1. GI Function
Digestion is the mechanical and chemical breakdown of food in the GI
Absorption is the transport if nutrients from the gut to the blood or lymphatic
Metabolism is the chemical utilization of nutrients mostly within the liver
Excretion is the removal of wastes or the release of toxins

9. Digestion
Alimentary canal includes the oral cavity, pharynx, esophagus, stomach, small intestine, and colon
Sphincters are ring muscles that separate segments of the canal and act as control valves
The mucosa secretes mucus to lubricate the canal to allow for peristalsis
Accessory organs include the liver, gallbladder, and pancreas

16. Digestion
Liver for digestion produces bile which breaks down fat by emulsion, excreted from the hepatic duct
The gallbladder stores and excretes bile when stimulates by the small intestines
Pancreas secretes enzymes for the breakdown of foods in the small intestines, like lipase and amylase
Digestion occurs mechanically, chemically, and passively

22. Digestion
Mechanical, is mastication, peristalsis, and gastric contractions by muscle actions
Chemical reactions are hydrolysis, oxidation, or emulsification of food, gastric and pancreatic juices
Hydrochloric acid in the stomach breaks down most food, and then bicarbonate is a buffer for alkalinity
After 6 hours, CHO are monosaccharides, TGs are FAs and glycerol, and proteins are amino acids

28. Digestion
Hormones trigger secretions such a mucus, electrolytes, water, enzymes
Gastrin secretes Hydrochloric acid in the stomach, often controlled by emotions
Fats cause the releasable of bile from the gallbladder
Certain foods that release excessive amounts of Hydrochloric acid can cause ulcers

32. Food Pathway
In the mouth chewing forms a bolus, which is swallowed into the pharynx
From the pharynx food enters the esophagus and propelled down to the duodenum by peristalsis
Salivary glands moisten food into chyme, which is then broken down by amylases
Before entering the stomach food must pass through the cardiac or esophageal sphincter

35. Food Pathway
A J-shaped pouch which can expand and contract relative to gastric emptying, controlled by CCK
Gastrin secretes Hydrochloric acid in the stomach, often controlled by emotions
Pepsinogen activates to Pepsin, which breaks peptide bonds in proteins
Gastric lipase along with bile acids break to fatty acids from lipids, stimulated by secretin

36. Food Pathway
Gastroparesis is the slowing of digestion which is often caused by neuropathy, DM, opiates
Symptoms include nausea, vomiting, bloating, abdominal pain
The small intestines make up 20 feet in total, starting at the pyloric sphincter
The first 10 inches is the duodenum, the next 8 feet is the jejunum, the last 11 feet is the ileum

39. Digestion
The pancreas secretes 3 kinds of amylases which breaks down carbohydrates
Maltase, for maltose into glucose and glucose; Sucrase, for glucose and fructose
Lactase, for glucose and galactose; which can cause lactose intolerance
Younger and Older populations often secrete less lactase, causing GI distress

46. Digestion
In cheese lactose separates into whey and curd, with most lactose in the whey
Who want to consume lactose include, lactaid, lactose- free, or lactase supplements
In the intestine trypsin and peptidases breakdown elemental proteins into single amino acids

48. Absorption
Nutrients either enter into the blood stream or the lymphatic system to be utilized
The lymphatic system empties into the thoracic duct which merges with the bloodstream
From inside the intestines folds of villi with thousands of microvilli collect nutrients
Then capillaries called lacteals absorb nutrients into circulation by active transport
The end destination for most nutrients is the liver via the hepatic portal circulation

52. Absorption
Fats must be broken down into glycerol and fatty acids to be absorbed and the repackaged to form chylomicrons
Chylomicrons or lipoproteins are the circulated in the lymphatic system
Microvilla have a shot half life and can begin to atrophy within 1 week, causing gut ischemia
The colon extends past the ileum and largely made up of the cecum which houses fluids and micro bacteria for elimination
Stool is composed of 75% water, which can be thickened by fiber and probiotics

60. Malabsorption
Typically determined by type and volume of stool with >350gm/d
Medication, parasites, surgical procedures, disease states, and medical complications
Gut failure typically presents with hypoactive bowl sounds, no flatus, distended and hard abdomen, nausea
In pancreatitis or cholecystisis steatorrhea can occur, fat malabsorption typically seen with flow smell and yellow color
Food allergies are immune response to particles found in food that can cause harm

65. Metabolism
Chemical reactions of anabolic or catabolic occurring within cells to produce energy from carbs, proteins, and fats
Breakdown of catabolism of nutrients yelled carbon dioxide, heat, water, and energy in the form of ATP
With excess energy outside metabolic ability to utilize, nutrients are converted to glycogen or lipids and stored as fat
Anabolic utilization of proteins helps to build muscle, skin, hair, and organ tissues
Any foods not digested, absorbed, or metabolized is excreted through the kidneys or the colon