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?

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?

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
For vitamin absorption what is required?
Co-enzymes or co-factors FOR metabolic reactions
26
Within the SI lumen,what is incorporated into micelles for absorption?
Fat-soluble vitamins
27
What is incorporated into chylomicrons for transport?
Fat-soluble vitamins
28
How are most water-soluble vitamins absorbed? What is the exception?
Na+/dependent co-transport in SI Vitamin B12 (cobalamin), which required inter since factor for absorption
29
What are the steps for B12 absorption?
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
What vitamin do you need to absorb calcium in SI?
Vitamin D
31
(TRUE/FALSE) Calcium is absorbed by both passive and active transport mechanisms
TRUE
32
How is vitamin D activated
Dietary vitamin D (cholecalciferol) -> 25-hydroxycholecalciferol in liver -> 1,25-dihydrocygcholecalciferol in kidney
33
What does active vitamin D promote synthesis of?
Calbindin D-28 K
34
What does a lack of active vitamin D or calcium result in?
Rickets and osteomalacia
35
What does heme iron mean?
Iron bound to hemoglobin or myoglobin
36
What is the iron transporter in the luminal membrane?
DMT-1
37
What is the heme iron digested into free iron by?
Lysosomal enzymes inside enterocytes
38
What does iron circulate bound to? What is it stored as?
Iron circulates bound to transferrin Stored as ferritin
39
What does free iron bind to inside the enterocyte?
Apoferritin
40
What does free iron bind to in the plasma?
Transferrin