Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Reproductive and Endocrine > Testes > Flashcards

Testes Flashcards

1
Q

What does the male reproductive system develop from?

A

The mesonephric duct and collecting duct tubules of the mesonephros, due to expression of the SRY gene.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the three accessory glands to the male reproductive tract?

A

Prostate gland, seminal vesicles, bulbo-urethral glands.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the two roles of the testes?

A

Produce sperm

Produce androgens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Where do all the highly convoluted seminiferous tubules connect?

A

To the rete testis in the mediastinum testis, which then empties into the head of the epididymis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the seminiferous tubules packed into within the testis?

A

Lobes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Why is it important that sperm are kept in the testis for a period of time?

A

So they can mature.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Which cells line the seminiferous tubules, and which cells are interstitial between the seminiferous tubules?

A

Sertoli cells line the seminiferous tubules and have tight junctions between then to form the blood-testes barrier. Leydig cells are outside of the basement membrane, in-between the seminiferous tubules.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the three layers of cells in the wall of the seminiferous tubule?

A

MYOID cells form a layer of smooth muscle cells outside the basal lamina.
BASAL LAMINA between the myoid cells and sertoli cells.
SERTOLI cells form inner epithelial layer.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the general role of the Sertoli cells?

A

Sustenacular cells which nuture the sperm and regulate development. They also have tight junctions to form the blood-testis barrier to prevent an immune response against the spermatozoa.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What happens to the blood-testes barrier in the absence of androgens?

A

It degrades. Androgens are required for a functional blood-testes barrier.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

During prophase 1, what are the sites called where homologous chromosomes swap sections of the chromatids (crossing-over)?

A

Chiasmata

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is different about the cell division in an oocyte compared to mitosis?

A

The cell division is UNEQUAL, so a polar body is formed and the oocyte receives most of the cytoplasm.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is different about the cell division in a spermatocyte compared to mitosis?

A

The cell division is INCOMPLETE, so the spermatids are still linked by cytoplasmic bridges.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the three phases of spermatogenesis?

A 
Mitotic proliferation (produces large numbers of cells)
Meiotic division (produces genetic diversity and halves the chromosome number)
Cytodifferentiation (package chromosomes for effective delivery to the oocyte)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What do mitotically arrested prospermatogonia become when they restart mitosis in puberty?

A

Spermatogonial stem cells (SSCs)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How many times can each spermatogonial stem cell divide by mitosis, and what do they produce?

A

Each SSC can divide up to 4 times and produce a Spermatogonium Type A1. So each SSC has the potential to produce 16 clones (Type A1 spermatogonia)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How many more mitotic divisions does each Type A1 spermatogonium undergo to reach the Type B spermatogonium, and what is produced at each step?

A

Type A1 spermatogonium undergoes 5 more mitotic divisions.
Type A1 spermatogonium -> Type A2 spermatogonium -> Type A3 spermatogonium -> Type A4 spermatogonium -> Intermediate Spermatogonium -> Type B spermatogonium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What does a Type B Spermatogonium divide mitotically to produce?

A

Resting primary spermatocyte

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What two things happen when the resting primary spermatocyte is produced?

A

Mitosis stops
The resting primary spermatocyte had to breach the blood-testes barrier by pushing its way through the tight junction to move from the basal compartment to the luminal compartment.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Why are the testes outside of the body cavity?

A

They are maintained at a slightly lower temperature than core body temperature, this could be because the very high rate of cell division produces a lot of excess heat.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What stage of the cell cycle are prospermatogonia in until puberty?

A

Interphase.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What happens when the primary spermatogonia enter the luminal compartment?

A

They complete meiosis I to form secondary spermatocytes (haploid). Secondary spermatocytes then complete meiosis II to form spermatids.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the name for the cytodifferentiation where the spermatids change shape from round to elongated, and develop a tail for motility?

A

Spermiogenesis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What happens to the Golgi body in spermiogenesis?

A

The Golgi apparatus migrates to one pole and forms the lysosomal like granules that coalesce to form the acrosome. The acrosome grows over the nuclear surface like a cap.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What happens to the centrioles in spermiogenesis?

A

The centrioles migrate to the opposite pole to the Golgi body, and microtubules extend from the distal centriole to form a flagellum.
The proximal centriole forms the neck which joins the tail to the head

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What happens to the nucleus during spermioogenesis?

A

The chromatin condenses, so the DNA become highly compacted so it can be packaged tighter and more efficiently.
Superfluous nucleoplasm and nuclear membrane are lost.

27
Q

What happens to the mitochondria during spermiogenesis?

A

They move to wrap around the flagellum in the middle piece.

28
Q

What happens to excess cytoplasm in spermiogenesis?

A

It is pinched off and leached away by the Sertoli cells.

29
Q

What is spermiation?

A

The cytoplasmic bridges of the syncytium rupture to release spermatozoa into the lumen.

30
Q

How is spermatogenesis organised in the seminiferous tubules, to ensure that the male always has spermatozoa ready to release?

A

Temporally organised - in any given section of the tubule, only one SSC will begin differentiation/division at a time.
Spatially organised - there is a spermatogenic wave along the tubule, so all the cells in each section are at the same stage, and adjacent sections are either advanced or retarded.

31
Q

Spermatogenesis proceeds at a characteristic and constant rate for each species, what proportion of the time taken is given to each of the stages?

