Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Physio > Chapter 20 - Gastrointestinal System > Flashcards

Chapter 20 - Gastrointestinal System Flashcards

1
Q

describe the GI tract in order

A

mouth - pharynx - esophagus - stomach - small intestine - colon - rectum - anus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what do accessory glands do

A

there are several glands outside the GI tract that secrete fluids and enzymes into the lumen of the GI tract

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

describe the four layers of the GI tract wall

A

mucosa (lining of lumen), submucosa (connective tissue), muscularis externa (smooth muscle), and serosa (connective tissue)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

describe the mucosa

A

a barrier that separates GI lumen from body’s internal environment. it consists of 3 layers: epithelial lining (entrocytes), lamina propria (connective tissue), and muscularis mucosae (thin smooth muscle). the features vary in different parts of the GI tract

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what cells make up epithelial lining of mucosa

A

absorptive cells, exocrine cells, and endocrine cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what cells make up lamina propria of mucosa

A

connective tissue, small blood vessels, lymphatic vessels, nerves and lymphoid tissue that defend against bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what cells make up muscularis mucosae

A

thin layer of smooth muscle (local movement of mucosa itself?)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

describe the submucosa

A

a thick layer of dense connective tissue deep to the mucosa. contains larger blood vessels and lymphatic vessels and nerves. contains the submucosal plexus (meissner’s plexus) which is a network of nerves of the enteric nervous system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

describe the muscularis externa

A

two layers of smooth muscle: inner circular layer that changes diameter of GI tract and outer longitudinal layer that changes length. also contains the myenteric plexus (auerbach’s plexus) which is also a network of nerves and another part of enteric nervous system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

describe the serosa

A

it is epithelium (and underlying connective tissue) that covers surface of GI tract. in the abdomen serosa is visceral peritoneum, which is continuous with parietal peritoneum and mesenteries.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

name the structures that make the GI tract

A

mouth, pharynx, and esophagus. stomach, small intestine, colon, rectum and anus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

describe mouth in digestion

A

digestion begins with mastication. mouth secretes saliva that is a lubricant and contains salivary amylase which digests starch and glycogen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

describe pharynx in digestion

A

common passageway for air and food. food leaves the pharynx and enters the esophagus (air leaves pharynx and enters larynx but this is not a part of digestion)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

describe the material that makes up esophagus

A

the upper 1/3 is skeletal muscles while the lower 2/3 is smooth muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

describe upper esophageal sphincter

A

skeletal muscle it is between pharynx and esophagus. relaxes to allow food to pass into esophagus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

describe lower esophageal sphincter

A

smooth muscle. between esophagus and stomach

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

describe the stomach in digestion

A

stores food after it’s swallowed. its empty volume is 50 mL but full volume is 1000 mL. it secretes gastric juice and releases food into intestine in controlled manner in small portions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

name the 4 parts of the stomach

A

fundus, body, antrum, and pylorus with pyloric sphincter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

describe processes of the stomach

A

mixes chyme, which is then passed through pylorus into duodenum (gastric emptying). stomach expands to acommodate food

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what are rugae

A

folds in mucosa that flatten on expansion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what are gastric pits

A

they’re located in the stomach lining and lead to gastric glands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

describe the different cells of the gastric pits

A

neck cells secrete mucus, chief cells secrete pepsinogen, parietal cells secrete acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what does pepsinogen do

A

precursor for pepsin, and enzyme that digests proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what do hydrogen ions do

A

maintain acidic environment in stomach

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

what is intrinsic factor and what secrets it

A

it is necessary for absorption of b12 and parietal cells secrete it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

what is gastrin and what secretes it

A

secreted from G cells (hormone)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

describe the acidic environment of the stomach

A

ph = 2. this is necessary for activating pepsinogen. denatures protein and kills bacteria. there is a gastric mucosal barrier which is a protective layer of mucus and bicarbonate secreted from neck cells and goblet cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

what does pyrolic sphincter do

A

regulates passage of chyme between stomach and small intestine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

describe the small intestine

A

coiled hollow tube 8-10 ft long between stomach and large intestine. primary site of digestion and absorption. it consists of three divisions: duodenum, jejunum, and ileum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

describe secretions into dueodenum

A

pancreatic juice enters duodenum this consists of digestive enzymes from pancreas and bicarbonate which neutralizes acidic chyme. bile enters the duodenum as well which is secreted from liver, can be stored in gallbladder and contains bile salts which aid in fat digestion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

describe absorption in small intestine

A

absorption completed within first 20% of intestine length. it is anatomically arranged for large surface area for absorption

