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BMS 752 (Medical Physiology) > GI > Flashcards

GI Flashcards

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USMLE® Step 1 flashcards
1
Q

what is found in the lamina propria of GI mucosa

A

lymph nodules and capillaries

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2
Q

what enzyme is sued in the liver to produce cholesterol

A

acetyl coa

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3
Q

what is the clinical relevance of intrinsic factor

A

because it is necessary for B12 absorption, insufficieny will cause defects in DNA synthesis and lead to pernicious anemia (megaloblastic)

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4
Q

what membrane protein allows secreteion of HCO3 into the lumen

A

Cl-HCO3 exchanger on the apical membrane

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5
Q

orad stomach

caudad stomach

A

the upper part

lower part

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6
Q

zollinger-ellison disease

A

a gastrin producing tumor that causes excessive production of H+

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7
Q

what is the purpose of emulsification

A

to break particles into smaller pieces

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8
Q

what properities of the gastic mucosa make it a good barrier to prevent peptic ullcers

A

tight junctions to prevent acid penetration

hydrophobic to prevent ionized water soluble molecules from entering

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9
Q

how is Na absorbed and K secreted in the large intestine

what happens in diarrhea in relation to K secretion

A

passive channels

high flow rate of K into the lumin causes hypokalemia

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10
Q

what is the driving force behind H2O absorption in the GI tract

how else is water absorbed

A

high osmolality in the intercellular spaces between enterocytes

bulk transport

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11
Q

three phases of swallowing

A

oral

pharyngeal

esophageal

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12
Q

what are the three phases that regulate gastric secretion

A

cephalic

gastric

intestinal

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13
Q

wha three structures are found in the muscularis propria

A

circular muscle

lognitudinal muscle

myenteric plexus

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14
Q

what enzyme will absorb free amino acids in the small intestine

A

Na/AA symporter

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15
Q

what drug will inihibt the stimulating effect of muscarinic receptors on the proton pump

what does it do

A

atropine

it stops ACh from binding to muscarninc receptors

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16
Q

what does the submandibular gland secrete

A

mixed serous and mucous secretion

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17
Q

what is the parasympathetic effect on gastric emptying

sympathetic

A

PNS enhances peristalsis

SNS inhibits peristalsis

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18
Q

what specific chemical is released in response to gastric emptying of lipids into the duodenum

what cells secrete it

A

cholecystokinin

I cellls

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19
Q

what happens in the cephalic phase of gastric secretion

whhat percent of acid secretion is produced by this

A

conditioned response sends efferent signals to the stomach before food arives from the limbic system via the vagus nerve

40%

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20
Q

two types of epithelium found in the GI mucosa and their function

A

columnar: barrier, enzyme production, absorption
goblet: secretion of mucus

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21
Q

symptoms associated with a motility disorder

A

heartburn

stomach pain

cramping

nausea

vomitting

constipation

diarrhea

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22
Q

what is the impact of intraabdominal pressure on defectation

A

increased pressure facilitates defeccaton, especially during forced expiration

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23
Q

what is the driving for behind CHO absorption in the jejunum and ileum

A

Na/CHO symporters on the apical membrane that follow the Na gradient set up by the Na/K pump on the basolateral membrane

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24
Q

what are the hormone GI peptides

where are the secreted

what is the target

A

gastrin, CCK, secretin, gastric inhibitory hormone

from the stomach into the splanchnic and systemic circulation

either GI tract cells or distant cells

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25
Q

what happens during the emptying phase of the gastric pump

A

the liquids in the antrum are expelled into the duodenum while the large particles are left in the bulge of the terminal antrum

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26
Q

how often does the antrum contract in a fed state

how does this change in a fasted state

A

3 contractions/min

the antrum will be still for 2-3 hours, then have 10-20 minutes of intense contractions with relaxed pyloric sphincter, followed by another quiet period

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27
Q

three actions of lipid metabolism in the liver

A

cholestrol synthesis to form bile salts

triglycerides and VLDL

fatty acid metabolism for ATP or Ketones

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28
Q

what cells secrete histamine

what does it do

A

ECL cells in the H+ secreting region of the stomach

stimulates H+ secretion by parietal cells

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29
Q

what deficiency is the root cause of disorders associated with CHO digestion

A

Lack of dissacharidases (lactose intolerance)

