Gastro Intestinal Physiology Flashcards
(117 cards)
1
Q
Digestion Process Steps
A
- Ingestion
- Propulsion
- Digestion
- Abosorbtion
- Defecation
2
Q
Ingestion
A
- Mastication
- Deglutition
3
Q
Mastication
A
chewing
4
Q
Deglutition
A
swallowing
5
Q
GI PHYSIOLOGY
Propulsion
A
movement of food
6
Q
Digestion
A
breakdown of food by:
1. Mechanical action
2. Chemical processes
7
Q
Digestion
Mechanical Action
A
chewing food into smaller pieces
8
Q
Digestion
Chemical Processes
A
mixing food with acids, enzymes, and emulsifiers to breakdown food
9
Q
Absorbtion
A
passage of nutrients into circulatory and lymphatic systems for distribution throughout the body
10
Q
Defecation
A
elimination of indigestible substances
11
Q
Divisions of the GI system
A
- Alimentary Canal
- accessory Digestive Organs
12
Q
Alimentary Canal
A
tube that winds through the body
mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum
13
Q
Accessory Digestive Organs
A
contribute to the breakdown of food
teeth, tongue, salivary glands, pancreas, liver, gall bladder
14
Q
4 Layers of the Alimentary Canal Wall
A
- Tunica Mucosa
- Tunica Submucosa
- Tunica Muscularis
- Tunica Serosa
Innermost to outermost
15
Q
Alimentary Canal Wall
Sublayers of the Tunica Mucosa
A
- Epithelium lining
- Lamina Propia
- Muscularis Mucosa
innermost to outermost
16
Q
Epithelium Lining of the Tunica Mucosa
A
absorbtion/protection/secretion, mucous production, glands-digestive enzymes
inner layer
stratified squamous or simple columnar
17
Q
Lamina Propia of the Tunica Mucosa
A
immune protection, contains capillaries and lymphatics
middle layer
loose connective tissue
18
Q
Muscularis Mucosa of the Tunica Mucosa
A
folds to increase surface area, local movement of GI epithelium
outer layer
19
Q
Alimentary Canal Wall
Tunica Submucosa
A
highly vascularized, innervated by the ANS, binds tunica mucosa to tunica muscularis, contains meissners plexus
2nd from middle
dense irregular connective tissue,
20
Q
meissners plexus
A
tells glands to secrete, tells muscularis mucosae to contract
21
Q
Alimentary Canal Wall
Tunica Muscularis
A
mechanical digestion, propulsion, contains Auerbach’s Plexus,
3rd from middle
smooth muscle, controlled by ANS
22
Q
Auerbach’s Plexus
A
located between muscle layers, controls GI motility
23
Q
Tunica Serosa
A
fluid secreting membrane, visceral peritioneum on organs, parietal peritoneum lines cavities
outermost layer
simple squamous epithelium
24
Q
Blood Flow of GI system
A
25% of cardiac output, liver recieves blood from hepatic artery and portal veins from organs.
25
Liver Functions
1. Carbohydrate Metabolism (stores glycogen, releases glucose)
2. Lipid Metabolism (manufacture of cholesterol (HMG CoA Reducatse)
3. Protein Synthesis (albumins, fibrinogens, prothrombin)
4. Breakdown of old RBC hemoglobin into bilirubin
5. Bile Production (used for emulsification of fats)
6. Detoxification (chemically alters alcohol, drugs, etc into kidney exretable compounds such as urea, ammonia, uric acid)
26
Portal Triad
portal vein, hepatic artery, bile duct
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portal vein
deoxygenated blood into the liver
28
hepatic artery
oxygenated blood into the liver
29
Hepatic Sinusoids process
1. Kuffler cells break down RBC's
2. Hemoglobin broken down into Iron + Bilirubin
3. Bilirubin binds to Albumin
4. Absorbed by Liver cell
5. Processed into Bile Salts
6. Stored by the Gall Bladder
7. Released by common bile duct
8. bile salts are recirculated multiple times per day in GI tract
30
Jaundice Causes
bile tract blockage, liver failure, hemolysis
31
Nutrient Absorbtion
most enzymes from Pancreas, bile for fat emulsification, from liver
32
Carbohydrate Absorbtion steps
1. broken down by Amylase (pancreas)
2. absorbed in mono and disaccharide form into capillaries
3. absorbtion coupled with Na+ down concentration gradient
