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Foundation to Bioscience 2 > Reproductive system > Flashcards

Reproductive system Flashcards

1
Q

How are gametes produced?

A

Via the process of meiosis

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2
Q

List some of the advantages of sexual reproduction compared to asexual reproduction

A

Creates variations among individuals, thus increasing the chance of survival, which leads to species preservation
Unfavourable genes will be eventually removed

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3
Q

Disadvantages of sexual reproduction compared to asexual reproduction

A

Need male and female
Need effort to choose mates
May prevent favourable genes from being passed on to offspring
Produces fewer offspring than asexual reproduction

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4
Q

Define the term ‘gonad’

A

The organ where gametes are produced. They also produce hormones that control secondary sexual characteristics

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5
Q

Name the gonad in males

A

Testis

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6
Q

Name the gonad in females

A

Ovary

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7
Q

Define the term ‘germ cells’

A

Any cell in the series of the germ line that eventually become gametes
Often indicate the cells before meiosis during spermatogenesis and oogenesis

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8
Q

What are the germ cells in females?

A

Oogonia

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9
Q

What are the germ cells in males?

A

Spermatogonia

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10
Q

What are primordial germ cells?

A

The origin of germ cells
Arises and stay in the posterior yolk sac
At 4-6 weeks in human, migrate into the gonad and then reside as germ cells

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11
Q

When do the semibiferous tubules mature?

A

They mature at puberty because of testosterone

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12
Q

What type of cell is the resident stem cell population of the seminiferous tubule of the testis?

A

Spermatogonium

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13
Q

What are testes made of?

A

Seminiferous tubules, which is where meiosis occurs in males

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14
Q

Define the term ‘spermiogenesis’

A

The differentiation step of spermatids to become a highly specialised spermatozoa

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15
Q

Give the main stages of spermiogenesis (5)

A
  • Nucleus condense
  • Formation of the acrosome
  • Formation of the flagellum
  • Mitochondria gathered at the midpiece
  • Removal of excess cytoplasm
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16
Q

What is the acrosome?

A

A secretory vesicle containing enzymes required for penetrating the oocyte

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17
Q

What is the flagellum?

A

a tail-like structure homologous to cilia

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18
Q

Why do sperm need a lot of mitochondria?

A

For the moving flagellum

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19
Q

When does spermiogenesis take place?

A

Spermiogenesis takes place when spermatids are still surrounded by Sertoli cells.

20
Q

Describe sertoli cells

A

Span from the basement membrane to the lumen, thus surrounding differentiating spermatogonia
Produce enzymes and growth factors required for spermatogenesis
Also function as a phagocyte to clean-up residual cytoplasm of sperm

21
Q

What are Leydig cells?

A

Leydig cells are interstitial cells that reside outside of seminiferous tubules. They secrete testosterone in response to LH

22
Q

What is spermiation?

A

The process of sperm being released in to the lumen from the sertoli cells

23
Q

What’s the epididymis?

A

A highly convoluted duct behind the testis, along which sperm passes to the vas deferens.

24
Q

Define the term ‘infertility’

A

An inability to conceive within 12 months

25
Q

List the causes of male infertility

A
  • Primary hypogonadism (Kleinfelter, cryptorchidism (absence of testes), chemotherapy, radiation, torsion etc) (30-40%)
  • Secondary hypogonadism (hypothalamic-pituitary disease) (2%)
  • Disordered sperm transport (10-20%)
  • Unknown (40-50%)
26
Q

Define ‘oogenesis’

A

The production or development of an ovum.

27
Q

What are the germ cells in females called when they enter the first phase of meiosis?

A

Primary oocytes

28
Q

One follicle=

A

One oocyte + surrounding follicular cells

29
Q

Why are polar bodies formed in female meiosis?

A

In the meiotic cell division, most of the cytoplasm is taken by one, so as not to waste cytoplasm

30
Q

What is the germ cell called when ovulation takes place?

A

A secondary oocyte

31
Q

Define the term ‘primordial follicle’

A

A primary oocyte with an enlarged cytoplasm, with a flat one-cell layer of follicular (granulosa) cells. The dormant status

32
Q

What are primary follicles?

A

Follicles chosen to re-commence growth. Follicular cells become cuboid and proliferate into multiple layers

33
Q

Define the term ‘zona pellucida’

A

A layer of glycoprotein, translucent.

34
Q

What are secondary follicles?

A

A follicle with antrum (a cavity) with fluid from granulosa cells

35
Q

What are preovulatory follicles?

A

Among several secondary follicles, one is chosen to mature for ovulation

36
Q

When is the first day of the menstrual cycle?

A

The first day of menstruation.

37
Q

What causes the endometrial lining to thicken?

A

After day 5, the follicle and thecal cells proliferate and secrete oestrogens. Oestrogens in turn cause the endometrial lining of the uterus to proliferate.

38
Q

What induces ovulation?

A

On about day 13 or 14, levels of FSH and LH suddenly rise very sharply, which induces ovulation and progresses meiosis

39
Q

What is ovulation?

A

The expulsion of the secondary oocyte from the follicle. It takes place about 38 hours after the LH surge

40
Q

What happens after ovulation?

A

After ovulation, the remaining follicle becomes a corpus luteum and secretes oestrogen and progesterone. This leads to the endometrium secretory phase, preparing for implantation

41
Q

What happens if implantation of a fertilised egg doesn’t take place?

A

If implantation doesn’t occurs, the corpus luteum degenerates after 14 days and becomes a scar-like structure called corpus albicans)

42
Q

When sperm reach the oocyte, what do they have to do in order to fertilise it?

A

When they encounter the oocyte, the sperm has to;

a) migrate through the layer of follicular cells (corona radiata)
b) penetrate the zona pellucia using enzyme in acrosome
c) fuse the plasma membrane to that of oocyte

43
Q

When does the second meiotic division of oocytes happen?

A

The second division of meiosis of oocyte completes when the sperm enters

44
Q

Describe implantation of the fertilised eg

A
  1. Blastocyst attaches to the endometrium at the embryonic pole
  2. Some trophoblast cells invade the endometrium, beginning to form a part of the placenta
  3. The inner cell mass becomes a flat sheet consisting of epiblasts and hypoblasts
  4. The amniotic cavity appears on the epiblast side
  5. human chorionic gonadotrophin (hCG), produced by the syncytiotrophoblast, enter the maternal blood
45
Q

What does human chorionic gonadotrophin do?

A

hCG maintains the hormonal activity of the corpus luteum in the ovary. The corpus luteum secretes estrogen and progesterone to maintain pregnancy.

Foundation to Bioscience 2 (15 decks)

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