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WJEC A2 Biology > Human Reproduction- Unit 4.1 > Flashcards

Human Reproduction- Unit 4.1 Flashcards

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1
Q

What is the labia majora?

A

Outer fold of flesh covering female’s vagina.

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2
Q

What is the labia minora?

A

Th inner fold of the vagina.

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3
Q

What do the labia majora and minora both do?

A

Help protect the vagina and urethra

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4
Q

What is the urethra?

A

A small tube carrying urine from the bladder, outside the body. (also semen in men)

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5
Q

What are the characteristics and functions of the vagina? (6)

A

-Soft
-Muscular elastic tube
-Moist
Secrete lubricant for intercourse
Birth canal
Allows menstrual flow to exit body

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6
Q

What is the uterus?

A

Pear shaped organ that stretches to house baby, placenta and amniotic fluid.
Is strong and muscular.

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7
Q

What is at the bottom of the uterus?

A

The cervix

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8
Q

Describe the cervix:

A

Slightly open in women but is plugged during pregnancy to avoid infection.

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9
Q

What is the function of the uterus lining?

A

Sheds every month if fertilisation does not occur.
Grows new lining for possibility of pregnancy for embryo to embed itself.

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10
Q

Function of fallopian tube?

A

Allows egg to be transported from ovary to uterus.
Journey takes about 3 days.
Fertilisation usually occurs here.

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11
Q

What are the fimbria?

A

Finger-like structures at the end of fallopian tubes

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12
Q

What are the cilia?

A

Internal, hair-like structures inside the fallopian tubes which help the egg move down the tube.

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13
Q

What are the functions of the ovaries?

A

Two egg shaped organs which contains all ova that the woman will ever produce.
Ovaries only house the eggs and release one every month (ovulation)

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14
Q

What is the scrotum?

A

A sac of loose skin which houses the testicles

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15
Q

What is the epididymis?

A

At the top of the scrotum and the end of the vas deferens.
When puberty occurs, sperm move to the epididymis to mature.

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16
Q

What is the vas deferens?

A

Allows sperm to move into the seminal vesicle. It curves around the top of the bladder and back down.

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17
Q

What is the seminal vesicle?

A

A gland located behind the bladder which produces fluids which activate sperm.

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18
Q

What is the prostate gland?

A

Is located just below bladder and supplies most of the liquid combined with the sperm prior to ejaculation.
Strong muscle contractions in & around prostate gland contract rapidly to force semen out of urethra.

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19
Q

What is the Cowper’s gland?

A

Rests just under prostate gland. It secretes fluid which removes acidity from the urethra before ejaculation, enhancing survival of sperm.

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20
Q

Describe the penis:

A

-Has spongy tissues containing blood vessels and nerves.
-This fills with blood during erection.

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21
Q

What is at the very tip of the penis?

A

The glans- covered sometimes by the foreskin if it is present

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22
Q

What is spermatogenesis?

A

(production/development of mature spermatozoa)
-Sperm develop in seminiferous tubules.
-The walls of these tubules are made of cells undergoing spermatogenesis.
-Approx 2 months to produce and 14 hrs to mature in epididymis.

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23
Q

What is the order of cells in spermatogenesis?

A
  1. Primordial germ cell
    (mitosis)
  2. Spermatogonium
    (mitosis)
  3. Primary spermatocyte
    (meiosis l)
  4. Secondary spermatocyte
    (meiosis ll)
  5. Spermatids (1n)
    (mature)
  6. Spermatoza (1n)
    (4 produced for every 1 primordial germ cell)
24
Q

What is oogenesis?

A

The production and development of ova.

25
Q

Where does oogenesis take place?

A

In the ovary up to the secondary oocyte

26
Q

When does oogenesis take place?

A

Begins in ovary of fetus and stops until a girl reaches puberty. It then continues with one cell maturing each month.

27
Q

What is the order of the cells in oogenesis?

A

1.Primordial germ cell
(mitosis)
2.Oogonium
(mitosis)
3.Primary oocyte
(meiosis l)
4.Polar body (1n) (& secondary oocyte)
(meiosis ll)
5.Ovum (1n)

28
Q

What are the similarities between spermatogenesis and oogenesis?

A

-Both begin with primordial germ cell
-Both go through mitosis, meiosis l and meiosis ll.

29
Q

Differences between spermatogenesis and oogenesis?

A

-1 ovum produced but 4 spermatozoa produced.
-Polar bodies produced in oogenesis, none in spermatogenesis.
-Spermatogenesis continues throughout male’s life, oogenesis is limited.

30
Q

What are the 4 hormones in control of the menstrual cycle? Where are they produced?

A

FSH- Anterior Pituitary Gland
LH- Anterior Pituitary Gland
Oestrogen- Graafian Follicle
Progesterone- Corpus Luteum

31
Q

What does FSH do?

A

Stimulates maturation/development of Graafian follicle and stimulates production of oestrogen

32
Q

Following menstruation, oestrogen levels increase, triggering…

A

The repair of the endometrium, inhibiting FSH production and stimulates LH production

33
Q

What does a high level of LH cause?

