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Flashcards in GI-Phys Deck (80)
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1

What is necessary for digesting fats?

Bile

2

What causes contraction of the GB?

CCK

3

What is an action of Secretin?

Stimulation of HCO3-

4

What causes Sphincter of Oddi to relax?

CCK
-->this allows bile and enzymes to flow to the duodenum

5

What determines the amount of bile salts the liver needs to produce?

Depends on the amount of bile salts reabsorbed

6

Where does carbohydrate digestion begin?

Mouth with salivary amylase

7

Where are disaccharides (sucrose, maltose, lactose, trehalose) digest?

Intestine

8

What are simple sugars?

-Glucose
-Galactose
-Fructose

9

Where are simple sugars absorbed?

Intestine by sodium cotransport (SGLT) and facilitated diffusion (Glut 2)

10

What is the action of Incretin?

Increases secretion of Insulin

11

Where does protein digestion begin?

Stomach with activation of GI proteases

12

What converts Pepsinogen?

-HCL (low pH)-->converts to Pepsin

13

What does Pepsin do?

-Breaks down proteins into amino acids and oligopeptides

14

What is the action of Enterokinase?

-Converts Trypsinogen to Trypsin in the small intestine
-Trypsin activates other proenzymes secreted from pancreas into ACTIVE form

15

Who does the bulk of protein digestion?

Active Pancreatic enzymes

16

What are the final products of protein digestion?

-Amino acids
-Dipeptides
-Tripeptides

17

How is protein absorbed?

-Na+-amino acid co-transport
-H+ di/tri-peptide co-transport

18

Where does fat digestion begin?

-Mouth with lingual lipase

19

Where are fats broken down?

Duodenum by digestive enzymes

20

What are the final products of lipids?

-Monoglyceride
-Cholesterol
-Lysolecithin
-Free fatty acids

21

Where are the final lipid products absorbed?

Jejunum via Michells and chylomicrons

22

What does B12 need to be absorbed in the intestine?

-Intrinsic factor

23

How are most water soluble vitamins absorbed?

Na+ co-transport

24

How is B6 absorbed?

Simple diffusion

25

What kind of contractions are present in the UES and LES?

Tonic

26

What is primarily responsible for increase tone of LES?

Loss of inhibitory enteric neurons--> achalasia

27

What is the progressive wave of muscle contractions that proceed along the esophagus, compressing the lumen and forcing food ahead called?

-Primary peristalsis

28

Nervous control of the GI tract would be impaired by damage to what?

Submucosa

29

Where does segmentation happen?

Intestine

30

Where does peristalsis happen?

-Esophagus
-Stomach
-Intestine

31

Where does haustration happen?

Colon

32

Define haustration

phasic contractions of long duration

33

Define mass movements

-Large infrequent peristaltic contractions, 1-3x/day
-Move contents over long distances, transverse colon-->sigmoid colon

34

Hirschsprungs dz

Decreases peristalsis- "megacolon"

35

When does migrating motility complex occur?

-Periods of fasting to move undigested material from stomach down to colon
-Every 90-120 minutes during fasting

36

Myogenic contractility

-Ability of the GI tract to contract even without nervous system input

37

What are the three layers of smooth muscle?

1. Outer longitudinal muscle
2. Inner circular muscle
3. Muscularis mucosa

38

What happens with longitudinal muscle contraction?

Decreased length

39

What happens with inner circular muscle contraction?

Decreased diameter

40

What stimulates enzyme secretion in the acing cells?

-CCK and ACh

41

What enzymes does the pancreas secrete?

-Lipase
-Amylase
-Trypsinogen

42

What do ductal cells sense?

-CCK
-ACh
-Secretin
*Begin alkaline secretion

43

What does Gastrin stimulate?

-ECL to release histamine-->histamine acts on parietal cells to release HCL

44

What is the primary event of the gastric phase process?

HCL release

45

What do peptides and amino acids in the food stimulate?

-G cells to release Gastrin

46

What does food block?

-Increases pH-->blocks stimulation of somatostatin secretion

47

what is the most important physiological antagonists of HCL secretion?

Somatostatin
-->Released when pH falls below 3 to inhibit acid secretion

48

What activates histamine?

-ACh
-Gastrin

49

What does Omeprazole do?

Inhibit H+-K+ ATPase pump so H+ ions can't be secreted into stomach

50

Where is intrinsic factor from?

Parietal cells

51

What happens as food moves into duodenum?

1. Enterogoastric Reflex-ACh release is inhibited (neural reflex) to STOP acid secretion
2. CCK and Secretin inhibit histamine release to further decrease acid secretion

52

are pancreas secretion isotonic or hypotonic?

Isotonic

53

What stimulates I cells?

Protein and fat in the duodenum

54

What do I cells release?

CCK

55

"Alkaline tide"

Increase pH of gastric venous blood after a meal (short lived)

56

Which phenomenon in salivary ducts explains why the final salivary secretion is hypotonic relative to the primary secretion of the acing cells?

-Absorption of more solute than water

57

What is the most important factor affecting salivary flow?

Hydration status

58

What gland contributes the most during stimulated salivary flow?

Parotid gland= very aqueous saliva

59

What gland contributes the most during unstimulated salivary flow?

Submandibular flow=more viscous

60

What carb must be digested before being absorbed by the small intestine?

Sucrose

61

Why do patients with diarrhea often have hypokalemia?

Faster chyme flow rate stimulates K+ secretion

62

How does V.Cholera cause diarrhea?

Increase cAMP levels

63

Resulting activation of cAMP or Ca2+ ?

Increased Cl- secretion

64

Hormones

Act @ locations far away from the source
-Gastrin, CCK, Secretin

65

Paracrines

Act locally
-Histamine, somatostatin

66

Neurocrines

Released from nerves and act locally @ short distance
-VIP, somatostatin, NO,

67

What does Sympathetic release of Norepinephrine cause?

-Decreased motility
-Decreased secretions
-Increased constriction of sphincters

68

What does Parasympathetics release of ACh cause?

-Increased motility
-Increased secretions

69

What does Parasympathetics release of vasoactive intestinal polypeptide (VIP) cause?

Decreased constriction of sphincters

70

What does Parasympathetics of Gastrin-Releasing Peptide (GRP) cause?

Increased Gastrin

71

What stimulates Secretin?

Acid entering duodenum

72

What is the action of secretin on stomach motility and secretions?

Inhibits

73

What is the action of Secretin at the Pancreas?

Stimulates HCO3-

74

What stimulates CCK?

-Fat and amino acids entering duodenum
-Inhibits stomach motility and secretions

75

Osmotic diarrhea

Ex: lactose intolerant
-Buildup of lactose in GI lumen holds water with it

76

Infectious/inflammatory diarrhea

-Salmonella, rotovirus
-Associated w/ widespread destruction of absorptive epithelium

77

Deranged motility causing diarrhea

Ex: hypermotility in some cases IBS

78

What is the major site of sodium absorption?

Jejunum

79

What is the net result of fecal fluid?

Alkalotic and high K+

80

Main electrolyte secreted from the crypt cells?

Chloride