PNA 200 Cardiovascular System PDF

PNA 200 Cardiovascu lar System SUBTITLE Cardiovascular System ▪ Heart is a metaphor for love and courage ▪ Nearly had a heart attack, to describe surprise or shock ▪ In one's blood qualities people have ▪ Blood runs hot or cold-found in speech and poetry ▪ Scientifically speaking, emotions...

PNA 200 Cardiovascu lar System SUBTITLE Cardiovascular System ▪ Heart is a metaphor for love and courage ▪ Nearly had a heart attack, to describe surprise or shock ▪ In one's blood qualities people have ▪ Blood runs hot or cold-found in speech and poetry ▪ Scientifically speaking, emotions are more a matter or hormones than myocardium, and everyone's blood is the same colour and temperature ▪ Heart is neither soft nor hard Introducing the Cardiovascular System ▪ Sometimes called the circulatory system ▪ Consists of the heart, blood vessels and lymphatic system ▪ Transportation network that: ▪ Brings life-sustaining oxygen and nutrients to the body’s cells ▪ Removes metabolic waste products ▪ Carries hormones, gases, products of digestion, immune cells Double Duty ▪ Heart is two separate pumps ▪ Right side pumps blood to the lungs ▪ Left side pumps blood to the rest of the body Where the heart lies ▪ About the size of a closed fist ▪ Lies beneath the sternum in the mediastinum (cavity between the lungs) ▪ Between the second and sixth ribs ▪ Most people the heart rests obliquely ▪ The pointed end (apex) is lower left, the top part is upper right ▪ Apex-point of maximal impulse (heart sounds the loudest) Heart Structure ▪ Surrounded by a sac-pericardium ▪ Wall made of three layers ▪ Myocardium ▪ Endocardium ▪ Epicardium ▪ Four chambers ▪ 2 atria ▪ 2 ventricles ▪ 4 valves ▪ 2 atrioventricular, two semilunar Pericardium ▪ Fibroserous sac that surrounds the heart and roots of the great vessels ▪ Fibrous pericardium ▪ Tough, white, fibrous tissue that fits loosely around the heart, protecting it ▪ Anchors the heart and major blood vessels to the sternum and diaphragm ▪ Serous pericardium ▪ Thin, smooth inner portion and has two layers ▪ The parietal layer lines the inside of the fibrous pericardium ▪ Secretes pericardial fluid into pericardial cavity ▪ Visceral layer adheres to the surfaces of the heart ▪ Between the fibrous and serous pericardium is the pericardial space/cavity ▪ Pericardial fluid lubricates the surfaces of the space and allows the heart to move easily/smoothly during contraction The Wall ▪ Three layers ▪ Epicardium ▪ The outer layer (and visceral layer of the serous pericardium) also surrounds roots of major blood vessels ▪ Made of squamous epithelium overlying connective tissue ▪ Secretes pericardial fluid into pericardial cavity ▪ Myocardium ▪ The middle layer forms most of the heart wall (heart muscle) ▪ Striated muscle fibres that cause the heart to contract with enough force to carry it through the arterial system and out into the capillaries ▪ Endocardium ▪ Heart inner layer ▪ Endothelial tissue with small blood vessels and bundles of smooth muscle ▪ Continuous with the vascular endothelium (artery lining) The Chambers ▪ 4 hollow chambers (2 atria, singular atrium) and two ventricles ▪ The atria (upper chambers) are separated by the interatrial septum. ▪ Receive blood returning to the heart and pump blood to the ventricles ▪ The right atrium receives blood from the superior and inferior vena cava. ▪ The left atrium, which is smaller but has thicker walls than the right atrium, forms the uppermost part of the heart’s left border Downstairs ▪ The right and left ventricles separated by the intraventricular septum, make up the two lower chambers ▪ The ventricles receive blood from the atria ▪ Composed of highly developed musculature, the ventricles are much larger and thicker walled than the atria ▪ The right ventricle pumps the blood to the lungs ▪ The left ventricle, larger to the right, pumps blood through all other vessels of the body Valves Heart has 4 valves ▪ 2 AV valves ▪ 2 semilunar valves ▪ The valves allow forward flow of blood through the heart and prevent backward flow ▪ They open and close in response to pressure changes caused by ventricular contraction and blood ejection ▪ The 2 AV valves separate the the atria from the ventricles ▪ The right AV valve is called the tricuspid valve (three triangular cusps), the left is called the mitral or bicuspid valve (has 2 cusps) ▪ They are attached by chordae tendineae to the papillary muscles