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30
Q

four functions of the GI system

A

mix and move food

digest mechanically and enyzmatically

absorb nutrients from food

excrete by products

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31
Q

what is the RMP of smoothmuscle in the GI

A

-50 to -60 mV

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32
Q

where do phasic contractions occur in the GI tract

A

esophagus, antrum of stomach, small intestine

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33
Q

what is the direction of bile flow in the liver compared to blood floe

A

blood flow goes from the portal triad and sinusiods to the central vein

bile flows from the hepatocyes into bile cannaliculi and into the bile duct

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34
Q

what is the migrating myoelectric complex

A

the pattern of muscle contractions during fasting

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35
Q

where are peptic ulcers most common

where else can they occur

when will this cause bleeding

A

the duodenum

the antrum of the stomach and lower esophagus

when the ulcer penetrates to the submucosa

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36
Q

which pancreatic fat enzyme is secreted in its active form

A

cholesterol ester hydrolase

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37
Q

craniosacral = ____

thoracolumbar = ____

A

PsNS

SNS

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38
Q

5 effects of the CCK

A

contraction of the gall bladder

secretion of pancreatic enzymes

secretion of HCO3 from the pancreas

growth of exocrine pancreas and gallbladder

inhibition of gastric emptying

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39
Q

what is the end produce of protein digestion in the Gi tract

A

dipeptides and amino acids that are absorbed in the small intestine

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40
Q

what pancreatic enyzme will break down carbohydrates

A

amylase

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41
Q

how is lipase-bile converted into lipase-colipase

A

procolipase from the pancreas is converted to lipase by tyrosine, which removes bile salts from lipase and binds with it

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42
Q

what part of the enteric nervous system is found in the submucosa

A

the submucosal plexus

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43
Q

what is the function of the enteric nervous system

A

integrate the motor and secretory functions of the GI tract

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44
Q

where are mucus cells in the stomach and what do they secrete

A

antrum

mucus and pepsinogen

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45
Q

what is the basic function of the large intestine

A

reabsorption of water and elimination of waste

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46
Q

what is the empty volume of the stomach

what volume can it hold before intramluminar pressure begins to rise

A

50mL

1000mL

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47
Q

why is bile important

A

it is needed for the digestion of lipids and fat soluble vitamins

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48
Q

four functions of GI peptides

A

motility of smooth muscles and sphincters

secretion of enzymes, fluid, electrolytes

growth

regulation of other peptides

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49
Q

how does food content change gastric emptying

A

liquid food empties faster than solid

CHO faster than protein faster than fat

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50
Q

where are ICC cells found

what is their function

how are thei regulated

A

muscularis externa

responsible for slow wave potentials in the GI

the action of other ICCs, SMC, and the ENS

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51
Q

what are the neurocrine GI peptides

where are they secreted

A

ACh, NE, VIP, gastrin releasing peptide, neuropeptide Y, and substance P

into the GI tract from neurons following an AP

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52
Q

what currents work to produce the plateau in phase 3

A

inward Ca and outward K

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53
Q

what is the fucntion of norepinephrine in the GI tract

A

relaxation in the SMC wall

contraction of sphincters

stimulation of salivary secretion

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54
Q

four basic digestive actions

A

motility

secretion

digestion

absorption

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55
Q

where are parietal cells found in the stomach

what do they secrete

A

body

HCl and intrinsic factor

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56
Q

propuslion

A

controlled movement of the contents of the GI tract froms stomach to large intestines

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57
Q

how is HCl secretion regulated in parietal cells

A

G cells

vagus nerve stimulation

ECL cells

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58
Q

5 functions of cholestrol in the body

A

cell membranes

Vitamin D

hormones

myelin

bile salts

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59
Q

what is the function of crypts in the large intestine

A

secretion of mucus

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60
Q

what determines if the pattern of action for SMCs will be peristalsis or segmentation

A

the orientation of the fibers (circular or longitudinal)

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61
Q

where are chief cells in teh stomach

what do they secrete

A

body

pepsinogen

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62
Q

what type of glands make up 90% of the pancreas

A

exocrine glands

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63
Q

what provides extrinsic innervation to the GI tract

A

autonomic nervous system

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64
Q

how often does the small intestine contract

what are the contraction patterns

A

12/min (constant)

