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S. MORRIS 2006 This Powerpoint is hosted on www.worldofteaching.com Please visit for 100’s more free powerpoints What is the circulatory system? The circulatory system carries blood and dissolved substances to and from different places in the body. The Heart has the job of pumping these things around the body. The Heart pumps blood and substances around the body in tubes called blood vessels. The Heart and blood vessels together make up the Circulatory System. Functions of the Circulatory System • Transport oxygen to cells • Transport nutrients from the digestive system to body cells • Transport hormones to body cells • Transport waste from body cells to excretory organs • Distribute body heat Double Circulation • The heart pumps oxygenated blood to all organs • Deoxygenated blood is returned to heart • This deoxygenated blood must be sent to the lungs to replenish its oxygen content • Once oxygenated, the blood returns to the heart again to be pumped to the rest of the body • This is known as double circulation (blood need to pass by the heart twice in one cycle) Double Circulation • Pulmonary Circulation – Transports blood to lungs and back to heart – Low pressure • Systemic Circulation – Pumps blood to rest of body and back to heart – Higher pressure Double Circulation Rest of Body Blood vessels to and from Heart Aortic arch Superior Vena Cava Pulmonary artery Pulmonary Vein Inferior Vena Cava How does this system work? pulmonary vein pulmonary artery lungs head & arms aorta main vein Right Left liver digestive system kidneys legs Circulatory System Our circulatory system is a double circulatory system. This means it has two parts parts. Lungs the right side of the left side of the system the system deals with deals with oxygenated deoxygenated blood. blood. Body cells Capillaries of head and arms The Heart •Circulation of Blood through the Body Superior vena cava •See it in action!Capillaries of right lungs Aorta Pulmonary vein Inferior vena cava Copyright Pearson Prentice Hall Pulmonary artery Capillaries of left lung Capillaries of abdominal organs and legs The pulmonary circuit consists of the right side of the heart (right atrium and right ventricle), the pulmonary arteries, which convey poorly oxygenated blood to the lungs, and the pulmonary veins, which convey oxygenated blood from the lungs to the left atrium. The systemic circuit consists of the chambers on the left side of the heart (left atrium and left ventricle) and all the named blood vessels that carry blood to the tissues (arteries) and all the named blood vessels that return the blood from the tissues (veins) back to the right atrium of the heart. The tissue capillaries are included. Inferior vena cava Superior vena cava Aorta The Location of the Heart • Your heart is located under your ribcage and is tilted to the left which is why everyone thinks it is on the left side of your body. The Heart This is a vein. It brings blood from the body, except the lungs. These are arteries. They carry blood away from the heart. 2 atria 2 ventricles Coronary arteries, the hearts own blood supply The heart has four chambers now lets look inside the heart THE ANATOMY • The heart has 4 chambers • 2 ventricles (right and left) • These are muscular chambers that move blood out of the heart’ • The 2 atriums hold the blood and at the right moment empty the blood into the right and left ventricles Textbook Pg 133, Fig 8.10 (b) Valves in the Heart Tricuspid Valve Chordae Tendineae Semilunar Valves Bicuspid Valve Chordae Tendineae • Cords / tendons that are attached to the tricuspid and bicuspid valves • Help to prevent the valves from being turned inside out The pumping action of the heart is essential to maintain blood circulation. It beats about 75 times per minute. The amount of blood pumped from one ventricle per minute is called the cardiac output. Coronary arteries ALBIO9700/2006JK The Heart Artery to Lungs Vein from Head and Body Right Atrium valve Right Ventricle Artery to Head and Body Vein from Lungs Left Atrium valve Left Ventricle Cross section of the Heart Oxygenated blood leaves the left ventricle to circulate through the body Receives blood from the venae cavae Control the flow & backflow of blood Carries deoxygenated blood away from the heart vena cava from the head Upper left chamber Upper right chamber vena cava from lower body Deoxygenated blood flows into the pulmonary arteries Lower right chamber Lower left chamber Receives blood from the pulmonary veins Control the flow & backflow of blood Oxygenated blood flows into the aorta. The heart is located left of the body midline posterior to the sternum in the mediastinum. But how does it work? 1. Atrial systole stage: The heart fills with blood > the atrial wall muscle contracts 2. The pressure forces the blood in the atria down into the ventricles 3. Semilunar valves prevent blood backflow 4. Ventricular systole stage: the ventricle thick muscular wall squeezes inwards > increasing pressure pushes the blood out of the heart 5. Backflow is prevented by the pressure difference that pushes the atrioventricular valves shut But how does it work? 6. The blood rushes upwards into the aorta & the pulmonary artery pushing open the semilunar valves 7. Ventricular diastole stage: all the heart muscles relax > low pressure blood from the veins flows into the 2 atria > Blood moves downwards into ventricles through the atrio-ventricular valves > the atrial muscle contracts to push the blood forcefully down into the ventricles > 8. The cycle begins again Cardiovascular Diseases • Diseases of the heart and blood: – – – – Coronary heart disease Hypertension (high BP) Arteriosclerosis (hardening of arteries) Atherosclerosis (narrowing of arteries) Coronary arteries • A lot of blood pass through the heart all the time • But heart is NOT nourished by the blood pass through it • Coronary arteries supply oxygen and nutrients to the heart Coronary Heart Diseases • Occur when coronary arteries become blocked • Result: Oxygen and nutrients cannot be supplied to the heart Steps in coronary heart disease 1. Coronary arteries become blocked when lipids (fat and cholesterol) carried by the blood get deposited on the walls of the arteries, thus making them narrower 2. This is called atherosclerosis 3. Calcium salts then cover the lipids to form a fibrous net called atheroma 4. Blood clots (thrombus) may also form 5. Coronary occlusion occurs when the artery is fully blocked and the supply of blood to the heart is stopped 6. A heart attack results, as part of the heart dies from the lack of oxygen Causes of Heart Diseases • • • • • Fatty diet (high in sodium, cholesterol and saturated fats) Lack of exercise Obesity Smoking Stress Mode of Action of the Heart (i.e. How the heart beats) • The chambers of the heart contract and relax in pairs • When both atria contract; ventricles are relaxed • When ventricles contract, atria are relaxed Heartbeat (Cardiac Cycle) One heartbeat (a cardiac cycle) consists of two parts: 1. Systole (ventricular contraction) 2. Diastole (ventricular relaxation) Systole (contraction) – – – – Ventricles contract Blood is forced into the pulmonary artery and aorta Tricuspid and bicuspid valves are closed Blood pressure normally rises to120 mmHg How does the Heart work? STEP ONE blood from the body blood from the lungs The heart beat begins when the heart muscles relax and blood flows into the atria. How does the Heart work? STEP TWO The atria then contract and the valves open to allow blood into the ventricles. How does the Heart work? STEP THREE The valves close to stop blood flowing backwards. The ventricles contract forcing the blood to leave the heart. At the same time, the atria are relaxing and once again filling with blood. The cycle then repeats itself. Heart sounds • During systole, “Lup” sound is caused by backflow of blood against closed tricuspid and bicuspid valves • During diastole, “Dup” sound is caused by backflow of blood against closed semilunar valves • Rhythmic “Lup-Dup” sounds results • Stethoscope can be used to hear the heart beat Heart action control Purkyne tissue ALBIO9700/2006JK Control of Heartbeat • The heart has a natural rhythmic contraction of its own • Can be also controlled by some nerves from the brain to increase or decrease the number of heart beats when necessary. Pacemaker • Group of specialized cells found at top right atrium • Pacemaker initiates heart beat • Pacemaker is controlled by nerves from the brain • To speed up or slow down heart rate when necessary http://www.phschool.com/science/biology_place/biocoach/cardio1/electrical.html Artificial Pacemaker • Some heart diseases can cause the heart to beat irregularly • Can be corrected by using an artificial (manmade) pacemaker • Doctors will implant this small electronic device near the patient’s heart • It will produce regular pulses of electricity which stimulates the heart to contract and relax at the right rate. Pulse Rate • The number of times the heart beats in one minute • The resting heart beats approximately 60 to 100 times per minute • Pulse rate increases during exercise, and when one is feeling stressed, nervous, angry or excited. Pulse Rate How many times does your heart beat in : • One minute? 70 • One day? 100,800 • One week? 705,600 • One month? 21,168,000 • One year? 254,016,000 Pulse Rate of… • Foetus: 140-150 beats/min • Newborn baby: • 3 year old: 130-140 95-100 • 10 year old: 84 • 25 year old: 72 • 50 year old: 76 Blood Pressure • Blood pressure is around 120/80 mmHg • Blood pressure is the force of the blood pushing against the walls of the arteries each time the heart beats. • Blood pressure is at its highest during systole. • Blood pressure is lowest when the heart is at rest, between beats (diastole) High Blood Pressure • Blood pressure of 140/90 or higher is considered high blood pressure Who is at risk? – middle-aged and elderly people – obese people – heavy drinker – Inherited form parents