male reproductive system Flashcards

1
Q

the male reproductive system produces what cells

A

sperm cells
which can be transferred to female

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2
Q

in what way is the male reproductive system different to females

A

anatomically

as Some hormones are same, but act in very different ways

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3
Q

what is the scrotum and what compartments is it divided into

A

Pouch containing testes
- L lower than R to avoid compression between thighs

Divided into R & L compartments
- by internal median septum
- Externally marked by seam
(perineal raphe)

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4
Q

what temp is required for sperm production

A

<37oC

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5
Q

name the 3 mechanisms for regulating testes temperature

A

cremaster muscle
dartos muscle
pampiniform complex

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6
Q

how does the cremaster muscle regulate testes temp

A

strips of internal abdominal oblique muscle, contracts when cold to draw testes nearer body

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7
Q

how does the dartos muscle regulate testes temp

A

subcutaneous layer of smooth muscle, contracts when cold, so taut & wrinkled

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8
Q

how does the pampiniform complex regulate testes temp

A

extensive vein network, cools blood [by 2oC] & testis [so sperm formed] by acting as a ‘countercurrent heat exchanger’.

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9
Q

explain the Countercurrent Heat Exchanger

A

blood flowing towards testis is leaving body at body temperature (37oC) but since the vessels (arteries) are close to the cooler blood from the testis entering the body, heat is lost (exchanged) and so blood enters the testis at the cooler temperature of 35oC, required for sperm production.
The cooler blood coming from the testis then gains heat from nearby vessels containing blood flowing in the opposite direction, so enters the body at a warmer temperature.

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10
Q

explain testes shape

A

Each testis is oval (4x2.5cm)

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11
Q

what glands do testes have

A

Both exocrine (sperm) & endocrine (testosterone ) glands

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12
Q

whats the outer cover of the testes called

A

tunica vaginalis

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13
Q

whats the White fibrous capsule of the testes called

A

tunica albuginea

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14
Q

what doe the Connective tissue septa divide testes organ into

A

300 cone/wedge-shaped lobules

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15
Q

each testes lobule conatins how many seminiferous tubules

A

1-3

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16
Q

what are seminiferous tubules

A

slender ducts [70cm long] where sperm produced

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17
Q

what between the Between sem.tub. (seminiferous tubules) in testes

A

clusters of interstitial cells [cells of Leydig], producing testosterone

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18
Q

what are sem.tub. (seminiferous tubules) lined by

A

several layers of germ cells (in process of becoming sperm) & fewer tall sustentacular [Sertoli] cells

  • provide nutrients, waste removal, growth factors; secrete inhibin –> which regulate rate of sperm production
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19
Q

Spermatogenesis occurs where

A

in the seminiferous tubules

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20
Q

how does spermatogenesis start and what happens

A

it starts at the outer edge of the tubule (at the top of the diagram) and sperm matures towards the lumen of the tubule (at the base of the diagram), to become a spermatozoon.

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21
Q

what forms the blood-testies barrier (BTB)

A

Tight junctions between adjacent Sertoli cells

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22
Q

what does the blood testes barrier prevent and whys this important

A

proteins & other large molecules from getting to germ cells, i.e., prevent attack from immune system

  • Important because germ cells are genetically different from other cells of body
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23
Q

what occurs when Blood testes barrier fails to form adequately in adolescence

A

sterility
- immune system produces autoantibodies against the germ cells.

24
Q

name the components of the Germinal epithelium of testis

A

1.Basal lamina
2.Spermatogonia
3.Spermatocyte 1st order
4.Spermatocyte 2nd order
5.Spermatid
6.Mature spermatid
7.Sertoli cell
8.tight junction (BTB)

1 starts at bottom of layer, cells 2 -6 go all the way up to 6 which is top of layer

8 is where the 2 sertoli cells(7) join, which is just above cell 2

number 7 are the big cells which the rest surround

25
Q

what are the Rete Testis (pronounced reetee)

A

Seminiferous tubules [combined length ~1/2 mile] lead into a network called the rete testis
(250 to 300 metres of seminiferous tubule per testis)

Where sperm partially mature

26
Q

Sperm is moved along by what

A

by flow of fluid secreted by sustentacular cells & possibly by cilia on some rete cells

Sperm do NOT swim while in the male reproductive tract!!!!!

