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THE MCAT-BIO 5
GAMETOGENESIS, MENSTRUAL CYCLE, BIRTH
Question | Answer |
---|---|
Why does menstrual cycle stop with menopause? | ovary is less responsive to pituitary gonadotropins and cyclic changes disappear |
Regulative Hypotheiss | Each cx has complete info for construction of multicx organism --> dependent on cx position and environmental factors |
Mosaic Hypothesis | parts of plans handed out to cx that need them during development |
Does sperm ever interact with blood? | NO --> protected by blood-testes barrier |
Where is sperm made? | seminiferous tubules |
Where is sperm stored? | epididymis |
What is path of sperm? | seminiferous tubules - epididymis - vas deferens - ejaculatory duct - nothing - urethra - penis |
What does GNRH stimulate? | release of FSH and LH |
What does the follicle house and produce? | houses oocyte and produces estrogen |
Estrogen normally inhibits ____ but causes ____ surge when it reaches a certain threshold | LH and FSH / LH |
What is necessary to maintain the endometrium? | progesterone (and estrogen) |
What maintains the corpus luteum? | HcG from placenta |
The corpus luteum goes away after the ______ trimester no matter what | first |
What takes over the job of the c.l. and makes progesterone? | placenta |
What does FSH stimulate in oogenesis? | primary oocyte --> secondary oocyte |
What is one of the first signs of pregnancy? | HcG in urine |
What causes menses? | no hx support of endometrium and it sloughs off |
What is a baby sperm called vs. a mature sperm? | spermatogonium vs. spermatozoa |
Where does fertilization take place? | oviduct in fallopian tubes |
Where does the primary oocyte halt before puberty? | Meiosis I at prophase |
Where does primary oocyte become upon completion of meiosis I? | secondary oocyte |
What does secondary oocyte halt at before fertilization? | Meiosis II at metaphase |
Both oogonium and spermatogonium become primary after? | puberty |
Spermatogonia --> sperm | spermatogonia - primary - secondary - spermatid - sperm |
What does sperm contribute to ovum? egg contribute? | -sperm = DNA only -egg = DNA + everything else |
What is the differentiation of ovum that implants in the endometrium? | blastocyst |
Zygote --> Blastocyst steps | zygote - morula - blasocyst |
What prevents additional sperm from penetrating egg? | cortical reaction |
What causes sperm to penetrate egg? | acrosomal reaction |
What is cleavage in relation to cell growth? | mitotic divisions without cell growth |
Blastula vs. blastocyst | -blastula = non-mammals -blastocyst = mammals |
Morula vs. blastocyst | -morula = solid ball -blastocyst = hollowed-out ball |
What are the basic stages of development (fertilization --> neuralation)? | fertilization, cleavage, blastula formation, gastrulation, neuralation |
Gastrulation in mammals | cx start migrating inward at primitive streak |
Primitive streak | where cx start migrating inwards during gasturlation |
What is importance of gastrulation? | forms primary germ layers (endoderm, mesoderm, ectoderm) |
How to form the brain and spinal cord during neuralation? | ectoderm folds into a tube |
Ectoderm | skin, nerves, brain, lens of eye |
Mesoderm | heart, muscle, skeleton, blood vessels, bone, kidney, gonads |
Endoderm | inner lining of digestive tract and respiratory tract, guts, lungs, liver, pancreas, digestive internal organs |
Determination | irreversible commitment to become a certain cx type |
Differentiation | becoming a cx type and adopting its specialized fxns |
specification | ccx is just beginnign to be committed to develop into a certain type --> reversible |
What are the stages of commitment? | specification followed by determination |
What causes induction? | physical touching of cells or by releasing chemicals |
What marks certain proteins for degradation? | ubiquitin |
What are the proteases called that act during apoptosis? | caspases |
What is a protease? | enzyme that catalyzes protein degradation |
Where are testes located? | scrotum |
How long does it take to mature sperm? | 72 days |
What contributes to seminal fluid? | seminal vesicles, prostate, bulbourethral glands |
What provides energy to the sperm? | fructose |
Sperm is ____ in order to survive in acidic female environment. | alkaline |
What does midpiece have in sperm? | lots o fmito for energy |
Primary spermatocyte are haploid / diploid while secondary are? | -diploid -haploid |
What is a mature spermatid called? | spermatozoa |
How does spermatozoa become activated for fertilization and where? | -vagina --> capacitation |
What is the path for sperm starting at the vagina? | vagina - v.canal. - cervix - uterus - fallopian tubes |
How are the testes both an exocrine and an endocrine gland? | -exocrine - seminal fluid -endocrine - androgens and peptides |
Function of leydig cells | convert cholesterol --> testosterone |
What effect does Testosterone have on sertoli cells? | T binds to a special rx and converted to DHT |
Role of DHT on sperm development. | DHT diffuses into Sertoli nucleus and instructs DNA to make RNA -->RNA affect spermatogenic cells |
Which male cx does LH bind to and what does it do? | Leydig cell - increases cholesterol --> T |
What male cx does FSH bind to and what does it do? | sertoli cx - increases T --> DHT --> also synthesizes rx for T |
What is the main androgen that affects sperm development? | DHT |
Testosterone has negative feedback on? | hypothalamus and a. pituitary -LH |
What happens when DHT is too high? | increase in inhibin which results in neg. feedback on a. pituitary -FSH |
All the oogonia a female will ever produce is made during the first___? | 3 months |
Atresia | process of oocyte degeneration |
When does the secondary oocyte underogo second meiotic division? | after fertilization has taken place |
When does primary oocyte undergo first meiotic division? | LH surge during puberty |
What is a primary follicle? | primary oocyte surrounded by follicle cells |
