Lecture 14 - Lactation Part 2 Flashcards

1
Q

Why does the mammary epithelium have a high mitochondrial density

A

ATP for synthetic processes
Uptake precursors, transport into lumen

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2
Q

How much arterial blood oxygen does the mammary epithelium consume

A

50%

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3
Q

What does the rough endoplasmic reticulum of the mammary epithelium do

A

Make proteins (ribosomes)

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4
Q

What do the smooth endoplasmic reticulum of the mammary epithelium do

A

Make phospholipids and triglycerides (fat droplets)
(f.a. synthesis and glycolysis in cytosol)

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5
Q

What does the golgi do in mammary epithelium

A

Synthesizes lactose
Lactose synthase = glucose+galactose

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6
Q

Where does glucose for lactose synthesis come from

A

Starch and sugar digestion/absorption in monogastrics
Ruminants main source is propionate and glucogenic aa converted in the liver

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7
Q

Where does galactose for lactose synthesis come from

A

Conversion of glucose

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8
Q

The main determinant of milk secretion is

A

Lactose

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9
Q

Decrease in blood glucose leads to

A

Decrease of lactose and milk volume

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10
Q

What turns on the enzymes for lactose production

A

Prolactin

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11
Q

Milk fat is made up mostly of

A

98% triglycerides

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12
Q

How does the mammary get free fatty acids

A

From chylomicrons or VLDL
OR de novo f.a. synthesis in alveolar epithelial cells

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13
Q

Fatty acids can be made from… (monogastric vs ruminant)

A

Glucose, acetate and ketone bodies
NOT glucose in ruminants (saved for making lactose)

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14
Q

What happens to large lipid droplets? What else do these provide the neonate?

A

They are drawn to the apex of the cell
provide phospholipids, cholesterol to neonate

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15
Q

Slide 16**

A

Fats

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16
Q

What can non-ruminants do with regards to acetyl coa that ruminants can not

A

Can lyse citrate with citrate lyase in presence of CoA to produce acetyl-CoA for f.a. synthesis (make f.a. from glucose)
Ruminants do not have citrate lyase

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17
Q

What f.a. are in milk

A

C4, C6, C8, C10, C12

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18
Q

Slide 20

A

help

19
Q

Milk protein is made in… Packed in…

A

Made in rough endoplasmic reticulum
Packaged in the golgi secretory vesicles

20
Q

What proteins are in milk

A

Whey proteins (B-lactoglobulin and a-lactalbumin, lactoferrin)
and casein (binds minerals)

21
Q

Free ions in milk:

A

Na, K, Cl

22
Q

Second most important osmotic component of milk determining milk volume (after lactose)

A

Ions

23
Q

How do ions get into milk

A

Na/K pump on basolateral membrane

24
Q

Slide 23, 24

A

Secretion of milk components

25
Q

What components are packaged in secretory vesicles in the golgi

A

Lactose, casein, whey proteins, citrate, Ca

26
Q

How does milk fat secretion occur

A

Portion of apical membrane surrounds the fat droplet

27
Q

How is milk production regulated

A

According to consumption by offspring (or milking)
Mediated by pressure in the glands

28
Q

How can we increase milk production in dairy

A

Increase milking frequency
Give a growth hormone

29
Q

Slides 25, 26

A

Curves

30
Q

Homeorhesis vs homeostasis

A

Rhesis = orchestrated changes to meet the priorities of a physiological state (e.g. lactation)

Stasis = maintenance of a steady state of a given physiological function

31
Q

Ways the GI tract adapts for lactation

A
  • expansion of reticulorumen to allow for greater intake
  • increase capacity of omasum, abomasum, SI
  • increase LI size for more water absorption
  • water absorption increases, excretion minimized
  • shift in partitioning of nutrients towards mammary gland
  • expansion to allow greater DMI driven by energy expense of milk production
32
Q

How many volumes of blood support 1 volume of milk produced

A

500

33
Q

How does blood volume and flow change during lactation

A
  • plasma volume increases to accommodate demand
  • potassium and sodium requirements increase
  • kidney adjusts to increase water absorption
34
Q

How does the liver adapt during lactation

A
  • nutrient partitioning of CHO, protein, fat
  • drains GIT and delivers absorbed nutrients
  • gluconeogenesis from propionate
  • glycogenolysis increases
  • acetate and butyrate used as E source and substrate for f.a.
  • TG synthesized in liver, exported
35
Q

Why does the liver maximize glucose available to the mammary gland during lactation

A

Large demand for glucose for lactose production (key determinant of how much milk we can produce)

36
Q

How does adipose tissue adapt to lactation

A
  • reduced uptake of glucose (insulin sensitivity to glucose lower)
  • mobilizes stored TG (priority over lipogenesis)
  • leptin secretion drops as adipose mass drops (increase feed intake)
37
Q

How does bone adapt to lactation

A
  • calcium uptake at gut and mobilization from bone
  • calcitonin prevents elevated calcium in blood
38
Q

Glucose sparing mechanisms by the rest of the body

A
  • acetate/propionate used for E
  • no pathway for glucose use for lipogenesis
  • glucose used for lactose synthesis in mammary
39
Q

During lactation, mammary gland increases uptake of…

A

amino acids (met and lys are first limiting milk production)
free f.a. and glycerol

de novo TG synthesis from circulating SCFA

40
Q

How does muscle adapt to lactation

A
  • utilizes f.a. for E instead of glucose
  • provides reservoir of aa (protein synthesis)
  • growth is prioritized over milk during the first lactation
41
Q

Slide 42

A

Preparturient E balance

42
Q

Growth hormones role in lactation

A

High at onset of lactation (can be used to maintain milk production)
Lipolytic effects to make f.a. available

43
Q

Leptins role in lactation

A

Produced by fat cells, as adipose accumulates, leptin increases
Declines as energy is mobilized from adipose (during lactation)