Class Notes (811,169)
Canada (494,539)
Physiology (1,038)

Physiology Digestion.pdf

8 Pages
Unlock Document

Western University
Physiology 1021
Anita Woods

GastrointestinalSystem Anatomy and Function April-15-13 5:25 PM Learning Objectives: 1. Describe the four processes of the digestive system a. Digestion - Mechanical: chewing, physical breakdown - Chemical: enzymes, chemical breakdown b. Absorption - From lumen to cells - Mostly transcellular c. Motility - Coordinate contraction/relaxationa long the gastrointestinal tract d. Secretion - By the cells into the lumen - Exocrine (secrete directly from glands) secretion- lumen - Endocrine (secreteinto the blood) secretion- blood vessels 2. Describe the regulation salivary secretions - Regulated by neuro pathways only - Positivelyregulated by both parasympathetic(PSNS) and sympathetic (SNS) pathways PSNS - Major pathway to stimulate saliva secretion SNS - Can't initiate salvation, can potentiate effects of PSNS 3. List and describe the 3 stages of swallowing a. Voluntary stage- movementof the bolus to the oropharynx b. Pharyngeal stage c. Esophageal stage- involuntary passage of the bolus into the stomach 4. List and describe the layers of the stomach a. Mucosa - Rugae: folds allow for more surface area - Single layer of epithelial cells □ Secrete enzymes, water and hormones - Alcohol can be absorbed in the stomach b. Submucosa - Connective tissue Enteric Nervous System - Short-loop (doesn't go to the brain) - Cell bodies of neurons - Myentericplexus: muscle contract/relaxto - Enteric nervous system churn c. Smooth muscle - Contains neurons - Brain can receive informationabout hunger - Circular and longitudinal muscles ○ Long-loop - SNS/PSNS innervation --> "fight or flight" or d. Serosa "rest and digest" 5. Explain the different functions of acid in the stomach a. Activate lingual lipase - Activated by pH change (HCl) b. Activates pepsin - Pepsinogen (secreted by chief cells) produces pepsin when in contact with acid - Pepsin begins protein digestion in the stomach c. Inactivates salivary amylase - Inactivated by the pH change (HCl) - Inactivated by the pH change (HCl) d. Kills microbes e. Denatures proteins f. Stimulates secretions of hormones - G cells release gastrin (gastric motility and function) Accessory Organs of the Digestive System April-15-13 7:10 PM Learning Objectives: 1. Anatomy of the pancreas - Ductal cells: secrete water and bicarbonate Endocrine cells - Alpha- glucagon - Beta- insulin - Delta- somatostatin Exocrine cells - Acinar cells- enzymes 2. List and describe the function of exocrine secretionsof the pancreas Exocrine: products are secreted from ducts a. Bicarbonate b. Pancreatic amylase c. Chymotrypsinogen--> chymotrypsin - Chymotrypsinogenis inactive - Chymotrypsinbreaks down proteins d. Trypsinogen --> trypsin - Trypsinogen is inactive - Trypsin breaks down proteins e. Procarboxypeptidase--> carboxypeptidase - Procarboxypeptidaseis inactive, cleaved by trypsin forming carboxypeptidase - Carboxypeptidasebreaks down poly peptides by cleaving the 3' of an amino acid chain f. Pancreatic lipase - Lipase digestion - Neutral environment 3. List and describe the function of endocrine secretions of the pancreas Endocrine: secreted hormones are delivered to the bloodstream for distribution - The endocrine cells in the pancreas are: Alpha, Beta, Delta and secretethe following hormones respectively: a. Glucagon b. Insulin c. Somatostatin 4. List and describe the three regions of the small intestine - Almost all digestion occurs here a. Duodenum - Contain many endocrine cells and chemo and mechanoreceptors - Functions to regulate digestion and absorption - Chemical receptors:protein, carbohydrates, lipids - Mechanoreceptors:stretch b. Jejunum - Most of nutrient absorption occurs here - Ability to do so I amplified by the number and length of the villi and the number of microvilli □ Increases the surface area for absorption c. Ileum - Less nutrient absorption (less villi) but does absorb specific moleculeslike bile - Less nutrient absorption (less villi) but does absorb specific moleculeslike bile - Can absorb more nutrients if necessary 5. List and describe the layers of the small intestine a. Mucosa- different than the stomach - Stomach:secretion storage - Intestine: absorbance - Epithelial cell layer at surface, connective tissue, small blood vessels and lacteals (vessels that absorb fat) b. Submucosa - Connective tissue, submucosa plexus c. Muscularis - Longitudinal and circular smooth muscle - Myentericplexus d. Serosa - Connective tissue 6. List the cell types of the intestinal wall and their function a. Absorptive cells: epithelial cells with microvilli b. Goblet cells- secrete mucus c. Intestinal gland cells- secrete intestinal juice (a water mucus that is slightly alkaline) d. Paneth cells- secretelysozyme (enzymedestroys bacteria) e. S cells- secretes secretin into blood - Acid causes secretion f. CCK cells- secretes cholecystokinin - Make CCK when there is protein or fat - Protein:pancreas to make more protease - Fat: increase bile- gal bladder contraction g. K cells- secretes glucose dependant insulinotrophic peptide - Carbohydrates present in small intestine causes ins
More Less

Related notes for Physiology 1021

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.