primary: segmentation, secondary: peristalsis

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65
Q

how is fat absorbed into the lymph after digestion in the small intestine

A

lacteals

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66
Q

how do ductal cells modify the compostion of saliva

A

extraction of Na and Cl

addition of K and HCO3

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67
Q

how are CHO and proteins absorbed after digestion in the small intestine

A

capillaries

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68
Q

four pancreatic enzymes that break down proteins

A

trypsin, chymotripsin, carboxypeptidase, elastase

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69
Q

where are G cells in the stomach and what do they secrete

A

antrum

gastrin

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70
Q

four regions of the stomach

A

fundus

body

antrum

pyloris

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71
Q

what are the endocrine cells of the pancreas

what do they do

A

islets of langerhans cells

secretes insulin and glucagon

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72
Q

what are the primary functons of motility in the small intestine

A

Digestion and absorption of nutrients

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73
Q

two types of motility in the large intestine

A

haustral movement

mass movement

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74
Q

where does intrinsic regulation of the GI tract come from

A

ENS

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75
Q

three functions of bacteria in the GI

A

protection against pathogens

metabolic functions

vitamin production

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76
Q

what digestive processes happen in the large intestine

A

none, water and Na are reclaimed, K is secreted, undigestable wastes are broken down by bacteria

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77
Q

function of secretion in the GI tract

A

producting liquid to lubricate the canal and aid in the process of digestion

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78
Q

what is the function of gastrin releasing peptide in the GI tract

A

releasing gastrin

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79
Q

what are the functions of HCl in the stomach

A

kills microorganisms

activates pepsin

reduces gastric emptying rate

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80
Q

what is controled by the enteric nervous system

A

intrinsic innervation of the GI

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81
Q

pharmacomechanical coupling

A

release of CA from the SR through G protein coupled receptors with no change in membrane potential

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82
Q

how do ECL cells regulate HCl production in parietal cells

A

producing histamine which stimulates H2 receptors to produce G protein and cAMP, increasing proton pump activity

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83
Q

what causes duodenal ulcers

A

rapid gastric emptying will cause too low of a pH to be effectively buffered by the duodenum, leading to ulcer

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84
Q

T/F there are no vili in the large intestine

A

true

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85
Q

two parts of the glandular structures in the mucosa of the stomach

A

gastric pits

gastric glands

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86
Q

gastrocolic reflex

A

the intiation of peristalsis in the GI tract caused by eating that can lead to defecation

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87
Q

three functions of bile salts

A

emulsification of fat

micelle formation to make fats soluble

removal of waste products (bilirubin)

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88
Q

what happens during phase 4 that allows for repolarization of SMCs in the Gi tract

A

voltage gated Ca channes close, activation of Ca gates K channels

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89
Q

describe the process of dysfunction in lactose intolerance

A

ingested lactose is not broken down in the small intestine

lactose in the large intestine feeds bacteria

bacteria ferment lactose to produce CO2, H2, and carbon metabolites

H2O is taken out of the body into the colon

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90
Q

patterns of GI motility

A

propulsion

trituration

mixing

reservoir functions

phasic contractions

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91
Q

three types of ducts found in salivons

A

intercalated ducts

striated

excretory

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92
Q

what triggers esophageal peristalsis

A

stimulation of stretch receptors in the wall that trigger local and CNS distension reflexes

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93
Q

what extracts bile slats from portal blood

A

hepatocytes

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94
Q

what is the relationship between flow rate and salivary composition

A

the higher the flow rate the less ionic modification can take place

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95
Q

two conditions that can cause osmotic diarrhea

A

ingestion of a poorly absorbed substrate such as epsom slats

malabsorption (lactose intolerance)

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96
Q

T/F the ENS can regulate all of the GI functions indepenently

A

true

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97
Q

what are the common manifestations of sjogrens syndrome

A

dry mouth

difficulty chewing and swallowing

candida

rotten teeth

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98
Q

what are the three main ways teh GI breaks down proteins

A

Pepsin in gastric juice

pancreatice enzymes

amino peptidases in the small intestine

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99
Q

what must accompany esophageal peristalsis

A

relaxation of the esophageal sphincter

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100
Q

why are micelles important to lipid digestion

A

because they are water soluble and will difuse across the apical membrane

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101
Q

portal triad

A

the trio of portal vein, hepatic artery, and bile duct that runs through every level of organization of the liver

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102
Q

what is the function of villi and microvilli in the small intestin

A

increase surface area of absorption

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103
Q

what is secreted by acinar mucous cells in the salivon

A

mucin

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104
Q

what causes gastric ulcers

A

regurgitation of duodenal contents can, because they are basic and gastric mucosa is resistant to acid, not base

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105
Q

where is B12 absorbed

A

the small intestine

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106
Q

what cells secrete Gastric inhibitory peptide

what is the secretion stimulus

A

K cells in the small intestine

fat, carbs, amino acids

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107
Q

T/F muscle contraction is always present in the GI tract

A

true, but the magnitude of contraction depends on the presence of an AP

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108
Q

describe primary perstalsis

what part of the brainr regulates this

A

perstalsis that follows the distention reflex in the esophagus

the brain stemm

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109
Q

what is the purpose of CCK inhibition of gastric emptying

A

ensures adequate time for digestion and absorption

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110
Q

describe the “alkaline tide”