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

describe the small intestine wall

A

villi increase surface area of epithelium (contain blood capillaries and lacteals for absorption of nutrients). microvilli increase surface area of epithelial cells (form brush border)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

describe crypts of lieberkuhn

A

in the mucosa of small intestines epithelial cells in crypts secrete bicarbonate-rich fluid (secreted in proximal small intestine and absorbed in distal small intestine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

describe the role of the liver in absorption

A

absorbed nutrients travel in blood to liver before entering general circulation. liver functions to detoxify substances and processes certain nutritents

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

describe the hepatic portal system

A

vasculature that delivers absorbed nutrients to liver before entering general circulation. nutrients are absorbed from small intestine into mesenteric veins, then nutrients travel from mesenteric veins to liver via hepatic portal vein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

where do nutrients go after liver

A

nutrients travel from liver to heart (general circulation) via hepatic vein. hepatic artery provides liver with fresh blood to supply oxygen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

describe the large intestine

A

consists of cecum, colon, and rectum. the ileocecal sphincter is between ileum and colon. the teniae coli are bands of longitudinal smooth muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

describe the colon

A

a hollow tube from small intestine to rectum. functions in concentration of wastes into feces, absorption of most water, and storage of feces until defecation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

name the 4 section of the colon

A

ascending colon, transverse colon, descending colon, and sigmoid colon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

describe rectum and anus

A

colon empties into rectum, then feces are excreted through anus. the internal anal sphincter is made of smooth muscle, the external anal sphincter is skeletal muscle. relaxation of both sphincters is necessary to excrete feces

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

name 3 accessory glands and their function

A

salivary glands which secrete saliva, pancreas, which secretes pancreatic juice, and liver which secretes bile

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

name the 3 salivary glands and locations

A

paratoid gland near cheek, submandibular below the mandibal and sublingual gland under tongue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

describe the characteristics of saliva

A

rich in bicarbonate ions, contains mucus, and has both salivary amylase and lysozyme enzymes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

describe the pancreas

A

has exocrine and endocrine portions. exocrine portion produces the pancreatic juice which is rich in bicarbonate and the following enzymes: pancreatic amylase and lipases, proteases, and nucleases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

what is main function of liver in digestion

A

secretes bile

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

describe metabolic processing of nutrients in liver

A

glucose –> glycogen, amino acids –> fatty acids, triglycerides and cholesterol synthesis, and lipoprotein synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

name 4 extra functions of liver

A

removal of old red blood cells (catabolize hemoglobin and generate bilirubin), elimination of wastes and toxins (bilirubin eliminated as bile pigments), synthesis of plasma proteins, and secretion of modification hormones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

describe the biliary system

A

consists of liver, gallbladder, and associated ducts. liver synthesis bile, gallbladder stores bile, and common bile ducts transport bile from liver and/or gallbladder to duodenum. they join with pancreatic duct before entering duodenum. the sphincter of oddi regulates flow from pancreas and gallbladder to duodenum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

describe liver anatomy

A

materials to make bile taken from blood in sinusoids into hepatocytes. the hepatocytes secrete bile into bile caniculi on side opposite of sinusoids. caniculi drain into bile ducts and bile ducts drain into common hepatic duct.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

how many grams/day of carbohydrates are typical

A

500 grams/day

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

how are most carbs consumed

A

as disaccharides or polysaccharides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

what carbs can be absorbed

A

only monosaccharides. disaccharides and polysaccharides must be digested into monosaccharides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

describe digestion of starch and glycogen

A

enzymes of digestion + salivary amylase and pancreatic amylase. the end product is disaccharides (maltose) and limit dextrins. amylases can only hydrolyze internal linkages between monomers. additional enzymes are needed to complete digestion of disaccharides and dextrins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

name 4 enzymes of digestion

A

dextrinase (dextrins into glucose), sucrase, lactase, and maltase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

where are digestion enzymes located

A

in brush border of small intestine. brush border enzymes are integral membrane proteins in the apical membrane, with their active sites facing lumen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

describe absorption of monosaccharides

A

absorption is transport of nutrients from lumen to blood. glucose and galactose are absorbed in two step process: secondary active transport across apical membrane and facilitated diffusion across basolateral membrane. fructose is absorbed by facilitated diffusion in both steps

