The Circulatory System Tuesday February 3, 2009 • Bell Ringer – Complete the Bell Ringer Activity given to you when you entered the room • Objectives 1. Explain the function of the circulatory system. 2. Describe the parts of the circulatory system. 3. Explain how the heart functions in the circulatory system. • Planner – Skeletal System Test Retakes due Today! – Bones Test Retakes due Friday February 6 – Muscular System Test Retakes due Monday February 9 – Path of Blood Flow Quiz Friday February 6 – Notebooks will be due on Monday February 9 The Circulatory System • Also called the cardiovascular system • Is made of the heart, blood, and blood vessels • Allows blood to flow to all parts of your body • Has 3 main jobs: 1. Carries needed substances to cells – Oxygen and glucose 2. Carries waste products away from cells – Carbon dioxide 3. Contains cells that fight disease The Heart The Heart • A hollow muscular organ that pumps blood throughout the body • About the size of your fist • Located in the center of the chest, beneath the sternum and inside the ribcage • Made of cardiac muscle – Contracts over and over without tiring out The Heart • Acts as two pumps – Right side: pumps blood into the lungs where it picks up oxygen – Left side: pumps blood into the arteries where it is sent throughout the body • The two sides are separated by a wall of tissue called the septum. The Heart • Each side has two chambers – The upper chambers are called atria. – The lower chambers are called ventricles. The Atria • The upper chambers of the heart • Job is to receive blood that comes into the heart • The right atrium has a group of cells called the pacemaker (sinoatrial node) that sends signals to make the heart muscle contract Pacemaker • Whenever someone has problems with an irregular heartbeat, doctors may give them an artificial pacemaker. • This helps their heart maintain a normal rhythm. Ventricles • The lower chambers • Job is to pump blood out of the heart – Right ventricle pumps blood to the lungs – Left ventricle pumps blood out of the heart and into the body Valves • The ventricles are separated from the atria by valves – Flaps of tissue that prevents blood from flowing backward – Also located between the ventricles and the large blood vessels that carry blood out of the heart How the Heart Works • Two phases 1. Heart muscle relaxes and atria fill with blood 2. Heart muscle contracts and blood pumps forward • This closes the valves between the atria and the ventricles – Creates the lub sound • The valves between the ventricles and the blood vessels snap shut – Creates the dup sound Two Loops • Overall pattern of blood flow in the body is like the figure eight. • In the first loop, blood travels from the heart to the lungs and then back to the heart. • In the second loop, blood is pumped from the heart throughout the body and then returns to the heart. • Blood travels in only one direction. • One drop of blood could make the journey through both loops in less than a minute. The Path of Blood Flow 1. Vena cava is a large vein that carries oxygen- poor blood to the heart 2. The right atrium receives the oxygen-poor blood from the vena cava. 3. Blood leaves the right atrium through the tricuspid valve and enters the right ventricle 4. From the right ventricle the blood passes through the pulmonary valve and enters the pulmonary artery, which sends the blood to the lungs The Path of Blood Flow 5. In the lungs, blood picks up oxygen; it then passes through the pulmonary veins. 6. From the pulmonary veins, oxygen-rich blood enters into the left atrium. 7. From the left atrium, the blood then passes through the mitral valve and empties into the left ventricle. 8. The blood leaves the left atrium through the aortic valve, and enters the aorta. 9. The aorta sends oxygen-rich blood to all parts of the body. 10. Once the body’s cells receive the blood, they exchange carbon dioxide for oxygen. 11. The oxygen-poor blood makes its way to the vena cava, where it can start its journey again. Pumping Heart Video Blood Vessels • There are three kinds of blood vessels – Arteries • Carry blood away from the heart – Veins • Carry blood to the heart – Capillaries • Exchange substances between the blood and body cells Wednesday February 4, 2009 • Bell Ringer • Objectives: 1. Describe the structures and the functions of the blood vessels. 2. Describe the components of blood. 