Brainscape's Knowledge GenomeTM

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


See full index

Reproductive System > Origins Of Gametes > Flashcards

Origins Of Gametes Flashcards

1
Q

After colonising the gonad, germ cells…

A

Proliferate by mitosis
Reshuffle genetically and reduce to haploid by meiosis
Cytodifferentiate into mature gametes

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

What are the sex chromosomes of the different genders?

A 
XX = female
XY = male
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Which part of the gonad do the germ cells colonise in males and females?

A 
XY = colonise medulla
XX = colonise cortex
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Approximately how many gametes has a woman got per lifetime?

A

400

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

How many sperm do men produce per day?

A

~ 200 million

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

What are the 2 main functions of meiosis?

A

Reduce to haploid (chromosome number = 23)

Ensure every gamete is genetically unique

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

What happens to the 4 daughter cells of meiosis in females?

A

1 becomes the mature oocyte

3 become polar bodies

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

When does crossing over occur?

A

Prophase 1

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

In meiosis, genetic variation arises from …

A

Crossing over
Random segregation
Independent assortment

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

Describe crossing over

A

Exchange of regions of DNA between 2 homologous chromosomes

In prophase 1

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

Describe the passage of sperm from inner testis to vas deferens

A

Seminiferous tubules > rete testis > ductus efferentes > epididymis (head, body, tail) > vas deferens

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

What do we call male germ cells?

A

Spermatogonia

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

What is the difference between Ad and Ap spermatogonia?

A 
Ad = maintains stock of spermatogonia 
Ap = gives rise to primary spermatocytes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe the order of cells from spermatogonium to sperm

A

Spermatogonium > primary spermatocyte > secondary spermatocyte > spermatid > spermatozoa (sperm)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the spermatogenic cycle?

A

Time taken for reappearance of the same stage within a given segment of tubule
(~ 16 days in humans)

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

What is the spermatogenic wave?

A

The distance between parts in the same stage

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

Define spermiation

A

Spermatids released into lumen of seminiferous tubules

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

Where does the final stage of spermiogenesis occur?

A

Epididymis

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

Describe how transport occurs in epididymis

A

Via Sertoli cell secretions assisted by peristaltic contractions

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

How much semen is there per ejaculate?

A

2ml

21
Q

What percentage of semen volume comes from the seminal vesicles?

A

70%

22
Q

What is in the seminal vesicle secretions?

A

Amino acids
Citrate
Fructose (main energy for sperm)
Prostaglandins

23
Q

What percentage of semen volume comes from the prostate?

A

25%

24
Q

What is in the prostatic secretions?

A

Proteolytic enzymes eg. PSA

Zinc

25
Q

What percentage of semen is sperm?

A

2 - 5%

26
Q

How many sperm are there per ejaculate?

A

200 - 500 million

27
Q

What percentage of the volume of semen comes from bulbourethral glands?

A

< 1%

28
Q

What is the other name for bulbourethral glands?

A

Cowper’s glands

29
Q

What is secreted from bulbourethral glands?

A

Mucoproteins to help lubricate urethra and neutralise acidic urine in distal urethra

30
Q

What is sperm capacitation?

A

Final maturation step required before sperm become fertile
Occurring in the female genital tract
Removal of glycoproteins and cholesterol to activate signalling to allow sperm to bind to zona pellucida

31
Q

When are female gametes produced?

A

All before birth

32
Q

Approximately what age is menopause?

A

55 years

33
Q

Where do germ cells arise from?

A

Yolk sac

34
Q

Primary oocytes are arrested in which phase?

A

Prophase 1

35
Q

How many oocytes remain by puberty?

A

40,000

Others have undergone atresia

36
Q

Approximately how many oocytes start to mature every month?

A

15 - 20

37
Q

What are the 3 stages of maturation an oocyte must pass through?

A

Pre-antral
Natural
Pre-ovulatory

38
Q

Describe the pre-antral stage

A

Primordial follicles begin to grow
Surrounding follicular cells get more cuboidal and proliferate
Produce a stratified epithelium of granulosa cells which secrete glycoprotein

39
Q

Describe the antral stage

A

Fluid filled spaces appear between granulosa cells

These coalesce to form the antrum

40
Q

What do we call the granulosa cells surrounding the oocyte directly?

A

Cumulus oophorus

41
Q

What are the 2 layers of thecal cells?

A

Outer fibrous

Inner secretory

42
Q

Describe the pre-ovulatory stage

A

Surge in LH gives growth phase
Meiosis I completed
Cells enter meiosis II and arrest in metaphase
Meiosis II only completed if fertilised

43
Q

Describe ovulation

A

FSH and LH stimulate rapid growth of follicle
Mature follicle 2.5 cm diameter (Graafian follicle)
Ruptures to release oocyte - LH surge (to increased collagenase activity)

44
Q

What is the corpus luteum?

A

Remaining granulosa and theca interna cells become vascularised
Develop yellowish pigment and change into lutein cells
Secrete oestrogens and progesterone
Stimulate uterine mucosa to enter secretory stage - prep for embryo implantation
Dies after 14 days if no fertilisation

45
Q

What is the corpus albicans?

A

When no fertilisation occurs the corpus luteum degenerates forming a mass of fibrotic scar tissue
Progesterone production decreases - menstrual bleeding

46
Q

What happens to the corpus luteum if fertilisation occurs?

A

Degeneration prevented via hCG
CL continues to grow and forms the CL of pregnancy
Cells continue to secrete progesterone until 4th months until secretion by placenta is adequate

47
Q

What are the main differences between spermatogenesis and oogenesis?

A 
4 spermatids vs 1 ovum 
200 million/day vs 1 per 28 day cycle 
Starts at puberty vs starts in foetus 
Motile gametes vs non-motile 
Continues vs ends at menopause
48
Q

Why do males have a blood-testis barrier?

A

To prevent autoimmune attack on sperm (as will be genetically different to the father’s cells)

Reproductive System (17 decks)

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