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Physiology Flashcards

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1
Q

What are the layers of the GI wall?

A

Mucosa
Submucosa
Circular & longitudinal smooth muscle
Serosa

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2
Q

What is part of the mucosa?

A

Layer of epithelial cells specialized for absorption and secretion
Highly vascularized
Innermost layer

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3
Q

What is the submucosa consist of?

A

Consists of collagen, elastin, glands, and blood vessels

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4
Q

What is the circular and longitudinal smooth muscle for?

A

Motility for GI tract

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5
Q

Functions of the Mouth

A 
Mostly mechanical digestion
Mastication
Food is broken down into small particles
Chemically digested
Bolus
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6
Q

Enzymes of the Mouth

A

Lingual amylase: carbs

Lingual lipase: lipids

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7
Q

What does lipase require to function appropriately?

A

Co-lipase

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8
Q

How many muscles and CN are used for swallowing?

A

26 muscles

5 CN

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9
Q

What CN are used for swallowing?

A 
5
7
9
10
12
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10
Q

Esophageal Stage of Swallowing

A

Begins with crico-pharyngeal relaxation

Involuntary

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11
Q

What salivary gland matches up with Stenson’s duct?

A

Parotid gland

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12
Q

What salivary glands match up with Wharton’s ducts?

A

Submandibular glands

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13
Q

What salivary glands match up with the sublingual ducts?

A

Sublingual glands

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14
Q

How much saliva does the salivary glands produce a day?

A

1 liter

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15
Q

Functions of Saliva

A

Initial digestion of starches & lipids by salivary enzymes
Dilution & buffering of ingested foods
Lubrication of ingested food to aid its movement

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16
Q

Secretions Produced By:

A

Salivary glands
Gastric mucosal cells
Pancreatic exocrine cells
Liver

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17
Q

Functions of the Stomach

A 
Short-term storage
Absorption
Digestion
Secretion
Chemical/enzymatic digestion
Liquefaction of food
Release slowly into sm. intestine
Pepsin & peptidase to break down proteins
Good environment for enzymes to work in
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18
Q

Functions of the Small Intestine

A

Absorption of nutrients

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19
Q

Function of the Large Intestine

A

Absorption of water

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20
Q

What does gastric juice convert food to?

A

Semiliquid called chyme

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21
Q

4 Parts of the Stomach

A

Cardia
Fundus
Body
Pylorus

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22
Q

What are the 3 phases of digestion?

