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GI Final > Digestion + Absorption > Flashcards

Digestion + Absorption Flashcards

1
Q

Absorption of food mainly takes place in the small intestine via what 2 pathways?

A
  1. cellular (membrane transport)
  2. paracellular (tight junctions)
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2
Q

What enzyme breaks down carbohydrates in the salive and pancreas?

A

Amylase

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3
Q

Sucrase, maltase, lactase, trehalase, and alpha dextrinase break down _______ in the _________.

A

carbs

intestinal mucosa

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4
Q

What enzyme breaks down proteins in the stomach?

A

pepsin

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5
Q

Proteases: Trypsin, chymotrypsin, elastase, carboxypeptidase A & B all break down ______ in the ________.

A

Proteins

Pancreas

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6
Q

Amino-oligopeptidase, dipeptidase, enterokinase all break down _____ in the __________.

A

Proteins

Intestinal mucosa

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7
Q

What protein breaks down lipids in the salvia?

A

Lingual lipase

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8
Q

What protein breaks down lipids in the stomach?

A

Gastric lipase

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9
Q

Lipase-colipase, phopholipase A2, and cholesterol ester hydrolase break down _______ in the __________.

A

lipids

pancreas

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10
Q

How does the structure of the intestinal mucosa make it ideal for absorption of a large amount of nutrients?

A

folds of Kerckring (longitudinal folds)

villi + microvilli (brush border w/enzymes)

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11
Q

What are the 3 cell types of the intestinal epithelium?

A

enterocytes, goblet cells, paneth cells

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12
Q

What is the function of enterocytes?

A

They are epithelial cells that aid in digestion, absorption, + secretion.

They control the flux of solutes + fluid between the lumen and the blood

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13
Q

What are goblet cells?

A

secrete mucous

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14
Q

what are paneth cells?

A

protect against infection

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15
Q

The enterocyte membrance controls the flux of solutes and flid between the blood and the lumen through the use of?

A

Pinocytosis, Diffusion, Active Transport

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16
Q

When a solute wants to move across an enterocyte from the lumen to the blood via transmural movement, what layers does it need to pass through?

A
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17
Q

What is the only cell to absorb monosaccharides (carbs)?

A

Enterocytes (after digestion you get glucose, galactose, and fructose)

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18
Q

In carbohydrate absorption, list the transporters on the lumen side:

A

SGLT1 (Na+, Glucose, Galactose)

GLUT 5 (fructose)

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19
Q

In carbohydrate absorption, list the transporters on the blood side:

A

GLUT 2 (recieves glucose, galactose, and fructose) w/ the help of a NA+ K+ ATPase pump

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20
Q

What happens if our bodies fail to digest carbohydrates?

A

Lactose intolerance!

Causes osmotic diarrhea

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21
Q

How are all these different enzymes formed to digest proteins?

A

Via autocatalysis of trypsin, which then forms more pancreatic preoteases to digest themselves + eachother

22
Q

How are proteins absorbed?

A

Via co-transport (lumen) and faciliatated diffusion (blood) one for each type of amino acid (neutral, basic,etc.)

23
Q

What happens to a patient with cystinuria?

A

Amino acids (cystine) are secreted in the urine as cystals/stones

24
Q

What can you not absord in hartnup disease?

A

neutral amino acids

25
Q

In cystic fibrosis(mutation of CFTR), what can you have a deficiency of?

A

pancreatic enzymes

26
Q

What is released when lipids first appear in the small intestine?

A

CCK –> releases bile to form micelles around the fats so they can be absorbed

27
Q

What is the optimal pH for pancreatic lipase?

A

6

28
Q

What are the steps for the absorption of lipids (complex):

A
  1. Solubilization by micelles
  2. Diffusion of micellar content across apical membrane
  3. Reesterfication
  4. Chylomicron formation
  5. Exocytosis of chylomicron into lymph
29
Q

If a patient has no ApoB, meaning they can’t absorb dietary lipids, which disorder do they have?

A

Abetalipoproteinemia

30
Q

If you have problems in any step of the lipid assimilation pathway what can happen?

Examples: pancreatic enzyme secretion, bile acid secretion, miccele formation, transfer of chylomicrons to lymph

A

Steatorrhea (fat in feces –> not absorbed)

31
Q

What is it called when you can’t secrete adequate amounts of pancreatic enzymes?

A

Pancreatic insufficiency

32
Q

What happens in Zollinger-Ellison syndrome?

A

Too much H+ is secreted from a gastrin-secreting tumor of the pancreas

It makes the duodenum too acidic

33
Q

The duodenum needs to always be at the right pH for pancreatic enzymes to work. It stays there via HCO3- neutralizing everything. When HCO3- and other enzymes are impaired, the patient has?

A

Pancreatitis

34
Q

What 2 things could cause a deficiency of bile salts, that interferes with the formation of micelles?

A
  1. Ileal resection
  2. Small intestinal bacterial overgrowth (SIBO)
    - can damage mucosa (from not enough gastric acid)
35
Q

What disorder is characterized by a decreased amount of epithelial cells, which affects lipid absorption?

A

Tropical sprue

Because the surface area is decreased, lipid absorption is decreased and this causes steatorrhea.

36
Q

What is celiac sprue?

A

An autoimmune disorder where antibodies form against a type of gluten (gliadin). This leads to destruction of the small intestice villi (atrophy) and hyperplasia of the intestinal crypts.

37
Q

How are fat soluble vitamins (Vit. A,D,E, K) absorbed?

A

Like fat

38
Q

How are water-soluble vitamins (all the B’s) absorbed?

A

Na+ dependent cotransport

39
Q

Vitamin B12 (Cobalamin) is important for?

A

DNA synthesis in RBC’s

40
Q

How is Vitamin B12 absorbed?

A

R protein –> IF receptors –> TCII

41
Q

What causes pernicious anemia?

A

The stomach does not produce enough IF, therefore Vit. B12 is deficient and red blood cells fail to mature.

2 common causes = atrophic gastritis (inflammed stomach mucosa –> lose parietal cells) + autoimmune metaplastic atrophic gastritits (attack IF)

42
Q

What happens in a gastrectomy?

A

loss of parietal cells (source of IF)

43
Q

What happens in a gastric bypass in relation to B12?

A

Since you are excluding the stomach, duodenum, and jejunum, this alters the absorption of vitamin B12

44
Q

What enzyme activates Vit. D?

A

1 alpha-hydroxylase

45
Q

MEMORIZE

A
46
Q

What is absorbed in the proximal small intestine (duodenum)?

A

Fat, sugar, peptides/aa, iron, folate, calcium, water, electrolytes

*highest amount of carbs, proteins, lipids*

47
Q

What is absorded in the jejunum?

A

sugar, peptides, calcium, water, electrolytes

48
Q

What is absorbed in the distal small intestine (ileum)?

A

Bile acids, Vitamin B12 (cobalamin), water, electrolytes

49
Q

What is absorbed in the colon?

A

Water, electrolytes, MCTs, calcium, amino acids

50
Q
A

GI Final (12 decks)

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