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

what ion allows glucose from maltose across apical membrane

A

sodium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

how much protein/ day in typical diet

A

125 grams/day which is more than the necessary 50 grams/day

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

describe digestion and absorption of proteins

A

secreted into lumen of intestinal tract and sloughed off with cells lining intestinal tract

60
Q

name 3 protein digestion products

A

amino acids, dipeptides, and tripeptides

61
Q

name 2 types of proteases

A

endopeptidases (split polypeptides at interior peptide bonds product = small peptide fragments), and exopeptidases (cleave amino acids from one end of polypeptide product = amino acids)

62
Q

describe zymogens

A

aka proenzymes. inactive storage form of proteases, stored in zymogen granules, secreted by exocytosis, and activated by proteolysis

63
Q

describe protein digestion in stomach

A

protein digestion begins in stomach with the enzyme pepsin which produces peptides. the inactive (secreted form) of pepsin is pepsinogen, it is activated by acid.

64
Q

describe activation of pepsin in stomach

A

chief cells secrete pepsinogen. parietal cells secrete Hcl which activates pepsinogen. active pepsinogen cleaves other pepsinogen to pepsin which is the active form

65
Q

name the enzymes for protein digestion in small intestine

A

pancreatic proteases are: trypsin, chymotrypsin, and carboxypeptidase. brush border proteases are aminopeptidase and enterokinase

66
Q

describe activates of proteases in small intestine

A

enterokinase activates trypsin which then activates both chymotrypsin and carboxypeptidase

67
Q

describe absorption of amino acids

A

cross the apical membrane by sodium-linked secondary active transport or facilitated diffusion. cross the basolateral membrane by facilitated diffusion

68
Q

describe absorption of dipeptides and tripeptides

A

cross apical membrane by active transport, and are broken down inside cells to amino acids. amino acids cross the basolateral membrane by facilitated diffusion

69
Q

how many grams/day of lipids is usual

A

140 grams/day and 90% of that is triglycerides

70
Q

describe the special problem facing lipids in digestion

A

they’re not water soluble, don’t mix with stomach or intestinal contents, and form fat droplets

71
Q

describe lipid digestion

A

the enzymes of digestion are lipases. these are secreted from pancreas. lipases can only act on molecules at the surface of a fat droplet. bile salts increase the combined surface area of droplets by breaking each large droplets into several small ones. this is called emulsification

72
Q

describe bile salts

A

synthesized in liver from cholesterol. secreted in bile to dueodenum. they’re amphipathic molecules that emulsify fat

73
Q

discribe how pancreatic lipases digest lipids

A

a triglyceride is turned into a monoglycride and 3 fatty acids. some fatty acids and monoglycerides are absorbed while others form micelles. equilibrium between micelles and the fatty acids and monoglycerides is formed by the action of lipases

74
Q

describe the enterohaptic circulation

A

the recycling of bile salts by the liver. gallbladder and liver share common bile duct into duodenum. bile salts travel from here to ileum where some are absorbed into capillaries and returned to the liver via the hepatic portal vein

75
Q

how are free form fatty acids transported across epithelium

A

via simple diffusion

76
Q

what happens inside epithelial cell to lipids

A

they enter the smooth ER and re-form triglycerides and other lipids. lipids enter golgi apparatus to be packaged into chylomicrons (aka lipoproteins)

77
Q

what happens to chylomicrons

A

they’re secreted by exocytosis into interstitial fluid. chylomicrons enter the lymphatic system via lacteals

78
Q

describe absorption of fat-soluble vitamins and name them

A

vitamins A, D, E and K are fat soluble and are absorbed with lipids. they dissolve in lipid droplets, micelles, and chylomicrons.

