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30 terms

Digestive System Chp.24

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Digestive organs
These are the organs which the food and liquid passes through during the process of digestion. The pathway is called the ALIMENTARY CANAL and includes the oral cavity, pharynx, esophagus, stomach,small intestine, and large intestine.
Accessory Organs
These organs aid in the process of digestion by secreting chemicals that break down the food and liquids we eat. The organs include salivary glands, pancreas, gall bladder, and the liver.
Absorption
Digested products pass through and into the blood for distribution into other organs. Most materials are first delivered to the liver for further processing.
Enteric Nervous System
Composed of extensive nerve plexuses in walls of digestive organs. Three plexuses are 1)Sensory neurons to CNS 2) AMS motor neurons to organs 3) Enteric neurons only in digestive system. This system acts locally to control contraction of the organ walls, regulate blood flow to organs, and control secretion of digestive juices. Special interstitial cells mediate impulse of transmission from ENS to nerve cells to smooth muscle cells & regulate gastrointestinal movement by forming pacemakers along the tract.
ANS in Digestive system
REflex control of general digestive functions is also controlled by this system which acts in conjunction with ENS. The parasympathetic division acting through the vagus nerve acts to speed up digestion which the sympathetic slows down the process.
Deglutination
Process of moving food into and through the pharynx.
Voluntary phase of Deglutination
Food is moved to the back of the mouth.
Pharyngeal Phase of Deglutination
Reflex action occurs controlled by the medulla oblongata and food bolus closes the epiglottis. The constrictor muscles force the food along the pathway.
Esophageal Phase of Deglutination
Where the upper esophagus sphincter muscles relax and allow food to enter the esophagus. Then food is removed by peristalsis through the esophagus. Peristalsis is controlled by the vagus nerve of the parasympathetic ANS.
Achalasia
Disorder of the esophagus where the valve does not open and causes chest pain and difficulty in eating. Nervous control problem.
Mucous Gastric Secretions
Thick material that lubricates food and coats stomach lining to protect against strong gastric secretions.
Intrinsic Factor Gastric Secretions
Produced with Hcl; Binds to vitamin B-12 to aid its absorption in the small intestine;[ B-12 DEFICIENCY (Pernicious Anemia)- Reduced red cell production and reduced oxygen in blood with feelings of fatigue, muscle weakness, and can be fatal and treatment is liver and B-12 injections.]
Hydrochloric Acid Gastric Secretions
Lowers pH to 1.5-2.5 during digestion and is activated by digestive enzymes and breaks down connective tissue in foods.
Pepsinogen Gastric Secretions
Hcl activates Zymogen to form pepsin enzyme; It digests proteins, breaks down bonds btwn amino acids to form smaller peptide chains.
Gastrin Gastric Secretions
Hormone made in gastric glands and stimulates production of other digestive juices.
Cephalic Phase
Phase where taste and smell of food starts salvation process. Cranial Nerve activates salivary glands. Vagus Nerve starts gastrin secretion.
Gastric Phase
Phase where activation of digestive processes in the stomach are stimulated by distention of stomach walls activating the vagus nerve, gastric hormone, and presence of material in stomach such as proteins, alcohol, and caffeine.
Gastrointestinal Phase
Phase where the small intestine acts to control stomach secretions in order to digest the materials being moved into it from the stomach.
Secretin
Increases bile production.
Cholecystokinin
Causes gall bladder to contract and empties into duodenum into small intestine.
Vagus Nerve
Presence of food in small intestine activates nerve to aid in contraction of gall bladder and controls bile secretions and delivery.
Protein Synthesis
When the liver makes special blood proteins.
HEPARIN-anticoagulant
FIBRINOGEN-needed for clotting
ALBUMIN-needs water in blood vessels to maintain blood pressure.
Glycogen Formation
When the liver stores glucose in the form of glycogen starch. Glycogen can be later converted back to glucose for maintaining blood sugar levels.
Vitamin Storage
Stores excess fat soluble vitamins in liver and also stores vitamin B-12.
Vitamin Synthesis
Aids process of vitamin D production by the body and cholesterol is converted to vitamin D when skin is exposed to sunlight.
Detoxification
Forms glucuronides where water soluble products to be excreted by kidneys.
Hepatitis
Inflammation of the liver. Symptoms are yellowing of the skin and eyes. Causes are chemical exposure, viral infection, bacterial infection, hepatitis C.
Cirrhosis
Condition of fatty infiltration of liver cells. Cells replaced by fat and connective tissue. Causes are excess alcohol consumption and toxic exposure to chemicals.
Pancreatic Secretions
Secretes insulin, and glucagon.
Pancreatic digestive enzymes
Enzymes are trypsin, chymotrypsin, and carboxypeptidase.