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Biology 6. Human Physiology > 11.4 Sexual Reproduction > Flashcards

11.4 Sexual Reproduction Flashcards

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1
Q

What are similarities of spermatogenesis and oogenesis?

A

Spermatogenesis and oogenesis both involve - mitosis - cell growth - two divisions of meiosis and differentiation They bot produce HAPLOID GAMETES

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2
Q

What is oogenesis?

A

is the production of egg cells in the ovaries and starts in ovaries of female fetus

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3
Q

How do germ cells divide in the fetal ovary?

A

Through mitosis

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4
Q

What mechanism does fertilization involve?

A

It involves the prevention of polyspermy

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5
Q

What happens to the fetus after 4 to 5 months?

A

Cells start to grow and divide by meiosis

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6
Q

What happens during the 7th month of a fetus?

A

Still in Meiosis I (single layer of cells) called follicle cells around them form

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7
Q

When does the fetus become a primary follicle?

A

When it has fused with surrounding follicle cells

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8
Q

Are there new primary follicles produced after birth?

A

No

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9
Q

What happens at the beginning of a menstrual cycle?

A

A small batch of primary follicles are stimulated to develop by FSH. Usually only ONE goes on to become a mature follicle with a secondary oocyte

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10
Q

What is spermatogensis?

A

production of sperm, occurs in testes in narrow tubes called seminiferous tubules

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11
Q

What are the gaps between seminiferous tubules called?

A

interstices with interstitial cells/leydig cells

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12
Q

What is the outer layer of cells in a seminiferous tubule called?

A

Germinal epithelium. This is where sperm production begins.

Cell in VARIOUS stages are found here with most mature closest to the centre of the tubule

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13
Q

What are spermatozoa?

A

cells that have developed tails (also known as sperm)

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14
Q

What are the large nurse cells in the seminiferous tubule called?

A

sertoli cells

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15
Q

Outline describe process of spermatosis

A
  • cell division by mitosis to form more cells of the germinal epithelium cells (2n) / spermatogonia - produce diploid cells (2n)
  • growth of cells / spermatogonia to form larger calls / primary spermatocytes
  • cells / primary spermatogonia divide by meiosis haploid cells /two spermatocytes (n)
  • second division of meiosis produces two spermatids
  • spermatids associate with sertoli cells to develop into spermatozoa (sperm with tails)/ cell differentiation
  • FSH, testosterone and LH all needed for spermatogenesis
  • sperm stored / maturation in epididymis / gain motility - fluid added to sperm by seminal vesicle (during ejaculation)
  • fluid from seminal vesicle contains nutrients / mucus
  • fluid added to sperm by prostate gland (during ejaculation) / fluid from prostate gland contains alkali / minerals
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16
Q

Outline process of oogenesis

A
  • germinal epithelium cells are found in cortex of ovary - primary follicle consists of central oocyte
  • primary follicle are surrounded by SINGLE layer of follicle cells
  • every menstrual cycle a few primary follicles start to DEVELOP (not produced)
  • oocyte complete first division of meiosis - in a secondary oocyte, the follicle cells PROLIFERATE
  • fluid filled cavity develops
  • oocyte starts second division of meiosis
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17
Q

Annotate diagram of a mature egg

A
  • Haploid nucleus
  • two centrioles
  • cytoplasm (containing fat)
  • first polar cell
  • plasma membrane
  • layer of follicle cells
  • layer of gel composed of glucoproteinss cortical granules (zona pellucida)
  • diameter of egg cell = 110 micrometers
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18
Q

Annotate diagram of a mature sperm

A
  • haploid nucleus
  • acrosome
  • centriole
  • plasma membrane
  • tail (has to be at least two thirds)
  • protein fibres
  • microtubules
  • mid-piece (7micrometers)
  • helical mitochondria
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19
Q

Difference between spermatogenesis and oogenesis

A
  • spermatogenesis starts at puberty versus oogenesis starts in the fetus
  • spermatogenesis until death versus oogenesis until menopause
  • millions of sperm versus one egg per month ejaculation of sperm any time versus ovulation in middle of menstrual cycle
  • four sperm per meiosis / spermatogenesis versus 2 or 3 polar bodies in oogenesis
  • spermatogenesis involves equal divisions versus oogenesis involves unequal cell / cytoplasm divisions - no polar bodies in speratogenesis versus 2 or 3 polar bodies in oogenesis
  • spermatogenesis involves Sertoli / nurse cells versus oogenesis does not
  • meiosis II completed before fertilization in spermatogenesis versus after in oogenesis
  • testosterone needed for spermatogenesis versus not needed for oogenesis
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20
Q

What allows directional swimming of sperms?

