Transcript Heart
The Heart Ch. 46: Circulatory System What is the heart? A specialized muscle that pumps blood through the body, which transports oxygen, carbon dioxide, nutrients and waste. Where is it? The heart is located in the middle of the chest, between the lungs. Its bottom is tipped to the left. It is about the size of two fists. Anatomy of the heart Left side- oxygenated Right side- deoxygenated What does it look like? The pericardium is a tough saclike membrane that surrounds the heart and secretes a fluid to reduce friction. Heart Chambers Heart is divided into four chambers. The upper chamber are the right and left atria. The lower chambers are the right and left ventricles. Heart valves Valves are flaps of tissue that direct blood to flow only in one direction. They prevent blood from entering that chamber that it just left. There are 4 heart valves Atrioventricular valves (AV) Separates the atrium from the ventricle. Right: tricuspid valve Left: bicuspid (mitral) valve Semilunar valves (SL) Separates the ventricles from vessels exiting the heart. Right: pulmonary valve Left: aortic valve Diagram of the Heart 1. 2. 3. 4. 5. 6. 7. Aorta- Largest artery in Body Superior Vena Cava Right Pulmonary Artery Right Pulmonary Vein Right Atrium Tricuspid Valve Right Ventricle 8. Inferior Vena Cava 9. Left Pulmonary Artery 10. Left Pulmonary Vein 11. Left Atrium 12. Bicuspid/Mitral Vale 13. Aortic Valve 14. Left Ventricle 15. Aorta 16. Septum Pulmonary circulation 1. 2. 3. 4. Vena cava (superior and inferior) from body Right atrium Right ventricle Pulmonary artery to lungs 5. 6. 7. 8. Pulmonary Veins Left Atrium Left Ventricle Aorta (to body) Heart Beat The heart contracts in waves, starting at the atria, followed by the ventricles. The heart independently stimulates an electrical impulse at the sinoatrial node in the right atrium, which stimulates the atrioventricular node in the septum. The heart pumps blood in two phases: In the systole phase, the ventricles contract and blood is pumped out of the heart. In the diastole phase, the ventricles relax and blood rushes into the heart. The lub dup sound of a heart beat is the close of the AV and SL valves. http://www.csulb.edu/colleges/coe/org/bme/respiratory_sounds/heart.au Pulse The pulse is caused by the contractions of the left ventricle. Blood surges through the arteries and the pressure causes the arteries to expand. Blood Blood is composed of a liquid medium (55%) and solids (45%). Plasma The sticky, yellowish colored liquid medium of blood. Contains: 90% water –Metabolites –Nutrients –Salt –Wastes –And proteins of various function Red blood cells AKA Erythrocytes: transports oxygen to cells all over the body Contain large amounts of the protein, hemoglobin. Hemoglobin Carries oxygen to necessary cells. Carries carbon dioxide from cells to be removed by lungs. White Blood cells AKA Leukocytes, help defend the body from disease. Platelets Cell fragments that release blood clotting enzymes when a blood vessel is damaged. A chemical chain reaction stimulates platelets to stick together at the tear site and release proteins to clog the tear. Eventually a scab forms. Blood vessels Artery – Carries blood away from the heart – Made of a thick muscle layer –Because the arteries feel the greatest amount of blood pressure. Veins –Carries blood back to the heart – Made of a thinner muscle layer and contains valves. –Because there is less blood pressure in the veins and valves prevent gravity from making blood flow backwards. Capillary –Thin vessels that allow the exchange of gases, nutrients, and waste between blood cells and other cells by the process of diffusion. Gas Exchange Occurs in the alveoli of the lungs Factors that facilitate exchange: –Alveoli are thin: one cell layer thick –Excellent capillary blood supply –Very large surface area –Moist lining helps in diffusion Oxygen transfer Atmospheric oxygen: 21% O2 readily diffuses from air in alveoli into the blood stream, where it is picked by the hemoglobin in red blood cells. Carbon dioxide transfer The concentration of CO2 is much higher in cells, so CO2 readily diffuses out of cells into the blood. 7% is dissolved in the plasma. 23% is carried by hemoglobin 70% reacts with water to become carbonic acid (H2CO3), which helps maintain blood pH. Mechanism of Breathing Diaphragm: muscle layer below the lungs and above the abdomen. Inspiration/ Inhale Process of taking in air. –Diaphragm contracts and pushes down the abdomen. –Rib cage expands. –Lung volume increases and fills with air because pressure outside lungs is greater than inside Expiration/ Exhale Process of releasing air: Diaphragm and rib muscles relax Rib cage condenses. Lung volume decreases and lungs deflate Human Respiratory System Sequence: Mouth Nasal passages Pharynx Larynx Trachea Bronchi Lungs (brochioles— alveoli) Cardiovascular Diseases Atherosclerosis hardening of narrowing _________ and _________ the arteries. Arteries feel higher blood pressure and suffer more damage. What happens? Inner lining of artery is damaged. LDL “Bad cholesterol”,_____, build up in the artery. White blood cells _______________engulf LDL accumulate and forms a but __________ plaque which clogs the artery. ______, Complications Cardiovascular disease is the one killer in America. number ____ arteries Blood clots in coronary ______ causes damage and death of heart muscles. Leads to myocardial infarction/ heart attacks. clots or ________ ruptures in _____ blood vessels in the brain can strokes lead to _______. Blood Causes Smoking High cholesterol High blood pressure/ hypertension Stress Diabetes Abdominal obesity Not eating fruits and vegetables Excess alcohol intake Not exercising regularly