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18 Cards in this Set
- Front
- Back
Where are germs cells found for spermatogenesis? |
Basement membrane Go through 3 types of division: mitosis, meiosis 1, meiosis 2 In the end, one cell gets left behind you and get 4 functional sperm cells Spermatogenesis occurs from birth to death |
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When does meiosis 1 start in oogenesis? |
Meiosis one occurs before birth Nothing happens in childhood other than degradation of eggs At puberty, a few eggs start dividing to form 2 cells. One cell becomes a polar body The other goes to an ovum Meiosis 2 occurs with fertilization |
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Where does fertilization occur? |
Occurs in outer 1/3 of uterine tube (Oviduct, fallopian tube) |
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Across me enzymes digest what part of the egg? |
Zone pellucida, and corona radiata (aka cumulus cells) |
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What happens when one sperm enters ovum? |
Block to polyspermy And the sperm releases its DNA into ovum |
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Cleavage |
When zygote immediately begins to divide upon fertilization (mitosis) |
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When does implantation occur? |
<10 days The store of nutrients in the ovum keeps it viable until implantation |
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Morola |
A solid clump/mass of cells which takes about 3 days to form. Occurs after the zygote |
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Blastocyst |
hollow ball of cells that has formed by the time it reaches the uterus. Is after the morola. Contains the:
Tropoblast- outer cell layer, forms fetal part of placenta. Contains chorionic villi (finger like projections in placenta) Inner cell mass- forms the embryo, yolk sac (non nutritive) , and amniotic cavity (fluid filled shock absorbing sac) . Blastocele
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Placenta |
Has important endocrine functions:
Secretes large amounts of HCG which stimulates the corpus luteum to continue its secretion of estrogen and progesterone HCG is the basis of a pregnancy test. |
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Stem cell types |
Totipotency- from fertilized egg. Differentiates into ANY kind of stem cell in zygote Pluripotency- what ^ divides into. Found in embryonic germ cells. Produce a broad range of cell types Multipotency - adult stem cell found in some tissues, can produce a few cell types. Has three layers: ectoderm, endoderm , mesoderm Unipotency - somatic cells. Keep generating just that type of cell |
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Formation if primary germ layers (histogenesis) |
Each germ layer arise in 1st trimester and give rise to specific organs and tissues
Ectoderm- outside layer (skin, brain, nerves) Mesoderm- middle layer (cardiac, skeletal, blood) Endoderm- inside layer (GI tract, lungs, pancreas) |
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Organogenesis- of the reproductive tract |
Organogenesis- The way tissues arrange themselves into organs.
Male and female reproductive tracts are similar. In embryonic development:
Males - gonads attach to the mesonephric (wolffian) ducts Females - gonads don't attach, but the paramesonephric (mullerian) ducts develop into female reproductive tract |
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Organogenesis of the external genitals |
In males the genital tubercle becomes the glans penis. Fold become penis shaft and scrotum. In female the genital tubercle becomes the clitoris and folds become labia. We are all born female until testosterone develops wolffian ducts in males. |
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Another name for birth |
Parturition |
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Hormone cycle of birthing |
Cortisol triggers labour, reduces HCG + progesterone, removes the brake on oxytocin, which causes uterine muscles to contract (positive feedback) Prostaglandins enhance oxytocins effect. |
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Neonatal period |
First 4 weeks after birth Dramatic changes at a rapid rate (resp and cardio) |
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Effects of aging |
Decline in every organ system Degeneration of mitochondria Limit on cell reproduction Environmental factors Muscle mass decreases to 50% by 80 |