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Foundations Of Medicine > 12.1 Male Reproductive System - Introduction > Flashcards

12.1 Male Reproductive System - Introduction Flashcards

1
Q

List the functions of the male reproductive system

A
  • Sperm production
  • Storage and transfer of sperm into female
  • Male sex hormone production
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2
Q

Primary vs Secondary Sex Organs

A

Primary: Gonads; produce gametes and hormones
Secondary: Sustain and transfer gametes

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3
Q

Describe the structure of the scrotum

A
  • Thin layer of smooth muscle called dartos muscles beneath scrotal skin
  • Two skeletal cremaster muscles that descends from the abdomen and covers each testis like a muscular net.
  • A rich blood and nerve supply.
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4
Q

What are the functions of the scrotum?

A
  • Support
  • Protection
  • Thermoregulation
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5
Q

Are the testes located externally in an embryo?

A
  • No
  • Develop with the abdomen, and migrate down into scrotum
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6
Q

What are some negative effects of core body temperature on testicular function?

A
  • Arrested/abnormal spermatogenesis
  • Abnormal metabolism
  • Increased risk of testicular cancer
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7
Q

If a man’s testicular temperature is radically decreased or increased, what changes would we see in his testosterone levels?

A
  • Probably none
  • Temp doesn’t influence endocrine activity of testes; as long as nothing is burnt or frozen off, he’s fine in that regard
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8
Q

Other than being located out of the pelvic cavity, how else is testicular temperature maintained?

A
  • Sweat glands in scrotal skin
  • Cremaster muscles contract when cold and relax when warm (like in Red Dead)
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9
Q

Where is are the cremaster muscles located relative to the scrotal skin?

A

Under dermis

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10
Q

Where is the dartos muscle located relative to the scrotal skin?

A

Within dermis

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11
Q

What causes regular wrinkling of scrotal surface?

A

Resting tone of dartos muscle

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12
Q

Describe the contraction and relaxation of the dartos muscle

A

Cold: Contract -> more wrinkling, more surface area for heat loss
Hot: Relax -> less wrinkling, more surface area for heat loss

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13
Q

Describe countercurrent heat exchange in the testicular blood supply

A

Heat is removed from testicular arteries as blood descends to the veins. Like passing contraband.

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14
Q

Function of testes

A

Sperm cell and sex hormone production

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15
Q

Approximate length of testis

A

4-5cm

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16
Q

How many lobules per testis?

A

200-300 compartments

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17
Q

What are the two membranes within the scrotum

A
  • Tunica vaginalis
  • Tunica albuginea
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18
Q

What type of membrane is the tunica vaginalis? What is its function?

A
  • Serous membrane
  • Secretes protein-rich fluid that decreases friction
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19
Q

What type of membrane is the tunica albuginea? What is its function?

A
  • Dense connective tissues capsule
  • Separates each testis into 200-300 lobules, each of which contains seminiferous tubules
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20
Q

Where is the site of spermatogenesis?

A

Seminiferous tubules, which are in lobules, which are in a testis, which are in the scrotum

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21
Q

What two cell types are located in the seminiferous tubules?

A
  • Spermatogenic cells
  • Sertoli cells
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22
Q

Why is it important that there are blood vessels running between seminiferous tubules?

A

Because hormones are also produced in the testis, and they travel in the blood

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23
Q

Which cells are responsible for testosterone production

A

Leydig cells

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24
Q

What happens to testosterone once it it produced in the leydig cells between seminiferous tubules?

A
  • Some goes into STs to stimulate sperm production
  • Some goes into blood vessels and enters systemic circulation
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25
Q

Where do sertoli cells span from? How are they connected to one another?

A
  • Span from basement membrane to lumen of Seminiferous tubule
  • Connected by tight junctions
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26
Q

Why are the tight junctions between sertoli cells important?

A
  • They stop some substances from diffusing through the cells
  • Prevents immune cells from recognising the developing sperm cells as “foreign”, which would result in it launching an attack
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27
Q

Can substances diffuse directly to and from developing sperm cells?

A
  • No
  • They pass through the sertoli cells as intermediaries
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28
Q

What hormone do sertoli cells release to slow sperm production?

A

Inhibin

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29
Q

Functions of sertoli cells

A
  1. Control release and movement of sperm cells
  2. Nourish sperm cells
  3. Prevent self-immune reaction
  4. Secrete inhibin to slow sperm production
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30
Q

What is it called when testicles fail to descend from the abdomen?

A

Cryptorchidism

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31
Q

How long does spermatogenesis take?

A

65-75 days

32
Q

Outline the process of spermatogenesis in three main steps

A
  1. Mitotic proliferation of spermatogonia
  2. Meiotic division (primary and secondary spermatocytes)
  3. Spermiogenesis (morphological change)
33
Q

What is the name of the cells that result from secondary spermatocytes undergoing Meiosis II?

A

Spermatid

34
Q

How many sperm does a man produce per day?

A

300 mil

35
Q

How long is a sperm?

A

60 micrometers

36
Q

What is the functional purpose of the elongated shape of sperm?

A

Adapted for reaching (flagellum) and penetrating (acrosome etc.) the egg

37
Q

What are the four key events of spermiogenesis?

A
  1. Acrosome development
  2. Flagellum Development
  3. Nucleus Condensation
  4. Shedding of excess cytoplasm
38
Q

Why is the nucleus of a spermatid condensed during spermiogenesis?

A

Protects DNA against damage -> protects against shearing forces during ejaculation

39
Q

Why do sperm shed cytoplasm during spermiogenesis? What isn’t shed?

