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Biology > Sexual reproduction in humans > Flashcards

Sexual reproduction in humans Flashcards

1
Q

Draw the male reproductive system and label

A

PG 125

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2
Q

Name all the accessory glands

A

Prostate
Seminal vesicle
Cowpers
Bulbo urethral

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3
Q

What do the secretions of the glands do?

A

Aid sperm mobility
Provides nutrients like fructose for sperm to respire for energy
Neutralises vaginal tract and urine in urethra

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4
Q

Take notes on histological examination of TS testis

A

PG 126

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5
Q

Draw the structure of the female reproductive system and label

A

PG 127

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6
Q

Take notes on histological examination of female reproductive system

A

PG 127

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7
Q

Explain the steps of spermatogenesis

A

Germinal epithelium divides by mitosis producing more germinal epithelium and diploid spermatogonia.
Diploid spermatogonia divide by mitosis producing more spermatogonia and diploid primary spermatocytes.
Primary spermatocytes divide by meiosis producing haploid secondary spermatocytes.
Secondary spermatocytes divide by meiosis producing diploid spermatids.
Spermatids mature to sperm

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8
Q

Draw a sperm and label its functions

A

PG 129

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9
Q

Explain the steps in Oogenesis

A

Germinal epithelium in ovary divides by mitosis producing more germinal epithelium and diploid oogonia, the oogonia divides by mitosis producing oogonia and diploid primary oocytes.
The primary oocytes start meiosis but stop and a girl is born.
Germinal epithelium divides by mitosis producing diploid follicle cells, they surround the primary oocyte making a primary follicle.
The primary follicle matures using hormones from puberty.
The primary oocyte has now completed meiosis I, producing a haploid secondary oocyte and a polar body
The primary follicle is now mature so is called a graafian follicle.
The graafian follicle migrates to the surface of the ovary and bursts releasing the secondary oocyte.
The secondary oocyte begins meiosis II making an ovum and a second polar body, only if fertilisation occurs

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10
Q

What happens to the graafian follicle after ovulation?

A

It becomes the corpus luteum and if fertilisation occurs it will produce hormones if not it regresses

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11
Q

What happens to the secondary oocyte if fertilisation doesn’t occur?

A

Stops meiosis II, an ovum wont form unless fertilised

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12
Q

What are cortical granules?

A

Secretory organelles in the cytoplasm, they prevent polyspermy

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13
Q

What is the zona pellucida?

A

A clear glycoprotein layer which surrounds the cell membrane of the secondary oocyte

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14
Q

What is the corona radiata?

A

Surrounds the secondary oocyte providing nutrients

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15
Q

How is sperm released into the vagina?

A

Physiological affects causes arterioles entering the penis to dilate and venules leaving the penis to constrict.
Movements of the penis inside the vagina cause the smooth muscle walls of the penis and vas deferens to contract which causes ejaculation.
This force pushes sperm pass the cervix

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16
Q

Explain the process of fertilisation

A

It takes 5 minutes for sperm to react to chemo attractants from secondary oocyte, they swim towards it.
Capacitation occurs where cholesterol and glycoproteins are removed from the acrosome to make it more fluid and permeable to calcium ions.
The acrosome releases proteases which digest the corona radiata, on contact with the zona pellucida the acrosome bursts and releases acrosin.
The sperms head goes into the oocytes cytoplasm, this is fertilisation.
After fertilisation the RER of the oocyte releases calcium ions which make the cortical granules fuse to the cell membrane and release their contents.
Zona pellucida is chemically modified and hardens, preventing polyspermy

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17
Q

What is ZP3?

A

A protein in the zona pellucida which binds to the sperm, so prevents fusion.

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18
Q

Describe the process of implantation. Remember days 3,7,9

A

As the embryo moves down the oviduct it divides by mitosis, this is called cleavage.
At 3 days a ball of 16 cells is formed, called a morula.
Cleavage continues, around day 7 the ball is now hollow and is called a blastocyst.
Trophoblastic cells surround the blastocyst and divide by mitosis forming a mass on one side.
The blastocyst moves to the uterus.
After ovulation, the endometrium thickens to prepare for implantation. There is an implantation window where the endometrium is receptive 6-10 days after ovulation.
At day 9 protrusions from the trophoblast cells called trophoblastic villi penetrate the endometrium.
This is implantation

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19
Q

What do the trophoblastic villi prodvide?

A

An increased SA for the absorption of nutrients from the endometrium

20
Q

Describe some features of the placenta

A

2cm thick , 22cm long, 500g

21
Q

What are the major roles of the placenta?

A

An endocrine organ, producing hormones to support the pregnancy.
Exchange of nutrients, waste, respiratory gases to and from mothers blood to foetal blood.
Provides passive immunity.
A barrier between mothers high blood pressure and foetuses low pressure.

22
Q

Why does the mother not make an immune response against the foetus?

A

Because the cells of the chorionic villi fuse forming a syncitium.
Immune cells like granulocytes cannot get through to foetal blood

23
Q

What is Rhesus disease?

A

Rhesus disease in a foetus is the destruction of its blood cells by antibodies made by a rhesus neg mother against the rhesus pos foetus.

24
Q

Draw a diagram of the placenta and label

A

PG 135

25
Q

What is the role of the umbilical cord?

A

It transfers blood between foetus and mother.
Deoxygenated blood flows in umbilical artery towards the placenta for gas exchange.
Oxygenated blood flows towards the foetus via umbilical vein.

26
Q

Where does the amnion come from?

A

the inner cell mass of the blastocyst

27
Q

What are the three layers of the uterus?

A

Endometrium- the innermost layer with a rich blood supply
Myometrium- middle muscle layer
Perimetrium- outermost layer

28
Q

What does amniotic fluid contains?

A

98% water, protein, trace salts

29
Q

What is the role of amniotic fluid?

A

Maintains foetus temperature
Lung development
Allows movement so muscles/bones function before birth
Acts as a shock absorber
Provides lubrication, finger/toes may becomes webbed if too little.

30
Q

What happens in the 1st trimester of pregnancy?

A

22 days- 2 brain hemispheres, heart beat
Week 10: eyes, mouth, ears visible

31
Q

What happens in the 2nd trimester of pregnancy?

A

Development stage, eyes open and movements can be felt.

32
Q

When is the embryo known as a foetus?

A

After 10 weeks, when miscarriage is less prone

33
Q

When is human gonadotrophin hormone secreted and what does it do?

A

6 days after fertilisation, secreted by the chorion it maintains the corpus luteum in its secretion of progesterone.

34
Q

What does progesterone do?

A

Maintains the endometrium

35
Q

What happens to trophoblast villi after implantation?

A

Trophoblast develops into the chorion.
Cells of the chorion move into trophoblastic villi which form chorionic villi.

36
Q

Describe the steps to the menstrual cycle

A

Oestrogen and progesterone inhibit FSH so no follicles mature.
Progesterone inhibits LH, so no ovulation occurs.

37
Q

What does LH hormone do?

A

Causes ovulation

38
Q

How does FSH and oestrogen act as negative feedback?

A

FSH stimulates the production of oestrogen.
Oestrogen inhibits the production of FSH from anterior pituitary which means there is reduced production of oestrogen, allowing ovulation.

39
Q

Where is GnRH released from and what does it do?

A

Gonadotrophic releasing hormone, released from Hypothalamus.
Stimulates pituitary gland to release FSH and LH

40
Q

Where is FSH released from and what does it do?

A

Released from anterior pituitary gland, stimulates development of primary follicles

41
Q

Where is LH released from and what does it do?

A

Released from anterior pituitary gland and stimulates ovulation

42
Q

Where is oestrogen released from and what does it do?

A

Released from follicle cells, triggers building of endometrium.
Inhibits production of FSH, negative feedback.
Stimulates LH hormone, positive feedback

43
Q

Where is progesterone secreted from and what does it do?

A

Secreted by the corpus luteum, maintains endometrium.
Inhibits FSH and LH

44
Q

Role of oestrogen?

A

Rebuild endometrium

45
Q

What does the corpus luteum secrete?

A

Progesterone and oestrogen

46
Q

How does oxytocin work?

A

Secreted by posterior pituitary gland and causes contractions of myometrium. The contractions stimulate secretion of more oxytocin by positive feedback.
Contractions become stronger.

47
Q

How does prolactin work?

A

Secreted by anterior pituitary gland and stimulates mammary glands to synthesise milk.
Milk is released when oxytocin causes the muscles to contract.

Biology (26 decks)

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