How long does follicular phase last? | 14 days |
Layers of a primary follicle from outside to inside. | theca cx - granulosa cx - zona pellucida |
Male: female :: leydig: ____ :: sertoli: ______ | theca / granulosa |
When does ovulation occur? | once secondary oocyte is released |
When does ovulation occur? | 14th day |
ANtrum | primary follicle fluid that primes for ovulation |
What does the burst follicle become? | corpus luteum |
What is main fxn of c.l.? | secrete progesterone (and estrogen) to maintain endometrium lining |
What do theca cx do? Where does it go after? | convert cholesterol --> T -diffuses into follicle cx to become Estrogen |
In the female, LH affects the ____ cx while FSH affects the ______ cx. | theca / follicle |
Low conc. of estrogen, there is _____ feedback on hypo and a.pit. HIgh conc. of estrogen, there is _______feedback on hypo and a.pit | -negative -positive |
From ovulation to beginning of menstrual phase, what is that phase called? | luteal phase |
Estrogen alone has _____ feedback. E and P in combo have ______. | positive /negative |
What is importance of E and P produced from c.l.? | negative feedback and prevents another follicle from developing |
What is the only thing that enters the secondary oocyte from the sperm? | nucleus |
What mem. does the sperm contact during fertilization? | zona pellucida |
When is HCG made? | ONLY during the first three months of pregnancy to maintain c.l. |
What takes over the role of the c.l. once it degrades? | placenta --> makes more E and P |
Cells of similar type form____? | tissues |
What is the structure called that is opposite to where sperm penetrates the egg? | gray crescent |
What is notochord derived from? | mesoderm |
What gives rise to nervous ssytem? | neural plate |
Where is neural plate derived from? | ectoderm |
What is formed from neural plate? | neural groove --> spinal cord and brain |
Intracellular interactions usually result in a _____. Intercellular interactions usually create ______. | -prepattern -developmental induction |
Animal pole vs. vegetal pole | -animal pole = cytoplasm -vegetal pole = yolk |
What sets up the initial prepattern? | grey crescent |
Dorsal lip | area where cells from animal pole invaginate into blastula |
What is main role of dorsal lip? | organizer of gastrulation and neuralation |
In order for the uterus to be receptive, it MUST be? | quiescent |
When is the uterus no longer quiescent? | At a certain ratio of P:E --> E increases faster than P |
When are the 2 main estrogen surges? | -LH surge for ovulation -surge to induce contractions |
2 main fxns of oxytocin. | induce contractions and milk ejection |
What does the formation of a primitive streak mark in mammals? | beginning of gastrulation followed by neuralation |
When will the embryo reach the uterus? | by the 5th or 6th day --> blastocyst |
What is the trophoblast? | surrounding ectodermal cx that cover inner cx mass |
Chorion vs. allantois | chorion = gas exchange and transfer of nutrients allantois = gas exchange and get rid of wastes |
What preserves teh barrier between the mother's and fetus' blood? | chorion - placenta |
monozygotic twins | genetically identical offspring when single zygote splits in 2 |
dizygotic twin (fraternal twins) | not genetically identical - 2 eggs are released and fertilized |
What are 3 main shunts for fetal circulation? | -foramen ovale -ductus venosus -ductus arteriosus |
Where is fetal respiration carried out in? | placenta |
HOw is placenta formed? | from chorion |
Does maternal and fetal blood mix together? | NO --> diffusion of everything |
What forms peripheral nervous system? | ectoderm |
adrenal cortex vs. adrenal medulla layers | -adrenal cortex = mesoderm -adrenal medulla = ectoderm |
archenteron | -cavity created by deep invagination -later becomes gut |
blastopore | -opening of archenteron -deuterosomes (humans), becomes anus -protosomes, becomes mouth |
What in the urine is the first sign of pregnancy? | HcG |
indeterminate cleavage vs. determinate cleavage | -cx that develop into complete organisms -cx that are determined to differentiate into a certain type of cx |
totipotent cx | any cx could produce complete individual |
morula | solid mass of embryotic stem cells |
blastula vs. blastocyst | blastula - non mammals blastocyst - mammals |
What doe s blastocyst consist of? | trophoblast and inner cell mass |
trophoblast vs. inner cx mass | -trophoblast makes chorion and placenta -inner cx mass makes actual organism |
Why is it so important during pregnancy to have neg. feedback on GnRH, LH, and FSH? | make sure development of another follicle |
What does c.l. degrade into? | corpus albicans |
What are 4 phases of menstrual cycle? | -follicular phase -ovulation -luteal phase -menstruation |
What are all of the developmental stages? | -fertilization -cleavage -gastrulation -neuralation -neural crest formation -organogenesis |
organogenesis | process by which layers of ectoderm, mesoderm, endoderm become internal organs |
parthenogenesis | ovum develops into a new individual without fertilization |
Are all nucleic acids circular / linear? | linear |
Division of oocyte during meiosis creates uneven ____ but even ______. | cytoplasm / nuclear material |
What does coelom form from? | mesoderm |
How do contraceptives work? | inhibit LH surge by altering E/P levels --> suppress ovulation |
SEVEP UP | seminiferous tubules, epididymus, vas deferens, ejaculatory duct, prostate, urethra, penis |
What is a major sign for ovulation? | sudden rise in LH |
Why are synthetic hx better? | last longer and less degraded |
How long is each phase of the menstrual cycle? | -Menstruation (0-5) -Follicular (5-15) -Ovulation (24 hours) -Luteal (secretory) phase - 14 daysalways |
What does LH release in males? | testosteroen |
What are the 3 type of cell population? | -rapidly dividing - skin cx, tympanic mem, GI tract -stable cx - pancreatic and liver that are normally arrested in Go but can divide if necessary -permanent cx - nerve and cardiac - no mitotic activity |