A

Ovulation and Graafian follicle to develop into a corpus luteum (which produces more oestrogen & progesterone)

34
Q

What does progesterone secretion cause?

A

Further development of endometrium prior to menstruation.
Inhibits FSH & LH, stopping follicle development.

35
Q

What hormone levels drop if implantation does not occur? What does this cause? (3)

A

Low FSH and LH cause corpus luteum to degenerate.
Progesterone cause endometrium break down which is lost during menstruation.

36
Q

Describe days 1-5 of the menstrual cycle:

A

FSH peaks
-Stimulates development of Graafian follicle and its theca to produce oestrogen

37
Q

Describe days 6-12 of menstrual cycle:

A

Oestrogen levels increase
-Promotes repair of endometrium
-Stimulates LH production
-Inhibits FSH (leading to less oestrogen)

38
Q

Describe days 13-14 of the menstrual cycle:

A

LH peaks
-Stimulates ovulation in presence of oestrogen, development of corpus luteum for it to produce progestrone

39
Q

Describe day 15-24 of menstrual cycle:

A

Progestrone increases
-Promotes thickening & growth of blood vessels in endometrium
-Inhibits production of FSH and LH

40
Q

Describe days 25-28 of the menstrual cycle:

A

LH inhibited
-Causes corpus luteum to degenerate
-Progestrone production decreased

41
Q

What is the first step in fertilisation? (2)

A

Many sperm encounter the secondary oocyte in the oviduct.
Their acrosomes have matured since the release.

42
Q

What is the second step in fertilisation? (3)

A

-Enzymes released from acrosome of many sperms by exocytosis.
-Enzymes digest material between inner follicle and glycoprotein jelly of zona pellucida (corona radiata), allowing sperm to pass, reaching oocyte membrane.
-Secondary oocyte is now ovum.

43
Q

What are the 3 layers of the uterus?

A

Perimetrium- thin, outer layer
Myoetrium- muscle layer
Endometrium- inner layer, rich blood supply and where embryo implants during pregnancy. Also is shed during menstruation.

44
Q

The next step in fertilisation after the secondary oocyte is an ovum, is the cortical reaction. What is this?

A

Zona pellucida thickens and separates from oocyte surface, preventing polyspermy.
Smooth ER release calcium ions into cytoplasm, causing cortical granules to fuse with cell membrane and release enzymes by exocytosis.
Oocyte is now diploid zygote, which divides by mitosis to become an embryo.

45
Q

What is cleavage?

A

Embryo travelling along fallopian tube, dividing by mitosis.
Within 3 days, morula is formed (16 cells).
By 7 days, this becomes a blastocyst.
The blastocyst takes 3 days to reach uterus, where it will implant in the endometrium.
Trophoblastic villi are produced which penetrate the endometrium and increase the SA for more nutrient intake.

46
Q

What is implantation?

A

The blastocyst takes 3 days to reach uterus, where it will implant in the endometrium.
Trophoblastic villi are produced which penetrate the endometrium and increase the SA for more nutrient intake.
(day 8-10)

47
Q

What do the trophoblasts develop into?

A

Chorion- outer membrane surrounding embryo.
Cells from chorion move to trophoblastic villi to form chorionic villi. (larger)
Blood capillaries & umbilical cord develop.

Amnion- develops amniotic sac, protecting foetus.

48
Q

Maternal and foetal blood come close but do not mix, what does the short distance allow?

A

Efficient exchange by:
-Diffusion/facilitated
-Active transport
-Pinocytosis
-Osmosis
(is countercurrent)

49
Q

Why is it important that the maternal and foetal blood do not mix?

A

Could cause an immune response.
Maternal blood’s pressure is too high and could damage feotus’ vessels.

50
Q

What is the blood in the umbilical artery rich in?

A

Oxygen & dissolved food (to foetus, away from heart)

51
Q

What is the blood in the umbilical vein rich in?

A

Carbon dioxide & urea (from foetus, to heart)

52
Q

What does the placenta do? (7)

A

-Takes over the role of hormone production, acting as an endocrine organ.
-Secretes progesterone, preventing ovulation and menstruation.
-Nourish foetus with nutrients it needs & antibodies.
-Removes waste from feotus.
-Acts as depressurising unit, protecting feotal capillaries from mother’s blood pressure.
-Prevents some of mother’s hormones passing onto feotus.
-Prevents pathogens from crossing & provides passive immunity.

53
Q

What are some limitations of the placenta? (4)

A

Some pathogens can pass through to feotus, like rubella and HIV.
Some drugs can pass through like heroin, nicotine and alcohol.
Spontaneous abortion can occur due to rejection.
Pre clampsia can occur due to abnormal immune response.

54
Q

What is the HCG hormone?

A

Blastocyst secretes it 6 days after fertilisation.
Once implanted, is secreted by chorion.
It prevents degeneration of the corpus luteum for first 16 weeks of pregnancy, allowing it to secrete progesterone. (to maintain thickness of endometrium)

55
Q

Why does the secretion of progesterone and oestrogen need to inhibit the secretion of FSH and LH?

A

To prevent FSH from stimulating follicle development.
To prevent LH from causing ovulation

WJEC A2 Biology (12 decks)

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