Chapter 3 Flashcards
Absorption
Process of taking substances into the interior of the body.
Gastrointestinal Tract (7)
Hollow tube aprox. 10m in length that runs from the mouth to the anus. Organs include: mouth, pharynx, esophagus, stomach, small intestine, large intestine, anus.
Transit Time
Amount of time it takes for food to pass the length of the GI tract. In a healthy adult transit time is about 24-72 hours.
Feces
Body waste, including unabsorbed food residue, bacteria and dead cells.
Produce saliva, which contains a starch-digesting enzyme
Salivary glands
Swallows chewed food mixed with saliva
Pharynx
Moves food (bolus) to the stomach by peristalsis.
Esophagus
Churns and mixes food (chyme); secretes acid and a protein-digesting enzyme pepsin and enzyme rennin.
Stomach
Makes bile, which aids in digestion and absorption of fat.
Liver
Releases bicarbonate to neutralize intestinal contents; produces enzymes that digest carbohydrate, protein, and fat.
Pancreas
Stores bile and releases it into the small intestine when needed.
Gallbladder
Completes digestion; absorbs nutrients into blood or lymph. Most nutrient absorption occurs here.
Small intestine.
Absorbs water and some vitamins and minerals; home to intestinal bacteria; passes waste material.
Large intestine
Opens to allow waste to leave the body
Anus
Structures of the GI tract wall from the inside out.
Lumen Mucosa Connective tissue Layers of smooth muscle External layer of connective tissue
Lumen
The tube inside the gastrointestinal tract. Food within the lumen has not yet been absorbed and is therefore technically still outside the body. Consists of 4 layers of tissue (mucosa, connective tissue, layers of smooth muscle, external layer of connective tissue).
Mucus
Viscous material produced by goblet cells; mucus moistens, lubricates and protects the GI tract. Secreted inside the lumen.
Enzymes
A digestive secretion/protein molecules that speeds up chemical reactions without being changed or destroyed in the process.
Enzymes that break down starches (2)
Salivary amylase, pancreatic amylase
Enzymes that break down protiens (6)
pepsin, trypsin, chymotrypsin, carboxypeptidase, aminopeptidase, dipeptidase
Enzymes that break down sugars (4)
Sucrase, lactase, maltase, dextrinase (all found in the small intestine)
Enzymes that break down fats (3)
Pancreatic lipase, lipase
Only 2 enzymes secreted in the stomach
Pepsin, rennin
What can stimulate activity in the digestive tract?
Sight and smell of food, presence of food in the gut, hormones.
The hormone that stimulates secretion of hydrochloric acid (HCL) and pepsinogen by gastric glands in the stomach and increases gastric motility and emptying.
Gastrin; comes from stomach mucosa
A hormone that inhibits the following: stomach secretion, motility, and emptying; pancreatic secretion; absorption in the small intestine; gallbladder contraction; and bile release.
Somatostasin; comes from stomach and duodenal mucosa
Secretin
A hormone secreted by the mucosal lining of the duodenum. Signals the pancreas to secrete pancreatic juice rich in bicarbonate ion and stimulates the liver to secrete bile into the gallbladder.
Mucosa
A layer of mucosal cells lining the lumen that serve as a protective layer and is responsible for the absorption of the end products of digestion. They reproduce rapidly and are one of the first parts of the body to be affected by nutrient deficiencies.
Cholecystokinin (CCK)
A hormone secreted by the mucosal lining of the duodenum. Signals the pancreas to secrete digestive enzymes and caused the gallbladder to contract and release bile into the duodenum.
A hormone that inhibits gastric secretion and motility
Gastric inhibitory peptide; duodenal mucosa
Digestion
Process of breaking food into components small enough to be absorbed by the body.
What characteristics of the wall of the GI tract enables it to propel food?
The rhythmic contraction of smooth muscles.
3 types of cells of the immune system that are present in the GI tract
Phagocytes
Lymphocytes
Antibodies