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Physiology > Week 8 > Flashcards

Week 8 Flashcards

1
Q

What are the reproductive systems?

A
  • gonads
  • external and internal genitalia/ reproductive tracts
  • accessory sex glands
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2
Q

What are external/ internal genitalia?

A

ducts that transport and or house gametes

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3
Q

What is the female reproductive tract?

A

mullein duct

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4
Q

What is the male reproductive tract?

A

wollfian duct

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5
Q

What are accessory reproductive organs?

A
  • transport gamete
  • glands: secrete fluids into reproductive tract
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6
Q

What are primary reproductive organs?

A

gonads
- pared in humans
- testes and ovaries

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7
Q

What are the two major functions of the gonads?

A
  1. produce haploid gametes (germ cells)
  2. produce/ secrete gonadal hormones, either peptide or steroid hormones
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8
Q

What is the production of germ cells called?

A

gamatogenesis
(spermatogenesis, oogenesis)

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9
Q

What is the production of gonadal hormones called?

A

steroidogenesis

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10
Q

Name some androgens

A
  • masculinising male sex hormone
  • testosterone from testes
  • dehydroepiandosterone from adrenal cortex - metabolic intermediate in biosynthesis of androgen and oestrogen sex steroids
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11
Q

What hormones are involved?

A

steroid hormones (testosterone, progesterone, oestrogens)

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12
Q

From what are steroid hormones produced and where?

A

cholesterol
in ovaries, testes, adrenal cortex

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13
Q

Can each steroidogenic organ produce all steroids?

A

No, only those for which it has a complete set of enzymes that modify cholesterol appropriately after firstly converting it to progenolone
- testis - testosterone (androgen)
- ovary - estradiol (estrogen) and porgesterone (progestogen)

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14
Q

Cholesterol (C27) becomes … when activated

A

Progestogen (C21)

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15
Q

Progesterone (C21) becomes … when activated

A

Estrogen (C18)

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16
Q

By which are the active steroids produced?

A
  • sequential enzymatic reactions of CYP and HSD enzymes
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17
Q

How do gonads differentiate into testis?

A
  • ovum with C sex chr. fertilised by sperm with Y
  • embryo with XY -> male
  • sex determining region of Y chr (SRY) codes for production f testis determining factor (TDF)
  • TDF directs differentiation into testis
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18
Q

How doe the testis create the rest of the reproductive system male repro tract and external genitalia (phenotype)?

A
  1. testis secrete testosterone and Mullein-inhibiting factor
  2. testosterone converted to dihydrotestosterone
    -> promotes development of undifferentiated external genitalia along male lines (penis, scrotum)
    -> transforms Wolffian ducts into male repro tract (epididymis, ducts deferent, ejaculatory duct, seminal vesicles)
  3. Mullein-inhibiting factor
    -> degeneration of Mullein ducts
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19
Q

How do gonads differentiate into ovaries?

A
  • ovum with X sex chr. fertilised by sperm with X
  • Embryo with XX -> female
  • no Y chr. no SRY and no TDF
  • with no TDF, undifferentiated gonads develop into ovaries
  • undifferentiated gonads develop into ovaries
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20
Q

How do the ovaries create the rest of the female repro system - female repro tract and external genitalia (phenotype)?

A
  • no testosterone or Mullerian inhibiting factor
    1. absence of mullein inhibiting factor
    -> development of Mulllerian ducts into female repro tract (oviducts, uterus)
    2. absence of testosterone
    -> degeneration of Wolffian ducts
    -> development of undifferentiated external genitalia along female lines (eg. clitoris, labia)
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21
Q

What are the functions of testosterone?

A
  • reproductive and non-reproductive actions
    eg. secondary sex characteristics, growth/ maturation of genitalia, spermatogenesis, libido at puberty, protein anabolic effect, bone growth at puberty (anabolic effect),
  • may induce aggressive behaviour
  • causes voice to deepen bc vocal folds thicken
  • male pattern of hair growth
  • controls gonadotropin hormone secretion
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22
Q

How are testosterone effects mediated?

A

via androgen receptor
0 in target tissue, testosterone converted to estradiol
- ligand for estrogen receptors in testes, prostate, bone, brain
- affects spermatogenesis, bone homeostasis and epiphyseal fusion

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23
Q

What are the functions of progesterone and estradiol in females?

