lung surfactant do?
decreases alveolar surface tension by disrupting H-bonds
What does ease of movement of air through airways change due to?
bronchoconstriction and bronchodilation
When does bronchodilation occur?
sympathetic inputB2 receptors
When does bronchoconstriction occur?
parasympathetic input
What are bronchoconstriction and bronchodilation under?
autonomic regulationlocal control
What is an example of local control?
if CO2 in expired air is sensed by the bronchioles, then they dilate
What is there a regional difference in?
lung ventilation
Describe the regional difference in lung ventilation
least perfusion and ventilation superiormost perfusion and ventilation inferior
When do pulmonary arterioles dilate?
high O2low CO2
When do pulmonary arterioles constrict?
low O2 high CO2
When do systemic arterioles constrict/dilate?
opposite circumstances than pulmonary arterioles
What do gasses have?
partial pressures
Gases reach a partial pressure ___________.
equilibrium
What are the percentages of the components in the air?
78.5% N221% O20.5% CO2
What does partial pressure depend on?
concentrationsolubility
What is solubility negatively correlated with?
osmolarity and temperature
How will CO2 and O2 diffuse?
down their pressure gradients
How is O2 transported?
98% transported O2 is bound to hemoglobin2% is dissolved
As Partial Pressure of O2 (PO2) increases...
percent saturation increases, but can't surpass 100%
Thus, at low PO2...
It is not very easy for O2 to bind
What does hemoglobin show?
cooperative binding
When does hemoglobin's O2 affinity decrease?
pH decreasesPCO2 increasestemperature increasesintracellular Cl- concentration increases
Right- shifted curve denotes:
low Hb-O2 affinity
Left- shifted curve denotes:
higher Hb-O2 affinity
How is CO2 transported?
7% dissolved CO270% is bicarbonate (HCO3-)23% is carbaminohemoglobin (HbCO2)
4 things about CO2 transport in any cell type but lung cells:
1. High PCO2 outside cell2. CO2 enters the cell3. Reaction driven to produce HCO3- and H+4. HCO3- leaves the cell and Cl- enters (via bicarbonate, chloride exchanger)
What do these factors of CO2 transport do to Hb's O2 affinity (in cells other than lung)?
It decreases due to:High PCO2Low pHHigher [Cl-]
4 things about CO2 transport in lung cells:
1. Low PCO2 outside cell2. CO2 leaves the cell3. Reaction driven to produce CO2 and H2O4. HCO3- enters the cell and Cl- leaves (via bicarbonate, chloride exchanger)
What do these factors of CO2 transport do to Hb's O2 affinity (in lung cells)?
It increases due to:low PCO2high pHlower [Cl-]
What do we have in our medulla?
central chemoreceptors
What occurs if high PCO2 is detected by chemoreceptors?
increased ventilation
What occurs if low PCO2 is detected by chemoreceptors?
decreased ventilation
What do we have in our aorta and carotid arteries?
peripheral chemoreceptors
What do peripheral chemoreceptors do?
sense PCO2, pH, and PO2
What occurs if high PCO2 and/or low pH is detected by peripheral chemoreceptors?
increased ventilation
What occurs if low PCO2 and/or high pH is detected by peripheral chemoreceptors?
decreased ventilation
What occurs if low PO2 is detected by peripheral chemoreceptors?
increased ventilation
What occurs if high PO2 is detected by peripheral chemoreceptors?
decreased ventilation
What has more of an influence on ventilation?
PCO2 and pH exert more influence on ventilation than PO2
What is hyperventilation?
when ventilation exceeds what is necessary
What does hyperventilation lead to?
respiratory alkalosis
What is hypoventilation?
when ventilation is less than what is necessary
What does hypoventilation lead to?
respiratory acidosis
What is regression used for?
To investigate the relationships between variables
What does the P-value tell us?
Whether the slope really is significantly different from zero (and significantly related).
What does R^2 tell us?
what percent of "y" variation is explained by "x" variation
What is the equation for pulmonary ventilation?
Breathing rate (fB) x Tidal volume (Vt)
What is anatomical dead space?
volume of non-gas exchange surface in the respiratory system (trachea, bronchi, bronchioles)
What is the equation for dead space?
