digestion

oxidation of glucose and fatty acids for energy

process by which glucose and fatty acids are obtained from food, occurs in lumen of alimentary canal (mouth to anus)

the transport of products of digestion from digestive tract into circulatory system for distribution

oral cavity (mouth), pharynx, esophagus, stomach, small intestine, large intestine, rectum (feces stored unless release)

neurons present in the walls of the digestive tract and trigger peristalsis of the gut tube

parasympathetic nervous system

hydrolyzing starch into smaller sugars

• nasopharynx, oropharynx (back of mouth) and laryngopharynx (above the vocal chords)
• food prevented from entering larynx by epiglottis

• top 1/3 is skeletal muscle (voluntary motor control)
• middle mixed
• bottom smooth muscle (involuntary)

gastric glands (mucous cells, chief cells and parietal cells)

pyloric glands

produce bicarbonate rich mucus to protect wall from acidic environment

• chief cells secrete pepsinogen 
• parietal cells secrete H (cleave pepsinogen to pepsin, also secrete intrinsic factor)

• contain G cells that secrete gastrin, a peptide hormone
• induces parietal cells to secrete more H, and signals the stomach to contract, mixing its contents.

• duodenum (digestion)
• jejunum (absorption)
• ileum (absorption)

at the luminal surface of cells liming the duodenum and break down dimers and trimers into monomers

pyloric sphincter

• need to be broken down to monosaccharides for absorption
• di and tripeptides can be absorbed across the small intestine wall

• regulates pH by reducing H from parietal cells and increasing bicarbonate secretion from pancreas
• also an enterogastrone (hormone that slows motility through the digestive tract)

activation of trypsinogen to trypsin, pancreatic protease

• secreted in response to entrance of chyme into duodenum
• stimulates the release of bile and pancreatic juices, also acts in the brain to promote satiety

• digest lipids, emulsify facts, creates micelles, facilitate lipase action
• amphiphatic

• pH 8.5 for those enzymes that work best in that pH
• digest all three types of nutrients: carbohydrates, fats and proteins

release of insulin, glucagon and somatostatin

• made of acinar cells that produce pancreatic juices
• amylase (breaks carbs)
• trypsinogen breaks down proteins

gallbladder and small intestine

• produces bile
• create glycogen and stores fats and reverse those reactions to produce glucose
• detox
• synthesis of albumin and clotting factors

• byproduct of breakdown of hemoglobin
• travels to the liver where it is conjugated (attached to a protein) and secreted into bile for excretion
• when liver cannot excrete it, jaundice occurs

stores and concentrates bile

amylase (break down starch) and lipase

pepsin

trypsin, chymotrypsin, carboxypeptidases A and B, amylase, lipase

bile miclles

sucrase, lactase, maltase (break down carbs), dipeptidases, amino peptidases (break down proteins

bile salts (amphipathic molecules), piments (bilirubin from breakdown of hemoglobin) and cholesterol

produced in the liver, stored in gallbladder and serves function in duodenum.

capillary bed for absorption of water soluble nutrients and lacteal (lymphatic channel that takes up fats for transport to the lymphatic system)

via concentration gradient, blood always has lower concentration of monosaccharides and amino acid than inside the epithelial cells

triglycerides and esterified cholesterol from small intestine are packaged and enters the lymphatic system

water can travel across cell membrane and also squeeze between cells to reach blood

water absorption, consists of cecum, colon and rectum