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85 Cards in this Set
- Front
- Back
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fertilization occurs in the....
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fallopian tube
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once fertilized, the single-celled thing moves to the ___ for implantation
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uterus
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while moving to uterus, the single-celled thing goes through ____ which is rapid mitotic cell division
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cleavage
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1st cleavage creates an ____
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embryo
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zygote is unicellular
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know
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several rounds of mitosis occur but the ___ of the cell does NOT increase
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size
-divisions become smaller but not larger overall |
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cells increase in two ratios:
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1. nuclear to cytoplasmic ratio
2. surface area to volume ratio |
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2 types of cleavage
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indeterminate
determinate |
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indeterminate =
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cells that can develop into complete organisms
-unmarked stem cells |
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determinate =
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fate of cell is pre-determined
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1st 2nd and 3rd cleavages of cell occur at...
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32, 60, 72 hrs
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after 8 cells (4 divisions)..mass becomes a morula
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solid mass
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blastulation occurs after morula;
blastulas = |
hollow, fluid-filled inner cavity
= blastocoel -greatest nuclear to cytoplasmic ratio! |
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mammalian blastula is known as a blastocyst and consists of two cell groups
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1. trophoblast
2. inner cell mass |
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trophoblast cells surround the blastocoel and give rise to the chorion
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know
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inner cell mass protrudes into the blastocoel and gives rise to the organism itself
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know
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blastocyst must implant on the uterine wall for development to continue
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know
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during blastulation, the blastocyst implants in the endometrium
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know
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progesterone promotes the proliferation on the mucosal layer to help the embryo attach
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know
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embryonic cells secrete enzymes that strategically burrow into the endometrial lining to allow for implantation
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know
-this is a key step since it form a connection to maternal circulation for nutrient and gas exchange |
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placenta is responsible for...
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nutrient and gas exchange with the endometrium
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gastrulation: formation of 3 distinct layers
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endoderm
mesoderm ectoderm |
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gastrulation begins with a small invagination in the blastula
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know
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cells move toward invagination, eliminating the blastocoel
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know
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endoderm forms the inside layer of the invagination and the site of invagination
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know
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ectoderm is the outer layer of the cell
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pg 104
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archenteron is the large invagination site forming (the mouth of a pacman for instance)
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know
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the archenteron later forms....
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the gut
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blastopore = the opening of the archenteron
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know
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deuterosomes
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blastopore develops into the anus
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protosomes
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the blastopore develops into the mouth
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mesoderm is between the ectoderm and the endoderm
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know
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ectoderm develops into....
HENNEL |
epidermis
hair nails epithelium of nose/mouth/anus lens of eye nervous system |
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mesoderm forms...
DR GEMC |
musculskeletal system
circulatory system excretory system gonads muscular and connective coats of digestive/respiratory system |
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endoderm form...
E(DR) LLPTB T(UR) |
Epithelial lining of digestive and respiratory tract
-lungs liver pancreas thyroid bladder urinary/reprod. tracts |
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adrenal cortex is part of the mesoderm
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know
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adrenal medulla is part of the ectooderm
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know
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all somatic cells in organism contain same DNA
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know
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selective transcription is concept of induction
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induction = ability of certain group to influence the fate of other nearby cells
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induction triggered by chemical substances called inducers that are passed from the organizing cells to the responsive cells
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the chemicals are responsible for guidance of neuronal axons
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neurulation
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development of the nervous system
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nervous system is derived from....
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ectoderm
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notochord = rod of mesodermal cells from along the long axis of organism
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these cells induce ectodermal cells to slide inward to form neural folds which surround a neural groove
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these neural folds grow toward one another until they fuse into a neural tube that gives rise to the NS
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know
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at tip of neural folds = neural crest cells...
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these cells migrate outward to form the peripheral nervous system
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gas exchange with baby occurs through structures...
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placenta
umbilical cord |
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placenta is primarily formed from the chorion
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chorion develops from trophoblast cells
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umbilical cord attaches to chorion and provides nutrient exchange with baby
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know
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what are the other 3 layers/membranes?
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allantois
amnion yolk sac |
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allantois is surorunded by the amnion
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know
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amnion = thin tough membrane filled with amniotic fluid
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the fluid acts like a shock absorber
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yolk sac is the site of blood vessel development
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know
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chorion is outermost layer
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provides additional protection...umbilical cord attached to this
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so the order from inside to most exterior is...
allantois, amnion, yolk sac, chorion |
know
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chorionic villi grow into the placenta to aid with gas exchange
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know
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placenta is the site of gas, nutrient and waster exchange occurs
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know
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can not mix fetal and maternal blood due to chance of different blood types...
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know
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wastes, gases etc exchanged through....what process
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diffusion
transfer of AA, water, glucose, and inorganic salts |
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in order for O2 to diffuse into fetus from the mother, the mother must have higher P(oxygen) in comparison to the fetal blood
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know
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the fetal blood is equipped with fetal hemoglobin (Hb-F)
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has an increased affinity for O2 in comparison to the maternal blood
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placental barrier acts as an immune protection
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know
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many bacteria/particles are too large to diffuse through placenta
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know
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however, viruses, alcohol and drugs/toxins can pass through...also hormones can pass through(also into mother's blood)
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know
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placenta = endocrine organ since it produces progesterone
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know
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what are the two most important organs for a fetus which rely on the placenta to exchange materials?
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lungs and liver
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in adults, blood is sent from heart to lungs to become oxygenated...
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durr
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this concept doesnt work with fetuses since dont breathe air...
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lungs are not yet able to oxygenate circulating blood.
-suspension in amniotic fluid |
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therefore, oxygen must come from maternal circulation and diffuse through placental vessels
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know
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so how does baby keep blood away from lungs?
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shunts reroute blood within heart
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1st shunt of blood with lungs
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foreman ovale; connects right and left atria; bypasses lungs completely
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higher pressure in the right atrium forces blood into the left atrium, overlooking the right ventricle
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know
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foreman ovale closes after birth
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know
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2nd shunt from lungs
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ductus arteriosus: shunts leftover blood from the pulmonary artery to the aorta
-this also bypasses lungs pressure on right side is greater than left! |
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liver and blood circulation
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liver = underdeveloped
ductus venosus: reroutes blood from placenta(via umbilical cord) to the inferior vena cava -skips body circulation to organs/liver |
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baby's liver is capable of being an O2 hog, so it is skipped over intentionally
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know
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umbilical arteries take blood....
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away from the fetus...to the mother
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umbilical veins take blood...
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toward the fetus...away from mother
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the umbilical vein carries ___ type of blood while the umbilical artery carries ___ type of blood
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oxygenated
deoxygenated |
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first trimester involves...
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major organ development
-eyes, gonads, limbs, liver form -skeleton formation -brain fairly developed -embryo = fetus |
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2nd trimester
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large amt of growth
-toes/fingers elongate |
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third trimester
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rapid growth
brain development antibodies develop for fetus |
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birth
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contractions of uterine smooth muscle
-prostaglandins and oxytocin |
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birth consists of three phases
1. cervix thins out and amniotic sac ruptures = water broken 2. strong uterine contractions result in birth of fetus 3. placenta/umbilical cord expelled |
know
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immediately after birth, the baby produces adult hemoglobin, pulmonary resistance decreases, and pressure in left atrium increases...
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however...pressure in inferior vena cava and right atrium does not increase
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placenta produces hcg, progesterone, and estrogen...NOT LH...?
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know
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