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week 7 > reproductive system > Flashcards

reproductive system Flashcards

1
Q

describe male reproductive system. overview

A
  • testes linked to epididymis thru efferent ductules, from epididymis sperm travels thru ductus/vas deferens in a loop and then enters the ejaculatory duct at prostate. At that time, seminal glands add secretions and together the fluid enters the urethra at the level of prostate. after travelling past prostate, bulbourethral glands add their secretion before it travels out into penis and out of it.

gonads- testes are covered by tunica vaginalis and by scrotum to keep the testes cool

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2
Q

overview of female reproductive system

A

there is the vagina, then cervix, then uterus (has fundus and body), uterine tubes connect the uterus to ovaries. ovaries are located on the lateral pelvic wall

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3
Q

overview of how sperm travels from testes

A

from seminiferous tubules into straight tubules then into efferent ductules then into the epididymis

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4
Q

describe scrotum and its parts

A

scrotum suspends the testes outside the body and keeps it cool. Its skin is rugose and has dartos smooth muscle. it has a midline called raphe and is divided by a septum

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5
Q

where is ovum released and how is it picked up?

A

the ovum released into the peritoneal cavity and is picked up by fimbriated ends of the uterine tube opening

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6
Q

what are the supportive uterine ligaments

A

uterine ligaments help support the uterus and are fascial thickenings on the pelvic floor that pass from uterus and cervix to the sacrum, pubis and lateral pelvic walls

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7
Q

function of gonadal hormones?

A

in both : production of gametes, affect bone, muscle, blood vessels
in females: support conception, pregnancy and lactation

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8
Q

describe the hypothalamic-pituitary-ovarian axis

A

The hypothalamic–pituitary–ovarian axis is the multi-tiered system regulating ovarian synthesis and release of estrogens and progestins from granulosa cells.

  1. preoptic and supraoptic nucleus secreted GnRH which travel via hypophyseal portal circulation to anterior pituitary to stimulate gonadotropes
  2. Gonadotropes produce LH and FSH which stimulate gonads.
  3. In female gonads (ovaries), the theca cells (superficial to granulosa cells) have LH receptors that detect LH and convert cholesterol into pregnenolone, then produce testosterone and androstenedione (only produced in the theca cells even though granulosa cells also have LH receptors because only theca cells have enzymes to convert progesterone into androstenedione).
  4. Theca cells donate androstenedione to granulosa cells. Granulosa cells have FSH and LH receptors and FSH binding activates aromatase which facilitates the formation of oestradiol.
  5. Oestradiol released into circulation
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9
Q

what are the Main hypothalamic areas involved in

ovarian control?

A

preoptic nucleus neurons secrete GnRH
supraoptic nucleus neurons as well

GnRH then secreted via the hypophyseal portal circulation to anterior pituitary

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10
Q

what is GnRH

A

GnRh is a peptide hormone

  • released as a prohormone and later modified into active form
  • secreted into the hypophyseal portal system
  • activates gonadotropes in the anterior pituitary
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11
Q

why is GnRH release pulsatile

A
  1. it requires energy so pulsatile = less energy required
  2. it can be influenced by other factors such as environment and stress
  3. to make sure target tissue receptors are not desensitized
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12
Q

what are the function of ovaries

A

secrete oestrogen and progestin, houses female germ cells (oocytes)

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13
Q

what are the stages of development of follicles in oocytes

A

primordial, primary, secondary, tertiary and Graafian

follicles

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14
Q

what are the function of theca and granulosa cells.

A

work together to synthesize and secrete oestradiol

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15
Q

describe theca cells

A

superficial to granulosa cells
have LH receptors
convert cholesterol to pregnenolone
produce testosterone and androstenedione

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16
Q

describe granulosa cells

A
  • deep to theca cells
  • this layer increases in size a lot in primary to secondary follicle development
  • have FSH and LH receptors
  • converts cholesterol into pregnenolone
  • activate aromatase
  • secrete oestradiol
17
Q

describe oogenesis

A

begins in fetal stage of females

  • primordial germ cells (oogonia) increases in numbers
  • some mature into primary oocytes
  • at 20 weeks gestation, no. of oocytes at its highest
  • after that, it decreases until exhausted
18
Q

what are the types of oestrogen and what are their functions on different target tissues?

