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Name the four layers of the digestive tract in order fromdeepest to
most superficial?
muscosa, submucosa, muscalaris, serosa
(unlikely to be a specific question on the mucosa on the final)
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Which is true of the submucosa?
a. has large blood vessels and lymphatic vessels
b. is the innermost lining of the digestive tract
c. a layer of dense, irregular connective tissue
d. secretes buffers and enzymes from exocrine glands
(more than one answer may be right. choose all that apply)
- a. has large blood vessels and lymphatic vessels
- c. a layer of dense, irregular connective tissue
- d. secretes buffers and enzymes from exocrine glands
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Fill in the blank:
The muscalaris is dominated by _________ (type of cell)
and has ______ (#) layer(s).
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The function of the muscalris is __________.
the movement and mecanical processing of food in the digestive tract
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The serosa is the _____ layer of the digestive tract except
in the ___________ (short list).
outermost layer
does not cover the oral cavity, pharynx, esophagus, and rectum (very beginning and end of the digestive tract - parts closest to outside world)
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What are the three phases of gastric activity?
cephalic, gastric, and intestinal phases
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What starts the gastric phase?
the arrival of food in the stomach
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What changes (cause by the arrival of food in the stomach) start the activities of the gastric phase?
- changes in ph (chemoreceptors)
- distention (strech receptors)
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In the gastric phase, what do _______ release?
mucous cells
chief cells
parietal cells
G cells
- mucous --> mucus
- chief --> pepsinogen
- parietal --> HCl
- G --> gastrin
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What does gastrin do?
- increases gastric motility
- stimulates parietal and chief cells (increasing gastric acid and enzyme production)
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What does secretin do?
- stimulates release of bicarbonate from the pancreas
- (the bicarbonate lowers the pH of chyme in the duodenum)
stimulates release of lipase
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What does CCK (cholesystokinin) do?
- releases pancreatic enzymes
- stimulates release of bile
- stimulates release of trypsin
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The enteric nervous system coordinates the movement of the_________.
muscalaris
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What does the pancreas secrete?
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What does bicarbonate do?
lowers the pH of chyme in the duodenum
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Bile is made where and stored where?
What is its function?
- Made in the liver
- Stored in the gall bladder
- Function: emulsification of lipids (to increase surface area for digestive enzymes)
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Functions of Digestive Enzymes:
amylase
amylase - breaks down starches
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Functions of Digestive Enzymes:
trypsin
trypsin - activates the proteases to break down protein
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Functions of Digestive Enzymes
pepsin
pepsin - secreted from the stomach and breaks down proteins
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Functions of Digestive Enzymes
enterokinase
enterokinase - activates trypsin
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Capillaries absorb _____ and ______ directly into the blood.
carbs and proteins
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After carbs and proteins are absorbed into the blood in the capillaries, where do they ultimately end up and what path do they take to get there?
Digestive system --> blood in capillaries --> mesenteric veins --> hepatic portal vein --> liver
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What are chylomicrons and what do they do?
- protein-lipid package
- carry fat and fat soluble vitamins (A, D, E, K)
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What are lacteals and what do they do?
Lacteals are small offshoots of the lymph system (like capillaries) in the villi of the digestive tract. They absorb things that cannot go into the capillaries (such as chylomicrons) and carry them through the thoracic duct to the left subclavian vein (bring them into the venous system).
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