A
  • except both reproductive and non reproductive actions
  • 2ndary sex characteristics
  • growth and maturation of repro tract
  • menstrual cycle
  • oogenesis
  • parturition
  • increase adipogenesis
  • increase bone mineral density
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24
Q

What three processes take place in the ovary

A
  • folliculogenesis (production of ovulatory follicle)
  • oogenesis (production fo haploid oocyte)
  • gonadal hormone synthesis
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25
Q

Name the steps In folliculogeneis

A

primordial -> primary -> secondary -> pre-astral -> astral -> ovulatory/ Graafian follicle

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26
Q

What two structures perform gonadal hormone synthesis?

A
  • follicle (androstenedione and estradiol)
  • corpus lutem (progesterone and estradiol)
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27
Q

How is estrogen secreted?

A
  • follicles contain one ovum, develop in ovary
  • primoral oocyte, oocyte and granulosa cells
  • granulosa cells: target cells of estrogen and FSH: secrete inhibit - provides -ve feedback to FSH secretion
  • transport nutrients to oocytes through gap junctions
  • secrete estrogens
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28
Q

What is the function of estrogen?

A
  • similar to testosterone in males
  • ova maturation and release (ovulation)
  • development of female sex characteristics
  • transport of sperm within the female
  • breast development in anticipation of lactation
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29
Q

What is the function of progesterone?

A
  • prepares suitable environment to nourish developing embryo/ foetus
  • breasts ability to produce milk (lobuloalverolar tissue)
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30
Q

Overview the menstrual and ovarian cycles

A

menstrual cycle:
menstrual phase day 1-5
proliferative phase days 5-14
Ovulation = day 14
secretory phase day 15-28

ovarian cycle
follicular phase - maturing follicles (till ovulation)
luteal phase - presence of corpus luteum (CL)

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31
Q

Explain how menstruation works

A
  • triggered by decrease of estrogen and progesterone
  • hormones decrease when corpus luteum degenerates
  • LH surge due to high level of estrogen produced by mature follicle
    -> triggers ovulation
  • LH influences empty follicle to convert into corpus luteum
    -> porduces progesterone and estrogen during last phase of cycle (luteal phase)
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32
Q

Where does oogenesis and estrogen secretion take place ?

A

Within ovarian follicle within first half of reproductive cycle (follicular face)

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33
Q

What happens if the ovulated oocyte Is fertilised?

A

CL prepares uterus - implantation

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34
Q

What happens if the oocyte is not fertilised?

A

CL degenerates (luteolysis) > no hormonal support for uterine lining
endometrium disintegrates > menstruation

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35
Q

Where are LH and FSH secreted from?

A

Anterior pituitary gland

36
Q

Where is estradiol secreted from?

A

follicle and CL

37
Q

Where is progesterone secreted from?

A

CL only

38
Q

Where are the testis located?

A

scrotum
- cool temp imp for spermatogenesis
- several degrees lower than normal BT

39
Q

What are the testis comprised of?

A

seminiferous tubules
- site of spermatogenesis

40
Q

What cell type is found within the seminiferous tubules?

A

Sertoli cells (within)
Leydig cells (between)

41
Q

What is the function of Sertoli cells?

A
  • epithelial cells within seminiferous tubules
  • support spermatogenesis - protect, support
  • secrete inhibin (inhibits FSH, completes -ve feedback loop)
42
Q

What is the function of Leydig cells?

A
  • interstitial cells
  • synthesise/ secrete testosterone (stimulated by LH, -ve feedback)
43
Q

Hypothalamo-pituitary-testicular axis

A

hypothalamus -> GnRh -> anterior pituitary -> FSH and LH into testis -> testosterone
1. dihydrotestosterone -> secondary sex organs
2. -ve feedback for hypothalamus or anterior pituitary

44
Q

Kiss peptin signalling

A
  1. Kiss1 neurons in arcuate nucleus of hypothalamus
  2. Kisspeptin from neurons in ARC stimulate hypothalamus - peptide neurotransmitters
  3. Kiss1 neurons have receptors for androgens, oestrogen and progesterone
  4. testosterone indirectly inhibits GnRH secreting neurons by blocking kiss 1 neurons excitatory action on GnRH- secreting neurons (no receptors for androgens)
    -> indirect action of testosterone on GnRH secretion through Kiss1 receptors
45
Q

For what is kisspeptin signalling important?

A

regulation of GnRH and thus FSH, LH and sex hormone output

46
Q

What does FSH do in relation to spermatogenesis?

