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Physiology Exam 5 > Reproduction > Flashcards

Reproduction Flashcards

1
Q

What does each individual produce that is formed in gonads by meiosis?

A

Gametes

-Haploid (23 or 1/2)

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2
Q

In males testes produce?

A

Sperm, testosterone

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3
Q

In females ovaries produce?

A

Ova, estrogens/progesterone

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4
Q

When are gametes united, resulting in restoration of diploid number (46)?

A

Fertilization

-Forms zygote

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5
Q

What are the 2 kinds of chromosomes?

A

1) Autosomal chromosomes (identical 1-22 pairs)

2) Sex chromosomes (23rd pair; XY - male; XX - female)

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6
Q

When are the gonads of males and females similar in appearance?

A

1st 40 days after conception

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7
Q

What promotes the conversion to testes?

A

TDF (testis-determining factor)

-located on SRY (sex determining region of Y)

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8
Q

What are the 2 structures in the testes?

A

1) Seminiferous tubules

2) Leydig cells (interstitial cells)

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9
Q

When do the seminiferous tubules form?

A

43-50 days postconception

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10
Q

What do the germinal cells form? The nongerminal cells?

A

Sperm; sertoli cells (sustenacular cells)

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11
Q

When do the leydig cells appear?

A

Day 65

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12
Q

What is the fx of leydig cells?

A

Endocrine fx (secrete androgens - mainly testosterone)******

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13
Q

When do leydig cells begin to secrete testosterone?

A

8th wk; peaks at 12-14th wk

-Masculinizes embryonic structures

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14
Q

What happens to testosterone levels by end of 2nd trimester?

A

Declines to very low levels until puberty

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15
Q

What happens to testes shortly before birth?

A

Descend into scrotum

-Temp about 3 degrees below internal temp (35 degrees C)

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16
Q

Ovaries develop in response to?

A

Absence of Y chromosomes and TDF

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17
Q

What do sertoli cells secrete that ensures proper production of scrotum and penis?

A

MIF (mullerian inhibition factor)

-Without this -> female presentation

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18
Q

What is responsible for development of male accessory sex organs?

A

Testosterone

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19
Q

What is the active agent of testosterone in target cells?

A

DHT (dihydrotestosterone)

-Needed for penis, spongy urethra, scrotum, prostrate

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20
Q

When are embryonic testes active?

A

1st trimester secrete large amounts of testosterone

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21
Q

When are embryonic ovaries mature?

A

3rd trimester

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22
Q

At the time of birth, gonads in both sexes are active or inactive?

A

Relatively inactive

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23
Q

What happens to levels of sex steroids before puberty?

A

Low due to lack of stimulation

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24
Q

What happens to levels of sex steroids at puberty?

A

Increased stimulation from gonadotropic hormones****** -> increase in sex hormones

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25
Q

What does the hypothalamus release into hypothalamo-hypophyseal portal vessels?

A

LHRH (GnRH)

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26
Q

What does LHRH stimulate anterior pituitary to release?

A

1) LH

2) FSH

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27
Q

What are the primary effects of LH and FSH on gonads?

A

1) Stimulation of spermatogenesis/oogenesis
2) Stimulation of gonadal hormone secretion
3) Maintenance of gonadal structure
* *********

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28
Q

What is the precursor for steroid hormones?

A

Cholesterol*********

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29
Q

When are FSH and LH high/ when do they fall to low levels?

A

High in newborn for 6 months -> falls to low levels until puberty

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30
Q

What is puberty driven by?

A

Increased FSH and LH

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31
Q

FSH and LH secretion at onset of puberty is increased by?

A
  • Brain maturation increases GnRH secretion

- Decreased sensitivity of GnRH to neg. feedback

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32
Q

During late puberty, secretion of what increases during sleep?

A

Pulsatile secretion of LH and FSH

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33
Q

The onset of puberty stimulates the rise of what?

A

Testosterone and estradiol-17-beta

-Produce secondary sex characteristics

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34
Q

What is the age of onset of puberty related to in females?

