Mammary glands and lactation

Question 1

What is mammogenesis?

Answer 1

How mammary glands are formed

Question 2

What is isometric growth?

Answer 2

growth that occurs at the same rate for all tissues so that the shape is consistent

Question 3

When does isometric growth occur for mammary glands?

Answer 3

From birth to puberty

Question 4

What is allometric growth?

Answer 4

growth that is faster than the growth rate of other tissues

Question 5

When is the fastest stage of mammary gland proliferation?

Answer 5

From conception to parturition

Question 6

What is milk secretion?

Answer 6

synthesis of milk by the alveolar cell and its transfer from the alveolar cell into the alveolar lamina.

Question 7

What two things does progesterone block?

Answer 7

Parturition and lactation

Question 8

What is the function of oestrogen (in terms of lactation)?

Answer 8

High levels can prevent lactation

Question 9

What does cortisol induce growth of?

Answer 9

Rough endoplasmic reticulum and golgi apparatus

Question 10

Why do we need golgi apparatus and RER in the epithelial cells?

Answer 10

allows prolactin to initiate lactation

Question 11

What is the main function of prolactin?

Answer 11

Removes the progesterone block so that parturition can be initiated

Question 12

What is galactopoiesis?

Answer 12

The maintenance of milk production

Question 13

What two factors play a role in milk production?

Answer 13

Both hormonal and local

Question 14

Where is prolactin produced from?

Answer 14

The anterior pituitary gland

Question 15

What is prolactin inhibited by?

Answer 15

dopamine

Question 16

What does suckling do to dopamine?

Answer 16

It has an inhibitory effect

Question 17

What hormone stimulates contraction of myoepithelial cells?

Answer 17

Oxytocin

Question 18

What is the milk ejection reflex?

Answer 18

A neuroendocrine reflex that allows milk to be let down/released by causing the posterior lobe of the pituitary to release oxytocin

Question 19

What does activation of the sympathetic nervous system do to milk let-down?

Answer 19

Inhibits it, e.g if they are anxious/ there is painful external stimuli

Question 20

What does FIL do?

Answer 20

reduces milk synthesis by reducing milk flow

Question 21

What is the composition of colostrum in comparison to regular milk?

Answer 21

Contains more fat, protein, minerals and vitamins
than regular milk and lower levels of lactose

Question 22

What animals is colostrum particularly important in and why?

Answer 22

ruminants, foals and piglets as they cannot receive nutrients via the placenta

Question 23

When is intestinal absorption of immunoglobins at its maximum

Answer 23

In the first 6 hours

Question 24

What enzymes facilitate the production of glucose?

Answer 24

lactose synthase and a-lactalbumin

Question 25

Where are Milk fats synthesised?

Answer 25

They are synthesised in the smooth ER (from precursor fatty acids and glycerol)

Question 26

What does suckling inhibit the secretion of?

Answer 26

Dopamine,

Question 27

What does progesterone stimulate the development of during pregnancy?

Answer 27

lobulo-alveolar development

Question 28

What do high levels of oestrogen prevent during pregnancy?

Answer 28

Lactation

Question 29

What is agalactia?

Answer 29

A failure to produce milk which will then lead to a failure to reproduce

Question 30

How does pro-lactin increase milk secretion?

Answer 30

Removal of the progesterone block also removes inhibition of the prolactin receptor synthesis
Increased binding of membrane receptors means that there is increased production of milk-protein genes (synthesis of lactose)

Question 31

Which hormone inhibits prolactin secretion?

Answer 31

Dopamine

Question 32

How do insulin and growth hormone effect milk production?

Answer 32

They regulate the metabolism to ensure there is adequate supplies

Question 33

When do FIL levels increase?

Answer 33

Suckling stops so milk builds up in the alveoli
this reduces milk synthesis
and eventually apoptosis of the secretory cells

autocrine effect, can be inhibited by milking

this is mammary gland involution (essential process)

Question 34

What is the final stage of lactose production and what enzymes regulate it?

Answer 34

UDP galacatose + glucose -> Lactose
this is regulated by lactose synthase and
a-lactoalbumin (milk protein)

Question 35

Where is milk fat synthesised and by what

Answer 35

It is synthesised in the smooth ER from precursor fatty acids and glycerol
the milk fat then moves towards the apical membrane in droplets

Question 36

What acids make up the preformed fatty acids?

Answer 36

C16 and C18
it is synthesised from adipose stores early on in lactation

Question 37

Where are the non-essential amino acids for milk proteins produced?

Answer 37

They are synthesised within the mammary epithelial cells

Question 38

How can you use urea to assess health in cattle?

Answer 38

Easily diffuses into milk
* Same concentration in milk as blood
Too low – nitrogen content in feed too low so animal must catabolise muscle protein and vicer versa

high urea could also be a sign of deydration

Question 39

How could acetone be used to assess cattle health

Answer 39

Easily diffuses into milk
* Same concentration in milk as blood
* Detected by colour reaction (Rothera’s test)
* Used for clinical investigation of ketosis

Question 40

How could progesterone be used to assess health in cattle?

Answer 40

• Lipid-soluble steroid hormone
• Low in non-cycling animals or in follicular phase
• Higher in luteal phase or pregnancy
• Used to assess reproductive status

Question 41

What do low fat levels in milk indicate?

Answer 41

High levels of concentrate feeding

Question 42

What kind of infection would increase the SCC of a cow?

Answer 42

Mastitis/ mammary infection

Question 43

When do FIL levels increase?

Answer 43

When the young stop suckling/weaning

due to increased pressure in the intramammary glands

Question 44

What happens to the secretory cells after lactation stops?

Answer 44

They are removed by apoptosis