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(undergrad) physiology > 4 week 23 > Flashcards

4 week 23 Flashcards

1
Q

what are the commonalities (2) among the male and female reproductive systems? what are the key diffs (2)?

A
  • commonalities:
  • hormonal control of reproduction
  • gametogenesis
  • diffs:
  • spermatozoa vs ova
  • females support development of fetus
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2
Q

what is the hypothalamic-pituitary-gonadal axis?

A

system whereby gonadal steroid feedback modulates GnRH, LH and FSH secretion

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3
Q

mitosis (3) vs meiosis (4)?

A
  • mitosis:
  • normal cells
  • DNA replicated once + cells divide once
  • produces genetically identical cells with 46 chromosomes
  • meiosis:
  • gametes
  • DNA replicated once + cells divide TWICE
  • gametes contain half the chromosomes (23) as parent cell (haploid)
  • contain combination of alleles and are not genetically identical
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4
Q

fill in the blanks: most cells in our body have __ chromosomes (“___”). specifically, __ autosomes (same size, shape, genetic information) and 1 pair of _______ (non-homologous)

A
  • 46
  • (“diploid”)
  • 22
  • sex chromosomes
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5
Q

what are the male accessory glands (3)?

A
  1. seminal vesicles: secrete alkaline fluid containing fructose, proteins, and prostaglandins… produce 70% of semen.
  2. prostate gland: secretes citrate, zinc, PSA and enzymes… produces 25-30% of semen.
  3. bulbourethral glands: secrete lubricant.
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6
Q

where is sperm produced? what is the optimal temp?

A
  • produced in the seminiferous tubules between the sertoli cells of the testis (further mature in rete testis and epididymis)
  • optimal temp = 2-3C below body temp
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7
Q

what 2 types of cells are in the seminiferous tubules and what do each do?

A
  1. leydig cells (interstitial): synthesize and secrete testosterone + androgens under influence of LH which supports spermatogenesis.
  2. sertoli cells (sustentacular): sustain + support sperm development, regulated by FSH. also secrete inhibin and androgen-binding protein.
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8
Q

what are the functions of the smooth muscle and tight junctions of the sertoli cells?

A
  • smooth muscle: peristaltic contractions propel sperm
  • tight junctions: form blood-testis barrier + break and re-form around developing sperm
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9
Q

what are the 4 steps of spermatogenesis?

A
  1. following mitosis, 1 spermatogonium stays to divide and the other becomes a primary spermatocyte form which DNA is duplicated.
  2. primary spermatocyte undergoes first meiotic division; = secondary spermatocytes.
  3. secondary spermatocytes undergo meiosis II to become 4 spermatids (23 chromosome haploids).
  4. spermatids mature into spermatozoa (lose cytoplasm and gain tail) + released into lumen and transported to the epididymus.
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10
Q

functions of inhibin (1) and androgen-binding protein (1)?

A
  • inhibin: inhibits FSH but not LH
  • androgen-binding protein: maintains steady androgen levels in lumenal fluid
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11
Q

T or F: in males, GnRH and gonadotropin release is pulsatile and exhibits cyclicity.

A

F – GnRH and gonadotropin release is pulsatile, but is steady in men throughout adult life; no cyclicity like in females.

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12
Q

what are oogonia? how many chromosomes do they contain?

A
  • germ cells contained in ovaries
  • 46 chromosomes
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13
Q

describe oogenesis in the fetal stage

A
  • oogonia undergo mitosis
  • primary oocyte enters but does not complete meiosis I (“meiotic arrest”): replication of DNA but NO division, 2 identical sets of 46 chromosomes
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14
Q

describe oogenesis at puberty

A
  • one primary oocyte per month completes meiosis I
  • secondary oocyte is produced (containing 2 sets of 23 chromosomes) and non- functioning polar body degenerates
  • secondary oocyte is released at ovulation
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15
Q

describe oogenesis after fertilization

A
  • secondary oocyte completes meiosis II only if it is fertilized
  • if fertilization occurs, ovum is produced (23 maternal and 23 paternal chromosomes = 46 chromosome diploid) along with polar body which degenerates
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16
Q

T or F: only one secondary oocyte is produced from each primary oocyte

A

T – known as asymmetric cell division!

17
Q

diff bw ovarian vs menstrual cycle?

A
  • ovarian = changes in the follicles of the ovary (follicular + luteal phase)
  • menstrual = changes in the endometrial lining of the uterus (menstrual + proliferative + secretory phase)
18
Q

ovarian cycle: describe the follicular phase (4)

A
  1. follicles begin to develop.
  2. become primary follicles with granulosa and theca cells. estrogen is released from granulosa cells.
  3. antrum (fluid-filled cavity) starts to form. now called a secondary follicle.
  4. dominant follicle develops and antrum grows larger; called the
    graafian follicle.
19
Q

ovarian cycle: describe the luteal phase (4)

A
  1. graafian follicle ruptures and ovulation occurs.
  2. cells left behind become corpus luteum, which secretes progesterone and estrogen.
    7-9. if fertilization does NOT occur, corpus luteum degenerates. the scar tissue remaining is called the corpus albicans. if fertilization DOES occur, the corpus luteum continues to make progesterone and estrogen until the end of the first trimester.
20
Q

describe the 3 parts of the menstrual cycle

A
  1. menstrual phase: blood vessels supplying the endometrium undergo constriction, endometrial lining is shed (days 1-5). declining levels of progesterone and estrogen.
  2. proliferative phase: endometrial lining thickens, blood supply is re-established and glands enlarge (days 5-14). rising estrogen levels.
  3. secretory phase: endometrial lining thickens and becomes more vascularized. glands in endometrium enlarge and secrete glycogen to support an early embryo (days 14-28). under influence of progesterone and estrogen.
21
Q

fill in the blanks: hypothalamus secretes GnRH, which causes the anterior pituitary to ___ LH secretion and ___ FSH secretion. this leads to increases in ___ and ___ at the ovaries. ____ modulates GnRH, LH and FSH secretion.

A
  • increase, increase
  • estrogen, progesterone
  • gonadal steroid feedback
22
Q

actions of estrogen? (3)

A
  • ovarian actions: stimulates oogenesis and follicular development
  • uterine actions: promotes proliferative phase of uterine cycle
  • other actions: stimulates growth hormone secretion (bone growth in adolescence) and promotes development of secondary sex characteristics (during puberty throughout adulthood)
23
Q

actions of progesterone? (2)

A
  • uterine actions: promotes changes in secretory phase of uterine cycle
  • other actions: suppresses uterine contractions during pregnancy + promotes growth of glandular tissue in breasts but suppresses milk production
24
Q

describe hormonal regulation during the early to mid-follicular phase

A
  • estrogen peaks
  • progesterone flat
  • LH low and constant
  • FSH peaks a bit and goes back down
  • note: +inhibin (FSH) and +plasma estrogen (LH) = negative feedback loop
25
Q

describe hormonal regulation during the late follicular phase and ovulation

A
  • second (smaller) peak of estrogen
  • progesterone peaks
  • LH peaks then declines
  • FSH peaks then declines
  • note: +estrogen secretion (LH) = positive feedback loop
26
Q

describe hormonal regulation during the luteal phase

A
  • estrogen, progesterone, LH declining
  • FSH increases slightly
  • drop in estrogen and progesterone triggers menstruation
27
Q

briefly describe fertilization and implantation

A
  • sperm + oocyte fuse which induces meiosis II… ovum = 46 chromosomes
  • chromosomes combine, DNA is replicated, mitosis occurs
  • blastocyst is formed, with trophoblast and inner cell mass
  • trophoblast invades endometrial tissue, this will form placenta
28
Q

describe the hormonal changes during pregnancy

A
  • human chorionic gonadotropin (hCG) secreted from placenta, sustains corpus luteum
  • corpus luteum secretes estrogens and progesterone first trimester of pregnancy under hCG influence
  • placenta takes over estrogen and progesterone production
29
Q

function of chorionic villi?

A
  • facilitate exchange of gases, nutrients between maternal and fetal blood at placenta, although blood does not actually mix

(undergrad) physiology (21 decks)

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