1/3 x Vtrest
How might a person living at a high altitude compensate for low PO2?
1. Increase ventilation2. Increase # of RBCs3. Increase hemoglobin content of RBCs4. Increase cardiac output (heart rate and stroke volume)5. Decrease activity/ metabolic rate
What are some negative consequences of low PO2?
1. Hyperventilation due to dumping too much CO22. Increases blood viscosity (due to higher hematocrit)3. Low PO2 causes pulmonary vasoconstriction--- this increases pressure--- which causes pulmonary edema and eventually death
What evolutionary adaptions allow native highlanders to live in hypoxic environments and avoid the negative side effects?
1. They have a blunted hypoxic ventilatory response2. They have a blunted hypoxic pulmonary vasoconstrictor response3. Andeans have higher hematocrits
What happens at high pulmonary pressure?
Blood gets pushed into the space between the vessel and the alveolus which increases the diffusion distance
What is a characteristic of the air that we inhale?
It is relatively dry
What do we do to air on its way to the lungs?
We humidify it
What helps us humidify air on its way to the lungs?
Turbinates in the nasal cavity
What happens during exhalation?
Water condenses on the cool turbinates
What three things do we regulate/do in regards to ion and water balance?
1. body-fluid volume2. ion composition and osmolarity3. excrete nitrogenous wastes
Why do we regulate body-fluid volume?
blood pressurecell volume
Why do we regulate ion composition and osmolarity?
action potentialscellular transportcell volume
Why do we excrete nitrogenous wastes?
products of protein and nucleic acid catabolism (urea, uric acid, ammonia)
What are the major ways that we lose water?
1. Sweating2. Urination (micturating)3. Respiratory water loss
How do we gain water?
1. Bulk water imbibing (drinking)2. Dietary water (from food)3. Metabolic water (we turn air into water)
What are epithelial tissues?
the interface between body and the external environment
What are some examples of epithelial tissues?
skingastrointestinal tracturinary tract
What is the apical membrane facing?
the external environment
What is the basolateral side facing?
blood/body
What are the two types of cells that make up epithelial tissue?
absorption or secretionstructural
What is a characteristic of absorption/ secretion cells on the apical side of the cell?
They have greater surface area on the apical side
What does skin act as?
a barrier to water loss
What is relatively impermeable to water?
the stratum corneum
_______________________ turns into ________________________
keratinocytescorneocytes
What do corneocytes produce?
bundles of keratin
When corneocytes die, what occurs?
their cell membranes are replaced by keratin/lipid matrix
What is the first characteristic of epithelial tissue?
different cells are specialized for different functions
What is the second characteristic of epithelial tissue?
the presence (or absence) of tight junctions prevents (or allows) paracellular transport
What are the two types of transport through epithelial cells?
paracellular transporttranscellular transport
How does paracellular transport occur?
via diffusion down a gradient
How does transcellular transport occur?
via passive or active transport
What is the third characteristic of epithelial tissue?
asymmetric distribution of transports allows unidirectional transport of some solute
What is the fourth characteristic of epithelial tissue?
have high density of mitochondria (especially in absorption and secretive cells)
What is the fifth characteristic of epithelial tissue?
aquaporin presence or absence affects water permeability
What are the five functions of kidneys?
1) excrete nitrogenous waste2) maintain water balance3) maintain ion balance4) produce hormones5) maintain acid-base balance
What do the hormones that are produced by kidneys do?
affect RBC production and arterial pressure
What ions does the kidneys maintain balance of?
Na+, K+, Cl-, Ca++
How is blood filtered?
from the glomerulus into the nephron
How is that filtrate modified?
by secretion and reabsorption
What does secreted mean?
Out of the body into the filtrate
What does reabsorbed mean?
Out of filtrate into the body
What is the renal cortex and what is its approximate osmolarity?
the outer part of the kidney~300 mOsM
What is the renal medulla and what is its osmolarity range?
the inner part of the kidney and has an osmotic gradient300-1200 mOsM
What does the renal medulla get its high osmolarity from?
mostly from salt and urea
What is the primary filtrate?
identical to blood except it doesn't have any blood cells, platelets, or proteins
What are the names of the structures found on a nephron?