A
  • Streamlined; better motility
  • Mitochondria remain for motility
40
Q

Are spermatogonia stem cells?

A

Indeed they are

41
Q

Can sperm fertilize an oocyte directly from the testes?

A

No; it needs to undergo maturation to gain motility

42
Q

What is the purpose of ducts in the male reproductive system?

A
  • Functional maturation
  • Nourishment
  • Storage
  • Transport
43
Q

What is the name of the tubule network that collects sperm from the seminiferous tubules?

A

Rete testis

44
Q

Where does sperm travel after making its way through the rete testis? What about after that?

A
  • From the rete testis, it moves to the efferent ducts
  • From here, it enters the epididymus
45
Q

What is another name for the vas deferens?

A

Ductus deferens

46
Q

How long is the epididymus?

A

7 fucking metres

47
Q

What are the functions of the epididymus?

A
  • Monitors and adjusts fluid composition
  • Recycling centre for damaged sperm (resorb and break down)
  • Stores and protects sperm
  • Concentrates sperm
  • Functional sperm maturation
48
Q

What part of sperm maturation occurs in the female reproductive tract?

A

Capacitation

49
Q

Proteins are secreted by the epididymus that bind to sperm and…

A
  • Stabilise sperm (withstand shearing forces)
  • Trigger flagellum to develop motility
50
Q

What class of hormones is sperm maturation dependent on? Why?

A
  • Androgens
  • Andorgens bind to epididymal cells which trigger protein release in sperm maturation
51
Q

How long is the vas deferens?

A

40-45cm

52
Q

What is the bulbous end of the ductus deferens called?

A

Ampulla of ductus deferens (like Roman Ampulla)

53
Q

How is sperm propelled along the ductus deferens?

A

The force comes from contraction of a thick layer of smooth muscle in the ductus deferens itself

54
Q

How long is the ejaculatory duct?

A

2cm

55
Q

Where is the ejaculatory duct located? What happens there?

A

Connects the ampulla of the ductus deferens and the seminal vesicle, and joins them to urethra.

56
Q

What are the three parts of the urethra, and where do they sit?

A
  • Prostatic (in prostate)
  • Membranous (in pelvic floor)
  • Spongy (in penis)
57
Q

What are the three accessory glands in the male reproductive system

A
  • Seminal vesicles (x2)
  • Prostate
  • Bulbourethral glands (x2)
58
Q

How long are seminal vesicles?

A

5cm

59
Q

Where are the seminal vesicles located relative to the bladder

A

Posterior wall of bladder

60
Q

What volume of semen is made of secretions from the seminal vesicles?

A

60%

61
Q

Describe the pH of seminal vesicle mucus-like fluid. Why is this the case?

A
  • Alkaline
  • Neutralise male urethra and female reproductive tract
62
Q

What are the key components of seminal vesicle fluid?

A
  • Fructose (sperm metabolism)
  • Prostaglandins (smooth muscle contractions in male and female reproductive tracts + motility and stability)
  • Fibrinogen (coagulate semen straight after ejaculation to protect from acidic environments)
63
Q

What is the prostate composed of (under a microscope)?

A
  • Cluster of 30-50 glands
  • Each drain into prostatic urethra
  • Surrounded by smooth muscle
64
Q

Prostate growth before puberty

A

Slow

65
Q

Prostate growth from puberty-30

A

Rapid

66
Q

Prostate growth 30-45

A

Slow & Steady

67
Q

Prostate growth 45+

A

May enlarge

68
Q

What volume of semen comes from prostatic secretions?

A

25-30%

69
Q

What are some key substances secreted from the prostate during ejaculation?

A
  • Citric acid (used for ATP production)
  • Proteloytic enzymes
  • Seminalplasmin (antibiotic; prevents bacterial infections)
70
Q

Describe the acidity of prostatic fluid

A

Slightly acidic (balanced by alkaline seminal vesicle secretions) -> makes sense: citric acid

71
Q

What proteolytic enzymes are in prostatic secretions?

A
  • Fibrinolysin (breaks down clotting proteins from seminal vesicles)
  • Prostate-specific antigen (can be used to test for enlarged prostate)
72
Q

What do the bulbourethral glands secrete, and why?

A

Secrete thick, alkaline mucus prior to ejaculation to:
- Neutralises urethra
- Lubricates glans penis

73
Q

What percentage of semen is seminal fluid, and what percentage is sperm?

A

Sperm: 10%
Seminal fluid: 90%

74
Q

What are the three main sections of a sperm?

A
  • Head
  • Mid-Piece
  • Tail
75
Q

Erection mech

A
  • Stimulation
  • Parasympathetic neurons release nitric oxide, dilating nearby arteries and causing increased bloodflow to cavernosal arteries is corporus cavernosa
  • Veins are compressed; blood accumulates in corporus cavernosa
  • Erection is maintained until parasympathetic contraction of arteries and smooth muscle, removing blood from penis
76
Q

Functions of testosterone

A
  • Spermatogenesis
  • Secondary sex traits
  • Libido
77
Q

Testosterone production and circulation mech

A
  1. GnRH from hypothalamus
  2. LH and FSH from Ant. Pituitary
  3. LH stimulated Leydig cells to release testosterone, and FSH stimulated sertoli cells to serete androgen binding protein (and Inhibin)
  4. ABP binds to testosterone, increasing local levels and causing spermatogenesis
    [note: high T levels have negative feedback on GnRH secretion]
  5. Circulating testosterone (entering from nearby blood vessels in the testes) increase libido and develop 2° sex traits

Foundations Of Medicine (98 decks)

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