in the ventricles ▪ One of the 2 semilunar valves is the pulmonic valve, which prevents backflow from the pulmonary artery into the right ventricle ▪ The other semilunar valve is the aortic valve, which prevents backflow from the aorta to the left ventricle  Valves Tricuspid Valve Mitral Valve Structure: Two leaflets. Structure: Three leaflets. Function: Function: Allows blood flow from the left atrium to the left ventricle. Allows blood flow from the right Prevents backward flow from the left ventricle atrium to the right ventricle. to the left atrium. Prevents backward flow from the Aortic Valve right ventricle to the right atrium. Structure: Three leaflets. Pulmonary Valve Function: Opens to allow blood flow from the left Structure: Three leaflets. ventricle to the aorta. Prevents backward flow from the aorta to the Function: left ventricle. Pumps blood from the right ventricle to the pulmonary artery, leading to the lungs. Prevents backward flow from the pulmonary artery to the right ventricle. Conditions and Disorders What conditions and disorders can affect the heart valves? ▪ If a heart valve doesn’t work correctly, your heart might have to work harder to pump blood. ▪ Heart valve problems can be related to: ▪ Changes to your body as you age. ▪ Congenital heart disease, birth defects in valve structure (for example, missing leaflets or leaflets with the wrong size or shape). ▪ Infections. ▪ Underlying conditions, such as diabetes or another heart problem. ▪ There are three main types of heart valve problems. Each type of problem can happen in any of the four valves: ▪ Regurgitation: Regurgitation is the backward flow of blood because a valve doesn’t close properly. (leaky heart valve) ▪ One specific type of regurgitation is prolapse. Prolapse involves a leaflet flopping or bulging backwards. It tends to occur in the mitral valve. ▪ Stenosis: Stenosis occurs when a valve’s leaflets get thick or stiff or stick together. ▪ Atresia: Atresia means that a valve is missing. What are the symptoms of heart valve problems? ▪ Some people can have a heart valve condition but not have any symptoms at all. Heart valve conditions tend to get worse over time, so symptoms may appear as a person gets older. ▪ The sound of your heartbeat is the sound of your heart valves opening and closing. The first sign of a heart valve problem is often a heart murmur (an unusual sound when your heart beats). However, a heart murmur can happen even with no valve problems. This is called an innocent heart murmur. ▪ Other signs and symptoms of a heart valve problem may include: ▪ Chest pain. ▪ Dizziness. ▪ Fainting. ▪ Fatigue (feeling extremely tired). ▪ Feeling of fluttering or racing in your chest. ▪ Shortness of breath, especially when exercising or lying down. ▪ Swelling in the ankles, feet, legs or belly. Heart Beat During one heartbeat ▪ Blood fills the right atrium from the vena cava ▪ then passes through the tricuspid valve, filling the right ventricle ▪ then pumped through the pulmonary valve into the pulmonary artery ▪ At the same time, the left atrium is being filled from the pulmonary veins ▪ Blood moves through the mitral valve into the left ventricle ▪ Exits the aortic valve into the aorta Blood to the heart ▪ Blood flows in and out of your heart every second of your life ▪ Blood needs to supply the cells of the heart itself with oxygen and nutrients ▪ Coronary arteries are the solution Coronary Arteries ▪ Coronary arteries ▪ 2 large coronary arteries and their many branches supply blood to the heart ▪ They branch off the aorta and carry blood to the left and right sides ▪ Called the left and right coronary arteries (sit atop the heart and look like a crown) ▪ Right coronary artery has two major branches-marginal artery and the posterior interventricular artery- supply right atrium and ventricle ▪ Left coronary artery has two branches-the anterior descending and left circumflex-primarily supply the left atrium and ventricle  Cardiac Veins ▪ Usually lies alongside the coronary arteries and their branches ▪ The left cardiac venous system receives deoxygenated blood from most of the superficial veins of the heart ▪ The right cardiac venous system is composed of veins that originate on the anterior and lateral surfaces ▪ The cardiac veins merge into the coronary sinus, which drains into the right atrium. ▪ The smallest vessels (the venae cordis minimae) drain the myocardium right into the chambers