A

Mitotic proliferation = 1/4
Meiotic division = 1/2
Cytodifferentiation = 1/4

32
Q

What three things happen to sperm in the epididymis?

A

Sperm are concentrated
Sperm are matured
Sperm are stored

33
Q

Why do sperm need to spend time in the epididymis?

A

To develop the capacity for motility and fertilisation

34
Q

Which cells in the testes does LH from the anterior pituitary act on?

A

Leydig cells, to stimulate them to produce testosterone (which is crucial for maintaining the blood-testes barrier).

35
Q

Which cells in the testes are stimulated by FSH, and what two things are they stimulated to produce?

A

Sertoli cells, stimulated to produce inhibin B (which suppresses FSH release) and androgen receptors.

36
Q

What are the two effects of inhibin B produced by the sertoli cells?

A

Inhibit FSH release

Act on Leydig cells and potentiate effect of LH so more testosterone is produced

37
Q

What do sertoli cells convert testosterone to, and which enzyme is involved?

A

Sertoli cells take up testosterone and convert it to dihydrotestosterone via the 5alpha reductase enzyme. Dihydrotestosterone is more potent and sustains the Leydig cells and supports spermatogenesis.

38
Q

How is testosterone carried to the accessory glands (prostate, seminal vesicles, bulbo-urethral glands)?

A

Through the lymph.

39
Q

In which tissues does 5alpha reductase act on testosterone to produce dihydrotestosterone?

A

Prostate gland, hair follicles

40
Q

In which tissues does androgen aromatase act on testosterone to produce oestradiol?

A

Testes, liver, fat and brain

41
Q

What sort of hormone is testosterone and where does it bind?

A

It is a steroid, so lipid soluble, and binds to androgen binding protein produced by the sertoli cells.

42
Q

How do testosterone levels effect release of LH?

A

Testosterone has a negative feedback effect on LH

43
Q

What happens at puberty that causes spermatogenesis to start?

A

The androgen level rises (before puberty the androgen level is minimal, so the blood-testes barrier is non-functional, so there is no spermatogenesis).

44
Q

What proportion of the volume of semen is made up of seminal fluid from the seminal vesicles, and what does it contain?

A

60% of semen
Contains fructose as an energy source for sperm, ascorbic acid as an antioxidant to counteract all the oxidants, prostaglandins. It has an acidic pH.

45
Q

What proportion of semen is made up of secretions from the prostate gland, and what does it contain?

A

20-30% of semen
Contains prostate specific antigen (high levels of which indicate a problem like benign prostate hyperplasia or prostate cancer), ions to keep the semen osmotically balanced (Ca2+, Mg2+, Cl-, Na+, K+)

46
Q

What proportion of semen is made up of secretions from the bulb-urethral glands, and what does it contain?

A

5% of semen

Contains mucus for lubrication

47
Q

What proportion of semen is from the vas deferens (spermatozoa)?

A

5%

48
Q

What is the total volume of semen?

A

2-5mls

49
Q

Which of the accessory glands is androgen-dependent (requires androgens to grow)?

A

Prostate gland

50
Q

What are 3 possible treatments for benign prostate hyperplasia and prostate cancer?

A

Goserelin - gonadotropin antagonist
Bicalutamide - androgen receptor antagonist
Finasteride - 5a reductase inhibitor

51
Q

What is the classification for sub fertility based on sperm count per ml?

A
52
Q

What is the classification for sub fertility based on total sperm count?

A
53
Q

What are the criteria to be fertile, based on sperm motility, progressive motility, and normal morphology?

A

> 40% of sperm must have motility
32% of sperm must have progressive motility (not swimming round in circles)
4% of sperm must have normal morphology

54
Q

What is the term for a low sperm count?

A

Oligozoospermia

55
Q

What is the term for complete absence of semen (e.g in retrograde ejaculation)?

A

Aspermia

56
Q

What is the term for complete absence of sperm in the semen?

A

Azoospermia

57
Q

What is the term for low motility of the sperm?

A

Asthenozoospermia

58
Q

What is the term for abnormal morphology of the sperm?

A

Teratospermia

59
Q

What effect does a higher temperature have on the testes?

A

Spermatogenesis destroyed, and steroidgenesis impaired.

60
Q

What causes an erection?

A

Sensory stimulation causes production of nitric oxide (a vasodilator).
Nitric oxide activates the enzyme which converts GTP to cGMP.
cGMP causes blood to be pushed into the corpus cavernosum of the penis from the crura.
Muscle spasm prevents blood leaving the penis so there is no blood flow at peak (this is tumescence).

61
Q

What causes detumescence?

A

The sensory stimulation stops, so levels of nitric oxide fall and the enzyme phosphodiesterase E5 (PDE5) breaks down cGMP into the inactive GTP, causing vasoconstriction.

62
Q

How does sildenafil work?

A

It inhibits the enzyme Phosphodiesterase E5, so cGMP isn’t broken down into inactive GTP, and the erection is sustained.

63
Q

How does alprostadil work?

A

Alprostadil is a prostaglandin E1 agonist and relaxes smooth muscle to increase blood flow to the penis.

64
Q

How do dopamine receptor agonists sustain an erection?

A

They indirectly relax smooth muscle and so cause vasodilation.

Reproductive and Endocrine (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions