Brainscape's Knowledge GenomeTM

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


See full index

A2 Biology > 4.1 Sexual AReproduction In Humans > Flashcards

4.1 Sexual AReproduction In Humans Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

What is the cell that begins oogenesis and where is its position? n?

A

Germinal Epithelium, and are the outer layer of cells of the ovary. They are diploid, 2n

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

(Oogenesis) What type of division does the germinal epithelium undergo and what are the products?

A

Undergoes mitosis many times to produce diploid oogonia and more germinal epithelium.

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

After growth and development of an oogonium, what is the product called?

A

A diploid primary oocyte.

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

At which stage does the primary oocyte stop meiosis I? And until when?

A

Meiosis I is stopped at prophase I, until puberty.

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

At puberty, what is the product after a diploid primary oocyte has gone through meiosis I fully?

A

The product is a haploid secondary oocyte, with a smaller first polar body.

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

At what stage of meiosis II does the secondary oocyte stop? Until when?

A

It stops at Metaphase II, until the egg is fertilised.

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

After the secondary oocyte is fertilised, what is the product?

A

A haploid ovum, with a second polar body.

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

Why are polar bodies formed?

A

Because the cell must divide its genetic material, but wants to keep as much cytoplasm as possible, so one cell has half genetic material and some cytoplasm, and one has half genetic material and most of the cytoplasm.

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

What surrounds a primary oocyte and how is it formed?

A

Diploid follicle cells, which are produced from germinal epithelium cells dividing. Diploid follicle cells surround the primary oocyte to form a primary follicle.

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

What is another name for a secondary follicle when it has matured?

A

A Graafian follicle.

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

Describe briefly the process of ovulation.

A

The Graafian follicle migrated to the surface of the ovary and bursts, releasing the secondary oocyte.

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

Where does fertilisation take place? What is the next product of oogenesis?

A

Fertilisation takes place in the oviduct, and an ovum with a second polar body is formed.

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

What happens to the Graafian follicle after ovulation? What happens if the egg is fertilised?

A

It becomes the corpus luteum/yellow body and degenerates. If fertilisation occurs, it produces hormones.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the structure that surrounds the cell membrane of the secondary oocyte?

A

A carbohydrate layer called the zona pellucida.

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

What are cortical granules? Where are they?

A

They are secretory organelles that prevent the entry of more than one sperm. They are found at the periphery of the cytoplasm of a secondary oocyte.

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

What are the cells that surround the secondary oocyte and provide nutrients?

A

Corona Radiata.

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

What is the sequence of layers of the secondary oocyte/ Graafian follicle, from inside to outside?

A

Secondary oocyte, zona pellucida, cells of corona radiata, antrum, theca.

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

What does the oocyte release that attract sperm to it?

A

Chemoattractants.

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

How long are spermicide viable for? What is their most fertile time period?

A

Viable for 2-5 days but most fertile between 12-24 hours after ejaculation.

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

When is a secondary oocyte most fertile?

A

Within 24 hours of ovulation, when it is in the oviduct.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Describe Capacitation.

A

Cholesterol and glycoproteins are removed from the cell membrane over the acrosome in the spermicide head. Hours later, the membrane is more fluid and permeable to calcium ions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Describe the second stage of fertilisation, the acrosome reaction.

A

The acrosome of the sperm head releases proteases and digests the cells of the corona radiata. When the acrosome touches the zona pellucida, it ruptures and releases the protease acrosin, which digests the zona pellucida.
The cell membranes of secondary oocyte and sperm fuse and spermicide head enter cytoplasm, to form an ovum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the cortical reaction?

A

After sperm head entry, the SER of the oocyte releases calcium ions, which makes the membranes of cortical granules fuse with the cell membrane and release their enzymes by exocytosis. The zona pellucida becomes hard and expands, making a fertilisation membrane which prevents more sperm penetrating: polyspermy.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What happens about 24 hours after fertilisation and the Meiosis II?

A

Mitosis combines sperm nucleus and ovum nucleus, as the sperm and ovum chromosomes line up on the cell’s equator. This is now a zygote. The first mitotic division occurs and two cells are formed.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is the ball of cells dividing by mitosis called up until it is 10 weeks and has organ formation?

A

And embryo

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is an embryo called after 10 weeks?

A

A foetus.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is the sequence of mitotic division called between 2 cells and 16 cells?

A

Cleavage.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

How long does it take for the embryo to form 16 cells, and what is this called?

A

3 days to form a morula.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What happens after 7 days of cleavage?

A

The morula becomes hollow and is called a blastocyst.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What are the cells around the outside of the blastocyst called? What do they divide to make? Where does the blastocyst move to?

A

Outer cells called trophoblast she and they form an inner cell mass on one side. The blastocyst moves from oviduct into uterus.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What is the process called where the blastocyst embeds on the endometrium wall?

A

Implantation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What does the trophoblast develop into?

A

Develops into the chorion, and its cells move into trophoblastic villi and form much larger chorionic villi.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What do chorionic villi do?

A

They acquire blood capillaries which connect to the umbilical artery and vein. These blood vessels connect the embryo to the uterus through the umbilical cord.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What are the maternal tissues of the placenta?

A

Projections from the endometrium wall that fit between the chorionic Villi.

35
Q

Briefly list the roles of the placenta. 5 main points

A
  1. Endocrine organ
  2. Exchange between mother and foetus
  3. Physical barrier between foetal and maternal circulation
  4. Provides passive immunity from mother to foetus
  5. Prevent attack from mothers immune system
36
Q

Explain how the placenta allows area of exchange between mother and baby.

A

Lacunae are inter-villous spaces that contain the mothers blood and surround chorionic villi.
Rate & efficiency increased because:
Chorionic microvilli
Small distance across the wall of chorionic villi
Conc gradient maintained by a countercurrent flow

37
Q

What is exchanged between a mother and foetus’ blood?

A

Nutrients, waste products, and respiratory gases.

38
Q

Why is the placenta important as a physical barrier?

A

Protects the fragile capillaries from higher blood pressure in mother,
Protects foetus from the mothers changes in blood pressure.

39
Q

How does the placenta provide immunity?

A

Maternal antibodies cross the placenta and attack pathogens without attacking the foetal cells.

40
Q

How does the placenta provide protection from the mother’s immune system?

A

Cells of the wall of the chorionic villi fuse together so there are no spaces between them, forming a syncitium, this prevents migratory immune cells from the mother from getting to the foetal blood.

41
Q

How does the placenta sometimes fail at providing immunological protection?

A
  • Spontaneous abortions caused by response similar to rejection of a transplanted organ.
  • Rhesus disease, where rhesus -ve mother creates antibodies that attacks a rhesus +ve foetus. Causes it to destruct foetal blood cells
  • an abnormal immune response can cause pre-eclampsia which is very high blood pressure of mother.
42
Q

What drugs/ virus can pass through placenta to foetus?

A

Rubella,

Nicotine and heroin

43
Q

What are the 4 significant hormones in the menstrual cycle?

A

Follicle Stimulating Hormone, Luteinising Hormone, Oestrogen, Progesterone

44
Q

What is the feedback system that controls the menstrual cycle?

A

Negative feedback

45
Q

Which Hormone is secreted by the Hypothalamus in the brain? What does this stimulate?

A

Gonadotrophic Releasing Hormone, which stimulates the anterior pituitary gland to secrete FSH and LH.

46
Q

What does FSH do?

A

It stimulates the development of primary follicles in the ovary, and causes them to develop a fibrous outer layer called the Theca.
FSH stimulates Thecal cells to secrete oestrogen.
The Theca secretes fluid into the Antrum.
Only one develops into a Graafian follicle.

47
Q

What 2 things does the oestrogen do, after it has been secreted by the Thecal cells?

A

It stimulates the build up of the endometrium, and inhibits the further secretion of FSH.

48
Q

What does a high level of Oestrogen cause?

A

It continues to build up the endometrium wall, but also stimulates the Anterior Pituitary Gland to secrete Luteinising Hormone

49
Q

What does LH do when the it is secreted by the APG?

A

It stimulates ovulation, and the Graafian follicle releases the secondary oocyte.
It also stimulates the conversion of the Graafian follicle into the corpus luteum / yellow body.

50
Q

What does the Corpus Luteum secrete? What does it do?

A

Corpus Luteum secretes Progesterone, which maintains the lining of the endometrium, so it is ready for implantation.
The Progesterone and Oestrogen both inhibit FSH and LH, to prevent development and ovulation. When FSH and LH get really low, the corpus Luteum begins to degenerate, so the endometrium lining is not maintained and it’s shed and Oestrogen levels are low.

51
Q

What happens when the oestrogen levels are low?

A

It is no longer inhibiting FSH, so the Hypothalamus begins the cycle again.

52
Q

Typically how long is a pregnancy and when does the timeframe start?

A

Between 39-40 weeks

Starts from the first day of the last period until birth.

53
Q

Where is the amnion derived from?

A

The inner cell mass of the blastocyst.

54
Q

When does amniotic fluid accumulate? How long does it accumulate for?

A

Week 4-5 for 6-7 months

55
Q

What does the amniotic sac have after 4 months?

A

Urine from the foetus

56
Q

What is is amniotic fluid?

