Basic Male reproductive physiology Flashcards

1
Q

What are the male reproductive organs? (7)

A
  • Penis
  • Testes
  • Scrotum
  • Epididymis
  • Vas deferens
  • Prostate
  • Seminal vesicles
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2
Q

Where is sperm produced?

A

Sperm is produced from the primordial germ cells present in the semineferous tubules within the testicles

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3
Q

Where is sperm stored?

A

In the Epididymis - sperm remains here for about 3 months and matures before travelling out

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4
Q

What is the Epididymis connected to?

A

The tail of the epididymis merges into the vas deferens

  • These then pass through the inguinal region and curls back round the bladder
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5
Q

Which 2 structures create the semen fluid which is mixed with the sperm?

A

Seminal vesicle and prostate

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6
Q

The vas deferens join with the seminal vesicle to form what?

A

The ejaculatory duct which passes through the prostate and empties into the urethra.

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7
Q

Why do the testicles sit outside of the main body cavity?

A

Testicular temperature must be below that of the body temperature in order to facilitate sperm production properly.

The scrotum sit outside the abdominal cavity and allow about 1-2ºC lower temp than the abdominal cavity

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8
Q

Normal process of ejaculation: see diagram

A
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9
Q

What is the name given to the fibrous capsule that surrounds the testes?

A

Tunica albuginea

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10
Q

Features of the Tunica albuginea

A

It penetrates into the structure of the testes dividing it into several tubules - the semineferous tubules lie in between these

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11
Q

What are the 3 different types of cells within the semineferous tubules?

A
  • Germ cells - immature sperm - become mature
  • Sertoli/sustentacular cells - situated between germ cells and support sperm production
  • Interstitial (Leydig) cells - produce testosterone
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12
Q

Describe the process of endocrine control of testicular function

A
  • Gonadotrophin releasing hormone released from the hypothalamus
  • GnRH acts on anterior pituitary to release FSH and LH (gonadotrophins)
  • FSH acts on testicles - stimulating the Sertoli cells, which facilitate spermatogenesis.
  • LH acts on testes - stimulating Leydig cells, to produce testosterone
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13
Q

Negative feedback loop in endocrine control of hormones

A

As testosterone production increases it creates a negative feedback loop – sends negative signal to the hypothalamus to reduce secretion of GnRH and subsequently decrease in release of gonadotrophins

Inhibin is produced by the fertilised cells and again it creates a negative feedback on the anterior pituitary

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14
Q

When does spermatogenesis start?

A

At puberty

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15
Q

How long is the average sperm cycle?

A

64 days from production to ejaculation - in which the germ cells pass through different developmental stages

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16
Q

What are the 2 distinct phases during spermatogenesis?

A
  • Spermatocytogenesis - Clonal expansion (replicate and multiply) and maturation through mitotic and meiotic process
  • Spermiogenesis - differentiation into mature sperm cells
17
Q

Describe Spermatocytogenesis - 1st phase of spermatogenesis

A
  • Involves 2 cell types:
    • Spermatogonia A - used to replenish the pool of spermatogonia. This replenishment of spermatogonia means that males are fertile throughout adult life.
    • Spermatogonia B will eventually form mature sperm.
  • Type B spermatogonia replicate by mitosis several times to form identical diploid cells linked by cytoplasm bridges, these cells are now known as primary spermatocytes.

Primary spermatocytes then undergo meiosis.

  • Meiosis I produces two haploid cells, known as secondary spermatocytes
  • Meiosis II produces four haploid cells, known as spermatids
18
Q

Spermiogenesis - 2nd phase of spermatogenesis

A
  • The cytoplasmic bridges break down and the spermatids are released into the lumen of the seminiferous tubule – a process called spermiation.
  • The spermatids mature into sperm as they travel along the seminiferous tubules until they reach the epididymis (here they are stored and undergo the final stages of maturation)
19
Q

Chromosomal division during spermatogenesis

A

Diploid chromosomes (46) before and after mitosis in 1st phase of spermatocytogenesis

Then undergoes meiosis in 2nd phase of spermatocytogenesis - here 2 haploid cells are produced - chromosome number halves (23)

2nd meiotic division - 4 haploid cells with 23 chromosomes each

20
Q

What factors affect spermatogenesis and as a result can affect male fertility?

A
  • Pretesticular - Problem with the hormonal control
    • Functional- excessive weight loss, gain, stress
    • Intracranial tumours, cysts, bleed
    • Prolactinoma
    • Medications- opiates, external testosterone, steroids(body building)
    • Genetic- Kallmann’s syndrome
  • Testicular - Problem at the site of production
    • Surgery- orchidectomy, orchidopexy
    • STI – affect reproductive system
    • Mumps orchitis
    • Testicular trauma or torsion
    • Radiotherapy or chemotherapy
    • Genetic- Klinefelter’s (46 XXY), Y-chromosome microdeletion
21
Q

What is Orchidoplexy?

A

Replacing a maldecended teste

22
Q

Steps to reduce the impact of factors affecting fertility

A
  • Improve lifestyle - normal BMI, stop smoking, alcohol in recommended limits, healthy diet, exercise, adjustments to occupational exposure
  • Optimise underlying medical condition
  • Stop medications or switch to alternative pregnancy compatible medications
  • Reduce STI risk and treat promptly if diagnosed.
  • Fertility preservation- sperm freezing prior to surgery or cancer treatment