Lecture 35: Male Reproductive System II Flashcards

1
Q

What six things does the scrotum contain?

A
  • two testes
  • two epididymides
  • two spermatic cords
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2
Q

What are three mechanisms that help regulate the body temperature of the testes?

A
  • the dartos muscle
  • the cremaster muscle
  • the venous plexus
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3
Q

Why does the scrotum house the testes away from the body at a temperature of about 34 °C?

A

because the optimal temperature for spermatogenesis is less than the 37°C of our internal body temperature

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4
Q

What is the dartos muscle and what is its role?

A

This lines the scrotum and its role is to contract and relax to wrinkle and unwrinkle the scrotum to maintain the temperature as needed

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5
Q

What is the effect of temperature on the testes when the dartos muscle is contracted and why?

A

when contracted, the dartos muscle causes the scrotum to wrinkle which reduces the surface area available for heat exchange so heat is retained

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6
Q

What is the effect of temperature on the testes when the dartos muscle is relaxed and why?

A

when relaxed, the dartos muscle causes the scrotum to unwrinkle which increases the surface area available for heat exchange so heat is lost

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7
Q

What is the cremaster muscle and what is its role?

A

This encloses the spermatic cord and testis which contracts to draw the testes up closer to the body to warm the testes up

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8
Q

When is the cremaster muscle contracted?

A
  • when it is cold to try and conserve heat

- during arousal for protection during intercourse

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9
Q

Where does the spermatic cord run?

A

between the abdomen and the testes

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10
Q

What 5 things does the spermatic cord contain?

A
  • ductus deferens
  • testicular arteries
  • testicular veins
  • nerves
  • lymphatics
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11
Q

The testicular veins form a network called the

A

venous plexus/pampiniform plexus

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12
Q

What is the role of the venous plexus/pampiniform plexus in terms of temperature regulation?

A

heat is transferred between the arteries entering the testes and the veins exiting the testes to regulate temperature

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13
Q

What are the two functions of the penis?

A
  • urination

- copulation

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14
Q

Define copulation

A

sexual intercourse

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15
Q

What are the three sections of the penis?

A

the root
the body
the glans covered by the foreskin

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16
Q

Where is the root of the penis located?

A

it adheres to the body wall

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17
Q

What is within the root of the penis?

A

the left and right crus

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18
Q

When erect, is it the dorsal or ventral side of the penis that lies against the body?

A

the dorsal side

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19
Q

When flaccid, is it the dorsal or ventral side that lies against the scrotum?

A

ventral

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20
Q

What three cylindrical erectile tissues does the penis contain?

A
  • two corpora cavernosa (singular is corpus cavernosum)

- one corpus spongiosum

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21
Q

What is the main erectile tissue? Where is this located?

A

the corpora cavernosa on the dorsal aspect

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22
Q

Which of erectile glands contains the urethra? Where is this located?

A

corpus spongiosum which forms bulb and glans on the ventral aspect

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23
Q

Why are the corpora cavernosa the main erectile tissue and not the corpus spongiosum?

A

because the corpora cavernosa contain the deep arteries whereas the corpus spongiosum contains the urethra and we don’t want the urethra closing over during ejaculation

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24
Q

What makes up semen?

A

the seminal fluid and the spermatozoa

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25
Q

Seminal fluid is mostly produced by which three accessory glands?

A
  • seminal vesicles
  • prostate gland
  • Bulbourethral glands
26
Q

Where are the seminal vesicles located?

A

posterior to the bladder, lateral to the ampulla

27
Q

What do the seminal vesicles produce?

What percentage of semen does this make up? What is the secretion?

A
  • produces viscous secretion
  • makes up 60% of semen
  • the secretion is an alkaline pH
28
Q

Why is the secretion from the seminal vesicles alkaline?

A

to protect the sperm against the acidic environment in the male urethra and the vagina

29
Q

Where is the prostate gland located?

A

inferior to the bladder, wrapped around the prostatic urethra

30
Q

What does the prostate gland produce?

What percentage of semen does this make up? What is the secretion?

A
  • slightly acidic, milky fluid
  • makes up 30% of semen
  • contains PSA (prostate-specific anigen)
31
Q

What is the purpose of the secretion from the prostate gland?

A

it contributes to sperm activation, viability and motility

32
Q

Where are the Bulbourethral glands located?

A

two glands located in the urogenital diaphragm

33
Q

What does the Bulbourethral glands open into?

