human reproduction

Question 1

Discuss the function of the hormone progesterone in maintaining pregnancy.

Answer 1

Progesterone levels increase; keeping the endometrium thickened;
which prevents menstruation / ovulation from taking place.

Question 2

Name any three functions of the placenta during pregnancy

Answer 2

Nutrition of the embryo 
excretion; gaseous exchange
acts as a micro-filter (barrier) 
prevents entry of pathogenic micro-organisms 
has an endocrine function

Question 3

Describe the importance of meiosis

Answer 3

Halving the number of chromosomes to balance the doubling effect of fertilization.
Ensures variability in the offspring / other gene combinations.
Formation of gametes

Question 4

Why does the cell divide twice during meiosis?

Answer 4

First meiotic division — parent cell split into two cells (2n) / reduction division.
and
second meiotic division — two cells divide to form four sex cells / gametes (n)

Question 5

Corpus cavernosa

Answer 5

two columns of erectile tissue

Question 6

Corpus spongiosum

Answer 6

erectile tissue that ensures the urethra stays open during erection for the passage of semen

Question 7

The testes

Answer 7

Produce sperm
Develop in abdominal cavity and descend into the scrotum just before birth
Optimum temperature for sperm development 350C – below body temperature
Sperm produced in seminiferous tubules
Process involves several cell divisions
Epididymis – stores and matures sperm cells

Question 8

where is testosterone produced

Answer 8

Leydig (interstitial) cells in testes produce male hormone testosterone

Question 9

where is the hormone oestrogen produced in females

Answer 9

produced by mature Graafian follicles – causes appearance of secondary sexual characteristics in young women

Question 10

where is the hormone progesterone produced in females

Answer 10

produced by the corpus luteum – establishes the menstrual cycle with the aid of oestrogen – maintains pregnancy – prepares breasts for milk production

Question 11

what is the site of fertilization

Answer 11

Fallopian tubes

Question 12

explain the ovarian cycle and ovulation

Answer 12

1. primodial follicle
2. mature graafican follicle
3. FSH stumlates the follicle to secrte oestrogen and form antrum ( cavity)
4. secondary oocyte
5. LH cause the ripe follicle burst and an oocyte is released

Question 13

what happens to the graafian follicle after ovulation

Answer 13

forms the corpus luteum which secretes progesterone

Question 14

what happens to the corpus luteum if fertilization takes place

Answer 14

its matures

Question 15

what is the purpose of the menstrual cycle

Answer 15

prepares body for pregnancy

Question 16

explain the negative feedback system between oestrogen and FSH

Answer 16

• FSH stimulates the development of the follicle which thus secretes oestrogen
• oestrogen stimulates pituitary gland to secrete LH as well as repairs the endometrium after menstruation has taken place
• LH inhibits the secretion of FSH
• therefore only one follicle is produced

Question 17

explain the negative feedback system between progesterone and LH

Answer 17

• LH stimulates the ovary to secrete progesterone from the corpus luteum
• progesterone prepares the endometrium for implantation and inhibits the secretion of LH and FSH

Question 18

what are the 4 phases of the menstrual cycle

Answer 18

• menstrual phase
• follicular phase
• ovulation phase
• luteal phase

Question 19

what structure allows the blasotocyst to embed itself into the endometrium

Answer 19

the chorion villi

Question 20

what is the function of glycoprotiens

Answer 20

allows blastocyst to attach to endometrium

Question 21

what is the outer layer of the blastocyst called

Answer 21

trophoblast

Question 22

what do the arteries in the umblical cord do

Answer 22

carry deoxygenated blood and waste from foetus to placenta

Question 23

what does the vien in the umblical cord do

Answer 23

carries oxygenated blood which is also rich in nutrients to the foetus from placenta

Question 24

functions of the placenta

Answer 24

• Water, by osmosis
• Nutrients – glucose, amino acids, fatty acids, ions, vitamins – active transport – good nutrition for mother important during pregnancy
• Nitrogenous waste such as urea – diffuse
• Antibodies produced by mother – move to foetus and provide short-term passive immunity

Question 25

what is the placenta

Answer 25

Transfer of substances by diffusion via the thin membranes separating maternal and foetal blood

Question 26

what hormone is secreted during pregancy

Answer 26

Human chorionic gonadotrophin

Question 27

what is another word for birth

Answer 27

parturition

Question 28

what hormones are secreted during birth

Answer 28

Placenta secretes hormone, relaxin, which causes pelvic ligaments to relax, widen and become more flexible in preparation of birth
Hormone oxytocin from pituitary stimulates uterine contractions which dilate the cervix and expel the baby