A

HCO3 from the parietal cells is absorbed into venous blood in the portal system and released into the duodenum via the pancreas

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111
Q

what parts of the stomach serve as a reservior

what allows them to do this

A

the fundus and upper body

relaxation of tonic contractions in the SM to distend the cavity

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112
Q

where is 92-97% of the diet absorbed

A

the small intestine

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3
4
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113
Q

how is the prophospholipase converted to phospholipase

A

trypsin in the small intestine

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114
Q

gastric punp

A

the contraction that periodically propels a portion of chyme through the pylorus int the duodenum

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115
Q

what is the serosa/adventitia

A

a layer of simple squamous epthelium furthest from the lumen in the GI tract that has little conective tissue

116
Q

during fasted contractions of the antrum, what will happen to indigestable objects in the stomach

A

they will be pushed into the duodenum

117
Q

why is pancreatic venous blood acidic

A

because H+ is secreted through the basolateral membrane into the blood

118
Q

what digestive processes happen in the mouth

A

chewing and break down of CHO by salivary amylase

119
Q

how do slow waves from the ICC induce peristalsis

A

they release a slow action potential that acts a pacemaker current and depolarizes SMCs when threshold is reacted

120
Q

three CHO metabolic functions of the liver

A

gluconeogenesis

glycogenolysis

glycogenesis

121
Q

what stimulates the gastrocolic reflex

what are the chemical/neurological mediators

what happens in response

A

stretch in the stomach and byproduct in the small intestine

gastrin and ANS

forceful peristaliss in the colon which increases rectum pressure and encourages the defecation

122
Q

two conditions that will cause a deficiency in proteases

A

chronic pancreatitis and cystic fibrosis

123
Q

what is the function of trypsin

A

to activate other proteases

124
Q

what is the only site for the secretion of intrinsic factor

what does IF do

A

parietal cells of teh stomach

absorps vitamin b

125
Q

what is the preganglionic parasympathetic neurotransmitter

postganglionic

A

acetylcholine for both

126
Q

what vitamin stored in the liver is important for Ca absorption

A

Vitamin D

127
Q

what is the role of the stomach in lipid digestion

A

it breaks fat into smaller parts and empties at a controlled rate into the small intestine to allow for proper absorption

128
Q

what is the function of substance P in the GI tract

A

contraction of smooth muscle

stimulation of salivary secretion

129
Q

what digestive processes happen in the esophagus

A

none, food bolus is sent to the stomach via peristalsis

130
Q

what is the function of segmentation

how does it work

A

to mix chyme and expose to enzymes and secretions

circular muscle contracts and splits the chyme, then the two halves merge during relaxation

131
Q

when would secondary peristalsis occur

A

when primary peristalsis is not enough to move food through the esophagus

132
Q

disaccharidases

A

enzymes located at the brush border of teh small intestine used to break dissacharides into glucose

133
Q

causes of maldigestion GI tract

A

pancreatin insufficiency

zollinger ellison

cholestasis/bile deficiency

lack of brush border enzymes

nutrient digestion by bacteria overgrowth

134
Q

what is the function of ducts in the salivon

A

modification of fluid compositon

135
Q

is saliva typically basic or acidic

A

basic (7-8)

136
Q

what are the AP phases of a GI SMC

A

Phase 0: resting MP (-50 to -60) with an outward K

Phase 1: Upstroke

Phase 2: transient repolarization

Phase 3: plateau

Phase 4: repolarization

137
Q

what happens to bile salts after lipids are absorbed

A

they are recirculated into the enterohepatic circulation

138
Q

two GI disorders related to abnormal motility

A

Duodenal and Gastric ulcers

139
Q

what are the two types of electrically coupled cells in the GI tract

A

smooth muscle cells

interstitial cells of cajal

140
Q

three proteins found in saliva with their function

A

amylase (breaks down starch into maltose)

lysozyme and IgA (antimicrobial)