A

3 main: oestradiol, oestrone and oestriol
function dependent on target tissue:
1. bone : increase growth by osteoblast
2. endocrine : increase progestrone responses
3. liver: increase clotting factors, decrease cholesterol and LDL, increase HDL, increase steroid-binding proteins
4. reproductive organs: increase uterine, fallopian tube, vaginal, breast growth
- increase cervical mucus secretions
- increase LH receptors on granulosa cells

19
Q

how is oestrogen secretion regulated? describe entire pathway with axis

A

ovaries produce oestrogens, progestins, inhibin and activins.

  1. activin positive feedback at level of anterior pituitary
  2. inhibin negative feedback at level of anterior pituitary
  3. oestrogen and pregestin negative feedback to hypothalamus and anterior pituitary except during mid-cycle where it becomes positive feedback (caused by upregulation of receptors such as GnRH in anterior pituitary) to increase LH and FSH prior to ovulation
20
Q

what are progestins and what are their effects on different target tissue?

A

Progesterone (& 17α-hydroxyprogesterone).
• Produced in theca and granulosa cells.
• Has short half life (5-mins) in circulation.
• Secretion regulation is intrinsically linked to
oestrogen secretion.

Function :

  1. breast : increase lobular development but decrease milk production (prep for lactation by preparing breast tissue)
  2. reproductive organs: aid in the conversion of endometrium cycling from proliferative phase to secretory phase
  3. elevate body temp during luteal phase of development of ovarian cycle
21
Q

what does the menstrual cycle consist of?

A

ovarian cycle and then endometrial cycle

22
Q

what is the ovarian cycle (describe the 2 phases)

A
  1. Follicular phase
    – Main result is development of mature Graafian follicle and secondary oocyte
2. Luteal	phase	
– Dominated	by	corpus	
luteum	actions	ie	synthesis/
secretion	of	oestrogen	and	
progesterone.	
• Needed	for	implantation	and	
maintenance	of	any	fertilised
oocytes.		
– Corpus	luteum	regresses	
and	degenerates	in	10-12	
days	if	no	fertilisation.
23
Q

what is the endometrial cycle (describe the 3 phases)

A 
1. Proliferative	phase	
– Endometrial growth	mediated	by	increased oestrogens.	
• From	1-2mm	to	8-10	mm	thick.	
• Blood	vessel	and	gland	growth	occur.	
– Ovulation	marks	end	of	phase.
  1. Secretory phase
    – Maturation (not growth) of endometrium due to decreasing oestrogens.
    – Mucus glands more fully develop.
    – Glands and blood vessels increase surface
    area.
  2. Menstruation
    – If no conception, endometrial lining is
    replaced.
    • Vasoconstriction of spiral arteries
    • Local ischaemic injury
    • Inflammatory cell infiltration eventually leading to loss of tissue
24
Q

function of mammary glands

A

for lactation, which is milk production then secretion

25
Q

what hormones are involved in the Hormonal regulation of lactation

A 
prolactin produces milk, oxytocin causes myoepithelial contraction and letdown of milk.
sensory feedback (suckling) provides positive feedback to the hypothalamus and anterior pituitary to produce more prolactin and oxytocin
26
Q

Describe the Hypothalamic-Pituitary-Testicular Axis

A
  1. preoptic and supraoptic nucleus secreted GnRH which travel via hypophyseal portal circulation to anterior pituitary to stimulate gonadotropes
  2. Gonadotropes produce LH and FSH which stimulate gonads.
  3. In the testes, Leydig cells have LH receptors that detect LH to produce testosterone. Testosterone donated to Sertoli cells which some exit to seminiferous tubule lumen. Sertoli cells have FSH receptors that activate aromatase which forms estradiol. estradiol helps regulate protein synthesis in nucleus of Leydig cells
27
Q

describe various stages of development in spermatogenesis

A

from spermatogonia to primary spermatocytes to secondary spermatocytes to spermatids and finally spermatozoa

28
Q

what is spermatogenesis regulated by

A

testosterone

29
Q

what are the effects of testosterone

A
  1. Bone: increase growth and connective tissue growth
  2. Muscle: increase growth
  3. reproductive organ: increase growth and development of testes, prostate, seminal vesicles and penis
    - growth of facial, axillary, pubic hair
    - growth of larynx
    - increase spermatogenesis
  4. skin: increase in the size of sebaceous glands and secretions
30
Q

how is testosterone secretion regulated

A

testes produce inhibin B and testosterone
inhibin B negative feedback at anterior pituitary
testosterone negative feedback at hypothalamus and anterior pituitary

31
Q

what develops breast tissue

A

breast tissue prepared during puberty by female gonadal hormones

  • further developed during pregnancy by :
    1. oestrogen
    2. progestin
    3. hCG from fetus
    4. prolactin

week 7 (6 decks)

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