Fluid and Electrolytes Flashcards

1
Q

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

A

Cytoskeleton disruption

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2
Q

What is absorbed and secreted in the large intestines?

A

HCO3 and K are secreted

Na, Cl, and H2O are absorbed

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3
Q

How is Na absorbed in the intestines? (3)

A

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

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4
Q

What ion always goes with HCO3?

A

Cl–always in opposite directions

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5
Q

What causes Cl absorption?

A

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

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6
Q

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

A

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

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7
Q

How is K secreted from the large intestines?

A

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

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8
Q

How is K reabsorbed in the small intestines?

A

Follows water back in the intestines between the cells

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9
Q

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

A

Inhibits Na/H pump, increases Cl channel

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

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10
Q

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

A

generally inhibitory, but promotes fluid absorption

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11
Q

What are the four causes of diarrhea?

A
  1. Increased intestinal secretion
  2. Decreased intestinal absorption
  3. Increased osmotic load
  4. Abnormal intestinal motility
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12
Q

What is osmotic diarrhea?

A

Diarrhea caused by a nonabsorbable nutrient

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13
Q

What is secretory diarrhea?

A

Diarrhea caused by intestinal secretion of fluid and electrolytes

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14
Q

Osmotic, secretory, or both: disaccharidase deficiency?

A

Osmotic

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15
Q

Osmotic, secretory, or both: enterotoxins?

A

Secretory

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16
Q

Osmotic, secretory, or both: inflammatory cytokines

A

Both

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17
Q

Osmotic, secretory, or both: pancreatic enzyme deficiency

A

Osmotic

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18
Q

Osmotic, secretory, or both: Nutrient-binding substances

A

Osmotic

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19
Q

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

A

Secretory

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20
Q

Osmotic, secretory, or both: infectious disease?

A

Both

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21
Q

Osmotic, secretory, or both: bacterial overgrowth?

A

Osmotic (think biofilm)

22
Q

Osmotic, secretory, or both: antacids

A

Osmotic

23
Q

Osmotic, secretory, or both: loss of electrolytes

A

Osmotic

24
Q

What is the primary cause of diarrhea in celiac?

A

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

25
Q

What is the effect of PPIs on intestinal microbiota?

A

pH increased, thus lost host defense

26
Q

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

A

Lowers intestinal motility, and thus makes matters worse

27
Q

True or false: pseudomembranes with C.diff = biofilm

A

False–it is immune cells, bacteria, and debris

28
Q

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

A

Neuronal
Paracrine
Bacterial toxins

29
Q

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?

A

Mineralocorticoids

Glucocorticoids

30
Q

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

A

Increases by increasing the Na-H exchanger

31
Q

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

A

Ach
VIP 5HT

Stimulates CFTR, inhibits Na-H exchanger

32
Q

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

A

Prostaglandins
Histamine

Stimulates CFTR, inhibits Na-H exchanger

33
Q

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

A

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

34
Q

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

A

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

35
Q

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

A

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

36
Q

What is the effect of exercise on GI motility?

A

Increases

37
Q

What is the effect of fluid intake on GI motility?

A

Increases

38
Q

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

A

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

39
Q

How can delayed gastric emptying cause diarrhea?

A

Inconsistent motility impairs digestive process

40
Q

How does Gluten intolerance cause diarrhea?

A

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

41
Q

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

A
Secretion = Inflammation
Osmotic = dead cells cause oncotic pressure
42
Q

Does the large intestine participate in and significant nutrient absorption?

A

With the exception of water and electrolytes, no

43
Q

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

A
Small = absorbed
Large = secreted
44
Q

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

A
  1. SLGT1
  2. AA transporter B
  3. Na-H exchanger
  4. Na channel
45
Q

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

A

Na/K pump

46
Q

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

A
  1. Passive diffusion following Na

2. Cl/HCO3 exchanger

47
Q

What is the main protein involved in Cl secretion?

A

CFTR

48
Q

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

A

Via solvent drag with Na

49
Q

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

A

Ca, cAMP, cGMP

Increases CFTR
Inhibits Na-H

50
Q

What is the MOA of inflammation causing diarrhea?

A

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