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Biology - Year 2 (Eduqas) > Chapter 7 - Sexual Reproduction in Humans. > Flashcards

Chapter 7 - Sexual Reproduction in Humans. Flashcards

1
Q

What does the male reproductive system consist of?

A
  • A pair of testes contained in the scrotum.
  • The penis.
  • Ducts connecting the testes with the penis (vas deferens and the urethra).
  • Accessory glands (seminal vesicles, prostate gland etc.).
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2
Q

What happens in the seminiferous tubules?

A

The cells lining them undergo sperm formation and throughout the process, move towards the the lumen, running through the middle of the tube.

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3
Q

What do the seminal vesicles do?

A

They secrete mucus which helps sperm mobility (contains fructose respired by the sperm).

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4
Q

What does the prostate gland do?

A

It produces an alkaline secretion that neutralises any urine left in urethra and aids in sperm mobility.

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5
Q

What do sertoli cells do?

A

They secrete a fluid which nourishes spermatids and protects them from the male’s immune system.

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6
Q

What are the stages in spermatogenesis?

A
  • Germinal Epithelial Cells (Mitosis).
  • Spermatogonia (Mitosis).
  • Primary spermatocytes (Meiosis I).
  • Secondary spermatocytes (Meiosis II).
  • Spermatids (Differentiation).
  • Spermatozoan.
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7
Q

What do interstitial cells (AKA. Leydig cells) do?

A

They secrete testosterone which has a role in sperm formation and maturation.

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8
Q

What are the layers of the uterus wall?

A
  • Myometrium muscle layer.
  • Endometrium, it’s a mucous membrane which is well supplied with blood. It is the layer which builds and is shed in a monthly cycle, unless an oocyte is fertilised.
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9
Q

What are the stages of oogenesis?

A
  • Germinal epithelial cells (Mitosis).
  • Oogonia (Mitosis).
  • Primary Oocytes (Meiosis I).
  • Secondary Oocyte +Polar body (Meiosis II).
  • Ovum + 2nd polar body (Only happens after fertilisation).
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10
Q

Where does Oogenesis have breaks?

A

-Primary Oocytes start to divide by mitosis but stop at Prophase I. Then, at puberty FSH stimulates one each month to complete Meiosis I and get to Metaphase II where it stops unless its fertilised.

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11
Q

How does a Graafian Follicle develop?

A

Some germinal epithelial cells also divide by mitosis to form follicle cells which surround the primary oocytes to form primary follicles. FSH will then cause one each month to develop into a secondary follicle and then forms a Graafian follicle.

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12
Q

What is the structure of a Graafian Follicle?

A
  • Secondary Oocyte.
  • Zona Pellucida.
  • Corona Radiata.
  • Antrum.
  • Theca.
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13
Q

What is the the temporary gland formed when the graafian follicle ruptures and what hormone does it produce if fertilised?

A

The corpus luteum which produces progesterone that maintains the endometrium.

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14
Q

What happens to the corpus luteum is the oocyte isn’t fertilised?

A

It regresses.

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15
Q

What in the oocytes prevents the entry of more than one sperm?

A

Cortical granules, they’re secretory organelles.

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16
Q

What is a major difference between spermatogenesis and oogenesis?

A

A primary spermatocyte will produce four gametes but a primary oocytes produces only one (Due to the polar body created).

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17
Q

What is the process of capacitation in a sperm cells?

A

It’s the removal of cholesterol and glycoproteins from the cell membrane over the acrosome in the sperm head. Over time, it becomes more fluid and permeable to Ca+ ions.

18
Q

What is the acrosome reaction?

A

Acrosome enzymes (proteases) digest the corona radiata and the zona pellucida, allowing the sperm and oocytes cell membranes to fuse.

19
Q

What is the reaction that prevents polyspermy and how does it occur?

A

The cortical reaction, when the sperm attaches to the secondary oocyte, the SER releases Calcium ions into the cytoplasm. They make the cortical granules fuse with the membrane and release their contents causing the zona pellucida to expand and harden.

20
Q

What is the sequence called as the embryo moves down the oviduct, dividing many times?