A

membrane of sperm have receptor to detect chemicals released by egg

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21
Q

What is zona pellucida?

A

coat of glycoproteins that surrounds the egg

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22
Q

What is acrosome?

A

large membrane bound sac of enzymes in the head of sperm

23
Q

What happens during acrosome reaction?

A

The acrosome will bind to the zona pellucida, and enzymes released from the acrosome digest the zona pellucida

24
Q

What happens during pentration of egg membrane?

A

with the exposed area of membrane, sperm (part with the proteins) binds to egg wher they FUSE TOGETHER and sperm nucleus ENTERS egg cell –> fertilization

25
Q

What are cortical granules?

A

vesicles located near egg membrane

26
Q

What happens during cortical reaction?

A

Activation of the egg, so enzymes of cortical granules are released by exocytosis which digest binding proteins –> no more sperms can bind –> enzymes also harden zona pellucida

27
Q

what are risks of external fertilization?

A

susceptible to environmental variation (temperature, pH) and pollution

28
Q

Why are terrestial animals dependent on internal fertilization?

A
  • Reduces risk of gametes drying out
  • speam and ova placed in close proximity
  • embryo is protected inside female
29
Q

What happens to ovum after fertlization?

A

divides by mitosis (two diploid nuclei with EQUAL embryo cells)

30
Q

What happens to two embryo cells from fertilized egg?

A

replicate DNA, and carry out mitosis (forms four-cell embryo)

31
Q

What happens after four-cell embryo is formed?

A

further cell divisions but UNEQUAL

32
Q

What is the blastocyst?

A

(Early stage of embryo) migration of cells to form embryo hollow ball shaped and reaches uterus after moving down the oviduct by cilia in oviduct wall (zona pellucida breaks down)

33
Q

What happens after blastocyst uses up all reserves of the egg for energy?

A

sinks into the endometrium/uterus lining in process called implantation

34
Q

What happens after implantation?

A

outlayer of blastocyst penetrates uterus lining and exchange materials in mother’s blood (absorbs food and oxygen)

35
Q

when is the embryo considered a fetus?

A

After it forms a bone tissue

36
Q

What does pregnancy depend on?

A

maintenance of endometrium which depends on production of progesterone and estrogen

37
Q

What does the production of progesterone and estrogen prevent?

A

prevent degeneration of uterus lining (needed for developing fetus

38
Q

What is hCG

A
  • Human chorionic gonadotropin
  • produced early in pregnancy
  • stimulates corpus luteum in ovary to continue progesterone and estrogen production
  • stimultate continues development of uterus wall
  • uterus wall supplies embryo with everything
39
Q

What is placenta?

A

made of fetal tissues, with maternal tissues in the uterus wall

40
Q

What kind of membrane does the fetus develop?

A

Amniotic sac with amniotic fluid which supports and protects the developing fetus

41
Q

What is placental villus?

A

basic functional unit of fetal tissue to increase exchange of material with the mother

42
Q

Where does maternal blood flow?

A

Inter-villous spaces around the villi. This is unusual because blood is usually confined in vessels

43
Q

Where does fetal blood flow?

A

In capillaries close to surface of villus (distance between fetal and maternal blood is small)

44
Q

What are the cells called that separate maternal and fetal blood?

A

placental barrier (selectively permeable)

45
Q

What does the placenta secret after ninth week of pregnancy?

A

Estrogen and progesteron (to sustain pregnancy)

46
Q

When is there a danger of miscarriage of pregnancy?

A

After the ninth week of pregnancy, placenta has to secrete progesteron and estrogen instead of corpus luteum. If this switch does not occur there could be miscarriage

47
Q

What does the secretion of progesterone inhibit?

A

Inhibits secretion of oxytoxin by pituitary glands inhibits contractions of the muscular outer wall of uterus

48
Q

What is the muscular outer wall of uterus called?

A

myometrium

49
Q

What is oxytocin?

A

Is secreted at end of pregnancy. Stimulates contraction of muscle fibres in the myometrium. Positive feedback loop.

50
Q

How is oxytocin detected?

A

Stretch receptors that signal pituitary glands to increase oxytocin release (positive feedback loop) which causes increase myometrial contraction allowing baby to be born

51
Q

How is the baby born once there intensity of myometrial muscle contraction increases?

A
  • Relaxation of cervix - cervix dilates - amniotic sac breaks - amniotic fluid passes out - after baby passes through cervix and vagina, umbiblical cord breaks
52
Q

What is the function of leydig cells?

A

produce testosterone which they release to nerby blood vessels

53
Q

What is the function of seroli cells?

A

nourish and protect the developing sperm cells

Biology 6. Human Physiology (15 decks)

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