A

98% water, urea, salts, a little protein and trace of sugar.

57
Q

What can the volume of amniotic fluid tell you and why?

A

If the foetus’ swallowing reflex is normal because they tend to swallow around 500ml per day.

58
Q

What does the amniotic fluid do?

A 
Maintain temperature
Provides lubricant
Contributes to lung development
Allows movement to exercise muscles
Shock absorber
59
Q

What happens during the first trimester of pregnancy?

A

Brain hemispheres,
electrical activity in brain
Eyes, mouth and ears visible and heart beats
Foetus makes involuntary movements

60
Q

What happens in the second trimester of pregnancy?

A

Some open their eyes

Movements can be felt

61
Q

What is hCG and where is it secreted from? What does it do?

A

Human Chorionic Gonadotrophin. 6 days after fertilisation the blastocyst secretes it
After implantation, Chorion secretes it.
It maintains the corpus luteum in its secretion of Progesterone, which maintains the endometrium lining.

62
Q

How long is hCG secreted for?

A

First 16 weeks

63
Q

The corpus luteum and placenta secretes oestrogen and progesterone, which inhibits….

A 
-FSH so no more follicles mature
Inhibits 
-LH to ovulation does not occur
-prolactin so milk isn't made
 Progesterone inhibits oxytocin, so myometrium and milk ducts don't contract
64
Q

What else does oestrogen do when secreted during pregnancy?

A
  • Stimulates growth of the uterus to accommodate for foetus

- stimulates growth of mammary glands, and increases their blood supply (mainly during 3rd trimester)

65
Q

What happens at the very end of pregnancy?

A

The foetus secretes hormones to the mother, and her progesterone levels in the blood decline, so oxytocin and prolactin is no longer inhibited.
Oxytocin is secreted which has a positive feedback on itself, secreting more and making the myometrium of the uterus contract.
Prolactin stimulates mammary glands to synthesis milk. Milk is released when oxytocin stimulates muscles around milk ducts to contract.

66
Q

Which feedback does FSH have on Oestrogen at the beginning of the cycle?

A

Positive

67
Q

What effect does LH have on FSH

A

Positive feedback

68
Q 
What feedback does Oestrogen have on,
FSH
LH,
Prolactin,
Oxytocin
A

Negative
Positive
Inhibit
Inhibit

69
Q

In males, what does LH or ICSH do?

A

Stimulate Leydig cells to secrete testosterone, which effects sleek development and secondary sexual characteristics

70
Q

What do germinal epithelium ceos form when they go through mitosis in males?

A

They form diploid spermatogonia and more germinal epithelium cells.

71
Q

What forms after spermatocytes grow and enlarge?

A

Forms diploid primary spermatocytes and more soermatogonia

72
Q

When primary spermatocytes undergo Meiosis I, what’s formed?

A

Secondary spermatocytes which are haploid

73
Q

What happens when secondary spermatocytes undergo Meiosis II?

A

They make haploid spermatocytes

74
Q

What do spermatids mature into?

A

Spermatozoa/ sperm

75
Q

When is sperm produced?

A

At puberty

76
Q

What modifications do spermatocytes cells have?

A

An acrid one filed with enzymes that help with fertilisation
Lots of mitochondria in the middle piece to give energy
Flagellum to propel it when it is mixed into semen

77
Q

What are Sertoli cells and where are they found?

A

They secrete a fluid that nourishes the spermatid and protects it from the male’s immune system.
They are found in the testes between the stands of developing spermatids

78
Q

Where is sleek produced?

A

In seminiferous tubules in the testes

79
Q

What are seminiferous tubules?

A

Coiled tubes. The outer layer are germinal epithelium and they undergo mitosis and meiosis so that sperm are formed.
Cells get closer and closer to the lumen of the tubules.

80
Q

What happens when spermatozoa reach the lumen?

A

They move through tubule and collect in the vasa efferentia which are coiled tubes that carry spermatocytes to the head of the epididymis. They remain here until they become motile.

81
Q

What happens during ejaculation?

A

Motile spermatozoa pass into the vas deferens and move towards the penis. On the way, seminal vesicles secrete mucus into the vas deferens, which contains fructose for energy. The sperm and mucus pass through the ejaculatory duct, which passes through the prostate gland, where zinc contains by fluid is secreted.

82
Q

What is the purpose of the fluid secreted by the seminal vesicles and prostrate gland?

A
  • maintain sperm mobility
  • provide nutrients
  • neutralise acidity of urine in urethra
  • neutralise acidity if vaginal tract
83
Q

What is the mixture of sperm, seminal mucus and prostate fluid known as?

A

Semen

A2 Biology (1 decks)

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