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Flashcards in Fluid and Electrolytes Deck (50):
1

What is the target of the C.diff toxin A and B?

Cytoskeleton disruption

2

What is absorbed and secreted in the large intestines?

HCO3 and K are secreted
Na, Cl, and H2O are absorbed

3

How is Na absorbed in the intestines? (3)

SLGT1, amino acid B transporters, and Na?h exchanger during the fed state with paired Na/K pump on the basolateral side

4

What ion always goes with HCO3?

Cl--always in opposite directions

5

What causes Cl absorption?

Na absorbed, so Cl pulled along, as well as a HCO3/Cl exchanger

6

What is the protein that regulates Cl/water secretion? What ion (not Cl) is needed for it to function?

CFTR (cystic fibrosis transport regulator)--need Ca, cAMP

7

How is K secreted from the large intestines?

Net negative lumen of the intestines, as well as Na/K pump

8

How is K reabsorbed in the small intestines?

Follows water back in the intestines between the cells

9

What is the function of increased cAMP, cGMP, and Ca in the intestinal lumen? (2) What is the net effect of this?

Inhibits Na/H pump, increases Cl channel

Thus Na remains in the lumen, and Cl is secreted into the lumen

10

Somatostatin always has what effect on the GI system (inhibitory or excitatory)?

generally inhibitory, but promotes fluid absorption

11

What are the four causes of diarrhea?

1. Increased intestinal secretion
2. Decreased intestinal absorption
3. Increased osmotic load
4. Abnormal intestinal motility

12

What is osmotic diarrhea?

Diarrhea caused by a nonabsorbable nutrient

13

What is secretory diarrhea?

Diarrhea caused by intestinal secretion of fluid and electrolytes

14

Osmotic, secretory, or both: disaccharidase deficiency?

Osmotic

15

Osmotic, secretory, or both: enterotoxins?

Secretory

16

Osmotic, secretory, or both: inflammatory cytokines

Both

17

Osmotic, secretory, or both: pancreatic enzyme deficiency

Osmotic

18

Osmotic, secretory, or both: Nutrient-binding substances

Osmotic

19

Osmotic, secretory, or both: tumor (VIP, 5HT secretion)?

Secretory

20

Osmotic, secretory, or both: infectious disease?

Both

21

Osmotic, secretory, or both: bacterial overgrowth?

Osmotic (think biofilm)

22

Osmotic, secretory, or both: antacids

Osmotic

23

Osmotic, secretory, or both: loss of electrolytes

Osmotic

24

What is the primary cause of diarrhea in celiac?

Increased oncotic pressure of the intestines d/t a lack of uptake--thus it is a osmotic diarrhea

25

What is the effect of PPIs on intestinal microbiota?

pH increased, thus lost host defense

26

What is the effect of antidiarrheal agents on c.diff infections?

Lowers intestinal motility, and thus makes matters worse

27

True or false: pseudomembranes with C.diff = biofilm

False--it is immune cells, bacteria, and debris

28

What are the three ways in which you can increase second messenger generation in the intestinal epithelial cells?

Neuronal
Paracrine
Bacterial toxins

29

What are the two endocrine regulators of the intestinal epithelium that can be upregulated via transcriptional regulation, and cause an increase in Na-K channels?

Mineralocorticoids
Glucocorticoids

30

What is the effect of somatostatin on fluid absorption? How?

Increases by increasing the Na-H exchanger

31

What are the three neuronal neurotransmitters that increase second messenger generation in the intestines? What does this do?

Ach
VIP 5HT

Stimulates CFTR, inhibits Na-H exchanger

32

What are the two paracrine regulators of the intestinal epithelium that generate second messengers? What is the effect of this?

Prostaglandins
Histamine

Stimulates CFTR, inhibits Na-H exchanger

33

What is the MOA of second messenger generation on fluid absorption vs secretion?

Increases secretion by increasing activity of CFTR, and inhibiting Na-H exchanger

34

What is the MOA of glucocorticoids/mineralocorticoids on fluid uptake/secretion?

Increases absorption via upregulation of Na channels and Na-K ATPase

35

What is the effect of VIP and 5HT on intestinal secretion? How?

Increases by increasing second messenger generation (e.g. cAMP, cGMP, Ca)

36

What is the effect of exercise on GI motility?

Increases

37

What is the effect of fluid intake on GI motility?

Increases

38

What is the effect of anticholinergics on GI motility? How?

Decreases d/t decreased stimulation of Ach, which increases smooth muscle contraction

39

How can delayed gastric emptying cause diarrhea?

Inconsistent motility impairs digestive process

40

How does Gluten intolerance cause diarrhea?

Dramatic decrease of surface area leads to a decrease in fluid absorption. Thus osmotic diarrhea.

41

What is responsible for the secretory part of diarrhea caused by C.diff? Osmotic?

Secretion = Inflammation
Osmotic = dead cells cause oncotic pressure

42

Does the large intestine participate in and significant nutrient absorption?

With the exception of water and electrolytes, no

43

Is K secreted or absorbed in the small intestines? Large?

Small = absorbed
Large = secreted

44

What are the four key transport proteins involved in the reuptake of Na in the intestines?

1. SLGT1
2. AA transporter B
3. Na-H exchanger
4. Na channel

45

What is the transport protein on the basolateral side of the intestinal membrane needed for the four main transport protein to work?

Na/K pump

46

What are the two mechanisms for Cl absorption in the intestines?

1. Passive diffusion following Na
2. Cl/HCO3 exchanger

47

What is the main protein involved in Cl secretion?

CFTR

48

What is the main way K is reabsorbed in the small intestines?

Via solvent drag with Na

49

What are the three secondary messengers that regulate CFTR and Na-H transporters? What effect do these have on the aforementioned transporters?

Ca, cAMP, cGMP

Increases CFTR
Inhibits Na-H

50

What is the MOA of inflammation causing diarrhea?

Death of epithelial cells = increased oncotic pressure, and decreased absorptive ability