4. secondary active transport
5. transport into liver via hepatic portal system
33
Protein Absorbtion steps
1. Broken down by stomach acid, pepsin, trypsin(pancreas)
2. absorbed as AA's and small peptides into capillaries
3. absorbtion coupled with Na+ down concentration gradient
4. Secondary active transport
5. Transport to liver via hepatic portal sytem
34
Fat and Cholesterol Absorbtion
1. Emulsified via action of Bile(liver)
2. broken down into fatty acids or monogylcerides by lipases(pancreas)
3. Lipids absorbed as FFA's and monoglycerides in small intestine
4. conjugated with Apoproteins by mucosal cell form Chylomicron
5. exocytosis via mucosal cells releases Chylomicrons
6. forms lacteals of lymphatic system for transport
7. stored as peripheral fat in the venous system
35
normal cholesterol level
200 mg/dl and below
36
LDL
low density lipoprotein, remains in circulation and promotes plaque formation
| bad cholesterol
37
HDL
high density lipoprotein, promotes storage of cholesterol in the liver
| good cholesterol
38
Ideal LDL level
LDL<130mg/dl
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Ideal HDL level
HDL>45mg/dl
40
At risk cholesterol levels
cholesterol 240mg/dl or above
LDL>160mg/dl
HDL<35mg/dl
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Natural Treatment of High Cholesterol
low fat diet with moderate alcohol
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Cholestyramine
binding resin, forms insoluable bile/fat complexes that are excreted
43
Statins
binds to HMG CoA Reductase, reduce cholesterol synthesis by Liver, decreases LDL's, increases HDL's
## Footnote
Lovastatin(mevacor), Simvastatin(Zocor), Atorvastatin(Lipitor), Pravastatin(Pravachol), Rosuvastatin(Crestor)
44
Ezetimibe(Zetia)
binds to NPC1L1 protein on enterocytes and hepatocytes, mediator of dietary absorbtion,
## Footnote
lower absorbtion rate enhances uptake of LDL by peripheral cells
45
Vytorin
Zocor + Zetia
46
Inputs of Water Balance
1200ml drinking/food
1500ml saliva
2000ml stomach
500ml bile
1500ml pancreas
1500ml small intestine
## Footnote
8200ml total
47
Reabsorbtion in water balance
8500ml small intestine
350ml large intestine
| exrete 150ml in feces
## Footnote
8850ml total
48
Water Absorbtion
water is absorbed until is is isoosmotic with plasma, the max urine flow is 16ml/min
49
Water Intoxication
Water intake above the max urine flow or if too much exogenous ADH is administered, swelling of brain, convulsions, coma, death
## Footnote
max urine flow is 16ml/min
50
Minimum Amount of Water Excreted
600mosm/L/day
51
Kidney Max Urine Concentration of Water
1200 mosm/L/day
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Amount of Water Excreted in Urine
0.5L/day
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Max Kidney Urine Concentration of Seawater
1400 mosm/L
54
# Digestion
Sight and Smell of food
stimulates salivary and gastric secretions
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Chemoreceptors in the Stomach
detects HCl levels
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Mechanoreceptors in the Stomach
detects distension and pressure in the stomach
57
# Neural Control of Digestion
Long Relex Innervation
connects parts of the GI tract together, connects to CNS, stimulated by Vagus nerve, ACh, and Serotonin,
## Footnote
activates Meissners and Auerbachs Plexus, Splanchnic Nerves are inhibitory
58
Splanchnic Nerves
sympathetic fibers that inhibit Long Reflex Innervation
## Footnote
stimulated by NE and E
59
Short Reflex Innervation
mediated through nerves confined to the GI tract, stimulated by chemicals, hormones, and distension
## Footnote
activates endocrine glands and smooth muscles in the tract
60
# Components of GI System
Mouth
Ingestion and digestion, contains salivary glands, buccal glands, parotid glands, submandibular glands, submaxillary glands, and sublignual glands.
