CARDIOVAS SYSTEM

• The innermost layer of the heart is the endocardium, which is the middle layer, and the thickest of the three layers.
• The outer layer of the heart is called the epicardium, which is surrounded by the pericardium, a sac that surrounds the heart.
• The pericardium is composed of two layers and has fluid in the space between the layers, which helps to reduce friction when the heart beats.
• The chambers of the heart include the left atrium, which forms most of the base of the heart and receives blood from the lungs through the four pulmonary veins.
• The right atrium forms the right surface of the heart and receives blood from three veins: Superior Vena Cava, Inferior Vena Cava and Coronary Sinus.
• The right ventricle is the thickest chamber of the heart, forms the apex of the heart, and has structures such as the trabecular carneae, chorda tendinae, aortic valve, ductus arteriosus, and fibrous skeleton of the heart.
• The left ventricle is the heart's main pumping chamber, is 10-15 mm (0.4-0.6in) in average thickness, forms the apex of the heart, and has structures such as the trabeculae carneae, chorda tendinae, interventricular septum, pulmonary valve, and fibrous skeleton of the heart.
• The heart has two types of heart valves: Artioventricular Valves, which allow blood to move from higher pressure in the atria to a lower pressure in the ventricles, and Semilunar Valves, which allow blood to start flowing back toward the heart.
• Normal heart sounds include Lubb Dubb, while abnormal heart sounds can include S1, S2, and Murmurs.
• Cardiac output is the volume of blood ejected from the left or right ventricle into the aorta or pulmonary trunk each minute, while stroke volume is the amount of blood pumped out of the ventricle in one beat.
• Cardiac reserve is the difference between a person’s maximum cardiac output and cardiac output at rest, and may have four or five times the resting value.
• Stroke volume is affected by preload, the degree of stretch on the heart before it contracts, and contractility, the forcefulness of contraction of individual ventricular muscle fibers.
• Afterload is the pressure that must be exceeded before ejection of blood from the ventricles can occur.
• Regulation of heart rate is influenced by hormones, ions, age, gender, physical fitness, and temperature.
• Exercise and aging can affect the heart, while heart disease can lead to changes in heart rate, heart sounds, and cardiac output.
• The heart has a specific cycle, known as the cardiac cycle, which includes systolic and diastolic phases.
• Cardiac output is important as it is the volume of blood ejected from the left or right ventricle into the aorta or pulmonary trunk each minute.
• Stroke volume is important as it is the amount of blood pumped out of the ventricle in one beat.
• Cardiac reserve is important as it is the difference between a person’s maximum cardiac output and cardiac output at rest, and may have four or five times the resting value.
• Afterload is important as it is the pressure that must be exceeded before ejection of blood from the ventricles can occur.
• The cardiovascular system contributes to the homeostasis of other body systems by transporting and distributing blood throughout the body to deliver materials such as oxygen, nutrients, and hormones, and carrying away wastes.
• The cardiovascular system helps regulate blood pressure and directs blood flow to tissues.
• The functions of the blood vessels include maintaining blood flow, vascular resistance, and hemodynamics.
• Diastolic blood pressure is the lowest arterial pressure during diastole.
• Mean arterial pressure (MAP) is the average blood pressure in arteries, roughly one-third of the way between the diastolic and systolic pressures, and can be estimated as MAP = diastolic BP + 1/3 (systolic BP - diastolic BP).
• Systolic blood pressure is the highest pressure attained in arteries during systole.
• Vascular resistance is the size of the lumen, blood viscosity, and systemic vascular resistance, and can be calculated as total blood vessel length.
• Capillary exchange, the most important method of which is simple diffusion, is important for the transport of materials such as oxygen and nutrients into the blood and the removal of waste products.
• Transcytosis is important mainly for large, lipid-insoluble molecules.
• Bulk flow is a passive process in which large numbers of ions, molecules, or particles in a fluid move together in the same direction.
• Local control of blood flow involves physical changes such as warming promoting vasodilation and cooling causing vasoconstriction.
• Neural control of blood flow involves the baroreceptor reflex and chemoreceptor reflex.
• Hormonal mechanisms involved in blood flow regulation include the renin–angiotensin–aldosterone (RAA) system, epinephrine and norepinephrine, Antidiuretic hormone (ADH), and Atrial natriuretic peptide (ANP).
• Effects of aging on blood vessels include changes in vascular resistance, blood flow, and hemodynamics.