Bowman's capsuleProximal tubuleLoop of HenleDistal tubuleCollecting duct
What happens at the proximal tubule?
Na+ and Cl- is actively reapsorbedH20 is passively reabsorbed (via aquaporins)Organic toxins, H+ or NH3 are secreted
What happens at the descending limb of the tubule?
H2O is passively reabsorbed (via auquaporins)
What happens at the ascending limb of the tubule?
Na+ and Cl- is actively reabsorbedH2O wants to enter the nephron but can't (no auquaporins)
Where are intercalated cells found?
in the distal tubule
What do intercalated cells do?
secrete either H+ (A-type) or HCO3- (B-type) to maintain acid base balance
When is an acid-secreting cell activated?
When the blood is too acidic(pH is too low)
Which direction is the reaction driven when an acid-secreting cell is activated?
the reaction is driven to the right (more HCO3- and H+)
What occurs when an acid-secreting cell is activated?
CO2 diffuses inH+ leaves via H+ ATPases and H+/K+ ATPase antiportersK+ enters via H+/K+ ATPase antiportersHCO3- leaves via HCO3-/Cl- exchangersCl- enters via HCO3-/Cl- exchangers
Where do the H+ ions from an acid-secreting cell go?
into the lumen (urine)
When is a base-secreting cell activated?
When the blood is too basic(pH is too high)
Which direction is the reaction driven when a base-secreting cell is activated?
the reaction is driven to the right (more HCO3- and H+)
What occurs when a base-secreting cell is activated?
CO2 diffuses inH+ leaves via H+ ATPases and H+/K+ ATPase antiportersK+ enters via H+/K+ ATPase antiportersHCO3- leaves via HCO3-/Cl- exchangersCl- enters via HCO3-/Cl- exchangers
Where do the H+ ions from a base-secreting cell go?
into the blood
What happens at the collecting duct?
Vassopressin leads to the passive reabsorption of water
What can the hypothalamus sense?
plasma osmolarity and arterial pressure
What occurs when the hypothalamus senses high plasma osmolarity and/or low arterial pressure?
the posterior pituitary releases vasopressin
What does vasopressin do?
causes collecting-duct cells to insert aquaporins into their membranes
Where is more water reabsorbed and what does that result in?
at the collecting duct, thereby concentrating the urine
What experiences countercurrent flow?
vasa recta blood filtrate
What does concurrent flow of vasa recta blood and filtrate allow for?
the blood to pick up the solutes and water that were reabsorbed and maintain the medullary osmotic gradient
What occurs in response to low blood pressure?
Granular cells release renin (a hormone)
What does renin then do?
It cleaves angiotensinogen to angiotensin 1 (ANG 1)
Where does this occur?
In the blood
What happens to ANG 1?
It is further cleaved by the angiotensin converting enzyme to make ANG 2
What does ANG 2 cause?
Cells in the adrenal cortex to release aldosterone
What does aldosterone cause?
The distal tubule to reabsorb more Na+ (and H2O follows)(which decreases urine production & no change in urine osmolarity cuz it occurs on distal tubule--not the collecting duct)
How is the glomerular filtration rate (GFR) regulated?
By vasoconstriction and vasodilation of the afferent and efferent arterioles
What does vasoconstriction of the afferent arteriole do to GFR?
it decreases GFR
What does vasoconstriction of the efferent arteriole do to GFR?
it increases GFR
What do cortical nephrons have?
short loops of Henle that do not make use of the medullary osmotic gradient
What do juxtamedullary nephrons have?
long loops of Henle that do make use of the medullary osmotic gradient
What do protein and nucleotide catabolism generate?
NH3 <------> NH4+
What is a characteristic of ammonia?
It is toxic at relatively high concentrations
What is a cost of ammonia excretion?
lots of water
What can we turn ammonia into?
Uric acid
How can uric acid be removed by the body?
it can be excreted out in feces, because it is relatively insoluble
Describe the relationship between water cost and energy cost?