## Footnote
entrance of Alimentary Canal, Mucosa lined
61
Salivary Glands
saliva production, contains Compound Acinar Gland
| accessory digestive organs
62
Compound Acinar Gland
makes Amylase for starch digestion, makes Lipase for fat digestion
| serous and mucous
63
Mumps
virus that causes inflammation of the parotid glands
64
Deglutition Steps
1. Medulla Signals Swallowing
2. Trigeminal, Glossopharyngeal, Vagus, and Hypoglossal Innervate
3. Mouth Closes
4. Tongue pushes food back
5. Contraction of Pharynx
6. Inhibition of respiration (Larynx raises, epiglottis closes)
7. Upper Esophageal Sphincter Relaxes
8. Peristaltic Wave initiated
9. Lower esophageal sphincter relaxes
10. Second painful Peristaltic wave if unsuccessful
## Footnote
Liquids via gravity
65
Stomach
widest part of Alimentary Canal, distentable/contractable, produces enzymes and acids
## Footnote
food storage, mechanical and chemical digestion
66
Cardiac Sphincter
sphincter at the upper end of the stomach
67
Heartburn
reflux of acid at the cardiac sphincter
68
Mucosa
protects from acids, secretes mucous, acids, and enzymes, absorbes water, alcohol, and drugs
## Footnote
has folds called Rugar, made from Simple Columnar Epithelium
69
Gastric Pits
contains stomach glands which produce Chyme, contains specialized cells
70
# Gastric Pit Cells
Mucous Neck Cells
produce mucous for protection
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# Gastric Pit Cells
Parietal Cells
produce HCl, absorb Vitamin B12
72
Pernicous Anemia
insufficient RBC production due to Vitamin B12 deficiencies
## Footnote
can be caused due to issues with Parietal Cells
73
# Gastric Pit Cells
Chief Cells
secretes Pepsinogen with acid to activate Pepsin, acts in protein digestion
## Footnote
these cells can be digested by the enzymes they secrete (autolyse)
74
# Gastric Pit Cells
G Cells or "APUD"
activated by food in the stomach and releases Gastrin into the blood causing increased Parietal Cell acid secretion and increased GI motility
## Footnote
when activated they speed up digestion
75
# Gastric Pit Cells
Enterochromaffin Cells
produce histamine, acid secretion stimulator
76
# Gastric Pit Cells
D Cells
produces somatostatin, acid secretion inhibitor
77
Tunica Muscularis Layers
1. Inner Oblique
2. Middle Circular
3. Outer Longitudinal
## Footnote
Innermost to Outermost
78
Pyloric Sphincter
controls the emptying of the stomach into the duodenum
79
Acid Production in the Stomach
1. H+ is exchanged with K+ and moves into the gastric lumen
2. HCO3- is exchanged with Cl-
3. cAMP activates protein kinase which drives the pump
4. ACh and Gastrin both increase Ca++ and also stimulate protein kinases
5. Histamine will activate cAMP
6. PGE2 will deactivate cAMP
## Footnote
HCl moved into gastic lumen and HCO3- is moved into the blood
80
Stomach Acid Inhibitors
1. ACh antagonists (Atropine)
2. Histamine blockers
3. Gastrin Blockers
81
Omeprazole
blocks H+/K+ ATPase pump
82
Acidity and Gastrin
high acidity in the stomach inhibits gastrin release and slows down the movement of HCl into the stomach
83
# Acid Production
high protein meals
high protein meals buffer acidity and stimulate acid production
84
# Acid Production
Empty Stomach
An empty stomach is high in acidity and inhibits Gastrin release
85
Ulcers
caused from a hyper secretion of acid or a lack of mucous protection, lesser curvature, pyloris, and duodenum are the most vulnerable,
## Footnote
usually caused by bacteria
86
Ulcer Treatments
H2 blockers, Omeprazole, Vagotomy(removal of part of the vagus nerve)
87
Vomiting Process
1. Irritation trigger vomiting center in the brain
2. Saliva Secretions Stimulated
3. Squeezing of the stomach beginning with the diaphragm and abdominal muscles (increased pressure)
4. Sphincters open
## Footnote
excessive vomiting can cause alkalosis due to vomiting out acids which would cause more acid to move into the stomach and more base to move into the blood
88
Small Intestine
longest portion of the Alimentary Canal, basic pH
89
Small Intestine Functions
