Fluid and Electrolytes

Question 1

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

Answer 1

Cytoskeleton disruption

Question 2

What is absorbed and secreted in the large intestines?

Answer 2

HCO3 and K are secreted

Na, Cl, and H2O are absorbed

Question 3

How is Na absorbed in the intestines? (3)

Answer 3

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

Question 4

What ion always goes with HCO3?

Answer 4

Cl–always in opposite directions

Question 5

What causes Cl absorption?

Answer 5

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

Question 6

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

Answer 6

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

Question 7

How is K secreted from the large intestines?

Answer 7

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

Question 8

How is K reabsorbed in the small intestines?

Answer 8

Follows water back in the intestines between the cells

Question 9

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

Answer 9

Inhibits Na/H pump, increases Cl channel

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

Question 10

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

Answer 10

generally inhibitory, but promotes fluid absorption

Question 11

What are the four causes of diarrhea?

Answer 11

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

Question 12

What is osmotic diarrhea?

Answer 12

Diarrhea caused by a nonabsorbable nutrient

Question 13

What is secretory diarrhea?

Answer 13

Diarrhea caused by intestinal secretion of fluid and electrolytes

Question 14

Osmotic, secretory, or both: disaccharidase deficiency?

Answer 14

Osmotic

Question 15

Osmotic, secretory, or both: enterotoxins?

Answer 15

Secretory

Question 16

Osmotic, secretory, or both: inflammatory cytokines

Answer 16

Both

Question 17

Osmotic, secretory, or both: pancreatic enzyme deficiency

Answer 17

Osmotic

Question 18

Osmotic, secretory, or both: Nutrient-binding substances

Answer 18

Osmotic

Question 19

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

Answer 19

Secretory

Question 20

Osmotic, secretory, or both: infectious disease?

Answer 20

Both

Question 21

Osmotic, secretory, or both: bacterial overgrowth?

Answer 21

Osmotic (think biofilm)

Question 22

Osmotic, secretory, or both: antacids

Answer 22

Osmotic

Question 23

Osmotic, secretory, or both: loss of electrolytes

Answer 23

Osmotic

Question 24

What is the primary cause of diarrhea in celiac?

Answer 24

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

Question 25

What is the effect of PPIs on intestinal microbiota?

Answer 25

pH increased, thus lost host defense

Question 26

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

Answer 26

Lowers intestinal motility, and thus makes matters worse

Question 27

True or false: pseudomembranes with C.diff = biofilm

Answer 27

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

Question 28

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

Answer 28

Neuronal Paracrine Bacterial toxins

Question 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?

Answer 29

Mineralocorticoids | Glucocorticoids

Question 30

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

Answer 30

Increases by increasing the Na-H exchanger

Question 31

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

Answer 31

Ach VIP 5HT Stimulates CFTR, inhibits Na-H exchanger

Question 32

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

Answer 32

Prostaglandins Histamine Stimulates CFTR, inhibits Na-H exchanger

Question 33

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

Answer 33

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

Question 34

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

Answer 34

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

Question 35

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

Answer 35

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

Question 36

What is the effect of exercise on GI motility?

Answer 36

Increases

Question 37

What is the effect of fluid intake on GI motility?

Answer 37

Increases

Question 38

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

Answer 38

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

Question 39

How can delayed gastric emptying cause diarrhea?

Answer 39

Inconsistent motility impairs digestive process

Question 40

How does Gluten intolerance cause diarrhea?

Answer 40

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

Question 41

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

Answer 41

``` Secretion = Inflammation Osmotic = dead cells cause oncotic pressure ```

Question 42

Does the large intestine participate in and significant nutrient absorption?

Answer 42

With the exception of water and electrolytes, no

Question 43

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

Answer 43

``` Small = absorbed Large = secreted ```

Question 44

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

Answer 44

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

Question 45

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

Answer 45

Na/K pump

Question 46

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

Answer 46

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

Question 47

What is the main protein involved in Cl secretion?

Answer 47

CFTR

Question 48

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

Answer 48

Via solvent drag with Na

Question 49

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

Answer 49

Ca, cAMP, cGMP Increases CFTR Inhibits Na-H

Question 50

What is the MOA of inflammation causing diarrhea?

Answer 50

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