Biology Chapter: Digestion and Glucose Synthesis

Protein Digestion

• Protein digestion in the stomach results primarily from secretions released by parietal cells
• Parietal cells release pepsinogen, which is converted to pepsin to digest proteins

Hormones and Digestion

• Secretin stimulates the production and secretion of pancreatic enzymes
• Cholecystokinin stimulates the release of pancreatic enzymes and bile
• Gastrin stimulates the release of pepsinogen and gastric acid

Glucose Synthesis

• Gluconeogenesis is the synthesis of glucose from simpler molecules
• Glycolysis is the breakdown of glucose into pyruvate
• Lipolysis is the breakdown of fats into fatty acids and glycerol
• Beta-oxidation is the breakdown of fatty acids into acetyl-CoA

Swallowing Mechanism

• The epiglottis prevents the entry of liquids or solid food into the respiratory passageways during swallowing
• The glottis is the opening between the vocal cords
• The arytenoid cartilage is involved in the movement of the vocal cords

Diaphragm Function

• When the diaphragm contracts, it tenses and moves inferiorly, causing an increase in the volume of the thoracic cavity
• This leads to a decrease in pressure in the thoracic cavity and an increase in pressure in the abdominopelvic cavity

Blood Pressure Regulation

• Elevated levels of ADH and angiotensin II produce increased peripheral vasoconstriction
• This leads to increased blood pressure and decreased blood flow to the periphery

Blood Types

• A person with Type A blood has A antigens on their red blood cells and anti-B antibodies in their plasma

Blood Coagulation

• When clotting proteins are removed from plasma, serum remains
• Fibrinogen is a clotting protein that is converted to fibrin during coagulation

White Blood Cell Differential Count

• Neutrophils are the most numerous WBCs found in a differential count of a "normal" individual

Lipid Transport

• Lipids are transported from the intestine to the liver by chylomicrons
• Chylomicrons are lipoprotein particles that transport dietary lipids

Respiration Regulation

• The concentration of carbon dioxide is most important in regulating the rate of respiration
• Increased CO2 levels stimulate the respiratory centers in the brain to increase breathing rate

Cardiac Muscle Physiology

• The peak of contraction is delayed by more than 100 ms relative to the action potential upstroke
• Dihydropyridine receptors and Ryanodine receptors are coupled during depolarization of the T-tubule membrane
• Cardiac contraction is inhibited by agents that block the Ca2+ current across plasma membranes

Arterial Compliance

• Arterial compliance decreases with age
• Compliance is directly proportional to the volume of the vessel and inversely proportional to the pressure

Impulse Conduction

• The impulse conduction is slowed down in the AV node to ensure complete atrial systole
• From the AV node, the impulse passes in the Purkinje fibers to reach working cardiomyocytes
• There is only one electrical pathway that connects the atrial and ventricular tissues

Fick Principle

• The Fick Principle allows the calculation of O2 consumption when the O2 concentrations in the pulmonary arteries and cardiac output are known
• It is based on the Law of conservation of mass