CCK
Stimulus: drop in pH, fatty acids, amino acids
Location: Small Intestine
ACTION: Bile Secretion, Pancreatic Enzymes
Secretin
Stimulus: fatty acids, amino acids, drop in pH
ACTION:
Pancreatic bicarbonate ion release
Enhances CCK
Pepsin secretion
What stimulates insulin release?
Gastrin Inhibitory Peptide (GIP)
What does does GIP stimulate?
insulin release
Why is mastication important?
Digestion, especially of foods that include indigestible contents such as cellulose membranes in fruit and raw vegetables.
Regulation of Gastric Juice secretion - phases?
Cephalic:
- sight or thought of food, stimulation of taste and smell receptors
- loss of appetite, depression
Gastric:
- stomach distension activates stretch receptors, food chemicals activate chemoreceptors.
- excessive axcidity, decline in gastric secretion
Intestinal:
- presence of partially digested food in intestines
- Enterogastric reflex
Where do nutrients go after digestive tract?
Into the hepatic portal circulation:
Non-fat, water-soluble: portal circulation to liver
Fats: absorbed into the intestinal lymphatics, travel to systemic circulation through thoracic duct bypassing the liver
What does the liver do with nutrients?
Absorbs for processing/storage before releasing back into circulation.
50-75% of nutrients absorbed.
What happens to blood supply during digestion?
Increased
- Hormonal vasodilators released from the GI mucosa (CCK, gastrin, secretin)
- GI glands release vasodilators (kallidin & bradykinin)
- Dec. PO2 in gut wall increases blood flow 50-100%
Sympathetic innervation causes widespread vasoconstriction in GI tract
Control of ADH secretion:
Inc ADH: Inc. plasma osmolarity dec. blood volume, pressure nausea hypoxia drugs: morphine, nicotine, cyclophosphamide
Dec. ADH:
Dec blood osmolarity, inc blood volume, pressure
Drugs: Alcohol, hypertensives, dopamine blocker