27
Q

Testes begin development where

A

near kidney

28
Q

explain the process of testes development (descend)

A

In foetus, testis goes through a passageway
- inguinal canal [weak spot inguinal hernia]

As testes descend
- accompanied by ever-elongating testicular arteries, veins, lymphatic vessels, nerves, sperm ducts & extensions of internal abdominal oblique muscle

29
Q

how many boys in uk are born with undescended testicles and why and what can be done

A

5%

infertility as testes too warm for spermatogenesis

correct with hormone injections or surgery

30
Q

where does sperm go after leaving testis

A

sperm travel through series of 4 ducts to reach outside

31
Q

name the 4 ducts that sperm travel through when leave testes

A

12 Efferent Ductules

Epididymis

Vas Deferens (ductus deferens)

Ejaculatory Duct

32
Q

explain the process and ducts used for sperm to travel through to exit the testes

A

Rete of Testis

then to:

12 Efferent Ductules:
- with clusters of ciliated cells to help drive sperm along

then to:
Epididymis
- Comma-shaped [head, body, tail] with 6m coiled duct where sperm matures

then to:

Vas Deferens (ductus deferens)
- Up through inguinal canal, down behind bladder, widens into ampulla, unites with duct of seminal vesicle

then to:
Ejaculatory Duct
- Where vas deferens & duct of seminal vesicle meet

33
Q

what happens in the epididymis spermatic duct

A

Sperm matures over 20 days

Stored sperm fertile for ~50 days

Duct reabsorbs 90% fluid secreted by testis

34
Q

what happens in the Vas Deferens spermatic duct

A

SMCs (smooth muscle cell) produce peristaltic contractions during ejaculation

  • drive sperm from epididymis to ejaculatory duct
35
Q

name the 3 sets of accessory gland

A

Seminal Vesicles (pair of)

Prostate Gland

Bulbourethral (Cowper) Glands

36
Q

explain the accessory glands Seminal Vesicles

A

theyre a pair

Posterior to urinary bladder

1 associated with each vas deferens

Size of little finger, complex labyrinth

Secretion ~60% of semen

37
Q

explain the Prostate accessory Gland

A

Surrounds urethra & ejaculatory duct

Walnut-sized

Aggregate of ~50 glands

Empty thro’ ~20 pores in urethral wall

Thin, milky secretion ~30% semen

38
Q

explain the Bulbourethral (Cowper) accessory Glands

A

Pair brownish, spherical 1cm diameter

Inner (near body) end of penis

Ducts lead into penile urethra

During sexual arousal produce clear, slippery fluid, lubricates head of penis & neutralises acidity of residual volume

39
Q

what 2 systems share the male urethra

A

urinary & reproductive systems

40
Q

how long is the male urethra

A

20cm

41
Q

explain the shape of the male urethra

A

S-shaped
- down from bladder, anterior at root of penis, down into penis

42
Q

what are the 3 regions of the male urethra

A

Prostatic
- near bladder

Membraneous
- passes through muscular floor of pelvic cavity

Penile

43
Q

what does the penis do in terms of for reproduction

A

Deposits semen in vagina

44
Q

explain the structure of the penis

A

3 columns of erectile tissue (fill with blood to enlarge & engorge):
- 2 corpus cavernosa
- 1 corpus spongiosum (forms cap = glans)

Loose fold of skin
- foreskin,covers glans

Root of penis
- bulb (from corpus spongiosum)
- crus (from corpus cavernosa)

45
Q

what is semen and how much is produced

A

seminal fluid
2-5ml per ejaculation

46
Q

what does semen compose of

A

60% seminal vesicle fluid

30% prostatic fluid

10% sperm & spermatic duct secretions

trace bulbourethral fluid

47
Q

what should sperm count be and what is it if someones infertile

A

Sperm count = 50-120 million sperm/ml

Infertility if <15 million/ml

48
Q

explain the structure of the mature spermatozoan

A

head:
- acrosome
- nucleus
-neck

tail:
- mitochondria
- middle piece
- principal piece
- end piece

49
Q

explain the composition of semen

A

Spermatozoa
- digest path through cervical mucus, fertilise egg

Fructose
- energy for sperm motility

Fibrinogen
- causes semen to clot
- clotting enzymes -> converts fibrinogen to fibrin after ejaculation, so semen clot & adhere to vagina/cervix

Fibrinolysin
- liquefies semen after 15 min ejaculation to liberate sperm

Prostaglandins
- reduce viscosity of cervical mucus

Spermine
- neutralise vaginal acidity

50
Q

what happens in a vasectomy

A

1cm segment of ductus deferens removed

Spermatozoa cannot pass
- Scar tissue forms permanent seal

Ejaculation seems ‘normal’ to the male
- Secretions of epididymis & testes semen volume only 5% total

Spermatozoa continue to develop but remain within epididymis until they degenerate

51
Q

explain ejaculation once having a vasectomy

A

still ejaculate but semen contains no sperm

sperm and hormones can still be produced but not ejaculated as vas defences cut

52
Q

inhibin is secreted by what cells

A

Sertoli cells

53
Q

what does inhibin do

A

reduce FSH secretion & sperm production without reducing LH & testosterone secretion

54
Q

what happens when inhibin secretion when sperm count drops

A

When sperm count drops
<20 million sperm /ml,
inhibin secretion drops &
FSH secretion rises to stimulate sperm production

55
Q

what happens to males at puberty

A

Hypothalamus becomes less sensitive to inhibitory effect of androgens

Rate of GnRH secretion increases

Increased FSH
- sperm cells formed)

LH release
- interstitial Leydig cells secrete more testosterone