A

Cleavage.

21
Q

What is the process of implantation?

A

The sinking of the blastocyst into the endometrium.

22
Q

What is a trophoblast and what are the villi they form used for?

A

The trophoblast is the name given to the cells forming the outer layer of the blastocyst. The trophoblastic villi penetrate the endometrium and they increase the surface area for the absorption of nutrients from the endometrium.

23
Q

What does the trophoblast develop into?

A

The chorion, these create larger villi and acquire blood capillaries which are connected to the umbilical artery and vein.

24
Q

What is the umbilical cord?

A

It develops from the chorion and transfers the foetal blood to the placenta in 2 umbilical arteries and returns it in a vein.

25
Q

What are the functions of the placenta?

A
  • Endocrine organ, producing hormones to support the pregnancy.
  • Exchange between the blood (Inter-villous spaces surround the chorionic villi).
  • A physical barrier, protecting the fragile foetal capillaries.
  • Provides passive immunity.
  • Protection against the mother’s immune system.
26
Q

What are the significant hormones in the menstrual cycle?

A
  • Follicle stimulating hormone (FSH).
  • Luteinising hormone (LH).
  • Oestrogen.
  • Progesterone.
27
Q

During pregnancy, what do each of the hormones do?

A
  • HCG made by the embryo maintains the corpus luteum maintaining pregnancy.
  • Progesterone, prevents uterine contractions.
  • Oestrogen, stimulates the growth of the uterus and mammary glands.
28
Q

In the menstrual cycle, what is day 0?

A

The first day of a period.

29
Q

What is a period?

A

The shedding of the endometrium wall if a blastocyst has not implanted.

30
Q

What hormones are secreted in the period?

A

GnRH is secreted by the hypothalamus thich stimulates the anterior pituitary gland to secrete FSH which stimulates the development of a primary follicle. This has a positive feedback mechanism as it stimulates the theca cells to produce oestrogen.

31
Q

What does increasing oestrogen levels cause to happen?

A
  • Triggers the rebuilding of the endometrium, that was shed during menstruation.
  • Inhibits FSH secretion by negative feedback, which in turn brings its own concentration down.
  • Stimulates LH production by positive feedback.
32
Q

What does the surge in LH cause to happen?

A

It causes ovulation (release of the secondary oocyte), and has a positive feedback on FSH and levels pick back up again.

33
Q

What does the ruptured graafian follicle develop into and what hormones does it secrete?

A

It develops into the corpus luteum which secretes oestrogen and progesterone.

34
Q

What do the increased levels of oestrogen and progesterone do?

A

They build and maintain the endometrium lining so that is a secondary oocyte is fertilised,, there with be suitable tissue in which the embryo can implant. These high levels also inhibit FSH and LH production.

35
Q

What does the falling levels of FSH and LH do to the corpus luteum?

A

It causes it to degenerate so progesterone and oestrogen production declines.

36
Q

What does the drop in progesterone cause to happen?

A

It causes mensuration so the endometrium is shed and the cycle starts over.

37
Q

Even if the secondary oocyte is fertilised, why may a pregnancy fail?

A
  • It may fail to divide.
  • It may implant in the wrong place.
  • It may fail to implant.
38
Q

What are the main roles of the main hormones during the menstrual cycle?

A
  • FSH, follicle development.
  • LH, ovulation.
  • Oestrogen, rebuild endometrium.
  • Progesterone, maintain endometrium.
39
Q

What is the function of the amniotic fluid?

A
  • Maintains the foetus’s temperature.
  • Provides lubrication.
  • Contributes to lung development.
  • Allows movement so muscles and bones function before birth.
  • Acts as a shock absorber.
40
Q

What does hCG do and when is it secreted?

A

It is secreted by the embryo and it maintains the corpus luteum.

41
Q

Before birth, what does the decrease of progesterone and oestrogen cause?

A

They are no longer inhibiting the production of oxytocin and prolactin. Oxytocin causes contractions of the myometrium in the uterus wall. The contractions are mild but they stimulate the secretion of more oxytosin so concentration increases

Biology - Year 2 (Eduqas) (14 decks)

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