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Physiology Exam 3 > Lecture 51- Digestion And Absorption Of Lipids; Absorption Of Vitamins And Minerals > Flashcards

Lecture 51- Digestion And Absorption Of Lipids; Absorption Of Vitamins And Minerals Flashcards

1
Q

What are the three main lipids?

A

Triglycerides (glycerol + 3 fatty acids)
Cholesterol
Phospholipids

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2
Q

How are lipids provided in diet for domestic animals?

A

Oils of vegetable or marine origin
Animal fats (tallow, lard, grease)

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3
Q

Dietary lipids must be solubilized in the ________ for digestion and absorption.

A

Small intestine

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4
Q

What is the function the stomach churning?

A

Churning breaks lipids into small droplets to increase surface area for enzymes

Mixes lipids, initiates enzymatic digestion

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5
Q

What does gastric lipase do?

A

Hydrolysis 10% of ingested TAG into glycerol + FFAs

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6
Q

What does the stomach slowly empty into the SI?

A

Chyme

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7
Q

How does the small intestine digest lipids?

A
  1. BILE SALTS EMULSIFY LIPIDS
  2. PANCREATIC ENZYMES DIGEST DIFFERENT LIPIDS
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8
Q

What does lipase + collapse allow?

A

Collapse binds to lipase and allows it to digest at lipid-water interface

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9
Q

What does cholesterol ester hydrolase do?

A

Hydrolyzes cholesterol ester -> free cholesterol + FA + releases glycerol from triglycerides

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10
Q

What is phospholipase A2 activated by?

A

Trypsin

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11
Q

What does phospholipase A2 hydrolyze?

A

It hydrolzyes phospholipids into lysolecithin + FA

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12
Q

What do bile salts solubilize products with SI lumen as _______.

A

Micelles

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13
Q

What does the core of the micelle contain? What is it surrounded by?

A

Contains products

Surrounded by bile salts

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14
Q

What does NOT diffuse into the enterocyte?

A

Bile salt

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15
Q

Re-estrified lipids + apoproteins = ________

A

Chylomicron

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16
Q

What is a chylomicron made up of?

A

Have cholesterol + TG in core, phospholipids + apoproteins around outside

Need to solubilize for absorption

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17
Q

What are lymphatic capillaries?

A

Chylomicrons can move between endothelial cells of lymphatic capillaries enter the blood at the thoracic duct

18
Q

What are the five steps for the absorption of lipids?

A
  1. Bile salts solubilize products within SI lumen as micelles (except glycerol)
  2. Micelles diffuse to brush-border membrane of enterocyte, products released and diffuse into cell
  3. Products are re-sterilized inside enterocyte to form original compounds
  4. Re-sterilized lipids are packaged with apoproteins to form chylmoicrons
  5. Chylmicrons packaged in secretory vesicles and exocytosed across basolateral membrane into lymphatic capillaries
19
Q

What is NOT solubilized within SI lumen as micelle?

A

Glycerol

20
Q

What are 6 abnormalities of lipid digestion and absorption?

A
  1. Pancreatic insufficiency
  2. Acidity of duodenal contents
  3. Deficiency of bile salt
  4. Bacterial overgrowth
  5. Decreased intestinal cells for absorption
  6. Failure to synthesize apoproteins
21
Q

What is the pH optimum for lipase?

A

6

22
Q

When does a tumor arise?

A

When there is an over production of gastrin

23
Q

What is ileal resection ?

A

No bile salt recycling

24
Q

What does a lack of Apo B causes ?

A

Abetalipoproteinemia

Chhylomicrons dont form and cant transport entothyroctes -> lymph

25
Q

For vitamin absorption what is required?

A

Co-enzymes or co-factors

FOR metabolic reactions

26
Q

Within the SI lumen,what is incorporated into micelles for absorption?

A

Fat-soluble vitamins

27
Q

What is incorporated into chylomicrons for transport?

A

Fat-soluble vitamins

28
Q

How are most water-soluble vitamins absorbed?

What is the exception?

A

Na+/dependent co-transport in SI

Vitamin B12 (cobalamin), which required inter since factor for absorption

29
Q

What are the steps for B12 absorption?

A
  1. B12 released from food by pepsin
  2. B12 binds to R proteins from salivary secretions
  3. Proteases in SI degrade
  4. B12/IF complex resists proteases, travels to ileum for absorption
30
Q

What vitamin do you need to absorb calcium in SI?

A

Vitamin D

31
Q

(TRUE/FALSE) Calcium is absorbed by both passive and active transport mechanisms

A

TRUE

32
Q

How is vitamin D activated

A

Dietary vitamin D (cholecalciferol) -> 25-hydroxycholecalciferol in liver -> 1,25-dihydrocygcholecalciferol in kidney

33
Q

What does active vitamin D promote synthesis of?

A

Calbindin D-28 K

34
Q

What does a lack of active vitamin D or calcium result in?

A

Rickets and osteomalacia

35
Q

What does heme iron mean?

A

Iron bound to hemoglobin or myoglobin

36
Q

What is the iron transporter in the luminal membrane?

A

DMT-1

37
Q

What is the heme iron digested into free iron by?

A

Lysosomal enzymes inside enterocytes

38
Q

What does iron circulate bound to? What is it stored as?

A

Iron circulates bound to transferrin

Stored as ferritin

39
Q

What does free iron bind to inside the enterocyte?

A

Apoferritin

40
Q

What does free iron bind to in the plasma?

A

Transferrin

Physiology Exam 3 (17 decks)

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