21 - Gamete Manufacture, Ovarian and uterine cycles

Question 1

What stage are primary oocytes held in

Answer 1

prophase of meiosis 1

Question 2

What is the follicular phase

Answer 2

where the ovum and surrounding cells (the follicle) develop up to the point of ovulation
- length is variable

Question 3

What is the luteal phase

Answer 3

where the remaining cells of the follicle hang around and secrete hormones (mainly progesterone)
- prepares the lining of the uterus and endometrium for a fertilized ovum (zygote)

Question 4

How is the antrum formed

Answer 4

granulosa cells secrete follicular fluid –> antrum

Question 5

What is the corona radiata

Answer 5

granulosa cells around the oocyte

Question 6

Describe the negative pituitary regulation of the ovarian cycle

Answer 6

Stimulus: low estrogen in the blood

Receptor and control centre: hypothalamus detects low estrogen levels

Effector:
1. GnRH released from the hypothalamus
2. LH and FSH released from the pituitary –> follicle growth
3. LH stimulates production of estrogens which inhibit GnRH, LH, and FSH release

Question 7

Describe the positive pituitary regulation of the ovarian cycle

Answer 7

Continued estrogen production stimulates GnRH, LH and FSH release

LH surges causing the follicle to rupture and the ovum to be released

Question 8

Describe uterine histology

Answer 8

1. endometrium - stratum basalis and stratum functionalis
2. myometrium - smooth muscle
3. serosa - visceral peritoneum

Question 9

What is the purpose of the menstural cycle/uterine cycle

Answer 9

to prepare the lining of the uterus for the fertilized egg to implant

Question 10

What are the layers of the endometrium

Answer 10

stratum functionalis (outest)
stratum basalis
myometrium

Question 11

Which part of the endometrium is shed

Answer 11

stratum functionalis

Question 12

What does the stratum functionalis growth do

Answer 12

proliferation of the stroma and growth and elongation of the endometrial glands – glands will produce material that will provide nutrition for the zygote (fertilized egg)

Question 13

What are the phases of the uterine cycle

Answer 13

menstural phase
proliferation phase
secretory phase

Question 14

What happens in the mentural phase

Answer 14

Shedding of the inner lining of the uterus, known as the endometrium – loss of cells in blood

Estrogen and progesterone levels are low
- Shedding of the endometrium triggered by a decrease in hormone levels

Question 15

What happens in the proliferation phase

Answer 15

rapid growth and thickening of the endometrium under the influence of rising estrogen levels

estrogen:
- stimulates the proliferation of endometrial cells
- blood vessel formation
- development of glandular structures within the endometrium

Prepares the uterus for potential implantation of a fertilized egg by creating a thick, vascularized lining.

Question 16

What happens in the secretory phase

Answer 16

secretion of progesterone from the corpus luteum

Progesterone (& some estrogen):
- acts on the endometrium to further thicken and vascularize it (preparing it for potential implantation of a fertilized egg)

If fertilization and implantation do not occur, the corpus luteum regresses –> decline in progesterone levels and triggering the onset of menstruation

Question 17

What triggers ovulation

Answer 17

surge in estrogen –> LH surge

Surge in LH and some FSH –> stimulate the final maturation and release of the egg from the ovary

Question 18

In which phase is estrogen most secreted

Answer 18

proliferative and secretory phase

Question 19

In which phase is progesterone most secreted

Answer 19

secretory phase

Question 20

what stops the degeneration of the corpus luteum

Answer 20

implanting zygote and the placenta releases human chorionic gonadotropin (hCG)

Question 21

What does human chorionic gonadotropin do

Answer 21

acts like LH and stimulates the corpus luteum to produce lots of progesterone and a little estrogen

Question 22

What does the progesterone released from the corpus luteum do

Answer 22

inhibits uterine contractions and prevents disintegration of the stratum functionalis that preceeded menstural flow

Question 23

What are the parts of the sperm

Answer 23

acrosome
nucleus
midpiece
flagellum

Question 24

What does the acrosome do

Answer 24

sperm head
contains digestive enzymes for penetrating the zona pellucida

Question 25

What does the midpiece of sperm do

Answer 25

supplied the energy for the flagellum with its abundant mitochondria

Question 26

Describe spermatogenesis

Answer 26

1. spermatogonia – divide nad undergo meiosis
2. Primary spematocyte
3. secondary spermatocyte
4. spermatid

Question 27

What is the path of the sperm

Answer 27

epididymis of testes
ductus deferens
ejaculatory duct
urethra
- protatic
- membranous
- spongy (penile)

Question 28

What structures secrete fluids into semen

Answer 28

prostate
seminal vesicles
bulborethral glands

Question 29

What do the seminal vesicles do

Answer 29

fructose and clotting protiens
alkaline – neutralizes acidic vaginal pH
prostaglandins: stimulate sperm to swim and the uterus to contract

Question 30

What does the prostate do

Answer 30

thin acidic/neutral fluid for spem to swim in
citirc acid (nutrients)
protein digesting enzyme: break down clotting proteins

Question 31

What do bulbourethral glands do

Answer 31

release alkaline fluid into the urethra to neutralize acidic urine and some mucus to decrease sperm damage during ejaculation