Small and Large Intestine -- Fluid and electrolytes Flashcards

1
Q

liters per day present in small intestin

A

~8.5 L/day

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2
Q

how much fluid does small intestine remove per day

A

~6.5 L/day

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3
Q

how much fluid does large intestine remove per day

A

~1.9L/day

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4
Q

how much fluid does large intestine leave in the feces per day

A

0.1 L/day

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5
Q

type of epithelium SI vs. LI

A

SI = leaky for bulk water and solute transport

LI = tight to generate or maintain ion concentration or osmotic gradients

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6
Q

fluid movement is always accompanied by

A

solute movement

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7
Q

what cells absorb is SI vs. LI

A

SI = villous cells

LI = surface epithelial

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8
Q

secretory cells in SI and LI

A

crypt cells

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9
Q

what ions absorbed in SI vs. LI

A

SI = Na+, Cl-, K+

LI = Na+ and Cl-

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10
Q

what ions are secreted in SI vs. LI

A

SI = HCO3-

LI = HCO3- and K+

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11
Q

what intracellular 2nd messengers regulated the overal electroneutral NaCl absorption?

A

cAMP, cGMP, and Ca2+

increases in these decrease absorption (increase secretion)

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12
Q

Na+ in duodenum and jejunum (general)

A

actively absorbed - enchanced by sugars and amino acids

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13
Q

Na+ in ileum (general)

A

actively absorbed

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14
Q

Na+ in colon (general)

A

actively absorbed

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15
Q

K+ in duodenum and jejunum (general)

A

passively absorbed when concentration rises because of the absorption of H2O

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16
Q

K+ in ileum (general)

A

passively absorbed

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17
Q

K+ in colon (general)

A

net secretion occurs when K+ concentration in lumen < 25mM

18
Q

Cl- in duodenum and jejunum (general)

A

absorbed

19
Q

Cl- in ileum and colon (general)

A

absorbed

some exchanged for HCO3-

20
Q

HCO3- in duodenum (general)

A

secreted

21
Q

HCO3- in jejunum (general)

A

absorbed

22
Q

HCO3- in ileum and colon (general)

A

secreted partly

some exchange for Cl-

23
Q

major mechanism of Na+ absorption postprandially (post meal)

A

Na-glucose and Na-amino acids cotransporters

mostly in jejunum and some in ileum

24
Q

Na+ absorption mechanism in response to acidity

A

electroneutral Na-H exchanger

mostly in jejunum and some in duodenum

25
Q

major mechanism of Na+ and Cl- absorption during interdigestive periods

A

parallel Na-H and Cl-HCO3 exchangers

ileum and proximal colon equally

26
Q

distal colon Na+ absorption

A

epithelial Na+ channels

gradient driven…basolateral Na-K pump establishs the gradient

27
Q

voltage dependent Cl- absorption

A

mostly jejunum and distal colon (some ileum)

Cl - diffuses paracellularly or through apical and basolateral channels

driven by negaitve lumen potential

28
Q

Na+Cl- absorption in the colon (mechanims)

A

Na+ enters via ENaC channel

and parallel Na-H and Cl-HCO3- exchangers

29
Q

K secretion in colon mechanism

A

apical and basolateral K channels

30
Q

aldosterone effect on colon

A

activates K+ secretion by activating Na-K ATPase on the basolateral

and K+ channels on apical side

31
Q

Na+ monocarboxylate transporter (SMCT1)

A

apical membrane in colon

transports butyrate, propionate, and acetate into cell

= short cahin FAs from bacterial digestion of non absorbed carbs

32
Q

Cl - secretion in the crypt cells

A

Cl - actively taken into cells on basolateral side via
- Na-K ATPase and Na-K-2Cl cotransporter (powered by Na gradient)

Cl- enters lumen via an electrogenic channel

resulting negative lumen from secreted Cl- drives Na+ secretion partially via tight junction

the secretion of Na and Cl results in osmotic movement of water into lumen

33
Q

compounds released from enteric neurons that stimulate

net secretion of water and electrolytes from intestine

A

ACh

NO

serotonin

Vasoactive intestinal peptide

34
Q

compounds released from enteric neurons that stimulate

net absorption of water and electrolytes from intestine

A

NE

opiods

35
Q

compounds released from enteroendocrine cells or immunocytes in mucosa or submocusa that stimulate

net secretion of water and electrolytes from intestine

A

histamine

calcitonin

prostaglandins

leukotrienes

ARA

adenosine

36
Q

compounds released from enteroendocrine cells or immunocytes in mucosa or submocusa that stimulate

net absorption of water and electrolytes from intestine

A

somatostatins

37
Q

hormones that stimulate

net secretion of water and electrolytes from intestine

A

prostaglandins

ANP

gastrin

motilin

bombesin

38
Q

hormones that stimulate

net absorption of water and electrolytes from intestine

A

Epi

Aldosterone

glucocorticoids

prolactin

growth hormone

39
Q

compounds present in the lumen that stimulate

net secretion of water and electrolytes from intestine

A

bile salts

long chain FAs

40
Q

compounds present in the lumen that stimulate

net absorption of water and electrolytes from intestine

A

short chain FAs