absorption and secretion Flashcards

1
Q

how are amino acids absorbed

A

sodium dependant co transport in the small intestine

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2
Q

how are dipetides absorbed

A

H+ dipeptide cotransport

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3
Q

how are tripeptides absorbed

A

H+ tripeptide cotransport

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4
Q

what is the role of gastric lipase

A

slow the rate of gastric emptying

hydrolyse triglycerides

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5
Q

what are chylomicrons made of

A

core of triglycerides and cholesterol ester

phospholipids and apolipoproteins on the outside

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6
Q

where do the chylomicrons go next

A

packaged into secretory vesicles on the Golgi membrane and exocytosed across the basolateral membrane

then enter the lacteals

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7
Q

describe the tight junctions in the intestine

A

small intestine- leaky

colon- impermeable so no paracellular route for fluids and electrolytes

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8
Q

what are crypts of Lieberkuhn for

A

secretion

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9
Q

what are colonic glands for

A

secretion

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10
Q

where is the zone of cell proliferation

A

base of the crypts, replaces the villous cells

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11
Q

what is a secretagog

A

a substance that promotes secretion

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12
Q

describe the absorption of lipids

A

Bile salts form micelles
Diffusion of products into intestinal cells
Re-esterification within the cell to
triglycerides and cholesterol
Chylomicrons form in the cell and transfer to
lymph

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13
Q

how is bile absorbed

A

sodium dependant co transport

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14
Q

how is iron absorbed

A

binds to apoferritin in the intestinal cell and transferrin in the blood

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15
Q

how is calcium absorbed

A

vitamin D dependant Ca+ binding protein- Calbindin

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16
Q

how are water soluble vitamins absorbed

A

na dependant cotransport

17
Q

how is glucose and galactose absorbed

A

Na dependant co transport in the small intestine via SGLT1

18
Q

how is fructose absorbed

A

facilitated diffusion Via glucose transporter 5, GLUT5

19
Q

how are monosaccharides absorbed into the blood

A

GLUT2

20
Q

name the pancreatic proteases which are secreted as inactive precursors into the small intestine

A

trypsinogen
chemotrypsinogen
proelastase
procarboxypeptidase A and B

21
Q

how is trypsinogen converted to trypsin

A

brush border enzyme enterokinase

trypsin then converts the others

22
Q

how is pepsinogen converted to pepsin

A

low pH

23
Q

what happens to dipeptides and tripeptides in the small intestine epithelia

A

they are broken down into amino acids

24
Q

where are lipases found

A

tongue, stomach and small intestine

25
Q

where is cholecystokinin released

A

i cells of the duodenum and jejunum in response to monoglycerides and peptides and fatty acids

26
Q

what is lysolecithin

A

emulsifies lipids

27
Q

what enzymes are involved in fat digestion

A

pancreatic lipase, cholesterol ester hydrolase, phospolipase A and colipase

28
Q

where are fatty acids and monoglycerides stored before absorption

A

micelles

29
Q

what are chylomicrons made of

A

fats, cholesterol and proteins

made in the intestinal cells, then to lacteals

30
Q

where are chylomicrons processed

A

golgi

31
Q

what is the function of cAMP in the small intestine

A

increased anion secretion

inhibited NaCl absorption

32
Q

what is the second messenger of VIP

A

cAMP