A

Cephalic phase
Gastric phase
Intestinal phase

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23
Q

Parts of the brain that are part of the cephalic phase

A

Cortex
Amygdala
Hypothalmus
Vagus nerve

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24
Q

Important Hormones of the Gastric Phase

A

HCl

Pepsin

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25
Define Enterogastrone
hormones in the GI tract as a group
26
Define Intestinal Phase
Enterogastrone hormones secreted in the duodenum & the lower GI tract
27
What does stimulation of the vagal nerve fibers cause release of?
Pancreatic juice and weak contractions of the gallbladder
28
What is released during the gastric phase of digestion?
Cholecystokinin into the blood stream
29
What happens when cholecystokinin reaches the pancreas?
Induces secretion of enzyme-rich pancreatic juice
30
What does secretin cause?
Copious secretion of bicarbonate-rich pancreatic juice
31
Gastric mucosal cells secrete what types of gastric juice?
HCl: protein digestion Pepsinogen: protein digestion Intrinsic factor: absorption of vit. B12
32
Cell Types of Gastric Mucosa in the Body of the Stomach
Parietal cells | Chief cells
33
What does parietal cells secrete?
HCl | Intrinsic factor
34
What do chief cells secrete?
Pepsinogen
35
Cell Types of Gastric Mucosa in the Antrum of the Stomach
G-cells | Mucous neck cells
36
What do G-cells secrete?
Gastrin
37
What does mucous neck cells secrete?
Mucus HCO3 Pepsinogen
38
What stimuli releases gastrin?
Proteins Distention of the stomach Vagal stimulation
39
When is gastrin-releasing peptide released?
Vagal stimulation of the G cells
40
What does Gastrin promote?
H secretion by gastric parietal cells
41
What does gastrin stimulate?
Growth of gastric mucosa
42
Other Functions of Gastrin Hormone
Pepsinogen release Increase stomach motility Relax pylori sphincter Contract LES
43
How does ACh regulate HCL secretion?
ACh released from vagus nerve Binds receptors on parietal cells Produces H secretion by parietal cells
44
What blocks muscarinic receptors on parietal cells?
Atropine
45
How does histamine regulate HCl secretion?
Released from mast like cells in gastric mucosa Binds to H2 receptors on parietal cells Produces H secretion by parietal cells
46
What blocks H2 receptors?
Cimetidine
47
How does gastrin regulate HCl secretion?
Released into circulation by G cells of stomach antrum Binds to receptors on parietal cells Stimulates H+ secretion
48
Define Segmentation Contractions
Circular muscle contracts sending chyme in both directions | Intestine then relaxes allowing chyme to merge back together
49
Define Peristaltic Contractions
Longitudinal muscle contracts propelling chyme along small intestine
50
How do varies occur?
Obstruction of the liver
51
When does a Mallory-Weise tear occur?
Frequent retching
52
What enzymes are released by the salivary glands?
Amylase | Lipase
53
What enzymes are released by the stomach?
Pepsin | Lipase
54
What enzymes are released by the pancreas?
``` Amylase Lipase & co-lipase Phospholipase Trypsin Chymotrypsin ```
55
What enzymes are released by the intestines?
Enterokinase Disaccharidases Peptidases
56
What does trypsin & chymotrypsin target?
Peptides
57
What does enterokinase activate?
Trypsin
58
What innervates the GI tract?
Autonomic nervous system
59
Parts of the Autonomic Nervous System
Extrinsic | Intrinsic
60
What does the extrinsic autonomic nervous system encompass?
Sympathetic | Parasympathetic
61
What does the intrinsic part of the autonomic nervous system do?
Communicates with the extrinsic component
62
What does the enteric nervous system do?
Myenteric plexus | Meissner's plexus
63
Where does the parasympathetic nerve supply come from?
Vagus nerve
64
Where does the sympathetic nerve supply come from?
Cervical & thoracic sympathetic chain
65
What does the parasympathetic nervous system do for the GI tract?
Motor innervation to the esophageal muscular coat and secretomotor innervation to the glands
66
What does the sympathetic nervous system do for the GI tract?
Regulates blood vessel constriction, esophageal sphincters contractions, relaxation of the muscular wall, and increases in glandular and peristaltic activity
67
What is a special function of the intrinsic innervations?
Can direct all functions of GI in absence of extrinsic innervation
68
What does intrinsic innervation control?
Contractile, secretory, and endocrine functions of the GI tract
69
Where does the intrinsic part of the ANS receive input from?
