Lactation

Question 1

Describe the stages of mammary gland development

Answer 1

1. birth - primary duct system, single duct
2. puberty - glands develop, if animal grows too quickly fat replaces epithelium & secretory cells in stroma
3. gestation - 2nd half of gestation, alveoli form under the influence of prolactin & progesterone

Question 2

define lactogenesis 1

Answer 2

secretory epithelium secrete modified blood serum, leaky junctions between cells means serum is reabsorbed from lumen

Question 3

define lactogenesis 2

Answer 3

at parturition tight junctions form, secretion stays in the canal

Question 4

what is the average milk composition?

Answer 4

• lipid - 3.5%
• lactose - 4.5%
• protein - 3.3%
• Ig - 1%
• NFS - 9%

Question 5

describe the milk let down reflex

Answer 5

1. mechanoreceptors at base of teat stimulated by suckly
2. signal transmitted to CNS via hypo
3. hypo signals posterior pituitary to produce oxytocin
4. oxytocin enters circulation & binds receptors on myoepithelial cells
5. SM in cells contracts, milk ejected in short bursts into the duct

Question 6

describe the milk production reflex

Answer 6

1. dopamine down regulated
2. mechanostimulation sends signal to hypo
3. hypo stimulates lactotroph cells in anterior pituitary to produce prolactin
4. prolactin travels systemically & binds to receptors in alveoli
5. lactogenesis stimulated

Question 7

describe the action of FIL

Answer 7

• autocrine peptide that controls milk production to meet demand
• secreted by epithelial cells when milk production needs to be downregulated
• binds to receptors on the epithelial cells and inhibits milk production