15. Biochemistry of the Mammary Gland and Lactation

Question 1

Which hormones play a role in lactation?

Answer 1

Prolactin, progesterone, estrogens, GH, cortisol, hPL

Question 2

What type of gland is the mammary gland?

Answer 2

Exocrine

Question 3

What are the functions of the mammary gland?

Answer 3

Provide the neonate with a source of food and immunological protection

Question 4

What is the function of myoepithelial cells?

Answer 4

Provide structural support to the lobules

Contract when stimulated by oxytocin to eject milk

Question 5

What are the WHO’s recommendations for breastfeeding?

Answer 5

Exclusive breastfeeding for first 6 months

In combination with other foods until age 2

Question 6

What inhibits prolactin?

Answer 6

Dopamine

Question 7

What stimulates prolactin?

Answer 7

TRH

Question 8

What are the causes of hyperprolactinemia?

Answer 8

Pituitary adenomas
Reduced dopamine
Suckling
Pregnancy, oestrogen therapy or hypothyroidism
Drugs: antipsychotics, opiates

Question 9

What is mammogenesis?

Answer 9

Development of ducts and alveolar systems of the breast

Question 10

What happens in mammogenesis?

Answer 10

Prolactin completes cellular differentiation and development of lactogenic capcity
Oestrogens stimulate ductal development
Progesterone completes mammogenesis of alveolar system
Insulin for multiplication of epithelial cells and development of luboulalveolar architecture

Question 11

What is the time period of lactogenesis 1?

Answer 11

Mid pregnancy to 30 hours after birth

Question 12

What is the time period of lactogenesis 2?

Answer 12

30-40 hours after birth to 2/3 months post-partum

Question 13

What is the time period of lactogenesis 3?

Answer 13

2/3 months post-partum onwards

Question 14

What are the events of lactogenesis 1?

Answer 14

Lactogenic capability but high levels of progesterone inhibit milk secretion and suppress volume

Question 15

What are the events of lactogenesis 2?

Answer 15

Delivery of the placenta results in decreased progesterone, oestrogen and hPL
Increase in milk volume

Question 16

What are the events of lactogenesis 3?

Answer 16

Established lactation

Autocrine control of milk synthesis: baby suckling

Question 17

How is lactose synthesised?

Answer 17

One glucose is converted to UDP-glucose, then UDP-galactose

Joined to a second unmodified glucose

Question 18

What is lactose synthase enzyme composed of?

Answer 18

Galactosyltransferase (catalytic component)

a-lactalbumin (regulatory)

Question 19

What is the technical term for milk letdown?

Answer 19

Galactogenesis

Question 20

What are the carbohydrates found in human milk?

Answer 20

Lactose

Oligosaccharides

Question 21

What proteins are found in human milk?

Answer 21

Casein

Whey proteins: lactoferrin, secretory immunoglobulin A, a-lactalbumin

Question 22

What minerals are found in human milk?

Answer 22

Na+, K+, Cl-, Ca++, Mg++

Question 23

What is the difference between human and bovine milk?

Answer 23

Human milk has more lactose but less protein and ionic constituents than bovine milk

Question 24

What processing does infant formula undergo?

Answer 24

Whey-to-casein protein balance changed
Fortification
Replacement of dairy fat with vegetable or marine fats

Question 25

What components of human milk aren't found in formula?

Answer 25

``` Lactoferrin Oligosaccharides and glycoconjugates Growth factors Long chain PUFAs (omegas) Lipase ```

Question 26

What are the benefits of human milk?

Answer 26

Improved GI function, digestion and absorption Improved cognitive and visual development Improved immunity Better maternal wellbeing and bonding Improves birth spacing

Question 27

What is the difference between colostrum and human milk?

Answer 27

Yellow and thicker Concentrated nutrition High in antibodies Laxative effect to help pass first bowel movements

Question 28

What is weaning?

Answer 28

Reduction of breast milk or formula to replace it with more solid food