lactoferrin (binds Fe to suppress bacteria

141
Q

T/F acinar cells in the salivon secrete mostly isotonic lfuid

what bout the ducts

A

true

the secrete a hypotonic fluid

142
Q

stellate cells

A

cells that store lipid droplets that contain vitamin A

143
Q

what is the functon of mixing movement

A

mixxes food and enzymes to facilitate digestion

144
Q

what are the exocrine cells of the pancreas

what do they do

A

acinar cells and ductal cells

secretes digestive enzymes into the dudodenum

145
Q

what is the action of acetylcholine in the GI tract

A

contraction of the SMC in the wall

relaxation of sphincters

stimulation of secretions

146
Q

what two reflex mechanisms increase or decrease saliva production

A

simple reflex

conditioned reflex

147
Q

How do g cells regulate HCl secretion by parietal cells

A

gastrin produced CCK, producing G protein and IP3Ca to stimulate the proton pump

148
Q

what is the function of the acini in the salivon

what are the two cells that make up this structure

A

secretion

serous cells and mucous cells

149
Q

mass movement leads to distention of the rectum, which does what

when will this lead to defecation

A

provides the urge to crap

reflexive relaxtion of the the internal anal sphincter and contraction of the rectum and sigmoid colon

if the external anal sphincter is relaxed

150
Q

what are the two main enyzmes that absorb Na in the GI tract

how is the gradient established

A

Na/glucose and Na/AA symporter

Na/K pumps on the basolateral membrane

151
Q

two enzymes secreted in gastric juices

A

protease, gastric lipase

152
Q

how does the vagus nerve regulate HCl secretion by parietal cells

A

acetylcholine stimulates muscarinic receptors, producing g protein to produce IP3Ca2, which stimulates the H/K proton pump

153
Q

in what part of the GI are slow waves always present

A

small intestine

154
Q

what is found in the submucosal layer of the GI tract

A

connetive tissue

blood

glands

submucosal plexus

155
Q

how is the constant movement produced by smooth muscle and ICC cells in the GI regulated

A

nerves, hormones, paracrine substances which can increase or decrease activity

156
Q

three major salivary glands

A

parotid gland

submandibular gland

sublingual

157
Q

T/F submucosa is present in the small and large intestines but not into the esophagus

A

true, it is also sparse in the stomach

158
Q

what are two inbitory pathways for the proton pump

A

somatostatin and prostaglandins will both produce g proteins that inhibit cAMP production and decrease pump activity

159
Q

what are five proteases of the Gi tract

A

trypsin, chymotrypsin, elastase, carbpxypeptidase A and B

160
Q

three layers of GI mucosa

A

epithelium

lamina propria

muscularis mucosa

161
Q

what is the function of somatostatin in the GI ttract

A

inhibition of GI hormones

inhibition of H+ secretion

162
Q

what are the receptors that feed into the ENS

A

autonomic nerve receptors in the CNS

mechano and chemoreceptors in the the mucosa

163
Q

what is the function of the migrating myoelectric complex

A

to empty the stomach of any residue from the last meal

164
Q

what cells secrete CCK

what is the secretion stimulus

A

I cells of the small intestine

ingested fatty acids or small peptides

165
Q

why is the size of micelles important

A

they are smalle enough to be absorbed past the apical membrane

166
Q

what is the purpose of carbonic anhydrase in ductal cells

what will happen to the components

A

it breaks carbonic acid into HCO3 and H+

H+ is exchanged with Na on the basolateral membrane

HCO3 is exchanged with Cl on the apical membrane

167
Q

why is there a high osmolality in the intercellular spaces between enterocytes

A

because a lot of sodium is secreted into this space

168
Q

which of the three regulatory pathways of gastric secretion is inbitory

A

the intestinal phase

acid and fat in the duodenum stimulate cells in the small intestine that will inhibit gastrin secretion and decrease empyting rate

169
Q

what is the function of the ENS

A

controls contractile, secretory, and endocrine functions of the GI

170
Q

how does pH effect gastric emptying rate

A

activation of H+ receptors in the duodenum reduce gastric emptying to allow for buffering by pancreatic HCO3

171
Q

cholera causes what type of diarrhea

A

secretiry diarrhea from cholera toxin

172
Q

what cells secrete somatostatin

what is the stimulus

A

D cells in the gastric antrum

decreased luminal pH

173
Q

three pancreatic enzymes that break down lipids

A

lipase/colipase, phospholipase, cholesterol esteras

174
Q

what is the state of the colon with no stimulus

what happens after feeding

what happens during mass movement

A

a quiet colon or haustral shuttling with no net movement of chyme

increased contractions shuttle chyme from one haustra to the next

there is multihaustral propulsion

175
Q

E-C coupling

A

the activation of Ca channels via action potentials

176
Q

what cells secrete secretin

what is the secretion stimulus

A

S cells in the duodenum

H+ and fatty acids

177
Q

cystinuria

A

a genetic disorder with the lack of a transporter for di-basic AAs

178
Q

what are the fat soluble vitamins

how are they absorbed

A

A, D, E, K

the same as lipids

179
Q

what converts stellate cells into myofibroblasts

what will myofibroblasts do

A

inflammation

secrete collagen and extracellular matrix into the perisinusoidal space

180
Q

why is motility of the GI tract important

A

grinding, mixing, and fragmenting digested food to prepare it for digestion and absorption, then movement throough the GI

