Male Reproduction Flashcards

1
Q

What are the functions of the male reproductive tract

A

Testis: sperm production and steroid hormone production

Epididymis: sperm collection and maturation

Ductus deferens: transport and storage

Accessory glands: contributions to seminal fluid

Urethra: transport

Seminiferous tubules: sperm production

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2
Q

Where does the majority of testosterone synthesis occur?

A

Leydig cells

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3
Q

Describe the process steroid binding to its receptor

A

Steroid bind to receptor

This produces a complex that acts on DNA

Binding of the complex to sites on DNA alters the the genes being expressed by target cells

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4
Q

Describe the process of androgens binding to their receptor

A

Androgens interact with AR - all major cell populations in the testis, epididymis and accessory glands express AR

Androgen-AR binding is needed in sperm production, transport and activation

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5
Q

Why are androgens important?

A

They are responsible for the development of secondary sex characteristics, anabolic effects and spermatogenesis

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6
Q

Describe the HPO axis for the production of spermatozoa and sex steroids

A

Hypothalamus stimulated to secrete GnRh which acts on the anterior pituitary to stimulate the secretion of LH and FSH which have their effect on the testis to produce spermatozoa and sex steroids

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7
Q

Describe gonadotropin action in the testis

A

Androgen binding protein (ABP) binds to testosterone and DHT and concentrated them in the luminal fluid of the seminiferous tubules and downstream regions f the male tract

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8
Q

What does ABP binding stimulate?

A

Spermatogenesis in the seminferous tubules
Spem maturation in the epididymis
Accessory gland secretions
Myoid cell contractile activity to propel sperm along the tract

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9
Q

Describe the process of spermatogensis

A

Maturation stages are androgen-dependent

Myoid cell contractility is required to to move released sperm along the seminiferous tubule
Myoid cells are AR positive, action is androgen-dependent

At the point of release of sperm into the lumen of the tubule, sperm are not yet motile

The ability to swim is initially acquired in the epididymis with further activation in the female tract

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10
Q

Describe the composition of semen

A

Volume of ejaculate: 1.5-5.0ml
Sperm count: 40-250 million/ml
Leukocyte count: 0-200/ml (indicative of UTI)

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11
Q

How does an erection occur?

A

Erectile tissue becomes engorged with blood, arterioles dilated as a result of parasympathetic nervous system activity

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12
Q

What are the causes of erectile dysfunction?

A

Pathological causes: psychogenic, neurogenic, vascular and endocrine

Latrogenic causes: drugs such as SSIRs, tricyclics, antihypertensives

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13
Q

What are the symptoms of prostate cancer?

A

Urgent and frequent urination
Nocturnal enuresis
Difficulty starting or emptying the bladder
Urine flow weak, interrupted or difficult to control
Back/pelvic pain

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14
Q

What is the treatment for prostate cancer?

A

GnRH agonists and antagonists
Androgen antagonist: cyproterone acetate
5⍺ reductase inhibitors: dustasteride and finesteride

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15
Q

Give a use of anabolic steroids

A

Treatment of some aplastic anaemias

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16
Q

How can testosterone be used as a contraceptive?

A

Exogenous testosterone reduces LH and FSH which reduces fertility

17
Q

What is the disadvantage of using exogenous testosterone as a contraceptive?

A

High doses are needed as it is difficult to reduce sperm count - can lead to iatrogenic hypogonadotropic hypogonadism

18
Q

Give an example of male contraceptive other than exogenous testosterone

A

Vasalgel - Reversible inhibition of sperm under guidance
Soft gel is injected into the lumen of the vas deferent
Sperm can’t penetrate and are reabsorbed