Lecture 10: male reproductive Flashcards

1
Q

Where does reproductive tissue originate from

A

the mesoderm

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2
Q

what seeds the reproductive tissue

A

germ cells which originate from the yolk sac

-future gonads (allows for future SPERMATOGONIA or OOGONIA)

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3
Q

What is sex determination based on

A

presence of the Y chromosome

-male Y chromosome is ~ 30% smaller

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4
Q

What are the 4 parts of the male reproductive system

A
  1. Gonads (testes, site of spermatogenesis)
  2. Genital ducts (transport, storage)
  3. Accessory glands (secretions)
  4. Penis (External support structure)
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5
Q

structure of Testes

A
  • paired
  • 2.5cm diameter and 4cm long
  • 2 tunics
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6
Q

what are the 2 tunics of the testes

A
  1. Tunica Vaginalis
    - derived from peritoneum
    - external
  2. Tunica Albuginea
    - fibrous capsule
    - internal
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7
Q

What are the lobules of the testes

A
  • testes contain 200-300 lobules
  • each lobule has 1 - 4 coiled seminiferous tubules
  • in their wall holds SPERMATOGONIA
  • stem cells (names change with stage of development)
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8
Q

What is the seminiferous tubules

A
  • located within the testes
  • specific site of meiosis allowing for the creation of SPERMATOZOA
  • leads into the epididymis
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9
Q

What are the Interstitial Endocrine Cells (LEYDIG) and their function

A
  • found in the c.t. surrounding seminiferous tubules

- produce androgens (the most abundant and effective being testosterone, small amounts of estrogen)

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10
Q

What are the Steroli Cells and their function

A
  • aka sustentacular cell “nurse”
  • btw spermatogonia (stem cells)
  • forms the blood-testis barrier (attached to each other by tight junctions, form 2 compartments, protects developing sperm from immune system)
  • secretin inhibin (can inhibit GnRH & FSH, negative feedback in sperm production)
  • secrete androgen-binding protein (makes testosterone more water soluble, increases testosterone concentration in seminiferous tubules)
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11
Q

How many spermatozoa are produced daily approx)

A

400 million

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12
Q

what are the 3 structural divisions of spermatozoa

A
  1. genetic division (head)
  2. Metabolic division (midpiece)
  3. Locomotor division (Tail))
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13
Q

how long does spermatogenesis take approx.

A

24 days

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14
Q

what is the name of the specialized tip of the sperm head

A

Acrosome
-it is a specialized type of lysosome that contains hydrolytic enzymes (hyaluronidase) that permit the penetration of the head into the ovum

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15
Q

what is in the head of the spermatozoa

A

contains the nucleus with genetic material = DNA

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16
Q

what is the process called CAPACITATION

A

when mature spermatozoa must remain in female reproductive system for 10hrs before being able to fertilize the ovocyte
- during this period the membrane of the acrosome is thinned so that it is easier to release its enzyme

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17
Q

how long do spermatozoa live in the female reproductive system

A

~ 48 hrs

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18
Q

when is the capacity to fertilize at its maximum

A

btw 24 and 72 hrs

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19
Q

how many sperm are required for fertilization

A

only 1

-but need multiple to break down membrane of ovum

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20
Q

What is in the midpiece of the spermotozoa

A
  • contains mitochondria that supplies energy necessary for its propulsion (movement)
  • mitochondria are lined up in the midpiece
  • only the mothers mitochondria are transferred (paternal mitochondria are separated from the gentic info)
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21
Q

what is the function of the Tail of the spermatozoa

A
  • aka Flagellum (formed from microtubules)

- that serve for propulsion (propeller)

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22
Q

What hormonal regulation is promoted by spermatogenesis

A

the production of testicular androgens

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23
Q

Androgen hormones are ANABOLIC and allow for

A
  • stimulate synthesis of proteins

- allows for sexual dimorphism (e.g. male-female difference in body size and muscle mass)

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24
Q

What controls the homeostasis and regulation of androgen release

A

Brain-testicular axis

  1. hypothalamus
  2. Adenohypophysis (anterior pituitary)
  3. testes

-each component of the brain-testicular axis is controlled by the CNS

25
Q

What is GnRH

A

Gonadotropin-releasing hormone

26
Q

how does GnRH arrive at the adenohypophysis

A

by hypophyseal portal system

  • binds to pituitary (hypophyseal) cells
  • leads to release of gonadotrophins of the anterior pituitary (adenohypophysis)
27
Q

what is FSH and function

A

Follicle stimulating hormone

-development of seminiferous tubules and spermatogenesis

28
Q

what is LH and its function

A

Luteinizing hormone
-stimulates interstitial cells to secrete testosterone (also a bit of estrogen which is essential for normal development of bone)

29
Q

What are the testicular hormones that bring about inhibition of cells

A
  • testosterone & inhibin
  • Sertoli (sustentacular) cells secrete INHIBIN when spermatogenesis is sufficient (secrete less when spermatogenesis is insufficient)
30
Q