They have an inverse relationshipIf high water cost then low energy cost
Describe the water cost and energy cost of uric acid
low water costhigh energy cost
Describe the water cost and energy cost of urea
middle water and energy cost
Describe the water cost and energy cost of ammonia
high water costlow energy cost
What are some examples of epithelial tissues?
skingastrointestinal tracturinary tract
What is the apical membrane facing?
the external environment
What are some examples of epithelial tissues?
skingastrointestinal tracturinary tract
Water diffuses from a highly concentrated solution toward...
a less concentrated solution.
When predicting tonicity which solutes do we account for?
Non-penetrating solutes
When predicting osmolarity which solutes do we account for?
All solutes (Penetrating and Non-penetrating)
What underlies organismal energy use?
energy use at the cellular level
When do we store energy as carbon-carbon bonds?
when energy input is greater than energy use (excess energy)
What are the types of carbon-carbon bonds?
Glycogen and Triglycerides
What is glycogen and where is it stored?
polymer of glucose stored in the liver and skeletal muscle
What are triglycerides and where are they stored?
polymers of fatty acidsmostly stored in adipose tissuesome stored in liver and elsewhere
What composes a triglyceride?
glycerolfatty acyl chains
Drawing upon energy stores is called what?
Catabolism
What can be stored and mobilized between tissues?
Energy substrates
How is energy made?
Glycogen ---> Glucose ---> Pyruvate ---> Acetyl CoA ---> Tricarboxilic Acid (TCA) Cycle ---> Electron Transport Chain (ETC) ---> (ADP to ATP)
What three things contribute to energy production?
Glycogen, Triglycerides, and Proteins
How does glycogen become glucose?
through glycogenolysis
How does glucose become pyruvate?
through glycolosis
How do triglycerides contribute to energy production?
Triglycerides ---> Fatty Acids ---> Acetyl CoAMakes Acetyl CoA through Beta-Oxidation
What is an additional way that triglycerides contribute to energy production?
Triglycerides ---> Fatty Acids ---> Keytone Bodies ---> Acetyl CoA
How do proteins contribute to energy production?
Proteins ---> Amino Acids ---> Pyruvate Proteins ---> Amino Acids ---> Acetyl CoAProteins ---> Amino Acids ---> TCA CycleAll through deamination
What is removed from gross energy?
Indigestible energy (cellulose, fiber, etc.)
How is indigestible energy removed?
Rid by egestion (pooping)
After indigestible energy is removed what kind of energy is it?
Digestible energy
What type of energy is removed from digestible energy?
Unmetabolizable energy
How is unmetabolizable energy removed?
Rid via urine
After unmetabolizable energy is removed what kind of energy is it?
Metabolizable energy
What type of energy is removed from metabolizable energy?
Specific dynamic action (energy used to get new energy)
After specific dynamic action, what energy is left?
Net energy assimilated
What does 1g of carbohydrate equal?
4 kcal1 g of protein
What does 1g of lipid equal?
9 kcal
What does the digestive system do?
breaks polymers into monomers that can be absorbed
What does the digestive system turn lipids into?
fatty acids
What are the anatomical structures of the digestive system?
mouth, esophagus, stomach, small intestine, large intestine, anus
What does the mouth do?
mechanical digestionsalivary amylase starts enzymatic digestion of carbs
What does the stomach do?
mechanical, acid, and enzymatic digestion
What does the small intestine do?
enzymatic digestion and absorption
What does the large intestine do?
absorbs water and vitamins
What are the accessory organs that help our GI tract with digestion?
Salivary glandslivergall bladderpancreas
What does our one-way gut allow for?
sequential specialization of gastrointestinal tract regions
Where is bile made and stored?
Made in the liverStored in the gall bladder
What happens to bile?
It is secreted into the small intestine where it emulsifies the lipid droplets
What do lipases in the small intestine do?
break down lipids into fatty acids
What do the fatty acids do?
diffuse into enterocytes and are transported in the blood or lymph
What type of fatty acids are transported in the blood?
glycerol and short-chain fatty acids
What type of fatty acids are transported in the lymph
larger chylomicrons (droplet of fat)
Where is pancreatic amylase found?
