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A LEVEL BIOLOGY > 7 - Sexual Reproduction in Humans (C2) > Flashcards

7 - Sexual Reproduction in Humans (C2) Flashcards

Doesn't include spermatogenesis and oogenesis

1
Q

What does the seminal vesicle do in the male reproductive system?

A

During ejaculation it adds alkaline mucus, containing fructose and amino acids, to nourish the sperm

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2
Q

What does the vas deferens do in the male reproductive system?

A

Transports sperm to the urethra via a peristaltic wave during ejaculation

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3
Q

What does the prostate gland do?

A
  • Produces a zinc containing alkaline secretion which neutralises any urine left in the urethra and acidic vaginal secretions
  • Aids in sperm mobility
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4
Q

What does the urethra do in the male reproductive system?

A

Transfers urine and semen out of the penis

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5
Q

What does the epididymis do in the male reproductive system?

A

It’s where sperm are collected and mature

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6
Q

What does the seminiferous tubule do in the male reproductive system?

A

It’s the site of sperm production

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7
Q

What does the testicle do in the male reproductive system?

A

Produces male gametes (spermatozoa)

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8
Q

What is the scrotum and what is its function?

A
  • It’s an external sac that holds the testes outside of the body
  • This provides an optimum temperature for sperm production of 35 degrees
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9
Q

What is the penis and what is its function?

A
  • An organ containing blood filled erectile tissue

- Passes semen into the vagina

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10
Q

What is the ovary and what is its function?

A
  • Female sex organ (gonad)
  • Starts gamete production and releases secondary oocytes
  • Secretes oestrogen and progesterone
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11
Q

What is the role of the uterus wall?

A
  • Retains the foetus

- Contracts during birth (controlled by oxytocin - positive feedback)

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12
Q

What is the cervix and what does it do?

A
  • A muscular ring at the neck of the uterus
  • Closes the entrance to the uterus
  • Dilates during birth from resting diameter of 2mm
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13
Q

What is the function of the fallopian tube/oviduct?

A
  • Ciliated epidermis wafts the oocyte/embryo to the uterus

- Site of fertilisation

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14
Q

What is the endometrium and what does it do?

A
  • Mucus rich membrane
  • Rich in blood capillaries
  • Shed monthly
  • Provides nutrients to implanted embryos
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15
Q

What is the vagina?

A
  • Muscular tube

- Site of sperm deposition

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16
Q

What are the 5 major roles of the placenta?

A
  • Production of oestrogen and progesterone
  • Exchange of O2/CO2, nutrients/waste
  • Barrier to high blood pressure, blood borne pathogens and toxins in maternal blood
  • Allows maternal antibodies to protect the foetus
  • Prevents antibodies attacking the foetus
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17
Q

What are problems the placenta can cause?

A
  • The immune system may attack the placenta or foetus due to Rhesus incompatibility
  • Small viruses or toxins are transferred across the placenta e.g. rubella, alcohol
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18
Q

What is the function of leydig cells?

A

Secrete testosterone

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19
Q

What is the amnion?

A

Fluid filled sac which eventually surrounds and protects the embryo from mechanical damage

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20
Q

What does amniotic fluid contain?

A
  • Foetal skin cells

- Can be sampled to check for chromosome abnormalities

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21
Q

What is the acrosome reaction?

A
  • Triggered when sperm bind to a protein
  • Acrosome membranes rupture and hydrolytic enzymes are released
  • Acrosin enzyme digests the zona pellucida
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22
Q

What happens as the sperm enters the egg?

A
  • Proteins in sperms cell membrane bind to the oocyte membrane and they fuse
  • Sperm nucleus enters
  • Entry of the head of the sperm causes the egg to complete meiosis and the 2 haploid nuclei fuse to form a zygote
23
Q

What is the cortical reaction?

A
  • Calcium ions enter the egg and vesicles of cortical granules move to and fuse with the oocyte membrane
  • Zona pellucida lifts and hardens, forming a fertilisation membrane
  • Binding proteins change shape
24
Q

How is polyspermy prevented?

A

Membrane polarity changes, due to cortical reaction

25
Q

What is the role of HCG?