181
Q

digestions

A

breaking down proteins, fats, and carbs in the GI traft

182
Q

the reservior function of the stomach is mediated by what reflex

afferent and efferent fibers of this reflex are carried by what nerve

A

vagovagal stretch reflex

the vagus nerve

183
Q

what two structures make up the myenteric plexus

A

submucosal and myenteric plexus

184
Q

what happens if the external anal sphincter doesn’t relax in response to the urge to defecate

A

the urge subsides

185
Q

what is the final product of lactose intolerance

A

osmotid diarrhea caused by CO2, H2, and carbon metabolites

186
Q

what will inhibit the secretion of gastrin

A

low pH in the stomach

187
Q

what is secreted by serous cells in the acini

A

watery fluid

digestive enzymes (amylase)

188
Q

what digestive processes happen in the small intestine

A

chemical digestion of macronutrients is completed and the products absorbed

189
Q

how much fluid is absorbed in the small intestine vs the colon

A

80% vs 20%

190
Q

what are the extrinsic factors that regulate the ENS

A

ANS

neuotransmitters

hormones

inflammatory mediators or stress factors

191
Q

three types of GI peptides

A

hormones, neurocrines, paracrines

192
Q

why are parietal cells considered polar

A

they have different membrane proteins on the apical and basolateral membranes

193
Q

four things that happen in the large intestine

A

absorption of H2O, Na, Cl

digestion and metabolism of remaining CHO

synthesis of vitamin K and B vitamins by flora

bacteral fermentation that produce gases and organic acids

194
Q

causes of malabsorption in the GI tract

A

celiac sprue

gastronenteritis

crohns

lymph obstriction

195
Q

two hormones found in gastric juices

A

gastrin and intrinsic factor

196
Q

what controls gastric emptying rate

A

pH and food contents

197
Q

what regulates the enzymatic secretion from acinar cells

A

CCK and Ach

198
Q

what channels open during Phase 1 to create upstroke

A

voltage gated Ca and K channels

199
Q

what is the function of secretin

A

promotes the secretion of pancreatic HCO3 to neutralize acid and inhibits the effect of gastrin on parietal cells

200
Q

four Gi hormones

A

Secretin, GIP, Gastrin, CCK

201
Q

what fat soluble vitamins are stored by the liver

A

A, D, K

202
Q

what is the paradox of lipid absorption

A

the body goes through a lot of troube breaking fat into micelles and chol/TF/PL, then builds them into large molecules before absorbing them

203
Q

describe the series of contractions that produces peristalsis

A

circular muscle behind the bolus pushes forward

contraction of longitudinal muscle and relaxation of the circular muscle ahead of the bolus makes space

204
Q

what is the first step of protein digestion

A

activation of trysinogen into trypsin by the brush border enzyme enterokinase

205
Q

where does the phasic contraction of the gastic (antral) pump start

why is the pump necessary

A

in the middle stomach

mixiing and trituration of food

206
Q

where are minerals absorbed in the GI tract

A

the small intestine

207
Q

what system plays a roll in regulation of all ENS functions

A

parasympathetic nervous system

208
Q

name four substances found in saliva

A

water

mucin

proteins

salts

209
Q

what is the function of striated and excretory cells in the salivon

A

they modify the ionic compositon of saliva

210
Q

what drives the conditioned reflex in regards to salivation

A

thinking about, seeing, or smelling food

211
Q

what happens in the gastric phase of regulation of gastric secretion

what percent of acid is secreted this way

A

distention in the stomach activates long and local reflexes in the stomach, increasing production of ACh, histamine, and gastrin to increase HCl production

212
Q

what is the functon of zymogen granuales in acinar serous cells

A

production and storage of amylase

213
Q

what is the process of breakdown of lipids after absorption into enterocytes

A

micelles are broken down into cholesterol, monoglycerides, phospholipids, and free fatty acids

fats are then formed into cholestrol, triglycerides, and phospholipids

cholestrol, triglycerides, and phospholipids are used to form chylomicrons

214
Q

define a tonic contraction

what happens during this time

A

when the contraction produced membrane potential of a slow wave is not enough to breach threshold

no AP is generated and the muscle undergoes small contractions with incomplete relaxations