In the small intestine
What does pancreatic amylase do?
breaks down polysaccharides to disaccharides (maltose, sucrose, lactose)
What happens to the disaccharides in the small intestine like maltase, sucrase, and lactase?
they are broken down to monosaccharides (glucose, fructose, galactose)
What happens to glucose and galactose (monosaccarides)?
They are cotransported with Na+ by a transporter in the apical membrane and use facilitated diffusion to leave the cell through a basolateral transporter
How does fructose (monosaccaride) enter and leave the cell?
by using facilitated diffusion through an apical transporter and a basolateral transporter
What in the small intestine breaks down proteins to amino acids?
trypsinchymotrypsincarboxypeptidasedipeptidases
What is secreted into the small intestine from the pancreas?
trypsin chymotrypsincarboxypeptidase
What are the names of the zymogens?
trypsinogenchymotrypsinogenprocarboxypeptidase
What does enterokinase do?
it cleaves trypsinogen to form active trypsin
What does trypsin then do?
it cleaves chymotrypsinogen and procarboxypeptidase to form active chymotrypsin and carboxypeptidase
How do amino acids enter the cell?
They are cotransported into the cell with Na+
How do dipeptides enter the cell?
They are cotransported with H+ on the apical membrane
How do amino acids leave the cell?
They leave the cell by antiport with Na+
How do dipeptides leave the cell?
They leave by antiport with H+ on the basolateral membrane
How are small peptides transported?
Via transcytosis
What are the four layers of the gastrointestinal tract?
1. mucosa2. submucosa3. muscularis externa (smooth muscle)4. serosa
What causes gut motility?
contractions in the muscularis externa
What are the two types of contractions?
segmental contractionsperistaltic contractions
What do segmental contractions do?
mix ingested contents
What do peristaltic contractions do?
move ingested contents down the gastrointestinal tract
What do some smooth muscle cells do?
spontaneously contract
What is this spontaneous contraction due to?
interstitial cells of Cajal
Describe digestion in the stomach:
mechanical, acid, enzymatic
What mechanically digests food in the stomach?
segmental contractions
How does the stomach produce chyme?
by mixing ingesta with hydrochloric acid (HCl) and mucus
What is mucus secreted by?
mucus neck cells
What is HCl secreted by?
parietal cells
What can acid secretion cause?
an alkaline tide
What does acid do?
dissolves mineralized tissue in our dietdenatures proteinskills potential pathogens
Where does enzymatic protein digestion start?
in the stomach
What do chief cells do?
make the digestive enzyme pepsinogen
What is pepsinogen?
inactive zymogen
What activates pepsinogen?
the low pH of the stomach lumen
What does the low pH of the stomach lumen do?
activates pepsinogen to pepsin
Describe digestion in the small intestine
enzymatic digestion and nutrient absorption
What underlies the high surface area of the small intestine?
small intestine length circular foldsvilli microvilli
What are the small intestine cell types?
EnterocytesGoblet cellsEnteroendocrine cells
What are enterocytes?
absorptive cells
What do enterocytes have?
nutrient transporters on the apical and basolateral membranes
What do Goblet cells do?
secrete mucus
What do enteroendocrine cells do?
make and release hormones that regulate small intestine's luminal environment
What do we do to dump excess heat?
send lots of blood to superficial vessels
What do we do to conserve heat?
keep hot blood away from superficial vessels
What does countercurrent blood flow do?
conserves heat at the body core
What does bypassing the countercurrent heat exchanger allow us to do?
It allows us to dump excess heat at the hands and feet
What does digestion in the small intestine require?
specific enzymes
What is lipid digestion aided by?
bile salts from the gall bladder
What does absorption of sugars and amino acids require?
specific transporters found on enterocytes
What transports newly absorbed sugars and amino acids?
hepatic portal vein
Where does the hepatic portal vein transport these newly absorbed sugars and amino acids?
directly to the liver
What cells sense and respond to the small intestine environment?
enteroendocrine cells
In acidic chyme, what is sensed?
acids and nutrients
What responds if acids are sensed?
enteroendocrine cells
What responds if nutrients are sensed?
enteroendocrine cells
What occurs if VIP is released?
pancreatic duct cells release HCO3-
What occurs if secretin is released?
the liver produces bile
What hormone do enteroendocrine cells release if nutrients are sensed?
cholecystokinin (CCK)
What does the release of cholecystokinin do?
causes pancreas to secrete digestive enzymescauses gall bladder to release bile
What do parietal cells do?
secrete HCl
Does the apical or basolateral side of parietal cells face the interstitial fluid?
the basolateral side
What channels and pumps are on the apical side of parietal cells?