A

Amount of body fat and physical activity

-Leptin secretion from adipocytes may be required

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35
Q

What does the pineal gland secrete?

A

Melatonin

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36
Q

What does melatonin do?

A

Inhibits gonadotropin secretion

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37
Q

What are the 4 phases of human sexual response?

A

1) Excitation (arousal)
2) Plateau
3) Orgasm
4) Resolution phase
* *****

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38
Q

What occurs only in males after human sexual response?

A

Refractory period

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39
Q

Where does spermatogenesis occur?

A

Seminiferous tubules

-Sertoli cells have receptor proteins for FSH

40
Q

What cells secrete testosterone and contain receptor proteins for LH?

A

Leydig cells

41
Q

What controls LH and FSH secretion?

A

Negative feedback at 2 levels:

1) Testosterone inhibits GnRH production at hypothalamus and LH secretion from anterior pituitary
2) Inhibin inhibits FSH secretion from anterior pituitary

42
Q

What is required for the neg. feedback effects of testosterone on LH?

A

Aromatization rxn producing estradiol

******

43
Q

What are 2 derivatives of testosterone?

A

1) Estradiol by aromatase
2) 5-alpha-DHT by 5-alpha-reductase
* ****

44
Q

What is responsible for initiation and maintenance of body changes in puberty?

A

Testosterone

-Stimulates growth of muscles, larynx, and bone growth until sealing of epiphyseal discs

45
Q

What keeps levels of gonadotropins relatively constant?

A

Neg. feedback of testosterone and inhibin

46
Q

In females what happens at menopause?

A

No more sex steroids

-In males, gradual decrease

47
Q

What is estradiol secretion responsible for in males?

A
  • Neg. feedback in brain
  • Sealing of epiphyseal plates
  • Regulatory fx in fertility
48
Q

In spermatogenesis spermatogonia replicate initially by?

A

Mitosis -> 2 cells each 2n

49
Q

A primary spermatocyte undergoes?

A

Meiosis -> 2 nuclear divisions -> 4 spermatids (n)

50
Q

What happens in spermiogenesis?

A

Spermatids mature to spermatozoa (n)

51
Q

What prevents autoimmune destruction of sperm?

A

Blood-testes barrier in sertoli cells*********

-Produce FAS ligand

52
Q

What do sertoli cells secrete?

A

Inhibin and ABP (androgen-binding protein)

53
Q

What hormones control spermatogenesis?

A
  • Testes secrete paracrine regulators: IGF-1 and inhibin

- FSH necessary in later stages of spermatid maturation

54
Q

What male accessory organ is responsible for maturational changes, resistant to pH changes/temp, and storage fx?

A

Epididymis

55
Q

What does the prostrate secrete?

A

Alkaline fluid, citric acid, Ca2+, coagulation proteins

56
Q

What do seminal vesicles secrete?

A

Fructose (sperm food)

57
Q

What NT is involved in erection and what does it cause?

A

NO; increased vasodilation of arterioles

-Parasympathetic

58
Q

Emission and ejaculation are controlled by PNS or SNS?

A

SNS****

59
Q

What do ovaries contain that enclose ova?

A

Large number of follicles******

-Extensions (fimbriae) partially cover each ovary

60
Q

What happens at ovulation?

A

Secondary oocyte extruded

61
Q

At 5 mo. gestation how many oogonia do ovaries contain?

A

6-7 mil

62
Q

What happens to most oogonia prenatally?

A

Apoptosis

-Remaining oogonia -> primary oocyte at end of gestation

63
Q

Are primary oocytes diploid or haploid?

A

Diploid; like
spermatogenesis in the male, oogenesis is arrested at prophase
I of the 1st meiotic division

64
Q

When does 2nd meiosis of oocyte occur?

A

Only when fertilized by sperm

65
Q

Once secondary oocyte is produced, what happens under FSH stimulation from anterior pituitary?