Parasympathetic & sympathetic nervous systems | Mechanoreceptors & chemoreceptors in the mucosa
70
Where does the intrinsic ANS send information to?
Smooth muscle, secretory, and endocrine cells
71
4 Functionally Different Cell Types that Compose Glands
Mucous cells Chief cells Parietal cells Enteroendocrine cell
72
What activity does gastrin have on the stomach?
Causes gastric glands to increase secretory activity | Stimulates gastric emptying
73
What activity does gastrin have on the small intestine?
Stimulates contraction of intestinal muscle
74
What activity does gastrin have on the ileocecal valve?
Relaxes ileocecal valve
75
What activity does gastrin have on the large intestine?
Stimulates mass movements
76
What activity does serotonin have on the stomach?
Causes contraction of the stomach muscle
77
What activity does histamine have on the stomach?
Activates parietal cells to release HCl
78
What activity does somatostatin have on the stomach?
Inhibits gastric secretion of all products | Inhibits gastric motility and emptying
79
What activity does somatostatin have on the pancreas?
Inhibits secretion
80
What activity does somatostatin have on the small intestine?
Inhibits GI blood flow | Inhibits intestinal absorption
81
What activity does somatostatin have on the gallbladder?
Inhibits contraction and bile release
82
What are the 3 parts of the small intestine?
Duodenum Jejunum Ileum
83
Function of the Small Intestine
Primary site for digestion and absorption of nutrients
84
What ducts empty into the duodenum?
Bile duct | Pancreatic duct
85
Where does the liver receive blood from?
Hepatic portal vein | Hepatic artery
86
What type of vascular resistance occurs in the liver?
Low vascular resistance
87
What happens to the liver circulation when someone has cirrhosis?
Vascular resistance increases | Blood flow decreases
88
Hepatic Functions
``` Carbohydrate metabolism Lipid metabolism Protein metabolism Removal of drugs and hormones Excretion/secretion of bilirubin Synthesis of bile salts Storage of some compounds (glucose) Phagocytosis Aids in synthesis of active vitamin D Urea formation from ammonium ```
89
Carbohydrate metabolism in the liver
Maintaining a normal blood glucose | Storage of glycogen
90
Why do alcohol abusers frequently have hypoglycemia?
Alcohol suppresses citrate cycle and impairs gluconeogenesis from amino acids
91
Why do patients with cirrhosis have hyperglycemia after a carbohydrate rich meal?
``` Liver insufficiency Decrease of glucose utilization Hyperglycemia Hyperinsulemia Down-regulation of insulin receptors Insulin resistence ```
92
Steps in Carbohydrate Breakdown
Disaccharides | Monosaccharides
93
Steps in Protein Breakdown
Peptides | Amino acids
94
Steps in Lipid Breakdown
Diglycerides | Monoglycerides & fatty acids
95
Where does most of our cholesterol come from?
Liver
96
Fat Metabolism in the Liver
Oxidation of fatty acids to supply energy Synthesis of large quantities of cholesterol, phospholipids, and lipoproteins Inactivation of steroids & excretion from the body
97
Disorders of Protein Metabolism
Ammonia detoxification disorder and failure of urea formation Hyperammonemia Hepatic coma
98
Ammonia Detoxification Disorder & Failure of Urea Formation
Ammonia comes from bacterial degradation of nitrogen substances in intestines, from intestinal mucosa during glutamine degradation, from degradation of amino acids in kidneys and muscles
99
Hyperammonemia SE
Mental changes: disorientation, sleeping disorders, chaotic speech, personality changes Motor changes: increased muscle reactivity, hyperreflexia, tremor
100
Types of Hepatic Coma
Endogenous | Exogenous
101
Endogenous Hepatic Coma
Viral hepatitis and poisoning | Hepatic cell disintegration
102
Exogenous Hepatic Coma
Final status of chronic cirrhosis
103
Basics of Bile Secretion
Necessary for digestion and absorption of lipids Mixture of bile salts, bile pigments, and cholesterol Bile salts emulsify lipids
104
Bile Secretion and Recycling
Produced and secreted by liver Stored in gallbladder Ejected into sm. intestine After lipid absorption, bile salts are recirculated to liver Extraction of bile salts from portal blood
105
Formation of Bilirubin
``` Formed from hemoglobin Hemoglobin phagocytosed Iron release bound to transferrin Remainder of heme group covered to biliverdin Biliverdin reduced to bilirubin Bilirubin attached to albumin Secretion of bilirubin into bile ```
106
Processing Bilirubin by Hepatocytes
Albumin removed as unconjugated bilirubin passes through liver Bilirubin conjugated
