Exam 3 Digestive System Flashcards
Know the functions of the accessory digestive organs
teeth: mastication
tongue: assist in swallowing
gallbladder: store bile
salivary glands: make saliva
liver: make and secrete bile
pancreas: make enzymes
Define segmentation. Where does it occur
The small intestine carries on mixing movements that include:
*Segmentation – ring-like contractions that can move chyme back and forth (intestines)
Define peristalsis. Where does it occur ?
The small intestine carries on mixing movements that include:
* Peristalsis – pushing movements that propel chyme ( GI tract)
Know where the following nutrients are broken down: carbohydrates, proteins
Carbohydrates: pancreas and mouth
proteins: small intestine
Know where the following nutrients are broken down: lipids, nucleic acids
Lipids: oral cavity and lingual lipases
Nucleic acids: small intestine
What are the 3 digestive enzymes
salivary amylase, pepsin, gastric lipase
Describe the digestive enzyme: pepsin
- pepsin: serves to digest proteins found in ingested food; Is a protein splitting enzyme
Break down proteins in consumed food
Describe the digestive enzyme: salivary amylase
- Salivary amylase: Serous cells produce a watery fluid with a digestive enzyme called salivary amylase, which splits starch into disaccharides
Describe the digestive enzymes: gastric lipase
gastric lipase: From chief cells, Fat splitting, Weak due to low pH
What are the functions of the following secretions: pepsinogen, intrinsic factor
pepsinogen: breaks down proteins in food during digestion.
intrinsic factor: transportation and absorption of the vital micronutrient vitamin B12
What are the functions of the following secretions: HCl, mucous
HCl: kills food-derived bacteria, facilitates food digestion
mucous: moistens, lubricates, and protects passages of the digestive and respiratory tracts
Describe the steps involved in swallowing.
1) Voluntary stage: saliva is mixed with chewed
food, forming a bolus
2) Swallowing begins and the swallowing reflex is
triggered
3) Peristalsis transports bolus in the esophagus to the stomach
The gastric cells secrete which substances? (chief and parietal)
Chief cells: pepsinogen, gastric lipase
parietal cells: hydrochloric acid, intrinsic factor
Which hormones affect gastric secretion and how? (Somatostatin, CCK, gastrin)
Somatostatin: inhibits acid secretion
CCK (Cholecystokinin): decreases gastric motility
gastrin: increases gastric juice secretion
Describe the 3 phases of gastric secretion
*Cephalic Phase: Gastric juice is secreted in response to stimulus such as the smell, or taste of food.
*Gastric Phase: food in stomach chemicallyy and mechanically stimulates release of gatrin which then stimulates secretion of gastric juice.
*Intestinal Phase: inhibits gastric juice secretion
What are the 4 substances the stomach can absorb?
water, certain salts, certain lipid-soluble drugs and alcohol
Define bolus
bolus: a small rounded mass of a substance, especially of chewed food at the moment of swallowing.
Define chyme
Chyme: the pulpy acidic fluid which passes from the stomach to the small intestine, consisting of gastric juices and partly digested food.
Describe the functions of the pancreatic enzymes (juice): lipase, amylase, trypsin, chymotrypsin,
- Lipase – breaks down fats into fatty acids and glycerol
*amylase – splits glycogen into disaccharides
*Trypsin – digests proteins
*Chymotrypsin – digest proteins
Describe the functions of the pancreatic enzymes (juice):
carboxypeptidase, nucleases, bicarbonate
- Carboxypeptidase – digests proteins
*Nucleases – digest nucleic acids - Bicarbonate ions – make pancreatic juice alkaline
Describe the functions of the liver. (there are many, probably should know them…..
- Produces glycogen from glucose
- Breaks down glycogen into glucose
- Oxidizes fatty acids
- Forms urea
- Synthesizes plasma proteins
- Acts as blood reservoir
- Stores glycogen, iron, and vitamins A, D, and B12
Describe the function of the hepatic portal system
returns blood from the digestive tract and spleen to the liver (where raw nutrients in blood are processed before the blood returns to the heart).
Describe the composition of bile and know its functions
Bile is a yellowish-green liquid that hepatic cells continuously secrete
Composition: water, bile salts, bile pigments, cholesterol and electrolytes.
Functions: helps with digestion. It breaks down fats into fatty acids
- Absorption of fat and fat-soluble vitamins.
What does each enzyme breakdown?( pancreatic juice);
chymotrypsin and nucleases
- Chymotrypsin – digest proteins – released as
inactive…activated by trypsin - Nucleases – digest nucleic acids
