Digestive System Flashcards
List four types of digestion that occur within the body.
- Intracellular
- Extracellular
- Mechanical
- Chemical
Intracellular Digestion vs. Extracellular Digestion
- Intracellular: Involves oxidation of glucose and fatty acids of energy. (In the cell)
- Extracellular: Process of obtaining nutrients from food. Occurs within Lumen of alimentary canal.
Mechanical Digestion
Physical Breakdown of food into smaller particles. Does not involve breaking of chemical bonds
Enzymatic cleavage of chemical bonds
Chemical Digestion
Describe overall pathway which food travels when moving down the alimentary canal
- Mouth
- Pharynx
- Esphagus
- Stomach
- Small Intestine
- Large Intestine
- Rectum
- Anus
What are accessory organs? List all accessory organs of digestive system within the human body.
Help to provide enzymes and lubrication necessary for the digestion of food.
- Salivary Glands
- Liver
- Pancreas
- Gallbladder
Part of the nervous system that control peristalisis in the wall of the alimentary canal.
Enterc Nervous System
- Upregulated by PSN System
- Downregulated by SNS
What do ADH and Aldosterone promote in regards to feeding behavior?
Thirst (to influence fluid consumption)
What does Glucagon and Ghrelin promote?
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Glucagon is release by pancreas
Ghrelin is release by the pancreas and stomach
What do leptin and cholecstokinin stimulate?
Feelings of satiety.
Explain what happens during chemical and physical digestion of food within the mouth.
-
Physical
- Mastication
- Involves physical breakdown of food to increase SA of food for enzymatic digestion as it passes through the gut
- Moderates size of food entering gut
- Moistening/Lubrication of food via saliva (realeased by salivary glands which are controlled by PSN System)
- Mastication
-
Chemical Breakdown
- W/i saliva there is
- Lipase (hydrolyzes lipids)
- Amylase (hydrolizes carbs into smaller sugars)
- W/i saliva there is
- Food is formed into a “bolus” and swallowed
What happens to food from the pharynx to the stomach?
- Swallowing is initiated at the upper esophageal sphincter
- Esophagus propels food down to stomach via peristalsis
- Food enters stomach via lower esophageal sphincter
It is important to note that not much chemical or physical digestion takes place during this phase.
Where is the stomach located in the abdomen and what is it comprised of?
- Location: LUQ, under the diaphragm
- Part of the Stomach (In order)
- Body
- Fundus
- Pylorus
- Antrum
- Additional Features
- Lesser and Greater Curvature
- Rugae (inner foldings)
What are the two types of glands in the stomach?
- Gastric
- Pyloric
The gastric gland releases enzymes in the stomach in response to the vagus vagus nerve of the PSN System. What is the vagus nerve activated by?
sight, smell, and taste of food.
What are the major enzymes secreted by the gastric gland of the stomach?
- Mucous cells
- Chief Cells
- Parietal Cells
Cells in the stomach that produce mucous that lines the stomach (also helps to prevent autodiegstion via mucous)
mucous cells
What do the chief cells do?
- Secrete Pepsinogen
- Zymogen form of Pepsin
- Pepsin: Hydrolytic enzyme that help break proteins into polypeptides (activated by increasing levels of HCL)
What do the parietal Cells of the stomach secrete?
- HCL
- Intrinsic Factor: glycoprotein involved in absorption of B12.
What is the major cell of the pyloric gland?
G-Cell: Secrete Gastrin
- Induces parietal cells to secrete more HCL
- Induces the contraction of the stomach muscles to mix stomach contents, which eventually becomes chyme
Sphincter which chyme passes to enter duodenum.
Pyloric Sphincter
What are the major structures of the small intesine?
- Duodenum
- Jejunum
- Ileum
What is the major role of the Duodenum of the stomach and what are its major enzymes?
Further Chemical Digestion
- Brush Border Enzymes
- Enteropeptidase
- Secretin and CCK
What are brush-border enzymes and what types exist within the duodenum?
Enzymes that line the lumenal surface the duodenum and further hydrolyze sugars (disiccharidses) and peptides (protein)
- Disaccharidases Hydrolyzes into monosaccharides
- Maltose
- Isomaltose
- Lactose
- Sucrose
- Peptidases Hydrolyzes Proteins into Peptides
- Aminopeptidases
- Dipeptidasis
Removes N-terminal AA from peptide
Aminopeptidases
Hydrolyzes peptide bond between two AA to release free AA.
Dipeptidasis
Activates the release of other digestive enzymes from accessory digestive system organs.
Enteropeptidase
What enzymes do enteropeptidase activate?
- Trypsinogen
- Enteropeptidases activates the transformation of Trypsinogen to Trypsin, which initiates activation cascade
- Procarboxypeptidase A and B into toehir active forms
What are the purposes of secretin?
- Stimulate the acinar cells in the pancrease to release contents nessary for neutralizing the acidic contents of chyme.
- Slow motility (enterogastrone)
- allow increased time for digestive enzymes to act on chyme.
What is the purpose of CCK?
- Stimulate the gallbladder to contract and release stored bile into small intestine (important for emulsification of facts)
- Release Pacreatic Juices
- Increase Satiety
What is the main purpose of bile?
- Help with emulsification of fats by getting fats into solution and increasing their SA by placing them into micelles
What importance do pancreatic juices play in digestion? (3)
- Neutralize acidic chyme with bicarbonate and H2O
- Provide an ideal working environment for digestive enzymes
- Contains enzymes that digest lipids, carbs, and proteins
The pancreas has endocrine and excrine fuctions. What is the exocrine function? What enzymes are released by the pancreas?
The pancreas is activated by the enteropeptidase (which converts trypsinogen to Trypsin) to release contents and enzymes to the stomach during digetion.
- Acinar cells: produce bicarbonate/H2O rich pancreatic juices that contain enzymes for digestion.
- Enzymes include
- Pancreatic Amylase
- Pancreatic Peptidase (Trypsin and Chymotrypson)
- Pancreatic Lypase
- All contents are released to the stomach via the pancreatic duct
What are the two unique structures of the liver when communicating with the digestive system?
- Bile Duct (releases contents to the gall bladder and stomach)
- Hepatic Portal Vein
What are the major functions of the liver?
- Make Bile
- Receives and stores nutrients after receiving nutrient rich blood from hepatic portal vein.
- Stores these nutrients (i.e. glycogen and triacylglycerols)
- Can also reverse the store process to release lipids and sugars when necassar
- (i.e. glycogenesis /glycogenolysis /gluconeogensis
- Detoxification
- Synthesis of proteins (i.e. albumin and clotting factors) for proper body function
Main function of the gallbladder.
- Store and concentrate bile
What are the main structure for absorption in the small intestine? What is the main structure that helps with absorption?
- Jejunum and Illeum
- Microvilla: finger-like projections on the lining of the lumen of the small intestine that increase SA for absorption
Lymphatic System that takes up fats for transport into the lymphatic system, located in the small Jejunum and illem of the small intestine
Lacteal
Fat soluble compounds in the samm intestine enter the ________, while water soluble compounds enter the _________.
- Lacteal
- Capillary bed
From the large intestine, how does stool get to the rectum, where it eventually exits the body through the anus?
- Enters the cecum from the small intestine through the illeoceal valve
- Passes the the colon (large intesine)
- Ascending, Transverse, Descending, and Sigmoid Colon
- Rectum
What are the primary purposes of the large intestine?
- Reabsorption of H2O.
- Electrolyte Absorption
- Houses e. Coli
What do e. coli produce?
- Vit K
- B12
- Thiamine
- Riboflavin
