Physiology of Digestive System

Digestive System

• Primary peristalsis in the esophagus is stimulated by swallowing
• Bicarbonates and enzymes have opposite effects on the digestive system
• Secretin inhibits stomach contractions
• Gastric acid secretion during the cephalic phase is stimulated by acetylcholine (ACh)
• Secretin is released in response to hydrochloric acid (HCl)
• Fats are transported from intestinal cells to blood plasma in the form of chylomicrons
• Gastric acid secretion is inhibited by somatostatin and high pH
• Cholecystokinin (CCK) is released in response to fat entering the small intestine
• Intestinal motility is increased by cholecystokinin (CCK) and gastrin
• All of the following stimulate cholecystokinin (CCK) secretion except bile acids
• Histamine, gastrin, and cholecystokinin (CCK) are important stimuli for gastric acid secretion
• Bombesin is the most important hormone for regulating gastrin secretion
• Cholecystokinin (CCK) is the most important hormone for regulating pancreatic enzyme secretion
• Cholecystokinin (CCK) is also the most important hormone for regulating gallbladder emptying

Respiratory System

• The tidal volume is equal to 300-500 ml
• Pulmonary ventilation is an exchange of gases between the atmosphere and blood
• The percentage of oxygen in atmospheric air is 20.94%
• The percentage of oxygen in expired air is 16.3%
• The percentage of oxygen in alveolar air is 14.5%
• The percentage of carbon dioxide in atmospheric air is 0.03%
• The percentage of carbon dioxide in alveolar air is 5.50%
• The percentage of carbon dioxide in expired air is 4.0%
• Residual volume is approximately 1200 ml
• Inspiration begins with contractions of inspiratory muscles
• Pressure in the pleural cavity decreases up to -4-8 mm Hg during quiet breathing
• Functional Residual Capacity (FRC) is the volume of air remaining in the lungs after a quiet expiration
• Vital Capacity (VC) includes Inspiratory Reserve Volume, Tidal Volume, and Expiratory Reserve Volume
• Inspiratory Capacity (IC) consists of Tidal Volume and Inspiratory Reserve Volume
• Total Lung Capacity (TLC) includes Tidal Volume, Inspiratory Reserve Volume, Expiratory Reserve Volume, and Residual Volume
• Pneumothorax is a condition in which air accumulates in the pleural cavity
• Reflex by Hering-Breuer originates from pulmonary stretch receptors

Blood and Blood Cells

• Leukocytosis is an increase in the number of leucocytes above standard
• Physiological leukocytosis can be digestive, myogenous, emotional, or reactive
• Leukopenia is a reduction in the number of leucocytes below standard
• Nuclear shift to the left means an increase in young forms of neutrophils
• The amount of protein in the solid residue of plasma is 7-8%
• The amount of platelets in 1 microliter of blood in a healthy adult is 200-400,000
• Erythrocytes are formed in cells of bone marrow and destroyed in the spleen and liver
• Isotonic solutions have the same osmotic pressure as blood
• Osmotic pressure of blood is defined by proteins and electrolytes
• Agglutinogens and agglutinins have specific names: A and alfa, B and beta
• Agglutinogens are antigens found on the surface of red blood cells
• Agglutinins are antibodies found in plasma that react with agglutinogens
• The I blood group has alfa and beta agglutinogens
• The II blood group has A and beta agglutinogens
• The III blood group has B and alfa agglutinogens
• The IV blood group has AB and O agglutinogens
• Serum is plasma without fibrinogen
• The Rh factor is found on the surface of red blood cells
• The Rh factor has significance in repeated transfusions and during pregnancy
• Blood coagulation involves three phases: formation of tissue and blood prothrombinase, conversion of prothrombin to thrombin, and formation of fibrin.