Small and Large Intestine -- Fluid and electrolytes

Question 1

liters per day present in small intestin

Answer 1

~8.5 L/day

Question 2

how much fluid does small intestine remove per day

Answer 2

~6.5 L/day

Question 3

how much fluid does large intestine remove per day

Answer 3

~1.9L/day

Question 4

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

Answer 4

0.1 L/day

Question 5

type of epithelium SI vs. LI

Answer 5

SI = leaky for bulk water and solute transport

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

Question 6

fluid movement is always accompanied by

Answer 6

solute movement

Question 7

what cells absorb is SI vs. LI

Answer 7

SI = villous cells

LI = surface epithelial

Question 8

secretory cells in SI and LI

Answer 8

crypt cells

Question 9

what ions absorbed in SI vs. LI

Answer 9

SI = Na+, Cl-, K+

LI = Na+ and Cl-

Question 10

what ions are secreted in SI vs. LI

Answer 10

SI = HCO3-

LI = HCO3- and K+

Question 11

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

Answer 11

cAMP, cGMP, and Ca2+

increases in these decrease absorption (increase secretion)

Question 12

Na+ in duodenum and jejunum (general)

Answer 12

actively absorbed - enchanced by sugars and amino acids

Question 13

Na+ in ileum (general)

Answer 13

actively absorbed

Question 14

Na+ in colon (general)

Answer 14

actively absorbed

Question 15

K+ in duodenum and jejunum (general)

Answer 15

passively absorbed when concentration rises because of the absorption of H2O

Question 16

K+ in ileum (general)

Answer 16

passively absorbed

Question 17

K+ in colon (general)

Answer 17

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

Question 18

Cl- in duodenum and jejunum (general)

Answer 18

absorbed

Question 19

Cl- in ileum and colon (general)

Answer 19

absorbed

some exchanged for HCO3-

Question 20

HCO3- in duodenum (general)

Answer 20

secreted

Question 21

HCO3- in jejunum (general)

Answer 21

absorbed

Question 22

HCO3- in ileum and colon (general)

Answer 22

secreted partly

some exchange for Cl-

Question 23

major mechanism of Na+ absorption postprandially (post meal)

Answer 23

Na-glucose and Na-amino acids cotransporters

mostly in jejunum and some in ileum

Question 24

Na+ absorption mechanism in response to acidity

Answer 24

electroneutral Na-H exchanger

mostly in jejunum and some in duodenum

Question 25

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

Answer 25

parallel Na-H and Cl-HCO3 exchangers ileum and proximal colon equally

Question 26

distal colon Na+ absorption

Answer 26

epithelial Na+ channels gradient driven...basolateral Na-K pump establishs the gradient

Question 27

voltage dependent Cl- absorption

Answer 27

mostly jejunum and distal colon (some ileum) Cl - diffuses paracellularly or through apical and basolateral channels driven by negaitve lumen potential

Question 28

Na+Cl- absorption in the colon (mechanims)

Answer 28

Na+ enters via ENaC channel and parallel Na-H and Cl-HCO3- exchangers

Question 29

K secretion in colon mechanism

Answer 29

apical and basolateral K channels

Question 30

aldosterone effect on colon

Answer 30

activates K+ secretion by activating Na-K ATPase on the basolateral and K+ channels on apical side

Question 31

Na+ monocarboxylate transporter (SMCT1)

Answer 31

apical membrane in colon transports butyrate, propionate, and acetate into cell = short cahin FAs from bacterial digestion of non absorbed carbs

Question 32

Cl - secretion in the crypt cells

Answer 32

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

Question 33

compounds released from enteric neurons that stimulate net secretion of water and electrolytes from intestine

Answer 33

ACh NO serotonin Vasoactive intestinal peptide

Question 34

compounds released from enteric neurons that stimulate net absorption of water and electrolytes from intestine

Answer 34

NE opiods

Question 35

compounds released from enteroendocrine cells or immunocytes in mucosa or submocusa that stimulate net secretion of water and electrolytes from intestine

Answer 35

histamine calcitonin prostaglandins leukotrienes ARA adenosine

Question 36

compounds released from enteroendocrine cells or immunocytes in mucosa or submocusa that stimulate net absorption of water and electrolytes from intestine

Answer 36

somatostatins

Question 37

hormones that stimulate net secretion of water and electrolytes from intestine

Answer 37

prostaglandins ANP gastrin motilin bombesin

Question 38

hormones that stimulate net absorption of water and electrolytes from intestine

Answer 38

Epi Aldosterone glucocorticoids prolactin growth hormone

Question 39

compounds present in the lumen that stimulate net secretion of water and electrolytes from intestine

Answer 39

bile salts long chain FAs

Question 40

compounds present in the lumen that stimulate net absorption of water and electrolytes from intestine

Answer 40

short chain FAs