H+ / K+ ATPases (pumps out H+ and K+ in)K+ leak channels (K+ out)Cl- leak channels (Cl- out)
What type of pump is on the basolateral side of parietal cells?
HCO3- / Cl- exchangers (pumps HCO3- out and Cl- in)
What do pancreatic duct cells do?
secrete HCO3-
Does the apical or basolateral side of pancreatic duct cells face the pancreatic duct lumen?
the apical side
Does the apical or basolateral side of pancreatic duct cells face the interstitial fluid?
the basolateral side
What channels and pumps are on the apical side of pancreatic duct cells?
HCO3- / Cl- exchangers (HCO3- out and Cl- in)Cl- leak channels (Cl- out)
What pumps are on the basolateral side of pancreatic duct cells?
H+ / Na+ exchangers (H+ out and Na+ in)Na+ / K+ ATPases (Na+ out and K+ in)
What is the equation that allows for acid-base regulation in parietal and pancreatic duct cells?
CO2 + H2O --- (CA) ---> HCO3- + H+
What do fermentation chambers do?
house beneficial bacteria that can digest cellulose
What are the two type fermentation chambers?
foregut fermentershindgut fermenters
Where is the fermentation chamber in foregut fermenters?
before the stomachmouth ---> fermentation chamber ---> stomach ---> small intestine ---> large intestine
In foregut fermenters, what does the bacteria do?
use cellulose energy to make sugars, fats, and proteins
Where is the fermentation chamber in hindgut fermenters?
after the small intestinemouth ---> stomach ---> small intestine ---> fermentation chamber ---> large intestine
What can the large intestine absorb?
free fatty acidsNOTsugars or proteins (amino acids)
What do hindgut fermenters often engage in?
coprophagy
Why do hindgut fermenters often engage in coprophagy?
To access the liberated energy from cellulose (sugars and proteins)
What is the appendix now thought to be? (rather than a vestigial organ)
It is thought to be a safehouse for gut bacteria
What is an indirect measure of energy use?
rate of oxygen consumption (VO2)
What is basal metabolic rate?
the metabolic rate at rest in a thermoneutral environment
What occurs during exercise?
VO2 increases abruptly
What is this increase in VO2 due to?
active skeletal muscles
What can muscles store?
some energy as phosphocreatine
What is the equation for muscles at rest?
ATP + creatine ---> P-Cr + ADP
What is the equation for muscles during activity?
ATP + creatine <---- P-Cr + ADP
What enzyme helps drive these reactions?
creatine kinase
What do ATP and P-Cr stores support?
exercise for around 10 seconds
What about after ten seconds?
muscles rely on intracellular stored glycogen, stored lipids, mobilized glucose, and mobilized fatty acids
What is VO2 max?
the maximum rate of O2 consumption
What is VO2 constrained by?
O2 acquisition and transportRate of O2 use at skeletal muscles
How is it constrained by O2 acquisition and transport?
low...Hb-O2 affinityHb contentalveolar ventilationmuscle perfusionheart ratehematocrit
How is it constrained by rate of O2 use at skeletal muscles?
O2 diffusion to muscle mitochondrianumber of mitochondria in musclemyofiber type
What exercise must also rely on anaerobic ATP production?
exercise that is intense enough to require higher ATP production than that supported by VO2 max
What makes lactic acid (lactate)?
glycolysis followed by fermentation
When is the lactate threshold reached?
when exercise is intense enough that lactate starts to be accumulated
What does VO2 do during recovery?
stays elevated above BMR
Why does VO2 stay elevated above BMR during recovery?
muscles needs to rebuild their intracellular P-Cr, glycogen, and lipid stores
What occurs as exercise intensity increases?
carbohydrates are more heavily relied on than lipids
What are lipids in terms of energy?
the most efficient energy storage molecule
What are carbohydrates in terms of energy?
the most O2-efficient energy substrate
What is the respiratory quotient?
VCO2 produced / VO2 used
What does the respiratory quotient tell us?
what substrate(s) is/are being used
Why are carbs the most O2-efficient energy substrate?
because they have the highest respiratory quotient
What can be transported in the blood?
fatty acids, glucose, amino acids, and ketone bodies
What occurs during recovery from anaerobic activity?
lactate is shuttled from muscles to the liver
In the liver, what can the lactate be converted to?
glucose via gluconeogenesis
What does cost of transport (COT) mean?
the energy cost to move a body a given distance
What do we change gaits for?
to keep cost of transport low over a wide range of speeds
What affects cell function?
temperature
What happens to the cell if high temperature?
makes membrane too fluid
What happens to the cell if low temperature?
make membrane too rigid
How can cell membranes compensate for rigidifying effects of cold?
by increasing phospholipid unsaturation (increasing number of double bonds in fatty acyl tails)
What does each enzyme have?
an optimal temperature at which it functions best
What has evolution selected?
enzymes that function best around body temperature
What can extreme temperatures do?
denature proteins
What is environmental temperature?
the temperature experienced by the organism
What is radiation?
heat exchange through space that is not through contactheat can be gained or lost
What is conduction?
heat exchange through physical contactheat can be gained or lost
What is convection?
heat exchange through contact with a moving fluidheat can be gained or lost
What does insulation increase?
the thermal boundary layer
What is evaporation?
heat lost to the state change of water to gasheat can only be lost
What is total heat flux?
âHtotal= âHradiation+ âHconduction+ âHconvection+ âHevaporation+ âHmetabolism
What can animals have?
high surface area/volume ratio (small animals)low surface area/volume ratio (large animals)
What happens with animals with high surface area/volume ratios?
change body temperature more quickly than large animals
What do we subconsciously do?
change our effective surface area to either increase or decrease heat flux
What does thermal conductivity describe?
a material's ease of movement for heat
Define endotherms
produce enough metabolic heat to have a high body temperature
Define ectotherms
do not produce enough metabolic heat to make a high body temperature
Give some examples of endotherms:
usmammalsbirdsdinosaurs?some insects and fish
Give some examples of ectotherms:
amphibiansreptilessome fish
Define homeotherms
have a relatively constant body temperature
Define poikilotherms
have a variable body temperature
What do endothermic homeotherms have?
a thermoneutral zone in which resting metabolic rate is minimized
What does LCT mean?
lower critical temperature
What does UCT mean?
upper critical temperature
What bounds the thermoneutral zone?
LCT and UCT
What composes a thermoneutral graph (which contains a thermoneutral zone)?
VO2 at restenvironmental temperature
What occurs on the graph to the left of the LCT?
VO2 at rest increases while environmental temp decreasesthis is active heating
What occurs on the graph to the right of the UCT?
VO2 at rest increases while environmental temp increasesthis is active cooling
What does shivering generate?
heat because muscles use ATP at high rates requiring catabolism to greatly increase
What is the generation of heat by shivering called?
shivering thermogenesis
What does non-shivering thermogenesis make?
heat by futilely cycling protons
What has special mitochondria?
brown adipose tissue
What are the layers of these mitochondria?
outer membraneinter-membrane spaceinner mito. membranematrix
What does the mitochondria contain?
multiple ETCs (3)ATP synthases (1)uncoupling protein (UCPs) (1)
What occurs in the mitochondria?
TCA Cycle makes NADH in matrixNADH is made into NAD+ and H+ by ETCsH+ goes into the inter-membrane spacecauses an increase in [H+] thereH+ passively travels through UCPs into matrixH+ used by ATP synthase (ADP ---> ATP)H+ from ATP synthase also goes into matrix
What do sweating and panting both use?
evaporative cooling
When is sweating not effective?
with fur or feathers
What is body temperature monitored/regulated by?
the hypothalamus