Module 9: Reproductive System Flashcards Preview

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Flashcards in Module 9: Reproductive System Deck (224)
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91

MEIOSIS

• Primordial germ cell originates from the primary ectoderm and migrates to the yolk sac; eventually, it finds its way into the testis
• Spermatogonia undergoes mitotic divisions, upon crossing the barrier to the Sertoli layer, enlarges and becomes primary spermatocytes.
• Primary spermatocytes undergo Meiosis I to become secondary spermatocytes
• Secondary spermatocytes undergo Meiosis II to become spermatids
• Formation of mature sperm cell from spermatids

92

• final product of meiosis

Spermatid (4 Spermatid)

93

MEIOSIS (2): Male

1. Meiosis I is the separation of homologous chromosomes
2. Meiosis II is the separation of sister chromatids
3. Duration of entire process: 74 days

94

(HORMONES AFFECTING SPERMATOGENESIS)

- Growth and division of spermatogonia

Testosterone

95

(HORMONES AFFECTING SPERMATOGENESIS)

- stimulates secretion of testosterone

Luteinizing Hormone (LH)

96

(HORMONES AFFECTING SPERMATOGENESIS)

- Conversion of spermatids to sperm (spermiogenesis)

Follicle-Stimulating Hormone (FSH)

97

(HORMONES AFFECTING SPERMATOGENESIS)

- formed from testosterone by the Sertoli Cells; probably essential for spermatogenesis

Estrogens

98

(HORMONES AFFECTING SPERMATOGENESIS)

- Background metabolism of the testis

Growth Hormone (GH)

99

What cells respond to the luteinizing hormone?

Leydig Cells

100

SEMEN: Composition

10%: Sperm from vas deferens

60%: fluid from seminal vesicles
- Contains fructose, citric acid, prostaglandins and fibrinogen
- Reacts with female cervical mucous
- Causes reverse peristalsis in female genital tract

30%: fluid from prostate gland
- Calcium, citrate, phosphate, clotting enzyme and profibrinolysin
- Alkalinizes the semen
Trace amounts from mucous glands and bulbourethral glands

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CAPACITATION

1. Uterine and fallopian tube fluids wash away inhibitory factors of sperm
2. Sperm loses cholesterol cap
3. Sperm membrane becomes more permeable to calcium

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- Enables the sperm to penetrate the ovarian granulosa cells
- Mediated by hyaluronidase and proteolytic enzymes

ACROSOME REACTION

103

FACTORS AFFECTING MALE FERTILITY

1. Temperature (i.e. cryptorchidism) - increase longevity in a cooler environment

2. Sperm Count
Normal: 35M-200M/mL
Abnormal:

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Normal semen analysis value

Volume: 2-5 ml
Concentration: >20 million/ml
Motility: >50%
Normal forms: >30%
pH: 7.2-7.8

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(MALE SEXUAL ACT)

• Male sexual act results from inherent reflex mechanisms integrated in the sacral and lumbar spinal cord
• Sexual Sensation signaling: Glans Penis >> Pudendal Nerve >> Sacral Plexus in Spinal Cord >> Undefined areas in the brain
• May also be caused by internal structures such as bladder, prostate
• Psychic stimuli can also enhance ability to engage in sexual act

NEURONAL STIMULUS

106

STAGES OF MALE SEXUAL ACT

1. Penile Erection
2. Lubrication
3. Emission and Ejaculation
4. Resolution

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- Due to the parasympathetic nervous system
- Release of nitric oxide which activates guanylyl cyclase
- cGMP relaxes the arteries of the penis

Penile Erection

108

- Due to parasympathetic nervous system
- Causes the bulbourethral glands to secrete mucus

Lubrication

109

- Due to sympathetic nervous system (T12-L2), hypogastric and pelvic sympathetic nerve plexus
- Emission: contraction of the vas deferens and ampulla to cause expulsion of sperm into urethra
- Ejaculation: wave-like and rhythmical contraction of urethra to expel semen to the external environment

Emission and Ejaculation

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- Erection ceases

Resolution

111

• Any hormone that has masculinizing effects
• Testosterone, dihydrotestosterone and androstenedione

ANDROGENS

112

EFFECTS OF TESTOSTERONE (1-6)

1. Causes development of male external genitalia
2. Causes descent of testis
3. Development of adult primary and secondary sexual characteristics
4. Growth of hair
5. Baldness
6. Hypertrophy of larynx

113

EFFECTS OF TESTOSTERONE (7-12)

7. Increases thickness of the skin and development of acne
8. Increases protein formation and muscle development
9. Increases bone matrix and cause calcium retention
10. Increases basal metabolic rate
11. Increases red blood cell
12. Effect on electrolyte and water balance

114

REGULATION OF HORMONAL CONTROL (MALE)

1. Gonadotrophin-releasing hormone
2. Luteinizing hormone (LH) and Follicular stimulating hormone (FSH)
3. Inhibin
4. Human Chorionic Gonadotrophin

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• Decrease in male sexual function
• Hot flushes, suffocation and psychic disorder

MALE CLIMACTERIC

116

• Impotence
• Inability to develop or maintain an erection of sufficient rigidity for satisfactory sexual intercourse
• Trauma to the parasympathetic nerves from prostate surgery, deficient levels of testosterone and some drugs (nicotine, alcohol, antidepressants)

ERECTILE DYSFUNCTION

117

FUNCTIONAL ANATOMY OF FEMALE REPRODUCTIVE TRACT

• Female reproductive system = GONADS (ovaries) + female reproductive TRACT (oviducts, uterus, cervix, vagina, and external genitalia)

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• Acts via the IP3 mechanism
• Arcuate nuclei of the hypothalamus secrete GnRH into the hypothalamic– hypophysial portal blood.
• stimulates the anterior pituitary to secrete FSH and LH.

GnRH

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• is initiated by the onset of pulsatile GnRH release from the hypothalamus >> FSH and LH are in turn secreted in pulsatile fashion >> GnRH up regulates its own receptor in the anterior pituitary.

PUBERTY

120

(GnRH and Lactation)
Ovulation is suppressed as long as lactation continues because PROLACTIN has the following effects:

– Inhibits hypothalamic GnRH secretion
– Inhibits the action of GnRH on the anterior pituitary >> inhibits LH and FSH secretion.
– Antagonizes the actions of LH and FSH on the ovaries.