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phys II, exam 3 > Lect 25 > Flashcards

Lect 25 Flashcards

1
Q

what is spermatogenesis

A

production of sperm

  • undifferentiated diploid primordial germ cells (spermatogonia) are converted into haploid spermatozoa (sperm)
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2
Q

descent of testes is usually complete by what month of gestation

A

7th month

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3
Q

Why do testes descend into the scrotum

A
  • provides cooler environment (1-2 C below body temperature) essential for spermatogenesis
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4
Q

testes perform what two functions

A
  1. produce sperm
  2. secrete testosterone
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5
Q

where is sperm produced

A

seminferous tubules

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6
Q

testosterone is produced in what cells

A

Leydig (interstitial) cells

  • found in connective tissue of testes
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7
Q

Seminiferous tubules contain what two cell types

A
  1. germ cells (spermatogonia)
  2. sertoli cells
    • provides nutrients to germ cells
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8
Q

function of sertoli cells

A
  1. form tight junctions: blood-testes barrier
  2. protect sperm and provide nourishment for sperm
  3. phagocytize bad germ cells
  4. secrete seminferous tubule fluid
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9
Q

sertoli cells secrete what three hormones? what is each’s function

A
  1. Inhibin: inhibit FSH release
  2. Andorgen Binding protein: maintains high level of testosterone in tubular fluid
  3. Anti-Mullerian hormone: development
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10
Q

Spermatogenesis is mediated by

A

testosterone

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11
Q

List the three major stages of Spermatogenesis

A
  1. Mitosis: daughter cell -> 4 identical primary spermatocytes
  2. Meiosis: each primary spermatocytes -> 4 spermatids
  3. Spermiogenesis
    • packaging process in which spermatids transform into mature spermatozoa
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12
Q

When is a cell considered a primary spematocyte

A

has finished mitotic division: four identical diploid (4N DNA) cells

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13
Q

when is cell considered a secondary spermatocyte

A

after it has undergone meitoic division once

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14
Q

secondary spermatocyte enters the second meiotic division, producing two what

A

spermatids

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15
Q

what is the name of mature sperm

A

spermatozoa

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16
Q

full cycle of spermatogenesis takes how long

A

60-70 days

17
Q

describe the spermatogenic wave

A
  • production of spermatogenesis happens in waves throughout the entire seminiferous tubule
  • guarentees a continuous supply of sperm
18
Q

what is spermiogenesis? what is it mediated by?

A
  • process by which spermatids mature into spermatozoa
  • testosterone
19
Q

what goes on during spermiogenesis

A
  1. packaging and elongation into mature spermatozoa
  2. remodeling of nucleus
  3. condensation of chromatin
  4. most of cytoplasm is lost
  5. formation of acrosome
20
Q

What is Spermiation

A

process by which mature spermatozoa are extruded from Sertoli cells into the lumen of semineferous tubules

21
Q

contraction of myoepithelial cells propels spermatozoa into

A

vas deferens

22
Q

Where are sperm under final maturation prior to storage

A

epididymus

23
Q

where are sperm stored

A

vas deferens

24
Q

What is the effect of temperature on spermatogenesis

A
  • lysosomal destruction prevented by cooler temperature
  • testes kept cooler by
    • air around scrotum, contraction/relaxation of muscles, venous blood flow
  • interference with ability of scrotum to stay cool -> low sperm counts
    • hot tubs, tight clothing, sitting too long
25
Q

What is Criptorchidism

A
  • undescended testes
  • affected individuals are unable to produce viable sperm
26
Q

Describe hormonal control of spermatogenesis

A
  1. hypothalamus releases gonadotropin-releasing hormones which acts on anterior pituitary to release FSH-secreting cells and LH secreting cells -> FSH and LH
  2. FSH sensitizes sertoli cells to testosterone and promotes secretion of inhibin and ABP from sertoli cells
  3. LH stimulates Leydig cells to produce testosterone by increasing activity of cholesterol desmolase
27
Q

LH stimulates Leydig cells to produce testosterone by increasing activity of

A

cholesterol desmolase

28
Q

function of androgen binding protein (ABP)

A

keeps high levels of testosterone within gonads

29
Q

Describe negative feedback mechanisms of spermatogenesis

A
  1. testosterone causes negative feedback on anterior pituitary to inhibit FSH and LH
  2. Inhibin acts on anterior pituitary to inhibit FSH
30
Q

testosterone can be sequestered within the seminiferous tubules by binding to

A

androgen binding protein by sertoli cells

31
Q

testosterone can circulate within the peripheral circulation bound to

A

sex-hormone binding globulin (SHBG)

32
Q

testosterone can be peripherally converted to what two things in target tissues

A
  1. dihydrotestosterone (DHT)
  2. estradiol
33
Q

List the actions of testosterone on target tissues

A
  1. differentiation of epididymis, vas deferens, and seminal vesicles
  2. increased muscle mass
  3. pubertal growth spurt
  4. growth of penis seminal vesicles
  5. deeping of voice
  6. libido
34
Q

List the actions of dihydrotestosterone on target tissues

A
  1. differentiation of penis, scrotum and prostate
  2. male hair pattern/pattern baldness
  3. sebaceous gland activity
  4. growth of prostate
35
Q

which is more potent: dihydrotestosterone or testosterone

A

dihydrotestosterone

36
Q

What are the primary effects of exogenous testosterone (steroid) use

A
  1. decrease LH and FSH release
  2. decrease sperm production
  3. increase in free estrogens (will free estrogens from binding proteins)
37
Q
A

phys II, exam 3 (8 decks)

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