A

remodels spermatids into highly specialised motile spermatozoa

47
Q

What hormones stimulate spermatogenesis?

A

testosterone and FSH

48
Q

What stimulates testosterone?

A

LH

49
Q

How do testosterone and FSH stimulate spermatogenesis?

A

testosteorne
- stimulates mitotic and meiotic divisions of undifferentiated diploid germ cells
- from spermatogonia into undifferentiated haploid spermatids
FSH
- simulates remodelling of haploid spermatids
- highly specialised motile spermatozoa through spermatogenesis via Sertoli cells

50
Q

What king of signalling is used by testosterone?

A

paracrine
- local chem messenger whose effect is exerted only on neighbouring cells in immediate vicinity of its site of secretion

51
Q

Is the testosterone concentration in testes higher than in the blood?

A

yes, much secreted locally by leydig cells, retained in intratubular fluid complexed with androgen-binding protein secreted by Sertoli cells
- high to sustain sperm production

52
Q

What are 2 examples of gonadotropins

A

FSH and LH

53
Q

Describe the steps of spermatogenesis in testes

A
  • spermatogonium -> spermatogonia by mitosis
  • chromosomes replicate (2 primary spermatocytes w 2n)
  • meiosis I (2 2ndary spermatocytes w 2n)
  • meiosis II (4 spermatids 1n)
  • differentiation (spermatozoa 1n)
  • from BM to lumen
  • following mitosis, 1 spermatogonium stays to maintain germ cell line
  • spermiogenesis
54
Q

Describe the stops of sperm maturation (spermiogenesis)

A
  • spermatozoa released into lumen of seminiferous tubules (immotile, 20 days)
  • move to epididymis by peristaltic contractions and flow lumens fluid (acquire motility)
55
Q

How long does spermatogenesis last?

A

64 days

56
Q

Describe the role of endocrine control of sperm production

A
  • complete spermatogenesis and spermiogenesis dependent on FSH + testosterone
  • FSH more important in early stages of meiosis via Sertoli cells
  • androgens more important latter+ spermiogenesis
57
Q

Epididymis

A
  • sperm complete spermiogenesis in caput epididymis
  • stored in cuada epididymis prior to ejaculation
  • epidermal secretions (eg. glycerylphosphorylcholine and inositol) fuel spermatozoa
58
Q

Accessory sexual organs/ glands

A

seminal vesicles
- fructose (anaerobic fructolysis)
prostate gland
- citrate (anticoagulant - chelates Ca2+)
- acid phosphatase (cleaves choline form glycerylphosphorylcholine)
- thrombin (coagulant - promotes lysis of fibrinogen and formation of fibrin)

59
Q

What are the adaptations in female physiology in pregnancy?

A
  • increased blood flow (30%) - heart enlarges
  • increased respiration (20%)
  • nutrient diversion
  • increased hepatic and renal function
  • hypercalcaemia (fatal skeleton)/ osteomalacia and/or osteoporosis
60
Q

What is the placenta?

A
  • develops after embryo implantation (transient)
  • endocrine organ of pregnancy
  • maternal and fatal tissue
61
Q

What is the function of the placenta?

A
  • exchange (maternal and foetal blood)
  • secretes hormones
    1. human chorionic gonadotropin (hCG)
    2. estrogens (estrange, estradiol, estriol)
    3. progesterone
62
Q

What are the placental hormones?

A
  • hCG
  • estrogen
  • progesterone
  • human chorionic somatomammotropin
  • relaxin
  • placental PTHRP
63
Q

What is the function of the hCG hormone?

A
  • maintains CL of pregnancy
  • stimulates testosterone synthesis in developing testes of XY embryos
64
Q

What is the function of the estrogen hormone?

A
  • stimulates endometrial growth
  • stimulates proliferation of mammary tissue (preparation for lactation)
65
Q

What is the function of progesterone?

A
  • promotes formation fo cervical mucus plug -> contamination
  • suppresses uterine contractions
  • stimulates differentiation of lobularveolar systems of mammary glands (for lactation)
  • prevents subsequent follicle development and ovulation (-ve feedback on Lh and Feh, suppresses ovulatory LH surge)
  • also secreted by CL during first trimester
66
Q

What is the function of human chorionic somatomammotropin?