79
Q

describe absorption of water-soluble vitamins

A

they require special transport proteins

80
Q

describe absorption of vitamin B12

A

absorbed only if bound to intrinsic factor

81
Q

describe absorption of sodium

A

solvent drag with water reabsorption, actively absorbed in jejunum, ileum, and colon

82
Q

describe chloride absorption

A

passively follows sodium absorption

83
Q

describe potassium absorption

A

passively absorbed, secreted when luminal concentrations are very low

84
Q

describe absorption of calcium

A

actively absorbed in duodenum and jejunum. binds to brush border protein (calcium-binding protein) and transported into epithelial cells. transported out of cells across basolateral membrane via Ca pump. 1,25-(OH)2D3 increases calcium absorption by increasing concentration of calcium-binding protein

85
Q

describe absorption of iron

A

transferrin is secreted by enterocytes into the lumen of the small intestine. transferrin binds iron. the transferrin-iron complex binds to receptor, and is taken into cells by receptor-mediated endocytosis. some iron is stored in enterocytes as ferritin. some iron is transported into blood: bound to transferrin

86
Q

describe absorption and secretion of bicarbonate in both jejunum and the ileum and colon

A

in jejunum bicarbonate ions are passively absorbed. in the ileum and colon bicarbonate ions are secreted in exchange for chloride ions

87
Q

describe absorption of water

A

7 liters of water/day is secreted in GI tract and 2 liters/day is taken in. water absorption is passive and follows absorption of solutes by osmosis

88
Q

describe GI regulation

A

it’s not based on concept of homeostasis. GI function is regulated to maximize absorption, regardless of whether nutrients are needed. conditions in the lumen of GI tract are regulated to maximize absorption

89
Q

describe neural control of GI

A

the enteric nervous system (ENS) consists of submucosal plexus, myenteric plexus, and reflexes mediated through ENS control many GI functions. the CNS contributes generally through communication of ANS with enteric nervous system

90
Q

describe endocrine control of GI

A

GI hormones are secreted from endocrine cells in stomach and small intestine. sensory receptors in GI tract detect the environment in the lumen to initiate relflexes

91
Q

describe gastrin site, stimuli, and action

A

secreted in stomach. activated by proteins and protein digestion products in stomach, distension of somach; parasympathetic input to stomach. its action stimulates gastric secretion and motility; stimulates ileal motility and relaxes ileocecal sphincter which stimulates mass movement of colon

92
Q

describe cholecystokinin (CCK) site, stimuli, and action

A

secreted in duodenum and jejunum, activated by fat or protein digestion products in duodenum. it inhibits gastric secretion and motility by potentiating actions of secretin on pancreatic bicarbonate secretion, stimulates pancreatic enzyme secretion, stimulates bile secretion by liver, and stimulates gallbladder contraction and relaxation of sphincter of oddi

93
Q

describe secretin site, stimuli, and action

A

secreted by duodenum and jejunum, activated by acid in duodenum, it inhibits gastric secretion and motility, stimulates pancreatic bicarbonate secretion, potentiates actions of CCK on pancreatic enzyme secretion, and stimulates bile secretion by liver

94
Q

describe glucose-dependent insulinotropic peptide (GIP) secretion site, stimuli, and action

A

secreted by duodenum and jujenum, activated by glucose, fats, or acid in duodenum or distension of duodenum. it inhibits gastric secretion and motility, stimulates insulin secretion by pancreas

95
Q

describe the steps of a short reflex pathway

A

stimulus in lumen - GI receptors - intrinsic nerve plexus (ENS) - effector organ in GI tract

96
Q

describe the steps of a long reflex pathway

A

stimulus in lumen - GI receptors - central nervous system - intrinsic nerve plexus (ENS) - effector organ in GI tract

97
Q

describe phases of GI control

A

cephalic phase are stimuli that originate in head: thoughts, taste, and smell. requires input from CNS. gastric phase stimuli originate in stomach: long and short reflexes and GI hormones. intestinal phase stimuli originate in small intestine: long and short reflexes and GI hormones

98
Q

how does hypothalamus regulate feeding behavior

A

it is satiety center: the hunger (or feeding) center

99
Q

describe satiety signal to hypothalamus

A

reduce sensation of hunger, reduce food intake, increase energy expenditure (stimulation of sympathetic activity), increase cell metabolism

100
Q

describe orexigenic signals to hypothalamus

A

stimulate hunger, induce feeding behavior, increase parasympathetic activity, decrease metabolism

101
Q

describe leptin

A

a hormone synthesized by adipose cells and released in proportion to amount of adipose tissue in body. it is released when calories intake exceeds body demands. leptin supresses hunger, decreases food intake, and increases metabolism it is the satiety signal.

