Repro 11.1 lactation

Question 1

Describe the realationship between mammary tissue and breast tissue.

Answer 1

Mammary tissue is found WITHIN breast tissue, and in the non lactating female there is much less mammary tissue than breast tissue.

Question 2

What is the mammary gland composed of?

Answer 2

around 15-20 lobules, which are divided by fibrous tissue and adipose tissue.

Question 3

Where do the mammary lobules drain?

Answer 3

Into the lactiferous ducts.

These combine to form a few lactiferous sinus’, which drain out of the nipple via pores.

Question 4

What are the single units of lactation known as?

Answer 4

Alveoli/acini

Question 5

What is the lining of the mammary alveoli?

Answer 5

collumnary epithelium which is supported by myoepithlium. (smooth muscle cells able to contract)

Question 6

What is the mammary tissue like at birth?

Answer 6

There is very little and it is underdevelopped.

Question 7

What happens to the mammary tissue at puberty?

Answer 7

The increase in oestrogens causes sprouting of the ducts and the formation of the alveoli (not yet functional).

More stroma is formed.

Question 8

What happens to the mammary glands during each stage of menstruation?

Answer 8

• follicular phase- dormant lobules
• luteal phase- cell proliferation and stromal oedema
• menses- decrease in the size of the lobules

Question 9

What happens to the mammary tissue with increasing age?

Answer 9

• lobular unit number decreases

- stroma is replaced by adipose tissue (which makes mammography easier)

Question 10

When does the majority of mammary gland development occur?

Answer 10

During pregnancy

Question 11

What happens to the mammary tissue during early pregnancy?

Answer 11

Hypertrophy of the ductular-lobular system

• lobules become capable of producing milk
• reduction in stromal levels

Question 12

With regards to mammary tissue and lactation, what are the effects of:

Oestrogen

Progesterone

Answer 12

Oestrogen- promotes milk production

Progesterone- promotes mammary tissue growth (As is seen at the beginning of pregnancy)

Question 13

Give some features of the milk produced soon after birth?

Answer 13

Colostrum

Yellow in colour, smelly

High levels of protein (particularly antibodies) and less water, fat and sugar than mature milk.

Question 14

How much Colotrum is produced per day after birth?

Answer 14

Around 40ml/day.

Question 15

Give some features of mature milk produced after birth of the neonate

Answer 15

• high in sugar (lactose)
• high water, and fat levels
• White in colour

Question 16

How long after partuition doe mature milk get produced?

Answer 16

2-3 weeks

Question 17

Describe the formation of different components of mature milk produced for the infant

Answer 17

• fats produced by the SER
• proteins produced and secreted by the golgi via exocytosis
• sugars- synthesised and exocytosed

Question 18

Which hormone is primarily responsible for lactogenesis?

Answer 18

Prolactin

Question 19

Why does milk production increase massively after birth?

Answer 19

The relative drop in progesterone compared to oestrogen causes the alveolar cells to become sensitive to prolactin, and the whole process to get switched on.

Question 20

How is prolactin secretion controlled?

Answer 20

It is secreted from the anterior pituitary, in respose to the hypothalamus.

It’s secretion is inhibited by dopamine.

Question 21

Describe how suckling promotes lactogenesis.

Answer 21

Neuro-endocrine reflex.

Suckling stimulates mechanical receptors in the nipple, which relay back to the hypothalamus.

this reduced dopamine, which means prolactin secretion rises

This allows lactogenesis to occur
(suckling causes milk production for the next feed, not the current one)

Question 22

Why should a baby be encouraged to suckle, even if they dont want to?

Answer 22

• promotes lactogenesis for the next feed
• without regular releiving, breasts become turgid and full of milk, which can damage surrounding blood vessels and reduce the ability to produce milk.
• breasts become sore if milk isnt relieved regularly
• keeps prolactin levels high (reduction of dopamine)

Question 23

Describe the process of milk ‘let down’.

Answer 23

Babies do not actively suck milk out of the breast.

sensation of baby suckling is relayed back to the hypothalamus.

There is increased oxytocin secretion (from the posterior pituitary)

Stimulates the myoepithelial cells to contract, releasing the milk into the babies mouth.

Question 24

Why might some mothers ‘leak’ milk when they dont want to, and in what situations might this happen?

Answer 24

The milk ‘let down’ reflex becomes conditioned when the mother anticipates suckling.

Eg hearing another baby cry, holding another baby.

Question 25

What is inflammation of the breast called?

Answer 25

Mastitis.

Question 26

What protection do the breasts have against infection?

Answer 26

They have lubricating glands known as montgomery tubercles, which produce a sebum lubricant. This prevents cracking of the nipple, which would allow infection to move into the breast.

Question 27

How much mature milk is the mother capable of producing each day?

Answer 27

800ml.

Question 28

Why is a large amount of milk needed to be produced by the mother during lactation?

Answer 28

The energy content of milk is low, so lots needs to get into the neonate.

27 Mjoules per litre,

Question 29

Other than reduced suckling, what factors can cause cessation of lactation?

Answer 29

• suppression of prolactin (eg some diuretics, some mushrooms, retained placenta)
• painful breasts, due to build up of milk
• menstrual changes, causes breasts to become lumpy, mother doesnt want to feed baby from these.

Question 30

For what reasons is breast feeding thought to be good?

Answer 30

• reduced infections in the newborn (passive immunity)
• bonding between mother and child
• reduced risk of breast/ovarian cancer in later life (due to reduced oestrogen exposure)
• aids loss of weight induced by pregnancy.

Question 31

When should breast feeding stop?

Answer 31

• around 6 months

- when the baby starts to develop teeth (will hurt mother)