A
  • Theca cells secrete testosterone

- Granulosa cells contain aromatase (converts testosterone -> estrogen)

66
Q

During ovulation what extrudes secondary oocyte into uterine tube?

A

Graafian follicle forms bulge on surface of ovary

****

67
Q

What does the empty follicle become during ovulation?

A

Corpus luteum -> secretes progesterone/estrogen

-If not fertilized -> corpus albicans

68
Q

What is the duration of the menstrual cycle?

A

28 days

  • Day 1 = 1st day of menstruation*****
  • Day 14 = ovulation (walls rupture)***
69
Q

What causes ovulation?

A

LH surge and some FSH****

->causes testosterone, estradiol release

70
Q

What happens in luteal phase?

A

Corpus luteum regresses unless fertilization occurs

-Estradiol/progesterone decreases

71
Q

What prepares endometrium for menstruation?

A

High progesterone

72
Q

In the proliferative phase what stimulates growth of endometrium?

A

Estradiol

73
Q

When does menopause (cessation of ovarian activity) occur?

A

Around 50 yrs -> ovaries depleted of follicles

74
Q

What causes hot flashes/ atrophy of vaginal wall in menopause?

A

Estradiol and inhibin withdrawal

75
Q

What increases in menopause?

A

LH and FSH****

76
Q

Where does fertilization occur?

A

Uterine tubes

77
Q

What rxn occurs during fertilization?

A

Acrosomal rxn (2n): acrosome of sperm contains hyauronidase********* -> digests a channel through zona pellucida -> sperm fuses w/ ovum cell membrane

78
Q

As fertilization occurs, what happens to secondary oocyte?

A

Completes 2nd meiotic division

79
Q

What is implantation?

A

6th day after fertilization, blastocyst attaches to uterine wall

80
Q

What is the basis of pregnancy tests?

A

hCG (human chorionic gonadotropin)

-secreted by trophoblasts

81
Q

What placental changes occur?

A

1) Maternal and fetal blood do not mix
2) Decidual rxn: endometrial growth, accumulation of glycogen
3) Decidua basalis: maternal tissue in contact w/ chorion frondosum

82
Q

What role does estrogen have as a placental hormone?

A

Stimulates endometrial growth, inhibits prolactin secretion, growth of mammary ducts, enlargement of mother’s uterus

83
Q

What does estrogen in late pregnancy do?

A
  • Increases amount of oxytocin stored
  • Stimulates production of oxytocin receptors in myometrium
  • Stimulates prostaglandin production
84
Q

What stimulates uterine contractions?

A

Oxytocin and prostaglandins

85
Q

What stimulates milk production?

A

Anterior pituitary releases prolactin

86
Q

What is necessary for “milk letdown” (ejection)?

A

Oxytocin

-Stimulates hypothalamus release PRH

87
Q

What does the stimulus of suckling trigger?

A

A neuroendocrine reflex that results in

increased secretion of oxytocin and prolactin

88
Q

The paramesonephric (mullerian) duct will give rise to the _______________.

A

Female accessory organs

89
Q

The mesonephric (wolffian) duct will give rise to the _____.

A

Male accessory organs

90
Q

What is the earliest haploid cell formed during spermatogenesis?

A

Secondary spermatocyte

91
Q

The average ejaculation expels 1.5 (–) 5.0 ml of semen, which contains about ____ sperm

A

40-250 mil

92
Q

An ovarian follicle that has multiple layers of granulose cells that surround the oocyte and has fluid-filled vesicles but no antrum is called a(n)

A

Secondary follicle

93
Q

The corpus luteum secretes progesterone in response to _________________

A

LH

94
Q

The secretory phase of the uterus corresponds in time to the _______ phase of the ovary

A

15-28th day of menstrual cycle

95
Q

Breast feeding is thought to inhibit ovulation by directly ___________

A

Inhibiting the secretion of GnRH

96
Q

The “surge” in LH secretion from the anterior pituitary that causes ovulation can be partially explained by the ______________________

A

(+) feedback of estradiol that increases release of LH

Physiology Exam 5 (5 decks)

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