1. Enzymatic Digestion (enzymes from pancreas)
2. Emulsification of Fats (via bile from the liver)
3. Absorbtion of Nutrients (capillaries and lacteals)
4. Secretion of Hormones
90
Main Parts of the Small Intestine
1. Duodenum
2. Jejunum
3. Ileum
91
Cell Types of the Small Intestine
1. Absorbative
2. Goblet (mucous)
3. Enteroendocrine (hormones)
4. Paneth (antibacterial enzymes)
92
# Small Intestine
Tunica Mucosa
different from usual as it has a greater surface area due to three modifications
93
# Small Intestine
Tunica Mucosa Modifications
1. Simple Columnar Epithelium with Microvilli
2. Arranged in Villi (contain artery, capillary, and vein)
3. Plica Sircularis (folds of mucosa and submucosa, where Enteroendocrine and Paneth cells are located)
94
Small Intestine Hormones
1. GIP-Gastric Inhibitory Peptide
2. CCK-PZ Cholecystokinin-Pancreozymin
3. Secretin
4. Motilin
5. VIP
## Footnote
produced by Enteroendocrine cells
95
# Small Intestine Hormones
GIP-Gastrin Inhibitory Peptide
released from duodenal filling or inceased acid in duodenum, inhibits GI motility and acid production,
## Footnote
increases time for absorbtion
96
# Small Intestine Hormones
CCK-PZ Cholecystokinin-Pancreozymin
released from duodenal filling, increased acid, increased protein, or increased fat in the duodenum, inhibits GI motility, stimulated Gall Bladder Contraction, stimulates Pancreatic secretion(digestive enzymes)
## Footnote
gall bladder releases bile for fat emulsification and pancreas releases enzymes for protein digestion
97
# Small Intestine Hormones
Secretin
released due to acid in duodenum, stimulates HCO3- release from Pancreas,
## Footnote
makes intestine basic which shuts down its secretion
98
# Small Intestine Hormones
Motilin
responsible for MMC(migrating motor complex), emptys stomach
99
Migrating Motor Compex (MMC)
peristaltic wave from esophagus to small intestine
## Footnote
during the interdigestive period, emptys stomach
100
# Small Intestine Hormones
VIP
decreases smooth muscle motility, dilation for peripheral vessels, inhibits acid secretion
101
# Small Intestine
Segmentation
mixing of Chyme and Enzymes, brings digested nutrients into contact with villi and microvilli for absorbtion
## Footnote
controlled by ANS(Auerbach's Plexus) and hormones
102
# Small Intestine
Peristalsis
propulsion of chyme along the small intestine, pumping up and down of villi and microvilli by Mucous Mucosa
## Footnote
controlled by ANS(Auerbach's Plexus) and hormones, Meissners Plexus
103
# Pancreas
Exocrine Functions
secretion into a duct of digestive enzymes and alkaline juice
104
Acinar Cells
produce Pancreatic Juice and digestive enzymes secreted into Pancreatic duct and moved into the Small Intestine
105
Alkaline Juice
neutralizes stomach chyme, HCO3- secretion in lumen, H+/Na+ exchange, Na+ secretion in lumen
106
Enzymatic Digestion Enzymes
Amylase, Trypsin, Lipase
## Footnote
the pancreas can digest all portions of a meal
107
# Pancreas
Endocrine Function
hormonal regulation of blood sugar with insulin and glucagon hormones
108
Large Intestine Functions
1. Abosrbtion of water and electrolytes
2. Vitamin production, K and B
3. Expulsion of Feces by mass peristalsis movements
109
Parts of the Large Intestine
1. Cecum
2. Colon (ascending, transverse, descending, sigmoid)
3. Rectum
## Footnote
First to Last
110
# Large Intestine
Tunica Muscosa Tissue Makeup
simple columnar but statified squamous at rectum
111
# Large Intestine
Tunica Muscularis Structure
contains Taenia Coli and Haustra
112
Taenia Coli
rope-like thickening of longitudinal muscle
113
Haustra
puckered pouches that form as a result of distension of one haustra, causes propulsion of contents into next haustra
114
Diverticulitis
diet lacks bulk causing outward herniation of Haustra wall
## Footnote
can become infection
115
Hirschsprung's Disease
constriction of large intestine wall (aganglionic megacolon)
## Footnote
feces backs up
116
Hemmorroids
varicose veins in anal canal, itching throbing, bleeding
## Footnote
destroyed by burning, cutting, or rubber banding
117