What is the Testosterone negative feedback mechanism

A
  • Elevated levels of testosterones
  • inhibits secretion of GnRH
  • Reduction in the release FSH & LH
  • Reduces testosterone production
31
Q

What is the basis of LIBIDO (sex drive)

A

Testosterone

  • for both sexes
  • females secrete via adrenal glands
32
Q

What is testosterone synthesized from

A

Cholesterol
-to be able to do it’s action, it must be converted to DHT (dihydrotestosterone) in certain target cells (e.g. testes, prostate, hair follicles, adrenal glands)

33
Q

what is the flow of spermtozoa

A
  • coiled semiferous tubules
  • tubules rectus (or straight tubules)
  • Rete testis

-fluid movement is controlled by testicular fluid pressure

34
Q

Structure and function of Epididymis

A
  • spermatozoa stay ~ 20 days
  • 4-6 meters long
  • if present many months they degenerate
  • increase surface of reabsorbtion of degenerated spermatozoa (phagocytosis)
  • reabsorb testicular fluid if in excess
  • feed spermatozoa
35
Q

What is Ductus (Vas) Deferens

A
  • ends at the Ampulla
  • it is about 45cm long (passes on the side of the urinary bladder, can take many months)
  • movement is controlled by PERISTALSIS
36
Q

Structure of the wall of ductus vas deferens and its function

A
  • pseudostratified columnar epithelium & 3 layers of smooth muscles
  • function: gamete storage
37
Q

What is a vasectomy

A

sectioning & ligature of ducts deferens

38
Q

Structure of the ejaculatory duct

A
  • ~ 2cm long
  • Formed by the union of 2 structures:
    1. AMPULLA of the ductus deferens
    2. Excretory duct of the seminal vesicle
  • movement is maintained by peristaltic contraction
39
Q

Structure of the urethra

A
  1. Prostatic urethra ~ 23cm in length
  2. Membranous urethra ~ 1cm
  3. Spongy / Penile urethra ~ 15cm
40
Q

Penis function

A
  • organ of copulation
  • delivery of sperm to female reproductive system
  • contains: body (shaft) & root
41
Q

Penis structure

A
  • made of 3 cylindrical bodies composed or erectile tissue (c.t & smooth muscle tissue riddled with vascular spaces)
  • there are 2 dorso-lateral bodies named Corpus (corpora) cavernosa
  • there is 1 medioventral body, smaller, called Corpus Spongiosum
  • Glans Penis = enlarged end of penis (skin covering called Prepuce = foreskin)
42
Q

What is circumcision

A

the removal of the prepuce via surgery

43
Q

What is location of the scrotum

A

exterior to the abdomino-pelvic cavity

44
Q

what is the structure scrotum

A
  • sac of skin containing the testes (divided in 2)

- the wall contains the Dartos (smooth muscle responsible for wrinkled appearance)

45
Q

What is the cremaster reflex

A

movement of scrotum away or closer to body for heat regulation
-Dartos and Cremaster (skeletal) adjusts height of testes

46
Q

Where does autonomic nervous system in scrotum receive it’s input from

A

from FSH of the endocrine system

47
Q

What do sympathetic and parasympathetic nervous system help with (scrotum)

A
  1. regulate testes temperature
  2. Irrigation: from abdominal aorta to testicular artery (testicular veins form the Pampiniform Plexus branches around the artery, it absorbs heat frm artery cooling it before it enters testes)
48
Q

What temp maximizes production of spermatozoa

A

when testes are 3 decrees C lower than the body

49
Q

What are the 3 different accessory gland types that emit secretions into the semen

A
  1. Seminal Vessicles (paired)
  2. Prostate (unpaired)
  3. Bulbourethral Gland (paired)
50
Q

What is structure and location of seminal vesicles

A

-convoluted pouches 5 to 7 cm long on posterior surface of bladder

51
Q

What is function of seminal vesicles

A

secrete the viscous, alkaline, nutrient-rich part of seminal fluid (60% of semen volume)

52
Q

What is structure and location of prostate gland

A
  • Doughnut shaped

- Encircles urethra just below bladder

53
Q

What is function of prostate gland

A

adds slightly acidic, watery, milky-looking secretion to seminal fluid (30% of semen volume)

54
Q

What is structure and location of Bulbourethral glands (glands of Cowper)

A
  • small pea-shaped structures with approx. 2.5cm long (1 inch) ducts leading into urethra
  • lie below prostate gland
55
Q

What is the function of Bulbourethral glands

A

-secrete fluid that is part of semen (5% of semen volume) during erotic stimulation

56
Q

What is appearance (origin of this appearance) of Semen

A
  • Whitish liquid (frm prostate)

- Slightly Sticky / Viscous (frm seminal vesicles & bulbourethral glands)

57
Q

What does semen contain

A

spermatozoa (50 - 130 million/ml)

secretions of all the accessory glands

58
Q

What is the pH of semen

A

7.2 - 7.6

59
Q

How much semen is secreted in ejaculation

A

~25ml