PHYSIO (CARDIO, PERIPHERAL CIRCULATION AND MICROCIRCULATION)

• The cardiac muscle differs from the non-cardiac muscle in terms of its action potential and contraction.
• The heart pumps blood through the circulation.
• The heart has a conduction system that can be read in an electrocardiogram.
• The heart is composed of four chambers: right atrium, left atrium, right ventricle, and left ventricle.
• The atria act as a reservoir of blood returning to the heart.
• The ventricles pump blood to the circulation.
• The heart has two separate pumps: right heart (RA-RV) which pumps blood through the lungs, and left heart (LA-LV) which pumps blood through the peripheral organs.
• The heart valves ensure that blood flows in one direction.
• The atrioventricular (AV) valves are the valves between the atrium and ventricles.
• The right AV valve, also called the tricuspid valve, has three cusps.
• The left AV valve, also known as mitral valve, has two cusps.
• The semilunar valves are the pulmonic valve between the right ventricle and pulmonary artery, and the aortic valve between the left ventricle and aorta.
• Blood flows through the heart in a specific sequence: right atrium, right ventricle, left atrium, left ventricle, and then back into the right atrium.
• The circulation refers to the movement or circulation of blood through the heart and blood vessels.
• Ascites is the accumulation of excess fluid in the abdomen.
• Anasarca is a generalized edema, often seen in aborted fetuses.
• Right sided heart failure in animals can cause pulmonary edema due to an increase in plasma protein concentration, which increases plasma osmotic pressure, resulting in decreased filtration of fluid out of the capillary tubes since the osmotic pressure opposing filtration pressure is increased.
• In the second mechanism, a decrease in the plasma protein concentration decreases plasma osmotic pressure, resulting in increased filtration of fluid out of the capillary tubes since the osmotic pressure opposing filtration pressure is decreased.
• Edema/pitting edema is the accumulation of excessive fluid in tissues.
• Lymphatic blockage may cause edema since this system is the one that sequesters excess filtered fluid from capillaries back into the blood, without this system, fluid will accumulate in the interstitium causing edema.
• The functions of the circulation include service the needs of tissues by transporting nutrients and waste products, and transporting hormones.
• The circulation is divided into two divisions: systemic circulation which supplies all tissues of the body with blood flow except the lungs, and pulmonary circulation which supplies blood flow to the lungs.
• Fibrillation is characterized by irregular and disorganized P (atrial fibrillation) or QRS (Ventricular fibrillation) waves.
• The cardiac cycle repeats with every heartbeat and includes two parts: Systole (contraction of the atrium and ventricles) and Diastole (relaxation of the atrium and ventricle).
• A cardiac cycle refers to each complete contraction and relaxation of the heart (sequence of events in one heartbeat) or the cardiac events that occur from the beginning of one heartbeat to the beginning of the next.
• Arrhythmia is the presence of arrhythmia or abnormal impulse formation and conduction through the heart.
• Heart sounds are heard through auscultation of the chest wall using a special instrument called stethoscope.
• In ventricular fibrillation, only QRS waves are seen, indicating that ventricular muscles are acting as pace makers.
• Defibrillator is an equipment used to send a large electrical current of short duration to the heart with the objective of repolarizing all the cells at the same time (reset the heart).
• Ectopic beat is when the myocardium is more active than the SA node, action potential originates in an abnormal location.
• A cardiac cycle is comprised of four periods: Ventricular filling period (VFP), Isovolumetric contraction period (ICP), Ventricular ejection period (VEP), and Isovolumetric ventricular relaxation period (IRP).
• The functional parts of the circulation include the heart, the peripheral blood vessels, and blood.
• To produce a given flow, the heart must do more work if turbulence develops in blood vessels.
• Blood flows in the body through a series of tubes (blood vessels).
• Ohm’s law states that blood flow is directly proportional to the pressure difference but inversely proportional to resistance.
• Central fluid has the fastest velocity than fluids at the wall.
• Resistance to fluid flow depends on the length of the tube (L), the radius (r) of the tube, and the viscosity of the fluid (n).
• Turbulent flow may occur when there is increased rate of blood flow or when there is narrowing, obstruction or irregularity in the tube or vessel wall.
• Conditions that may alter viscosity of blood include Roleaux formation and Polycythemia.
• Laminar flow is a type of motion in which the fluid moves as a series of infinitesimally thin layers, with each layer moving at a velocity different from that of its neighboring layers.