102
Q

how does leptin act on hypothalamus

A

leptin acting on hypothalamus initiates multiple pathways: stimulates aMSH and CARt, these both increase sympathetic activity and stimulate release of TSH and ACTH, both TSH and ACTH increase metabolic rate and reduce fat storage

103
Q

what does a congenital deficiency in leptin lead to

A

hyperphagia and severe obesity

104
Q

name 3 short term satiety factors

A

insulin, CCK, and neural input from mechano and chemoreceptors

105
Q

name 1 short term orexigenic factor

A

ghrelin is a hormone released by the empty stomach

106
Q

describe the pathway of saliva secretion

A

taste, smell and texture of food - mechanoreceptors and taste receptors in mouth as well as olfactory receptors - salivary center of medulla - autonomic nervous system - stimulate salivation

107
Q

describe autonomic input to salivary glands

A

parasympathetic leads to large amount of watery saliva. sympathetic input leads to more mucus, thick viscous saliva, and only a small amount

108
Q

describe gastric acid secretion

A

parietal cells secrete HCl, carbonic anhydrase catalyzes production of bicarbonate and H+, H+ are actively secreted into lumen of stomach, bicarbonate is transported into interstitial fluid for Cl-, Cl- diffuses into lumen of stomach through channels

109
Q

what is the net result of acid production

A

H+ and Cl- are secreted into lumen of stomach, and bicarbonate enters the interstitial fluid and then blood

110
Q

how is acid secretion stimulated

A

parasympathetic activity, gastrin, and histamine (paracrine)

111
Q

how is pepsinogen secretion regulated in sync with acid secretion

A

parasympathetic nervous system, gastrin, and histamine

112
Q

describe cephalic-phase regulation of secretion

A

stimuli that increase acid and pepsinogen secretion: sight of food, taste, smell, chewing, and swallowing. all of these activate parasympathetic nervous system and this stimulates gastrin secretion

113
Q

describe gastric-phase regulation of secretion

A

proteins, peptides, and amino acids as well as distension of stomach stimulate gastric secretion. short and long reflex pathways trigger gastrin, acid, and pepsinogen release

114
Q

describe inhibition of secretion in gastric phase

A

exit of food removes stimuli for secretion. increased acidity inhibits gastrin release

115
Q

describe inhibition of secretion in intestinal phase

A

this is feedback regulation. the effects of food entry into duodenum leads to increased: osmolarity, fat and acid, and increased distension. long and short reflex pathways inhibit acid and pepsinogen secretion in the stomach

116
Q

describe secretion of pancreatic juice

A

acinar cells makes a small volume of primary secretion and contains water, electrolytes, and digestive enzymes. duct cells are large volume bicarbonate-rich secretion

117
Q

how are pancreatic enzyme and bicarbonate secretion regulated

A

independently. composition of pancreatic juice varies based on lumenal contents

118
Q

describe CCK effect on regulation

A

stimulates acinar cell to secrete enzymes (small stimulant for bicarbonate release, CCK potentiates secretin effects on bicarbonate release)

119
Q

describe secretin effect on regulation

A

secretin stimulates duct cells to secrete bicarbonate (small stimulate for enzymes release, secretin potentiates CCK effects on enzymes release)

120
Q

describe daily fluid flow in GI system

A

9000 mL entering lumen daily and 8900 mL leaving lumen daily. so 100mL of fluid is excreted in feces

121
Q

describe GI motility

A

this is the movement of the wall of the GI tract. due primarily to contractions of the muscularis externa (outer muscle layers) the function is to mix and propel

122
Q

describe electrical activity in GI smooth muscle

A

spontaneous slow waves of depolarization are called slow waves. regular, constant frequency of waves = basic electric rhythm. BER varies in areas of GI. amplitude of BER affected by neural and hormonal input