107
Secretion of Conjugated Bilirubin into Bile
Hepatocytes transport conjugated bilirubin into bile clinical Conjugated bilirubin enters duodenum
108
Role of Small Intestine in Bile Metabolism
Bile & bile salts increase growth of intestinal bacteria Intestinal bacteria metabolize conjugated bile to urobilirubin Urobilirubin reabsorbed into blood
109
What happens to the bile when the duodenal orifice is closed?
Bile is stored and concentrated in the gallbladder
110
How much bile does the liver produce in a day?
500-1000 mL
111
Composition of Bile
``` Water Bile Salts Bile pigment Cholesterol Inorganic salts Fatty acids Lecithin Fat Alkaline phosphatase ```
112
What are the ways people become jaundice?
Too much production of bilirubin Conjugation of bilirubin Obstruction of path to the duodenum
113
Obstructive Jaundice
Bile prevented from flowing out of biliary duct Conjugated bilirubin builds up in biliary duct Conjugated bilirubin is returned to blood Unconjugated bilirubin normal or decreased
114
Formation and Secretion of Bile
``` Detoxification of various substances Synthesis of plasma proteins Coagulation Blood reservoir Immunity Vitamins Relation to blood formation ```
115
Function of the Gallbladder
Blind pouch that stores bile
116
Ducts of the Gallbladder
Hepatic duct Cystic duct Common bile duct
117
What duct joins the common duct?
Pancreatic duct
118
Why is the pancreatic duct pressure greater than the common bile duct pressure?
Reflux of bile into the pancreas will give the patient severe pancreatitis
119
Innervation of the Pancreas
Sympathetic: splanchnic nerves Parasympathetic: vagus
120
Exocrine Glands in the Pancreas
Secrete essential digestive enzymes through pancreatic duct into duodenum
121
Endocrine Gland of the Pancreas
Islets of Langerhans
122
Four Major Cell Types in the Islets of Langerhans
Alpha: glucagon Beta: insulin Delta: somatostatin F cells: pancreatic polypeptide
123
What does the pancreatic polypeptide do?
Secretes insulin and glucagon into the blood stream
124
What do the exocrine pancreas enzymes digest?
Carbohydrates Proteins Fats
125
Major Stimulants of Bicarbonate Secretion
Secretin Cholecystokinin Gastrin Acetylcholine
126
Major Inhibitors of Bicarbonate Secretion
Atropine Somatostatin Pancreatic polypeptide Glucagon
127
Amylase from the Pancreas
Only enzyme to be released in active form | Hydrolyzes starch & glycogen to glucose, maltose, maltotriose, and dextrins
128
Function of Lipase from the Pancreas
Emulsify and hydrolyze fat in the presence of bile salts
129
How much of the islet cell mass must be removed before diabetes will become clinically apparent?
80%
130
Most Important Stimulant of Acinar Cells
CCK
131
Major Stimulant of Ductal Cells
Secretin
132
What is secretin secreted in response to?
H+ in intestine
133
Big Adipose Secretions
Resistin Adiponectin Leptin
134
Where is the pain when posterior ulcers erode?
Back pain
135
Where is the pain when anterior ulcers perforate?
Peritonitis
136
Why is the third portion most vulnerable to traumatic rupture?
It's fixed
137
How do GI peptides regulate functions of the GI tract?
Contraction and relaxation of smooth muscle wall & sphincters Secretion of enzymes for digestion Secretion of fluid & electrolytes Regulate secretion of other GI peptides
138
What activity does intestinal gastrin have on the stomach?
Stimulates gastric glands and motility
139
What activity does secretin have on the stomach?
Inhibits gastric gland secretion and gastric motility during gastric phase of secretion
140
What activity does secretin have on the pancreas?
Increases output of pancreatic juice rich in bicarbonate ions Potentiates CCK's action
141
What activity does secretin have on the liver?
Increases bile output
142
What activity does cholecystokinin (CCK) have on the liver/pancreas?
Potentiates secretin's actions on these organs
143
What activity does cholecystokinin (CCK) have on the pancreas?
Increases output of enzyme-rich pancreatic juice
144
What activity does cholecystokinin (CCK) have on the gallbladder?
Stimulates organ to contract and expel stored bile
145
What activity does cholecystokinin (CCK) have on the hepatopancreatic sphincter of Oddi?
Relaxes sphincter to allow entry of bile and pancreatic juice into duodenum
146
What activity does vasoactive intestinal peptide (VIP) have on the duodenum?
Stimulates buffer secretion | Dilates intestinal capillaries
147
What activity does vasoactive intestinal peptide (VIP) have on the stomach?
Inhibits HCl production
148
