REPRODUCTIVE (PART 3)

Question 1

Where does fertilisation (conception) occur?

Answer 1

In the fallopian tubes, when a sperm fertilises the ovum (egg)

Question 2

What is a zygote?

Answer 2

The first cell formed after fertilisation, containing genetic information from both sperm and ovum

Question 2

What is the acrosome reaction?

Answer 2

A biochemical reaction triggered when a sperm reaches the ovum, allowing it to penetrate the ovum’s outer layer

Question 3

What are the two main parts of a blastocyst?

Answer 3

Inner cell mass (forms embryo, amnion and umbilical cord) and outer cell mass (forms placenta and chorion)

Question 3

How many sperm can fertilise an ovum?

Answer 3

Only one
After fertilisation, the ovum changes to prevent other sperm from entering

Question 4

What is the role of hCG (human chorionic gonadotropin)?

Answer 4

Produced by the trophoblast, it prepares the endometrium for implantation by causing decidualization (structural changes)

Question 4

What is implantation?

Answer 4

The attachment of the blastocyst to the endometrium of the uterus

Question 4

What is the difference between fertilisation and pregnancy?

Answer 4

Fertilisation is the fusion of sperm and ovum
Pregnancy begins with implantation of the fertilised egg (zygote) in the uterus

Question 5

What are the three main stages of embryonic development?

Answer 5

Pre-embryonic (weeks 1 - 2): Implantation
Embryonic (weeks 2 - 8): Early organ formation
Foetal (weeks 8 - birth): Growth and development of organs and systems

Question 5

What happens to the zygote after fertilisation?

Answer 5

It travels to the uterus, dividing into a morula and then a blastocyst

Question 6

How does the foetus receive nutrients and oxygen?

Answer 6

Through the placenta, which increases in size and function throughout pregnancy

Question 6

What is the placenta’s role?

Answer 6

An organ formed from the trophoblast that allows nutrient and gas exchange between mother and embryo/foetus

Question 7

What are the three stages of labour?

Answer 7

Stage one: period from onset of uterine contractions until dilation of the cervix is complete
Stage two: period from the time of maximal cervical dilation until the baby exits through the vagina i.e. birth
Stage three: process of expulsion of the placenta through the vagina

Question 7

What separates maternal and foetal blood in the placenta?

Answer 7

The placental membrane (barrier) with five layers

Question 7

Why doesn’t maternal blood directly mix with foetal blood?

Answer 7

So substances pass through the placental barrier between the two circulations

Question 8

How do uterine arteries change during pregnancy?

Answer 8

The trophoblast remodels them, making them wider and less resistant for increased blood flow to the placenta

Question 9

What is a multiple birth?

Answer 9

The birth of two or more babies from the same pregnancy
Twins are most common

Question 10

What are the risks of multiple births for babies?

Answer 10

They are more likely to be born prematurely and have complications in infancy

Question 11

How can identical twins develop?

Answer 11

From a single fertilised egg (zygote) splitting early in development, like the inner cell mass dividing in a blastocyst

Question 12

What is the role of oxytocin in labour?

Answer 12

Oxytocin causes contractions, and its release is a positive feedback loop that strengthens them

Question 12

What can cause multiple ovulation?

Answer 12

Genetics or fertility drugs used in procedures like in vitro fertilisation (IVF)

Question 12

How do fraternal twins develop?

Answer 12

From two separate eggs fertilised by two separate sperm
This often requires multiple eggs released in one menstrual cycle

Question 13

How can labour be medically induced?

Answer 13

By introducing oxytocin to stimulate contractions

Question 14

What triggers the hormonal changes that lead to labour?

Answer 14

High cortisol levels near the end of pregnancy causes falling hCG levels

Question 15

How does hCG affect labour?

Answer 15

Falling hCG levels causes decreased progesterone production which allows oxytocin release

Question 16

What is the role of prostaglandins in labour?

Answer 16

Make the uterus more sensitive to oxytocin’s effects

Question 16

What are the main structures of the breast?

Answer 16

Mammary glands (produce milk)

Question 17

When does most breast development occur?

Answer 17

During pregnancy, with increased size, darker areolas, and more erect nipples

Question 18

What are the two stages of lactogenesis (milk production)?

Answer 18

Mammary gland development during pregnancy (oestrogen, progesterone, prolactin)
Milk secretion after birth (triggered by drop in progesterone)

Question 19

What hormone triggers milk letdown (milk release)?

Answer 19

Oxytocin

Question 19

What is colostrum and what is its role?

Answer 19

Colostrum is the first milk produced, high in protein and minerals, and helps establish gut bacteria in newborns

Question 19

What determines milk supply?

Answer 19

The frequency and effectiveness of milk removal by the baby (supply and demand)

Question 20

How does suckling stimulate milk letdown?

Answer 20

Suckiling triggers oxytocin release from the pituitary gland

Question 21

What other benefits are there to breastfeeding besides nutrition?

Answer 21

Promotes uterine involution (contraction) after birth
May aid postpartum weight loss
Releases oxytocin which strengthens the maternal bond