A
  • similar to growth hormone and prolactin (lactation)
  • reduces maternal use of glucose and promotes breakdown of stored fat > high availability of glucose and FAs for foetus
67
Q

What is the function of relaxin ?

A
  • softens cervix pre parturition - for cervical dilation at parturition
  • loosens CT breaks pelvic bones - in prep for parturition
  • also secreted by CL
68
Q

What is the function of placental PTHRP?

A
  • increases maternal calcium for calcifying fatal bones
  • related to parathyroid
69
Q

What is the corpus luteum?

A

ovarian structure that develops form ruptured follicle following ovulation (release of ovum from mature ovarian follicle)

70
Q

What are the hormonal changes during the first trimester of pregnancy?

A
  • placenta secretes hCG -> activates LH chronic gonadotropin receptors in CL -> stimulates progesterone and estradiol synthesis/secretion
71
Q

What are the hormonal changes during the second and third trimester of pregnancy?

A
  • placenta secretes progesterone and estradiol
  • produces estriol form fetal adrenal androgen substrate
72
Q

What surpasses lactation?

A

estrogen and progesterone at high levels

73
Q

What simulates lactation?

A

prolactin and oxytocin

74
Q

What is the trigger of imitation of parturition?

A
  • unknown, 4 theories
    1. high levels of estrogen
  • up regulate connexins - gap junctions
  • up regulate myometrial receptors for oxytocin
  • stimulate local prostaglandin synthesis
    2. occytoxin
  • myometrial responsiveness exceeds critical threshold
  • increases Ca2+ - activates MLCK (myosin light chain kinase which trigger contractions)
    3. CRH (corticotropin-releasing hormone from placenta)
  • increase estrogen synthesis form metal adrenal androgens
  • increases cortisol (increased local prostaglandin synthesis and lung maturation)
    4. inflammation
  • increased number factor K-B unregulated inflammatory cytokines and increases local prostaglandin synthesis - softens cervix
75
Q

How can bacterial infections and allergic reactions induce premature labour?

A

by activating NF-kB

76
Q

Describe the feedback loop for parturition

A
  • +ve feedback spiral (furgusson reflex)
  • more uterine contractions -> pushes foetus against cervix -> neuroendocrine reflex -> more oxytocin secretion -> more prostaglandin production and +ve feedback back to more uterine contractions
    -> progressive increase in force
77
Q

what are the three stages of labor?

A
  1. cervix dilation
  2. birth of baby
  3. delivering of placenta - afterbirth
78
Q

How do oestrogen influence parturition?

A

first spike:
- increase responsiveness to OT
- promotes synthesis of connections within uterine smooth-muscle cells
- inserted into myometrial plasma membranes to form gap junctions
-> smooth muscle contractions
second spike:
- oestrogen’s increase concentration of myometrial receptors for OT
- fetal pressure stimulates receptors in cervix - neural signal to spinal cord -> hypothalamus -> triggers OT release form PP

79
Q

how does lactation work?

A
  • estorgen and progesterone inhibit lactation
  • levels fall during labor
  • prolactin stimulates milk synthesis
  • oxytocin stimulates smooth muscle of breast in same way it stimulates smooth muscle in myometrium
  • more milk ejected, more suckle, afferent arc -> brain stimulated more oxytocin secretion -> milk production
80
Q

Sex hormone anomalies XO

A

turner syndrome, female, no SRY, no TDF, 0.04%, infertile

81
Q

Sex hormone anomalies XXX

A

female, fertile 0.1%

82
Q

Sex hormone anomalies XXY

A

klinefelter syndrome, male, smaller testicles, infertile, 0.1%

83
Q

Sex hormone anomalies XYY

A

Jacobs syndrome, male, 2 copies of SRY, super male, less fertile, 0.1%

84
Q

How does the pill work?

A
  • contains progesterone
  • high levels will keep u in the secretory phase
  • circle doesn’t start again
85
Q

meiosis in oocyte

A
  • pre puberty, all oocytes arrested in prophase 1, once a month one cell moves to metaphase 2, decade long arrest greatly increases risk of aneuploidy in human oocytes, miscarriage, trisomy 21
86
Q

function of Oxytocin

A
  1. muscle contraction
    - pregnancy and labour contractions of uterus
    lactation contraction of myoepithelial cells to release milk
    sec intercourse
  2. neruomediator
    - recognition
    - trust
    - romantic attachment
    - parent-infant bondin
    - addiction, depression

Physiology (18 decks)

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