L17

Question 1

what must happen to the sperm deposited in the vagina before fertilisation?

Answer 1

it must mature and travel before fertilization

Question 2

what is the importance of capacitation?

Answer 2

sperm must undergo capacitation to become hyperactive

Question 3

what does capacitation consist of?

Answer 3

albumin, enzymes, and lipoproteins bind to the sperm, causing:
- glycoprotein coat to be removed
- intracellular changes
- sperm develops a strong, whip-like motion

Question 4

label a diagram of the sperm

Question 5

describe the travel of the sperm in the woman

Answer 5

• sperm must pass through the cervical mucous (~30 mins), which is thin due to estrogen
• uterine and oviduct contractions aid transport due to estrogen and semen prostaglandins

Question 6

what issue does capacitation have?

Answer 6

it is an issue for IVF, where the sperm must undergo capacitation artificially through physiologic saline solutions and human serum

Question 7

where does fertilisation occur?

Answer 7

in the fallopian tube

Question 8

what is formed after fertilisation?

Answer 8

a zygote

Question 9

viability of the oocyte

Answer 9

24h

Question 10

viability of the spermatozoa

Answer 10

4-6 days

Question 11

why is the longer viability of the spermatozoa important?

Answer 11

as it makes it possible for the sperm to be deposited before the female even ovulates

Question 12

label a diagram of an oocyte before fertilisation

Question 13

how many sperm reach the oocyte?

Answer 13

about 100 sperm

Question 14

chemotaxis

Answer 14

• a chemical method of attracting and guiding sperm to the egg
• consists of progesterone from cumulus cells

Question 15

how does the sperm tunnel through the various barriers of the egg?

Answer 15

• with acrosomal enzymes
• acrosomal reaction releases enzymes and breaks down the zona pellucida, allowing sperm to fuse with egg

Question 16

how is polyspermy prevented?

Answer 16

• the first sperm to fuse with the egg wins
• once the egg has been fertilised, the oocyte will prevent penetration by additional sperm

Question 17

describe the process of fertilisation

Answer 17

1. sperm docks with sperm-binding proteins on oocyte membrane, triggering depolarisation of the oocyte
2. cortical reaction: fusion of cortical granules (oocyte intracellular vesicles) with outer membrane
3. sperm nucleus moves into cytoplasm of the egg
4. oocyte nucleus completes meiosis II
5. the sperm and egg nuclei fuse to form zygote nucleus and the second polar body is expelled

Question 18

describe the 5 days after fertilisation

Answer 18

day 1: fertilisation
days 2-4: cell division takes place in the fallopian tube
days 4-5: blastocyst reaches uterus
days 5-9: blastocyst implants

Question 19

blastocyst

Answer 19

an early-stage embryo that is a hollow ball of cells with an inner cluster and an outer layer.

Question 20

trophoblast

Answer 20

a layer of cells on the outer surface of a blastocyst that provides nutrients to the embryo and forms the fetal part of the placenta

Question 21

hCG

Answer 21

• human chorionic gonadotropin
• secreted from trophoblast
• takes over from pituitary to maintain corpus luteum and prevent next menstrual cycle

Question 22

hCG is similar in structure to

Answer 22

LH

Question 23

how is hCG useful in clinical applications?

Answer 23

basis of pregnancy tests

Question 24

function of progesterone, estrogen and inhibin during hCG action

Answer 24

• progesterone keeps endometrium intact
• progesterone, estrogen, inhibin: feedback suppression of the pituitary

Question 25

what is the role of the placenta?

Answer 25

- performs role of digestive, respiratory and renal systems for the foetus - exchange of nutrients/waste, oxygen/carbon dioxide, proteins, chemicals, etc

Question 26

describe circulation in the placenta

Answer 26

- maternal vasculature is not physically linked to fetal vasculature - maternal blood forms a lacunae - fetal chorionic villi transfer gases and solutes between mother and foetus

Question 27

umbilical arteries

Answer 27

Fetal vessel, from placenta -> fetus

Question 28

umbilical veins

Answer 28

Fetal vessels, from fetus -> placenta

Question 29

define the placenta

Answer 29

a temporary endocrine organ

Question 30

draw a diagram of changes in hormones with days of pregnancy

Question 31

draw a table of hormone exchanges between the mother's blood, placenta, fetal blood, and fetal adrenal cortex

Question 32

hCG - function

Answer 32

maintains corpus luteum; stimulates fetal testis

Question 33

progesterone - function

Answer 33

suppresses uterine contractions, cervical plug, mammary gland development

Question 34

estrogen - function

Answer 34

uterine development (growth, blood supply, oxytocin receptors), breast duct development

Question 35

human placental lactose - structure

Answer 35

structurally related to growth hormone and prolactin

Question 36

human placental lactose - concentrations

Answer 36

high in mother/low in foetus

Question 37

human placental lactose - function

Answer 37

- decreases maternal cellular uptake of glucose - enhances maternal lipolysis

Question 38

first trimester

Answer 38

0-12 weeks: embryo development

Question 39

second trimester

Answer 39

12-28 weeks: fetal development

Question 40

third trimester

Answer 40

28 weeks to delivery: fetal maturation

Question 41

normal birth

Answer 41

37-42 weeks after last menstrual cycle

Question 42

preterm

Answer 42

fetus born > 28 weeks, usually viable without intervention (lungs not developed before then)

Question 43

postterm

Answer 43

>42 weeks

Question 44

state the 4 maternal adaptations to pregnancy

Answer 44

renal, cardiovascular, immune sytem, calcium homeostasis

Question 45

maternal adaptations to pregnancy - renal

Answer 45

- increased vasopressin levels increase blood volume - increased activity of RAS: sodium and fluid retention

Question 46

maternal adaptations to pregnancy - cardiovascular

Answer 46

increased output

Question 47

maternal adaptations to pregnancy - immune system

Answer 47

partially suppressed

Question 48

maternal adaptations to pregnancy - calcium homeostasis

Answer 48

pregnancy associated hyperparathyroidism: - calcium transfer to fetus - increased calcitonin to limit mobilisation of maternal bone

Question 49

relaxin

Answer 49

before parturition, relaxin released from ovary and placenta loosens the ligaments in the pelvic bone and cause the cervix to soften

Question 50

triggers of labour

Answer 50

- increased estrogen and oxytocin receptors in the uterus - increased fetal cortisol - increased placental corticotropin-releasing hormone (CRH) - increased prostaglandin

Question 51

how can labour be induced?

Answer 51

using synthetic form of oxytocin known as Pitocin

Question 52

draw a flow chart of how labour happens

Question 53

breast milk - before parturition

Answer 53

oestrogen's and progesterone needed for the development of mammary glands but inhibit milk production

Question 54

breast milk - after parturition

Answer 54

prolactin and oxytocin are both released from the pituitary gland: - prolactin stimulates epithelial milk-producing cells - oxytocin causes contraction of myoepithelial cells to squeeze milk into the nipple

Question 55

draw a flow chart of regulation of milk release

Question 56

what are the two main triggers for milk release?

Answer 56

sound of child's cry and baby suckling