A
  • Maintains the corpus luteum and prevents it being broken down
  • Maintains progesterone production
26
Q

Why are there high levels of oestrogen and progesterone in the blood plasma until the end of the pregnancy?

A

This inhibits the secretion of:

  • FSH, so no more follicles mature
  • LH, so ovulation is not possible
  • Prolactin, so no milk is made
  • Oxytocin, so the myometrium and muscles in the milk ducts don’t contract
27
Q

What does oestrogen stimulate during pregnancy?

A
  • The growth of the uterus

- The growth of the mammary glands

28
Q

What are the functions of the amniotic fluid?

A
  • Maintains foetus’s temperature
  • Provides lubrication
  • Contributes to lung development
  • Allows movement so muscles and bones function before birth
  • Acts as a shock absorber
29
Q

What is the role of oestrogen?

A
  • Rebuilds the endometrium
  • Inhibits FSH secretion
  • Stimulates LH production
30
Q

What does the alkaline prostate fluid do?

A
  • Maintains sperm mobility
  • Provides nutrients, including fructose, amino acids and zinc
  • Neutralise the acidity of urine in urethra
  • Neutralise the acidity of vaginal tract
31
Q

What do Sertoli cells do?

A

Secrete a fluid which nourishes spermatids and protects them from male’s immune system

32
Q

What does testosterone do?

A

Has roles in sperm formation and maturation, and the development of male secondary sexual characteristics

33
Q

What are the 3 layers of the uterus wall?

A
  • Perimetrium - thin layer around outside
  • Myometrium - muscle layer
  • Endometrium - innermost layer
34
Q

What does the endometrium do?

A

Builds and sheds blood in a monthly cycle

35
Q

Why does the middle piece of sperm have lots of mitochondria?

A

To provide ATP for movement

36
Q

What does the corpus luteum do if fertilisation occurs and what does it do if it doesn’t?

A
  • Does -> Produces hormones

- Doesn’t -> Regresses

37
Q

What do cortical granules do?

A

Prevent the entry of more than 1 sperm

38
Q

What is capacitation?

A

The removal of cholesterol and glycoproteins from cell membrane over acrosome in sperm head, which increases its fluidity and allows acrosome reaction to occur

39
Q

What events make up the fertilisation sequence?

A
  • Sperm surround secondary oocyte
  • Capacitation
  • Acrosome reaction
  • Sperm head entry
  • Cortical reaction
  • Meiosis II
  • Mitosis
40
Q

What is cleavage?

A

A sequence by which the embryo divides by mitosis, as it moves down the oviduct

41
Q

What is implantation?

A

The sinking of the blastocyst into the endometrium

42
Q

What are trophoblasts?

A

Cells forming the outer layer of the blastocyst

43
Q

How is a concentration gradient ensured between the maternal and foetal blood?

A

By a counter-current flow

44
Q

What does FSH stand for?

A

Follicle stimulating hormone

45
Q

What is Rhesus disease in a foetus?

A

The destruction of its blood cells by antibodies made by a Rhesus negative mother against blood cells of a Rhesus positive foetus

46
Q

What is the role of FSH?

A
  • Stimulates development of primary follicles
  • Stimulates Graafian follicle development
  • Stimulates production of oestrogen
47
Q

What is the role of LH?

A
  • Induces ovulation
  • It’s high conc on day 14 causes the Graafian follicle to release the secondary oocyte
  • Has a positive feedback effect on FSH
48
Q

What is the role of FSH?

A
  • Stimulates development of primary follicles

- Stimulates production of oestrogen

49
Q

What is the role of LH?

A
  • Induces ovulation

- It’s high conc on day 14 causes the Graafian follicle

50
Q

What does progesterone do?

A
  • Maintains the endometrium

- Inhibits oxytocin

51
Q

What does oxytocin do?

A
  • Causes contractions of myometrium in uterus wall so foetus can be pushed out through cervix
  • These contractions stimulate secretion of more oxytocin by positive feedback
52
Q

What does progesterone do?

A

Maintains the endometrium

53
Q

What does prolactin do?

A

Stimulates glandular tissue in mammary glands to synthesise milk

A LEVEL BIOLOGY (13 decks)

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