Lecture 19 Flashcards
What are the 4 basic process in digestion?
Digestion
Motility
Secretion
Absorption
What occurs in digestion?
The break down of large food pieces into small molecules by mechanical or chemical methods
What occurs during motility in digestion?
The mixing (churning) and movement through GI tract
What is another term for moving food through the body?
Peristalsis
What occurs during secretion in digestion?
Digestive juice into lumen of IG tract to break down molecules and kill bacteria
What are the 2 enzymes in the mouth? And what do each break down?
Lingual lipase -> triglycerides to fatty acids
Salivary amylase -> carbs/glycogen/ starch to disaccharides
Does absorption occur in the mouth?
No.
Maybe some drugs
What are the 3 phases during swallowing?
Buccal phase - food into bolts and moved back of mouth while uvula prevents food going into nose (voluntary)
Pharyngeal phase - tongue does a body roll to throw it back while epiglottis covers trachea
Esophageal phase - bolus moves down esophagus by peristalsis
What innervates each divisions of the esophagus?
Upper 1/3 somatic neurons - skeletal muscle
Middle 1/3 mix of skeletal and smooth muscle
Lower 1/3 PSNS neurons - smooth muscle
What are the 2 sphincters to enter and exit the stomach?
Esophageal sphincter
Pyloric sphincter
What occurs in the stomach during digestion?
Chemical digestion - Salivary amylase, lingual lipase, gastric lipase continues to break down till pH goes below 5- 6
Mechanical digestion - muscular, circular and oblique muscle layers churns food
Drugs and alcohol is absorbed
How is chyme transitioned to small intestine?
By the pyloric sphincter letting small amount of chyme enter and neutralize acidity with secretin and Chloe from pancreas and gallbladder
What proteins does the pancreas release?
Trypsin, chyme trypsin, carboxypeptidase
What induces the secretion of Chloe from the pancreas?
Amino acids and fatty acids which will cause more secretion of pancreas enzyme -> more gallbladder -> lower gastric motiloity and secretion
What enzyme are present in the intestine?
Sucrase, maltase, lactase, aminopeptidases
What molecule is not digested in the intestine?
Lipids
What is the small intestine known for?
The main site of absorption due to the folds in the villi making the surface area greater
Where do the absorbed nutrients go after small intestine?
Liver via the hepatic vein
Lacteals/ lymphatic vessels (lipids)
Where do lipids go after getting absorbed by the lymphatic system?
Via thoracic duct empties into leftsubclavian vein
How is fat digested and absorbed?
Requires bile from the liver and gallbladder to travel through hepatopancreatic duct to duodenum and enter enterocytes to be packaged as chylomicrons -> go to lymphatic vessel
What is the composition of bile?
Water
Bile salts
Bile pigments
Ions
Detoxified hormone/drugs
How does bile work?
Emulsifies fat - break into small droplets (like soap)
Micelle formation - keeps fat in a bubble like solution
What are the characteristics of micelles?
Composed of bile salts and phospholipids
Exterior is hydrophilic - interior is hydrophobic
What are the phases of gastric motility?
Cephalic phase - prepare stomach from food triggered by sight, smell, thought
Gastric phase - stimulation of secretion and motility of stomach triggered by stretch and chemo receptors
Intestinal phase - prevents tonicity of chyme from overwhelming the intestine and slow absorption/ digest -> inhibitory signal to gastric secretion
What are the different motility types in the large intestine?
Haustral contractions - slow and weak contractions to move material down but allows absorption and mixing
Mass movement/ parastolysis - food ingestion sends contraction waves to transverse colon to poo
How is defecation reflex triggered?
Stimulating the stretch reflex in the rectum to the sacral (S1-3 -> smooth muscle/ visceral NS) spinal cord
Contract and relax in the anal canal by sphincters
Do we have voluntary control over defecation reflex?
Yes by the external anal sphincter but it can be overridden
What digestion and secretion occurs at the large intestine?
No digestion
Bacteria creates vitamins
K and HCO is secreated
What is absorbed in the large intestine?
400 ml of water via osmosis/ day
Drugs
How is glucose moved from the blood to the tissue cells?
Via facilitated diffusion
What percent of body energy stores does glycogen serve as?
1%
What is cholesterol used to make?
Steroid hormones, bile and cell membranes
How are amino acids enter a cell?
Facilitated diffusion or secondary active transport
Where are amino acids stored?
They’re not!
Excess is converted into fat
What is the metabolic rate?
The body’s rate of energy use by chemical and mechanical work
Why is basal rate important?
It is the energy your body needs to perform the bare minimum (breathing, HR, kidney function)
What are the main hormones form the stomach?
Gastrin - high acid/gastric enzymes (lipase and pepsinogen)
Secretin - high alkaline secretion from pancreas and gall bladder
- low gastric secreation
CCK - high pancreatic enzymes secreted
- high gall bladder contraction
- low gastric motility and secretion
