4.11: The reproductive system (part 2 of 3)

Question 1

What does tubular fluid reabsorption result in

Answer 1

Concentration (induced by oestrogen)

Question 2

What does the epididymis secrete into the epididymis fluid

Answer 2

Nutrients and glycoproteins
(Induced by androgens)

Question 3

How far does the sperm travel from the testis to fallopian tube

Answer 3

100,000 x it’s length

Question 4

What does Semen contain (3)

Answer 4

Spermatozoa 15-120 million/ml
Seminal fluid 2-5ml
Leuococytes
(Potentially viruses: hep B, HIV)

Question 5

How many spermatozoa in ejaculate enter the cervix

Answer 5

1/100

Question 6

How many sperm enter the ovum from the cervix

Answer 6

1/10,000

Question 7

Overall how many sperm reach the ovum

Answer 7

1/1 million

Question 8

Where does seminal fluid mainly arise from (3)

Answer 8

Seminal vesicles
Prostate
Bulbourethral glands
(Small contribution from epididymis/ testis)

Question 9

Capacitation of sperm

Answer 9

Achieve fertilising capability in the female reproductive tract

Question 10

3 ways sperm becomes capacitance

Answer 10

Loss of glycoprotein coat
Change in surface membrane characteristics
Develop whiplash movement of tail

Question 11

Where does sperm capacitation occur

Answer 11

Ionic and proteolytic environment of the fallopian tube

Question 12

What 2 things is sperm capacitation dependent on

Answer 12

Oestrogen
Ca2+

Question 13

What is the sperm receptor on the egg

Answer 13

ZP3

Question 14

In the acrosome reaction

Answer 14

Ca2+ influx into sperm - Stimulated by progesterone
Release of hyaluronidase and proteolytic enzymes (from acrosome)
Spermatozoon penetrates the zona pellucida

Question 15

Where does fertilisation occur

Answer 15

Within the fallopian tube

Question 16

What does fertilisation trigger

Answer 16

Cortical reaction

Question 17

What happens in the cortical reaction

Answer 17

Cortical granules release molecules which degrade Zona Pellucida
Preventing further sperm binding as no receptors
Haploid -> Diploid

Question 18

What is the conceptus

Answer 18

Embryo in the uterus, especially during early stages of pregnancy

Question 19

Development of conceptus

Answer 19

Continues to divide as it moves down fallopian tube to uterus (3-4days)

Question 20

What does the conceptus receive nutrients from

Answer 20

Uterine secretions

Question 21

How long can the conceptus free living phase last for

Answer 21

9-10 days

Question 22

Two phases of Implantation

Answer 22

Attachment phase
Decidualisation phase

Question 23

In the attachment phase

Answer 23

Outer trophoblast cells contact uterine surface epithelium

Question 24

What does the attachment phase trigger

Answer 24

Decidualisation phase

Question 25

What occurs in the Decidualisation phase

Answer 25

Changes in underlying uterine stromal tissue (within a few hours)

Question 26

What does implantation require

Answer 26

Progesterone domination in the presence of oestrogen

Question 27

What two hormones aid implantation

Answer 27

LIF - leukaemia inhibitory factor IL11 - interleukin-11

Question 28

How does LIF aid implantation

Answer 28

LIF from endometrial cells stimulates adhesion of blastocyst to endometrial cells

Question 29

How does IL11 aid implantation

Answer 29

IL11 from endometrial cells is released into uterine fluid, and may be involved

Question 30

4 endometrial changes due to progesterone

Answer 30

Glandular epithelial secretion Glycogen accumulation in stromal cell cytoplasm Growth of capillaries Increased vascular permeability (-> oedema)

Question 31

Factors involved in Decidualisation

Answer 31

Interleukin 11 Histamine Prostaglandins TGF B -> promotes angiogenesis

Question 32

Progesterone and oestrogen production in the first 40 days

Answer 32

Produced in corpus luteum (maternal ovary) and stimulated by hCG which acts on LH receptors Essential for developing fetoplacental unit Inhibits maternal LH and FSH ( negative feedback )

Question 33

Progesterone and oestrogen production from day 40

Answer 33

Placenta takes over

Question 34

What 4 hormones does DHEAS stimulate the placenta to produce

Answer 34

Progesterone Oestradiol Oestrone Oestriol

Question 35

What 6 maternal hormones increase during pregnancy

Answer 35

ACTH Adrenal steroids Prolactin IGF-1 (stimulated by placental GH- variant Iodothyronines PHT related peptides

Question 36

What 6 maternal hormones decrease during pregnancy

Answer 36

Gonadotropins Pituitary GH TSH

Question 37

3 functions of oxytocin

Answer 37

Uterine contraction Cervical dilation Milk ejection

Question 38

Endocrine control of lactation

Answer 38

Suckling on the nipple (stimulus) Neural pathways travel to hypothalamus Hypothalamus signals to pituitary Neurohypophysis - oxytocin - milk ejection Adenohypophysis - prolactin - milk synthesis