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ANS 415 CH 1
Terms in this set (55)
What are the 3 main types of digestive system?
3. hindgut fermenters
What are the functions of the GI tract?
1. Intake of feed
How does digestion occur?
1. Mechanical forces
2. Chemical Action
3. Enzymatic activity
What are the gastro-intestinal organs?
Small Intestine (SI)
Large Intestine (LI)
What are the functions of the mouth?
1. Receiving food
3. Saliva secretion
What enzyme is present in the mouth and what is it's purpose?
α-amylase; initiate starch digestion
What are the three main glands for saliva secretion?
What is the function of saliva in non-ruminants?
Initiate starch digestion
Protection of membranes in mouth
What are used to affect taste, smell and texture of pet foods to increase their desirability to animals?
Palatability enhancer products
What is the esophagus?
Hollow muscular tube that transport ingested feed from the mouth to stomach. There is a valve at the end of the esophagus to prevent digests from moving back up. Food can only go down.
What are the 4 regions of the mongastric stomach?
1. Esophageal region
2. Cardiac gland region
3. Fundic gland region
4. Pyloric gland region
What is the valve at the end of the stomach called?
Describe the esophageal region.
- Extension of esophagus
- non-glandular area
- some microbial activity
- some α-amylase activity (if any is left over from mouth)
What happens in the cardiac gland region?
Describe the fundic gland region.
has 2-types of cells
- parietal cells → secret HCL
- chief cells → secrete enzymes
Describe the pyloric gland region.
- mucus secretion
- Gastrin hormone
- control the flow of chyme to small intestine
What is secreted in the stomach?
Why is hydrochloric acid needed in the stomach?
It lowers the pH to 1-3. This denatures dietary protein and activates the digestive enzyme (pepsin).
What two enzymes are secreted in the stomach?
Pepsinogen and rennin
it is secreted by chief cells in the fundric area and is the precursor for pepsin.
- Produced by cells in fundic area in young mammals
- Proteolytic enzyme (coagulate milk; separate solids from liquid)
What is the function of gastrin?
It stimulates HCL and pepsinogen production and stomach motility. Entry of feed stimulates gastrin release
Describe the mucus released in the stomach.
It is produced in the cardiac and pyloric regions. Its function is to protect stomach lining cells and act as a lubricant. A malfunction could lead to an ulcer.
T/F: Absorption occurs in the stomach.
What are the functions of the stomach?
1. Storage and mixing of feed
2. Regulate the flow of ingested feed to small intestine (SI)
3. Feed digestion
What are the functions of the liver when it comes to digestion?
Storage of CHO (glycogen) and vitamins
Synthesis of glucose (regulate blood glucose)
Metabolism of amino acids, fatty acids and sugars
What is the production path of bile?
Made in the liver, stored in gallbladder, and released into duodenum (SI) via bile duct.
What is the function of bile?
facilitate lipid digestion and absorption in the small intestine (SI).
What are the functions of the pancreas?
- Secretion of enzymes involved in digestion in the SI
- Bicarbonate production (buffer)
- Hormones production
What enzymes are secreted by the pancreas? What are they used for?
(a-d involved in protein digestion)
amylase (starch digestion)
lipase (lipid digestion)
What is the production pathway of pancreatic enzymes?
made in pancreas → released into duodenum (SI) through pancreatic duct.
What is the bicarbonate buffer and why is it important?
It is made in pancreas and released into duodenum (SI) to neutralize the pH. Digestive enzymes in duodenum require pH > 6.5 to function.
What is secretin?
It stimulates pancreatic bicarbonate release and is released when chyme (pH 2-3) enters duodenum.
What are the hormones produced my the pancreas and what are their functions?
Insulin and glucagon regulate blood glucose level.
When blood glucose is high, insulin is released and more is absorbed by tissues.
When blood glucose is low, glucagon is released and more glycogen is broken down and more glucose is synthesized.
Describe the small intestine.
it's between the stomach and LI. The surface is folded and wall lined with villi and microvillie to increase surface area for absorption (~ 600X)
What are the functions of the SI.
1. Digestion of organic nutrients (most CHO, protein & lipids digestion occur here.)
2. Absorption (most amino acids, fatty acids and sugars absorption occur here)
What are the three parts of he SI?
Describe the duodenum.
- First part of SI
- Shortest (9.9 inch in length)
- Active site for digestion (majority occurs here)
- pH = 6 -7
What does the duodenum secrete?
Describe the alkaline mucus.
Comes from the Brunner glands. It neutralizes duodenum content and acts as a lubricant to protect duodenal wall.
What enzymes are released in the duodenum? What are they used for?
a-c help in CHO digestion
d-e help in protein digestion
f. Intestinal lipase (help in lipid digestion)
Where does most of the absorption of amino acids, sugars, and vitamins occur?
Where does most of the absorption of FA and bile salts occur?
Describe passive absorption.
High concentration to low concentration across membrane pores. Exs: water, CO2, O2, minerals.
Describe facilitated diffusion.
Move from high concentrations to low, but requires a carrier. It does not require energy. Exs: fructose, vit B-6
Describe active absorption.
Move against concentrations and requires energy and specific protein carriers. Exs: Glucose, amino acids, FA, K, Mg, B-1, B-2,vit A, C
What are the 3 sections of the large intestine?
Cecum, colon, rectum.
Describe the cecum.
first section of LI and contains active bacteria. It is the site of fermentation. Little function significance in most omnivores animals (little digestion takes place there). Important in herbivores and hindgut fermenters (significant digestion takes place there)
Describe the colon.
fermentation, storage and absorption site
What are the functions of the large intestine?
What is digested in the LI?
fiber is digested by by bacteria inhabiting the cecum/colon (No digestive enzyme secretions by intestinal cells)
What is absorbed in the large intestine?
- Major site for water absorption (colon).
- some minerals (Na, CL), vitamins (B-vit) and VFA absorption.
- very limited AA, FA or glucose absorption
It is released in the stomach. It stimulates HCL release and muscle movement.
It is released in the duodenum. It stimulated the release of pancreatic bicarbonate and reduces stomach motility and acid release.
Describe CCK (cholecystokinin).
It's release is stimulated by lipids in the duodenum. CCK stimulated the release of bile and pancreatic enzymes.
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