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HUBS192 > Lecture 35: Male reproduction 2 > Flashcards

Lecture 35: Male reproduction 2 Flashcards

1
Q

Why are the testes held on the outside of the body?

A

The testes are held away from the body in the scrotum to maintain a lower temperature of 34 degrees. Holding these away from the core, with the relevant mechanisms allow the testes to maintain this temperature

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2
Q

What are the two muscles found within the scrotum and what do they each do?

A

Scrotum lined by dartos muscle - wrinkles skin to reduce surface area and minimise heat transfer, eg. when it is cold

Cremaster muscle contracts the scrotum pulling the testes closer the body for warmth when it gets cold.

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3
Q

Where do the two spermatic cords run and what do they contain? What is special about the veins here?

A
  • Runs between abdomen and testes

Contains:
* ductus deferens
* nerves
* lymphatics
* blood vessels - testicular arteries and veins (venous plexus)

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4
Q

What is special about these veins in the spermatic cords?

A

They form a venous plexus or pampiniform plexus, which are arranged in a web like structure around the arteries, this allows for more heat transfer and cools the incoming blood so the testes can maintain a temperature of 34 degrees

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5
Q

What are the two functions of the penis?

A

Urination
Copulation - delivery of sperm into females (sex)

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6
Q

What are the three sections of the penis called?

A

Cylindrical organ:
* Root (bulb)
* Body
* Glans covered by prepuce/foreskin

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7
Q

What are the three erectile tissues of the penis?

A

Two corpora cavernosa (corpus cavernosum)
* Main erectile tissue
* Dorsal aspect (bit different.. REMEMBER top of penis)

One corpus spongiosum
* Contains urethra
* Forms bulb and glans
* Ventral aspect (bottom of penis against balls)

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8
Q

Which erectile tissue of the penis is less erectile and why?

A

The corpus spongiosum which houses the urethra is less erectile than the two corpora cavernosa as this ensures the urethra remains open during ejaculation

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9
Q

What three types of glands that produce seminal fluid?

A
  • Seminal vesicles
  • Prostate gland
  • Bulbourethral glands
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10
Q

What is the difference between seminal fluid and semen?

A

Seminal fluid is all the fluid produced apart from spermatozoa (sperm)

Semen is the combination of sperm and seminal fluid

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11
Q

What is the location and role of seminal vesicles?

A

Two glands located:
* posterior to bladder
* lateral to ampulla

Produce viscous secretion
* Makes up ~60% of semen
* Alkaline pH protects sperm against acidic environment in urethra and vagina

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12
Q

What is the location and role of the prostate gland?

A

Location
* Inferior to bladder
* Wraps around prostatic urethra

Produces secretion
* ~30% of semen
* Slightly acidic, milky fluid
* Contains PSA: prostate-specific antigen
* Contributes to sperm activation, viability and motility

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13
Q

What is the location and role of the Bulbourethral glands?

A

Two glands:
* located in the urogenital diaphragm
* Open into spongy/penile urethra

Produces secretion:
* Contribute ~5% of semen volume
* Secretions lubricate and neutralise acidity in urethra prior to ejaculation

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14
Q

What percentage of semen does spermatozoa make up?

A

~5%

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15
Q

What is a vasectomy?

A
  • Surgical method of sterilisation in males
  • Cut the ductus deferens (cut ends tied or cauterised)

This means only seminal fluid is released during intercourse - Not semen … no sperm (sterile)

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16
Q

What is the name for the process of generating sperm and how does this occur?

A
  • Spermatogenesis in males
  • Occurs via mitosis and meiosis
  • Cells need to be haploid (23 chromosomes)
17
Q

Name the process by which spermatogonia are
transformed to mature spermatozoa (sperm):

A

Spermatogenesis (occurs in seminiferous tubules)

18
Q

Describe the first stage of spermatogenesis:

A
  • Spermatogonia divide by mitosis into 2 daughter cells
    (diploid - 46 chromosomes)
  • One spermatogonium (type A) stays at the basement membrane of the seminiferous tubule - so we can continuously produce sperm in the future
19
Q

Describe the second stage of spermatogenesis:

A
  • The second spermatogonia (type B) differentiates into a
    primary spermatocyte (diploid), which undergoes meiosis I
  • Forms 2 secondary spermatocytes (haploid - 23 chromosomes)
20
Q

Describe the third stage of spermatogenesis:

A
  • The 2 secondary spermatocytes undergo meiosis II to form spermatids (haploid)
  • Spermatids differentiate into spermatozoa with a head, body and tail via spermiogenesis
  • Spermatozoa released into lumen
21
Q

What is spermiogenesis?

A

A specific part of spermatogenesis where spermatids mature and transform into fully developed spermatozoa (sperm cells) by undergoing morphological changes like the formation of the acrosome, condensation of the nucleus, and development of the flagellum.

22
Q

What is the role of the acrosome in the head of spermatozoa?

A

to help the sperm penetrate the egg during fertilization. It contains enzymes that digest the outer layers of the egg, allowing the sperm to reach and fuse with the egg’s plasma membrane.

23
Q

What is a gonadotropin?

A

= hormone that acts on the gonads

24
Q

How many sperm are produced from one primary
spermatocyte?

A

Four spermatozoa are produced from one primary spermatocyte

25
Q

What are the two gonadotropin hormones and what other hormone stimulates their release?

A

GnRH
* gonadotropin releasing hormone produced by the hypothalamus

LH
* Luteinizing hormone (a gonadotropin) produced by the anterior pituitary

FSH
* Follicle stimulating hormone (a gonadotropin) produced by the anterior pituitary

26
Q

What are the two male reproductive hormones?

A

Inhibin and testosterone

27
Q

What does Luteinizing hormone (LH) do?

A
  • LH stimulates production of testosterone (interstitial endocrine [Leydig] cells)
28
Q

What does Follicle stimulating hormone (FSH) do?

A
  • FSH stimulates Inhibin production (nurse [Sertoli] cells)
29
Q

What are the negative feedback mechanisms for inhibin and testosterone?

A
  • Inhibin suppresses FSH
  • Testosterone suppresses LH & GnRH (which subsequently inhibits both LH and FSH)
30
Q

What two hormones control and regulate spermatogenesis?

A
  • FSH and testosterone control spermatogenesis
31
Q

What is the role of testosterone?

A
  • Type of androgen
  • Group of steroid hormones
  • Responsible for male characteristics (maturation of sex organs, spermatogenesis, secondary sex characteristics, libido)

*Can be used as Synthetic androgens (steroids) - for therapeutic purposes

HUBS192 (39 decks)

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