215
Q

what regulates motility of the small intestine

A

inhibitory and excitatory impulses from the SNS or PNS transmitted through the enteric nervous system

216
Q

describe the process of B12 absorption

A

dietary B12 is released from food by pepsin

free B12 binds to R protein in salivary juice

pancreatic proteases degrade R protien, allowing B12 to be picked up by intrinsic factor

intrinstic factor-B12 is absorbed in the iluem

217
Q

interstitial cells of cajal

A

pacemaker like cells in the GI tract that contract spontaneously

218
Q

absorption in the GI tract

A

the process by which the products of digestion are absorbed into mucosa and enters the lymph or blood

219
Q

how much fluid is secreted by the stomach each day

what is the pH

A

2-2.5L

1-4

220
Q

three different names for heartburn

A

GERD

Pyrosis

Esophagitis

221
Q

what is secreted by the intercalated ducts of the salivon

A

epidermal growth factor

ribonuclease

amylase

proteinases

222
Q

what the preganglionic sympathetic neurotransmitter

what is the post ganglionic

A

acetylcholine

norepinephrine

223
Q

what is the break down of cholestrol in terms of where it is produced in the body

A

85% is produced by our own cells
15% is taken from food

224
Q

where is bile ejected into

A

the small intestine

225
Q

two sources of blood flow to the liver

A

portal vein from the GI tract

hepatic artery from the celiac artery

226
Q

what happens during the retropulsion phase of the gastric pump

A

large partiles are pushed back into the body and the antrum is cleared

227
Q

what digestive processes happen in the stomach

A

mechanical digestion of food via churning

chemical breakdown via pepsin and HCl

228
Q

6 functions of the liver

A

detoxification of drugs

CHO metabolism

Protein metabolism

lipid metabolism

bile formation

removal of RBC’s and ammonium

229
Q

what does the sublingual gland predominately secrete

A

mucous (70%)

230
Q

T/F the ENS can function with or without autonmic regulation

A

true

231
Q

three unique features of the GI tract

A

large population of bacteria

well developed local immune system

enteric nervous system for regulation

232
Q

what is secreted by gastric glands

what is the compositon

A

gastric juices

Acid, enzymes, mucus, horomes

233
Q

what is sjogrens syndrome

what is the result of this

A

a chronic autoimmune disorder where T and B cells attack salivary, lacrimal, or other exocrine glands

ductal lumen narrowing and atrophy of the gland

234
Q

what simtulates secretion from ductal cells

what is the major stimulant

A

CCK, Ach, and secretin

secretin

235
Q

what is the function of Vitamin A

A

important for vision (forms photoreceptors)

236
Q

what is the sympathetic response that increases saliva production

A

NE stimiulates beta adrenergic receptors in acinor or ductal cells by producing cAMP

237
Q

what type of contraction allows for reserrvior functions in teh GI

where is this function found (4)

A

tonic contrations

the lower esophagus, upper stomach, ileocecal valve, and internal anal sphincter

238
Q

what is the chemical reponsible for most of the fat digestion in the small intestine

A

pancreatic lipase

239
Q

what is the simple reflex

what will produce the strongest response via this reflex

A

salivation based on whats in the mouth

citric acid

240
Q

what is the primary enzyme responsible for absorbing digested protein

A

H+/di - tripeptide symporter

241
Q

what are the effectors of the GI tract

A

smooth muscle

exocrine galdns

endocrine galnds

242
Q

what is the function of Vitamin K

A

synthesis of clotting factors II, IIV, IX, and X

243
Q

4 plasma proteins formed by the liver

A

fibrinogen

albumin

prothrombin

trasnferrin

244
Q

are ducts high or low in flow rate

A

low 1mL/min

245
Q

T/F the SMCs of the GI function independent of each other

A

fallse, they function as a syncytium

246
Q

two GI paracrines

A

Somatostatin, Histamine

247
Q

two functions of chewing

A

reduce size of food particles

mix food with amalyse and saliva

248
Q

two types of esophageal peristalsis

A

primary

secondary

249
Q

what are the two types of GI contractions

A

tonic and phasic

250
Q

two mechanisms that drive GI tract motility

A

E-C coupling

pharmacomechanical coupling

251
Q

describe the muscular actions needed for defecation

A

relaxation of the puborectalis and the internal anal sphincter

contraction of the rectum and the anal canal

relaxation of the external anal sphincter

252
Q

what four events must happen for lipid digestion

A

secretion of bile and lipases

emulsification by bile salts

enzymatic hydrolysis by lipases

micelle formation with bile salts

253
Q

what are the five major secretory areas of the GI tract

A

mouth

stomach

pancreas

liver/gallbladder

small intestine

254
Q

what are the functions of gastric motility

A

reservior

mixing, dividing, emptying in the lower stomach

contractions in the antrum open the pylorus

255
Q

what structure helps enhance the local immune system in the GI

where is it found

A

peyers patches

ileum

256
Q

how often is mucus secreted

how much is secreted each dayq

A

it is continuous in varying amounts

1-2 L day

257
Q

what does the parotid gland secrete

A

serous secretion and amylase

258
Q

describe the vagovasal flex in the stomach

A

postganglionic peptidergic vagal efferent fibers release vasoactive intestinal peptide (VIP) which relaxes the cardiac sphincter and smooth msucle in the orad stomach

259
Q

describe the mechanism of HCl secretion by parietal cells

A

CO2 and H2O are formed into carbonic acid with carbonic anhydrase, which dissociates into H and HCO3

H is pumped into the lumen of the stomach via H/K exchanger on the apical surface

HCO3 is sent into the blood via HCO3/Cl exchanger

Cl passivly diffuses through channels into the lumen to form HCl

260
Q

what cells secrete gastrin

what is the trigger stimulus

what are the effects

A

G cells

protein, dstomach distention, vagal stimulaton

promotes H secretion by parietal cells, stimulates growth of gastric mucosa

261
Q

common cuases of peptic ulcers

A

H pylori, smoking, alcohol, NSAIDs, stress, ischemia

262
Q

what happens during the propulsion phase of the gastric pump

A

thre is a rapid flow of chyme with delayed flow of large particles towards the pylorus

263
Q

what are the three phases of the gastric (antral) pump

A

propulsion

emptying

retropulsion

264
Q

define a phasic contraction

what will cause stronger contractions

A

a contraction started when the slow wave is enough to depolarize the SMCs and produce an AP

more APs on top of the slow wave produce stronger contractions

265
Q

what is the storage capacity of the stomach

A

around 4 cups or 1L

266
Q

is defecation reflexive or voluntary

A

both, both sphincters have to be relaxed in order to defecate

267
Q

trituration

A

the crushing and grinding of ingested food

268
Q

what element is most important for the absorption of monosaccharides in the small intestine

why

A

sodium

because Na/glucose and galactose symporters are important cell proteins in the process

269
Q

what is the function of mucus in gastric juices

A

protecting the stomach from dehydration and helping form chyme

270
Q

what are the paracrine GI peptides

where are they secreted

what is their target

A

somatostatin and histamine

in the endocrine cells of the GI tract

other cells with in the same tissue that secretes them

271
Q

define peristalsis

A

a progressive wave of contractions along the wall of the GI tract from esophagus to large intestine

272
Q

what are the four layers of te GI tract

A

mucosa, submucosa, mucularis propria, serosa/adventitia

273
Q

what is the basic unit of the salivary gland

what are the two parts of this structure

A

salvion

acini and ducts

274
Q

what happens to micelles as they are absorbed

A

the lose their bile salts

they are broken into triglycerides and protein, then formed into chylomicrons

chylomicrons are secreted into blood

275
Q

motility

A

the movement of the GI system that transmits contents from mouth to rectum

276
Q

three compnonents of bile

A

bile salts, bilrubin, cholestrol

277
Q

kupffer cells

A

liver macrophages that line the hepatic sinusoid and ingest bacteria

278
Q

where is the integration center for defecation found

does it take input from high CNS structures

A

the sacral spinal cord

yes

279
Q

four types of diarrhea

A

decreased surface area (celiac sprue)

osmotic diarrhea

secretory diarrhea

intestinal infections

280
Q

what is the PsNS response to the conditioned salivary reflex

what is the neurotransmitter

A

parasympathetic will increase saliva secretion in response to food, nausea, smells

decrease production due to dehydration, fear, sleep

ACh, which stimulates muscarinic receptors with atropine

281
Q

how does bile function to digest fat

A

it emulsifies liquid to prepare them for digestion, then packages them into micelles for transport

282
Q

what current provides transient repolarization during phase 2

A

`transient outward K rectifiers

283
Q

what is mucin

A

a glycoprotein found in saliva that helps thicken saliva

284
Q

how is SMC contraction started in the GI tract

how is the AP conducted

two orientations of SMC in the GI

A

response to membrane potentials created by teh ICC

gap junctions

circular and longitudinal

285
Q

what do the acinar and ductal pancreatic cells do

A

acinar cells secrete pancreatic enzymes

ductal cells secrete HCO3 soloution

BMS 752 (Medical Physiology) (13 decks)

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