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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
What does the hypothalamus release into hypothalamo-hypophyseal portal vessels?
LHRH (GnRH)
26
What does LHRH stimulate anterior pituitary to release?
1) LH | 2) FSH
27
What are the primary effects of LH and FSH on gonads?
1) Stimulation of spermatogenesis/oogenesis 2) Stimulation of gonadal hormone secretion 3) Maintenance of gonadal structure * *******************
28
What is the precursor for steroid hormones?
Cholesterol*************************
29
When are FSH and LH high/ when do they fall to low levels?
High in newborn for 6 months -> falls to low levels until puberty
30
What is puberty driven by?
Increased FSH and LH
31
FSH and LH secretion at onset of puberty is increased by?
- Brain maturation increases GnRH secretion | - Decreased sensitivity of GnRH to neg. feedback
32
During late puberty, secretion of what increases during sleep?
Pulsatile secretion of LH and FSH
33
The onset of puberty stimulates the rise of what?
Testosterone and estradiol-17-beta | -Produce secondary sex characteristics
34
What is the age of onset of puberty related to in females?
Amount of body fat and physical activity | -Leptin secretion from adipocytes may be required
35
What does the pineal gland secrete?
Melatonin
36
What does melatonin do?
Inhibits gonadotropin secretion
37
What are the 4 phases of human sexual response?
1) Excitation (arousal) 2) Plateau 3) Orgasm 4) Resolution phase * *********************
38
What occurs only in males after human sexual response?
Refractory period
39
Where does spermatogenesis occur?
Seminiferous tubules | -Sertoli cells have receptor proteins for FSH
40
What cells secrete testosterone and contain receptor proteins for LH?
Leydig cells
41
What controls LH and FSH secretion?
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
What is required for the neg. feedback effects of testosterone on LH?
Aromatization rxn producing estradiol | **********************
43
What are 2 derivatives of testosterone?
1) Estradiol by aromatase 2) 5-alpha-DHT by 5-alpha-reductase * ************
44
What is responsible for initiation and maintenance of body changes in puberty?
Testosterone | -Stimulates growth of muscles, larynx, and bone growth until sealing of epiphyseal discs
45
What keeps levels of gonadotropins relatively constant?
Neg. feedback of testosterone and inhibin
46
In females what happens at menopause?
No more sex steroids | -In males, gradual decrease
47
What is estradiol secretion responsible for in males?
- Neg. feedback in brain - Sealing of epiphyseal plates - Regulatory fx in fertility
48
In spermatogenesis spermatogonia replicate initially by?
Mitosis -> 2 cells each 2n
49
A primary spermatocyte undergoes?
Meiosis -> 2 nuclear divisions -> 4 spermatids (n)
50
What happens in spermiogenesis?
Spermatids mature to spermatozoa (n)
51
What prevents autoimmune destruction of sperm?
Blood-testes barrier in sertoli cells******************* | -Produce FAS ligand
52
What do sertoli cells secrete?
Inhibin and ABP (androgen-binding protein)
53
What hormones control spermatogenesis?
- Testes secrete paracrine regulators: IGF-1 and inhibin | - FSH necessary in later stages of spermatid maturation
54
What male accessory organ is responsible for maturational changes, resistant to pH changes/temp, and storage fx?
Epididymis
55
What does the prostrate secrete?
Alkaline fluid, citric acid, Ca2+, coagulation proteins
56
What do seminal vesicles secrete?
Fructose (sperm food)
57
What NT is involved in erection and what does it cause?
NO; increased vasodilation of arterioles | -Parasympathetic
58
Emission and ejaculation are controlled by PNS or SNS?
SNS********************
59
What do ovaries contain that enclose ova?
Large number of follicles**************** | -Extensions (fimbriae) partially cover each ovary
60
What happens at ovulation?
Secondary oocyte extruded
61
At 5 mo. gestation how many oogonia do ovaries contain?
6-7 mil
62
What happens to most oogonia prenatally?
Apoptosis | -Remaining oogonia -> primary oocyte at end of gestation
63
Are primary oocytes diploid or haploid?
Diploid; like spermatogenesis in the male, oogenesis is arrested at prophase I of the 1st meiotic division
64
When does 2nd meiosis of oocyte occur?
Only when fertilized by sperm
65
Once secondary oocyte is produced, what happens under FSH stimulation from anterior pituitary?
- Theca cells secrete testosterone | - Granulosa cells contain aromatase (converts testosterone -> estrogen)
66
During ovulation what extrudes secondary oocyte into uterine tube?
Graafian follicle forms bulge on surface of ovary | ******************
67
What does the empty follicle become during ovulation?
Corpus luteum -> secretes progesterone/estrogen | -If not fertilized -> corpus albicans
68
What is the duration of the menstrual cycle?
28 days - Day 1 = 1st day of menstruation***************** - Day 14 = ovulation (walls rupture)*******
69
What causes ovulation?
LH surge and some FSH************ | ->causes testosterone, estradiol release
70
What happens in luteal phase?
Corpus luteum regresses unless fertilization occurs | -Estradiol/progesterone decreases
71
What prepares endometrium for menstruation?
High progesterone
72
In the proliferative phase what stimulates growth of endometrium?
Estradiol
73
When does menopause (cessation of ovarian activity) occur?
Around 50 yrs -> ovaries depleted of follicles
74
What causes hot flashes/ atrophy of vaginal wall in menopause?
Estradiol and inhibin withdrawal
75
What increases in menopause?
LH and FSH********************
76
Where does fertilization occur?
Uterine tubes
77
What rxn occurs during fertilization?
Acrosomal rxn (2n): acrosome of sperm contains hyauronidase******************* -> digests a channel through zona pellucida -> sperm fuses w/ ovum cell membrane
78
As fertilization occurs, what happens to secondary oocyte?
Completes 2nd meiotic division
79
What is implantation?
6th day after fertilization, blastocyst attaches to uterine wall
80
What is the basis of pregnancy tests?
hCG (human chorionic gonadotropin) | -secreted by trophoblasts
81
What placental changes occur?
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
What role does estrogen have as a placental hormone?
Stimulates endometrial growth, inhibits prolactin secretion, growth of mammary ducts, enlargement of mother's uterus
83
What does estrogen in late pregnancy do?
- Increases amount of oxytocin stored - Stimulates production of oxytocin receptors in myometrium - Stimulates prostaglandin production
84
What stimulates uterine contractions?
Oxytocin and prostaglandins
85
What stimulates milk production?
Anterior pituitary releases prolactin
86
What is necessary for "milk letdown" (ejection)?
Oxytocin | -Stimulates hypothalamus release PRH
87
What does the stimulus of suckling trigger?
A neuroendocrine reflex that results in | increased secretion of oxytocin and prolactin
88
The paramesonephric (mullerian) duct will give rise to the _______________.
Female accessory organs
89
The mesonephric (wolffian) duct will give rise to the _____.
Male accessory organs
90
What is the earliest haploid cell formed during spermatogenesis?
Secondary spermatocyte
91
The average ejaculation expels 1.5 (--) 5.0 ml of semen, which contains about ____ sperm
40-250 mil
92
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)
Secondary follicle
93
The corpus luteum secretes progesterone in response to _________________
LH
94
The secretory phase of the uterus corresponds in time to the _______ phase of the ovary
15-28th day of menstrual cycle
95
Breast feeding is thought to inhibit ovulation by directly ___________
Inhibiting the secretion of GnRH
96
The "surge" in LH secretion from the anterior pituitary that causes ovulation can be partially explained by the ______________________
(+) feedback of estradiol that increases release of LH

Physiology Exam 5 (5 decks)

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