What activity does vasoactive intestinal peptide (VIP) have on the small intestine?
Relaxes intestinal smooth muscle
149
What activity does motilin have on the proximal duodenum?
Stimulates migrating motility complex
150
How does digestion occur in the small intestine?
Hydrolysis then absorption
151
Causes of Malabsorption of Nutrients
Anything that interferes with delivery of bile or pancreatic juice Damaged intestinal mucosa Diarrhea
152
Functions of the Small Intestine
Electrolyte absorption | Water absorption
153
Electrolyte Absorption in the Small Intestine
Along whole length Iron & calcium in duodenum Sodium coupled with absorption of glucose & amino acid Ionic iron stored in mucosal cells with ferritin Potassium diffuses with osmotic gradients Calcium absorption is regulated by vitamin D and PTH
154
Water Absorption in the Small Intestine
95% absorbed via osmosis Net osmosis occurs when gradient is created via transport of solutes Water uptake coupled with solute uptake
155
How does the intestinal lining increase absorptive surface area?
Villi | Microvilli
156
Define Villi
Finger-like projections of the mucosa
157
Define Microvilli
Tiny projections on luminal membrane of each intestinal cell
158
When do the final stages of chemical digestion occur?
Just prior to absorption of amino acids, glucose and fatty acids
159
What does carbohydrates have to be broken down to, to be absorbed?
Monosaccharides
160
What does protein have to be broken down to, to be absorbed?
Small peptides | Amino acids
161
What does fat have to be broken down to, to be absorbed?
Monoglycerides | Free fatty acids
162
Path of Absorption of Carbohydrate Digestion
Glucose/galactose co-transport with sodium ions | Fructose via facilitate diffusion
163
Path of Absorption of Protein Digestion
Co-transport with sodium ions
164
Path of Absorptions of Fat Digestion
Diffusion | Combine with proteins (chylomicrons)
165
Path of Absorption of Nucleic Acid Digestion
Active transport via membrane carriers
166
Emptying at the Ileocecal Valve
Fluidity of contents promotes emptying Pressure & chemical irritation relax sphincter and excite peristalsis Pressure or chemical irritation in cecum inhibits peristalsis of ileum and excites sphincter
167
Functions of the Large Intestine
Reabsorb water Compact material into feces Absorb vitamins Store fecal matter
168
Physiology of the Ascending Colon
Processing chyme delivered from the terminal ileum
169
Physiology of the Transverse Colon
Storage and dehydration of feces Primary site for removal of water & electrolytes Storage of feces
170
Physiology of the Descending Colon
Conduit between transverse and sigmoid colon
171
Physiology of the Rectosigmoid Region
Maintains fecal continence
172
Types of Motions of the Colon
Haustrations- mixing movements | Mass movements- propulsive movements
173
Define Haustrations (Mixing Movements)
Ring-like contractions divide colon into pockets
174
When does net forward propulsion occur?
When sequential migration of hausfrau occurs the length of the bowel
175
Define Mass Movements (Propulsive Movements)
Starts in middle of transverse colon and precede by relaxation of the circular muscle and the downstream disappearance of austral contractions
176
What movements are inhibited during massive movements?
Haustral contractions
177
Physiology of the Large Intestine in Regards to Reabsorption
``` Water Vitamins K, biotin, B5 Organic wastes- urobilinogens & sterobilinogens Bile salts Toxins ```
178
Define Crypts
Tubular glands responsible for mucus secretion
179
What happens when crypts are occluded?
Diverticulitis
180
What is the last portion of the digestive tract?
Rectum
181
Where does the rectum terminate?
Anal canal
182
Rectum Function
Storage of feces
183
Define Feces
Particles of waste matter that is left over after the body has processed and absorbed nourishment from foods
184
What does feces contain?
``` Water Dietary fiber Inorganic salts Dead cells Bacteria Anything the body cannot or will not absorb ```
185
What type of sensory receptors does the rectum have?
Pain Temperature Touch
186
What structures maintain fecal continence?
Contraction of internal anal sphincter and puborectalis muscle
187
How does a bowel movement exit the anus?
Rectum fills with feces Contraction of muscles increase intra-abdominal pressure Increases intra-rectal pressure Sphincter relax Feces enter canal Peristaltic waves push feces out Relaxation of internal/external anal sphincters allows feces to exit

GI (20 decks)

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