123
Q

describe parasympathetic and sympathetic effects on BER

A

parasympathetic excites and leads to increased contractile force while sympathetic inhibits which leads to decreased contractile force

124
Q

describe relationship between electrical and mechanical activity in stomach smooth muscle

A

action potentials are not required for contractions. larger depolarizations of slow waves leads to stronger contractions. action potentials lead to even stronger contractions

125
Q

describe relationship between electrical and mechanical activity in intestinal smooth muscle

A

actions potentials are required for contractions. strength of contraction varies with frequency of action potentials

126
Q

what are peristalsis and segmentation

A

peristalsis propels contents forward while segmentation mixes the contents

127
Q

describe peristalsis

A

requires circular and longitudinal muscle contractions. in proximal segment: circular muscle contracts; longitudinal relaxes and diameter increases. in distal segment: circular relaxes; longitudinal contracts diameter increases. contents are propelled forward from small diameter to large

128
Q

describe segmentation

A

a type of motility of small intestine that requires circular muscle layer. alternation contractions between intestinal segments mixes chime with digestive juices and exposes it to mucosal lining

129
Q

describe chewing and swallowing

A

control is both voluntary and involuntary. chewed food + saliva = bolus. tongue moves bolus to pharynx, this initiates swallowing reflex. integration center = swallowing center of medulla oblongata

130
Q

describe swallowing reflex

A

bolus is pushed by tongue into pharynx, pressing on epiglottis. epiglottis cover glottis so food doesn’t enter trachea. larynx is pulled superiorly and anteriorly. glottis closes, breathing inhibited temporarily. upper esophageal sphincter relaxes, bolus enters esophagus, sphincter closes behind bolus. bolus stretches esophagus which triggers peristalsis which propels bolus to stomach. travel time is around 9 seconds

131
Q

describe bolus after arriving at stomach

A

bolus arrives at stomach triggering relaxation of lower esophageal sphincter. bolus enters stomach. if necessary, additional peristalsis waves comes to move bolus into stomach

132
Q

describe receptive relaxation of stomach

A

swallowing center also initiates relaxation of stomach smooth muscle as it prepares for receipt of bolus

133
Q

how is gastric motility coordinated

A

by the enteric nervous system

134
Q

describe gastric motility patterns

A

waves of peristalsis: upper body –> pylorus. they strengthen as they approach the pylorus. functions in mixing of chyme: pyloric sphincter closed. functions in gastric emptying: stronger contractions open pyloric sphincter volume of chyme in stomach and strength of gastric peristalsis govern the emptying rate

135
Q

describe migrating motility complex

A

wave of intense contractions. travel short distances. occur between meals to clear the stomach

136
Q

describe regulation of gastric motility (both increase force and decrease force)

A

gastrin increasing contraction force while CCK, secretin, and GIP decrease force of contraction

137
Q

describe excitation and inhibition of cephalic phase

A

anger and aggression excites while pain, fear, and depression inhibits

138
Q

where is vomiting mediated

A

through vomiting center in medulla

139
Q

describe the vomiting reflex

A

abs contract and puts pressure on stomach contents. reverse peristalsis in stomach and small intestine. lower esophageal relaxes. epiglottis closes and contents come up and out

140
Q

describe intestino-intestinal reflex

A

injury or severe stress inhibits intestinal contractions

141
Q

describe ileogastric reflex

A

destinsion of ileum inhibits gastric motility

142
Q

describe gastroileal reflex

A

presence of chyme in stomach increases motility in ileum

143
Q

describe haustrations

A

takes place in proximal colon. it is like segmentation but slower

144
Q

describe mass movement

A

propels bolus toward rectum. similar to peristalsis and contraction lasts longer than relaxation

145
Q

describe colonocolinic reflex

A

distension of colon in one area causes relaxation of other areas.

146
Q

describe gastrocolic reflex

A

food in stomach increases colonic motility

147
Q

describe process of defecation

A

voluntary and involuntary control of colon distension - stretch receptors - rectum smooth muscle contracts - increase pressure in rectum - internal anal sphincter relaxes while external contracts - both sphincters relax - defecation

Physio (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions