reproductive physiology

Question 1

male reproductive tract: significance of urethra

Answer 1

testis (sperm produced) -> ductal system -> connects to same outflow tract (urethra) as urinary system; other glands (e.g. Cowper’s, prostate), seminal vesicles

Question 2

4 regulatory hormones of reproduction and location of release

Answer 2

GnRH (hypothalamus), LH and FSH (anterior pituitary), testosterone (testis)

Question 3

main regulatory pathways withn adult male reproductive system: LH

Answer 3

hypothalamus -> GnRH (pulsatile) -> anterior pituitary -> LH to Leydig cells (only cells expressing LH receptors) -> testosterone (negative feedback to anterior pituitary and hypothalamus) -> primary tole in spermatogenic cells in seminiferous tubule for gamete production (has other roles) -> Sertoli cells release inhibin (negative feedback to hypothalamus)

Question 4

main regulatory pathways withn adult male reproductive system: FSH

Answer 4

hypothalamus -> GnRH (pulsatile) -> anterior pituitary -> FSH to spermatogenic (Sertoli) cells in seminiferous tubule which regulates function and enhances production of sperm -> Sertoli cells release inhibin (negative feedback to hypothalamus)

Question 5

anaotmy of spermatogenesis

Answer 5

testis, epididymis, seminiferous tubules

Question 6

cells on outer layer of seminiferous tubule

Answer 6

Sertoli cells

Question 7

process of spermatogenesis (very rapid and imperfect process, but enough normal ones produced to fertilise an egg)

Answer 7

primordial germ cell (46 chromosomomes) -> spermatogonium -> (mitotic division) -> primary spermatocyte -> (1st meiotic division) -> secondary spermatocyte -> (2nd meiotic division) -> spertmatids -> mature sperm (23 chromosomes: 22X and Y, or 23X)

Question 8

contents of mature sperm

Answer 8

acrosome, sperm head, spermatid cytoplasm

Question 9

when does male and female reproductive function start

Answer 9

puberty

Question 10

duration of male reproductive function

Answer 10

continually throughout rest of life

Question 11

what happens to sperm with increasing age

Answer 11

sperm quantity and quality generally decrease

Question 12

what does LH stimulate in male reproductive tract

Answer 12

testosterone production

Question 13

what cells do FSH and testosterone sustain in male reproductive tract

Answer 13

Sertoli cell

Question 14

function of Sertoli cells in male reproductive tract

Answer 14

support spermatogenesis

Question 15

regulatory and duration of female reproductive function

Answer 15

cyclically until approx 45 y/o

Question 16

what happens to eggs with increasing age

Answer 16

quality generally decreases

Question 17

what does FSH stimulate in female reproductive tract

Answer 17

some development of ovarian follicels and 17B-oestradiol synthesis

Question 18

what does LH stimulate in female reproductive tract

Answer 18

progesterone function

Question 19

function of 17B-oestradiol and progesterone in female reproductive tract

Answer 19

regulate uterine endometrium

Question 20

female reproductive system pathway

Answer 20

hypothalamus -> GnRH -> anterior pituitary -> LH and FSH -> ovaries -> progesterone and oestrogen (negative feedback to hypothalamus and anterior pituitary)

Question 21

female reproductive system pathway: ovarian cycle - follicular phase

Answer 21

hypothalamus -> GnRH -> anterior pituitary -> LH and FSH -> ovaries -> oestrogen (negative feedback to hypothalamus and anterior pituitary)

Question 22

female reproductive system pathway: ovarian cycle - midcycle

Answer 22

hypothalamus -> GnRH -> anterior pituitary -> rapid peak of LH and FSH (ovulation) -> ovaries -> oestrogen (positive feedback to hypothalamus and anterior pituitary, upregulating GnRH, FSH and LH so huge increases in oestrogen levels)

Question 23

female reproductive system pathway: ovarian cycle - luteal phase

Answer 23

hypothalamus -> GnRH -> anterior pituitary -> LH and FSH -> ovaries -> progesterone (negative feedback to hypothalamus and anterior pituitary)

Question 24

describe changes in female circulating hormones during the ovarian cycle

Answer 24

oestrogen peaks just before midcycle, with progesterone and oestrogen high in luteal phase; following peak of oestrogen, have peaks of LH and FSH (accelerate growth of follicle and release egg in ovulation)

Question 25

changes in endometrium during normal menstrual cycle

Answer 25

endometrium is relatively thin (2-4mm) increases during proliferative and secretory phase to 7-16mm, but in last 3-4 days endometrium is shed in menstruation

Question 26

what controls menstrual cycle

Answer 26

oestrogen drives early (proliferative) phase, later (secretory) phase driven by oestrogen and progesterone

Question 27

what causes menstruation

Answer 27

decline in progesterone due to break down of corpus luteum (following ovulation and release of egg, follicle becomes corpus luteum)

Question 28

describe process of oogenesis

Answer 28

primordial germ cell -> oogonium -> primary oocyte -> secondary oocyte (and first polar body) -> ovum (and second polar body)

Question 29

describe process of folliculogenesis in ovary (eggs produced in utero, but last stages after puberty)

Answer 29

primordial follicle -> primary follice -> growing follicle -> antral follicle -> ruptured follicle -> following ovulation (in puberty), -> corpus luteum -> degenerating corpus luteum

Question 30

folliculogenesis (elongated process taking approx. 3 months, with multiple eggs undergoing process in both ovaries at the same time, producing non-identical twins if both fertilised)

Answer 30

resting follicle begins initiation -> basal growth (pre-antral -> early antral) -> recruitable (atresia of other follicles) -> selected (only dominant follicle (s) are ovulated)

Question 31

define ovulation

Answer 31

release of mature oocyte from ovary

Question 32

during ovulation, what is the number of chromosomes of the oocyte

Answer 32

2n (hasn’t become haploid), in meiotic arrest (metaphase II)

Question 33

where does the oocyte enter following ovulation

Answer 33

Fallopian tube

Question 34

how soon does the oocyte need to be fertilised to prevent degeneration

Answer 34

within 24 hours

Question 35

what do sperm have to do in order to accomplish fertilisation which filters out malfunctioning sperm

Answer 35

swim up cervix, uterus, and Fallopian tubes to egg, then release acrosome digestive enzymes (make way through cells left by follicle on outside of egg, and zona pellucida of egg, allowing head of sperm to enter cytoplasm of egg), with head contributing male pronucleus (23 chromosomes)

Question 36

process of fertilisation

Answer 36

as fertilisation occurs, meiotic arrest of egg is removed, so meiosis continues (so instead of 2n structure, is converted to single n gamete to form single female pronucleus and 2nd polar body) -> DNA in both pronuclei duplicates -> form mitotic spindle without a nucleus -> metaphase of first cleavage division -> metaphase of cleavage division 1 -> separation of chromosomes -> 2 nuclei containing one cluster of chromosomes -> 2-cell stage

Question 37

what happens to maternal chromosomes in oocyte after fertilisation

Answer 37

meiosis of maternal chromosomes resumes, forming female pronucleus (23 chromatids - 23 paired chromosomes) and 2nd polar body

Question 38

what happens to sperm chromosomes in oocyte after fertilisation

Answer 38

sperm chromosomes decondence to form male pronucleus (23 chromatids - 23 paired chromosomes)

Question 39

what happens to chromatids in both pronuclei following decondensation

Answer 39

duplication before aligning on mitotic spindle to be separated into 2 identical daughter cells (1st cleavage division of embryo)