A

spongy/penile urethra

34
Q

What volume of semen does the secretions of the Bulbourethral glands make up?

A

5%

35
Q

What is purpose of the secretions from the Bulbourethral glands?

A

it lubricates and neutralises the acidity in the urethra prior to ejaculation

36
Q

What is a vasectomy?

A

when the ductus deferens is cut to ensure sterilisation

37
Q

What is gametogenesis?

A

formation of the gametes

38
Q

What is formation of sperm called?

A

spermatogenesis

39
Q

What is formation of the eggs called?

A

oogenesis

40
Q

Gametogenesis is under ______ control and occurs via ________ and ________

A

hormonal
mitosis
meiosis

41
Q

Briefly describe meiosis

A

the original cell has 46 chromosomes (2n) and there are two cycles to produce gametes (n):

  • meiosis I: 2 haploid cells produced from 1 original diploid cell
  • meiosis II: each cell produced from meiosis I divides to produce two haploid cells with 23 chromosome cells
42
Q

What is the stem cell of sperm?

A

spermatogonia

43
Q

What is spermatogenesis?

A

the process by which spermatogonia are transformed to mature spermatozoa

44
Q

Where does spermatogenesis occur?

A

in the seminiferous tubules

45
Q

Describe the process of spermatogenesis

A

Spermatogonia divide by mitosis into two daughter cells (2n). One of the daughter cells (type A) stays in the basement membrane of the seminiferous tubule and the other (type B) differentiates into a primary spermatocyte (2n) which undergoes meiosis. This forms a secondary spermatocyte (n) but with two chromatids. These undergo meiosis 2 to form spermatids (n).

46
Q

What do spermatids differentiate into?

A

spermatozoa with a head, body and tail via spermiogenesis

47
Q

What happens once the spermatids have been differentiated into spermatozoa?

A

the sperm is released into the lumen

48
Q

What is the difference between spermiogenesis and spermatogenesis?

A
  • spermatogenesis is the process by which spermatogonia are transformed to mature spermatozoa
  • spermiogenesis is the differentiation of spermatid to spermatozoa
49
Q

What are some differences between round spermatids and structurally mature sperm and why are these differences important?

A
  • there is an acrosome over the nucleus in the head which is needed for penetration during fertilisation
  • there is mitochondria in the body of the sperm for energy to get through the female reproductive tract
  • there is flagella for movement through the female reproductive tract
50
Q

What are the four purposes for the seminal fluid?

A

it provides a transport medium, it provides the sperm with nutrition and energy, protection against the urethra and it helps activate sperm to start the beating of the flagella

51
Q

What is a gonadotropin?

A

hormone that acts on the gonads

52
Q

What is the role of GnRH? Where is it produced?

A

it is gonadotropin releasing hormone produced by the hypothalamus that stimulates the release of LH and FSH

53
Q

What is Luteinising hormone (LH)? Where is it produced?

A

it is a gonadotropin produced by the anterior pituitary gland

54
Q

What is follicle stimulating hormone? Where is it produced?

A

it is a gonadotropin produced by the anterior pituitary gland

55
Q

Where is inhibin secreted from?

A

the nurse (sertoli) cells

56
Q

Where is testosterone produced?

A

the interstitial endocrine (Leydig) cells

57
Q

Testosterone is a type of androgen. What is an androgen?

A

it has effects that stimulate the male reproductive system

58
Q

What is testosterone responsible for?

A

male characteristics (maturation of the sex organs, spermatogenesis, secondary sex characteristics, libido)

59
Q

Describe the negative feedback loop of the hormone production

A

GnRH is produced in the hypothalamus and and it travels into the anterior pituitary gland to stimulate the secretion of LH. This travels to the Leydig cells which releases testosterone. Testosterone is responsible for spermatogenesis and secondary characteristics locally in the seminiferous tubules. It also travels in the blood back to the anterior pituitary gland to stop the release of LH and to the hypothalamus to stop the release of GnRH.
GnRH also stimulates the release of FSH from the anterior pituitary gland which controls speratogenesis and travels to the nurse cells to stimulate inhibin secretion which inhibits further release of FSH

60
Q

Spermatogenesis is the formation of ________ from spermatogonia

A

spermatozoa

61
Q

Four spermatozoa are produced from one primary _________

A

spermatocyte

62
Q

Spermatogenesis is regulated by a negative feedback loop with hormones produced by the hypothalamus and anterior _______, and the interstitial endocrine and __________ cells in the testes

A

pituitary

nurse