Human Development Flashcards
zygote
Fertilized egg
morula
A solid ball of cells ; in humans, this stage occurs within four days of fertilization.
blastocyst
Hollow ball of cells that is implanted in the uterine wall approximately seven (7) days after fertilization
fertilization
Union of male and female gametes.
implantation
process in which the blastocyst attaches to the wall of the uterus
umbilical cord
a tube containing the blood vessels connecting the fetus and placenta
placenta
allows for the exchange of nutrients between mother and fetus and produce hormones to maintain the pregnancy.
amniotic sac
a fluid-filled sac that cushions and protects a developing embryo and fetus in the uterusthe innermost membrane that surrounds the embryo in the uterus
amniotic fluid
fluid within the amniotic sac that surrounds and protects the fetusthe fluid surrounding a fetus within the amnion.
gastulation
process that produces the three cell layers of the embryo
ectoderm
outer layer; epidermis, hair and nail follicles, sweat glands, nervous system (brain and spinal cord), lens, cornea, internal ear etc...outermost germ layer; produces sense organs, nerves, and outer layer of skin
mesoderm
middle layer; dermis, bone, cartilage, skeletal muscles, cardiac muscle, most smooth muscles, bone marrow, blood, lymphatic tissue and lining of blood vessels.the middle layer of an embryo in early development, between the endoderm and ectoderm.
endoderm
inner layer; mucosa of esophagus, stomach, and intestines, epithelium of respiratory tract, mucosa of gallbladder, glands (liver, pancreas, and thyroid)the inner germ layer that develops into the lining of the digestive and respiratory systems
yolk sac
site of formation of first blood vessels and cells that will become spermatogonia and oogonia.Does not contain nutrient yolk like in reptiles and birds.source of blood cells and future sex cells for the fetus
chorion
outermost layer of the two membranes surrounding the embryo; it forms the fetal part of the placenta
chorionic villi
small, finger-like projections that extend into the uterine lining to absorb oxygen and nutrients
allantois
forms near the yolk sac; sac of mesoderm and endoderm that forms away from embryo; base becomes urinary bladder (liquid waste removal)disposes of (liquid) waste products and contributes to gas exchange
corpus luteum
an endocrine structure made of follicle cells after ovulation occurs; secretes estrogen and progesterone; will disintegrate in 12 days after ovulation if fertilization does not occur
human chorionic gonadotropin (hCG)
Hormone produced in the human placenta that maintains the corpus luteum until the placenta takes over secretion of hCG; It is detected in urine and blood to determine preganancy.Blood tests are more precise and can determine pregnancy before period is missed.
Function of estrogen and progesterone during pregnancy
to inhibit secretion of FSH and LH by anterior pituitary gland to prevent ovarian follicles from maturing; prepare mammary glands for lactation
Estrogen function in mammary glands
cause duct formation
Progesterone function in mammary glands
cause growth of secretory cells
Prolactin function in mammary glands
cause milk production
oxytocin function in mammary glands
cause milk release
oxytocin during parturition
released from posterior pituitary gland and perhaps placenta (from fetus); powerful muscular contractions from the uterus used to deliver fetus; example of positive feedback