3. Explain what determines the type of blood that a person can receive in a transfusion. • Planner: – Skeletal System Test Retakes due Today! – Bones Test Retakes due Friday February 6 – Muscular System Test Retakes due Monday February 9 – Path of Blood Flow Quiz Friday February 6 – Notebooks will be due on Monday February 9 Arteries • Job is to carry blood away from the heart • Each artery branches into smaller and smaller branches – Smallest branches are called arterioles. • Arterioles join to capillaries • Aorta is the largest artery in the body – Has many branches Coronary Arteries • The coronary arteries are the branches of the aorta that supply the heart muscle with blood • Blockages of these arteries can lead to heart attacks Structure of an Artery • Have very thick walls made of three cell layers 1. The innermost layer is smooth and is made of epithelial cells. • Lets blood flow freely 2. The middle layer is made of muscle tissue. • Acts as a control gate, controlling how much blood enters the vessel 3. The outer layer is made of flexible connective tissue • Allows the arteries to withstand the force of the blood being pushed through them. • Arteries are strong and flexible • Able to withstand much pressure • The pulse is caused by the alternating expansion and relaxation of the artery wall Veins • Veins carry blood to the heart. • Veins branch into smaller and smaller branches. – The smallest branches are called venules. • Venules are attached to the capillaries. Structure of the Veins • Veins are made of three layers, but are thinner than arteries. • Because the force of blood flow is not as strong when blood reaches the veins, the blood needs help moving. 1. Contractions of skeletal muscles helps to push blood through the veins. 2. Larger veins have valves in them to prevent blood from flowing backward. 3. Breathing movements help to force blood to the heart. Capillaries • In the capillaries, materials are exchanged between the blood and the body’s cells. • The capillaries form a web between the arteries and the veins. • Capillary walls are made of epithelial tissue. • Capillary walls are only one cell thick. – Materials pass easily through them using the process of diffusion, molecules moving from areas of high to low concentration. Blood Blood • Blood is made of four components, or parts: – Plasma, red blood cells (RBCs), white blood cells (WBCs), and platelets • About 45% of the volume of blood is cells; the rest is plasma Plasma • Most of the materials transported in the blood travel in the plasma. • Plasma is the liquid part of blood. – 90% of plasma is water – 10% is dissolved materials, such as glucose, fats, vitamins, and minerals • Many waste products are carried away by the plasma Plasma • Proteins give plasma its yellow color – Three groups of plasma proteins 1. Helps regulate amount of water in blood 2. Helps fight disease 3. Interacts with platelets to form blood clots. Red Blood Cells (RBCs) • RBCs take up oxygen in the lungs and deliver it to cells throughout your body • Produced in the bone marrow (like other blood cells) • Look like doughnuts that someone forgot to cut out the hole – Because they are thin in the middle, they are able to bend and twist easily • Allows them to squeeze into tiny capillaries RBCs • Made mostly of hemoglobin, an iron-containing protein that chemically binds to oxygen. – Hemoglobin is also able to pick up some carbon dioxide, but most is carried by the plasma – When hemoglobin and oxygen join together, the cell becomes bright red; without oxygen, the cell is dark red • Arteries have blood that is bright red • Veins have blood that is dark red RBCs • Mature RBCs have no nuclei – Without a nucleus, it cannot reproduce or repair itself • Only are able to live 120 days – Every second, about 2 million RBCs die » Bone marrow makes new cells at the same rate Thursday February 5, 2009 • Bell Ringer • Objectives: 1. Name the structures and functions of the lymphatic system. 2. Identify some diseases of the cardiovascular system. 3. Describe behaviors that can help maintain cardiovascular health. • Planner: – Skeletal System Test Retakes due Today! – Bones Test Retakes due Friday February 6 – Muscular System Test Retakes due Monday February 9 – Path of Blood Flow Quiz Friday February 6 – Notebooks will be due on Monday February 9 White Blood Cells (WBCs) • Produced in the bone marrow • WBCs are the body’s disease fighters. – Some recognize disease causing organisms and alert the body that it has been invaded – Others produce chemicals to fight the invaders – Others surround and kill the invaders WBCs • There are fewer WBCs than RBCs. • Larger than RBCs • Several different types of WBCs • WBCs have nuclei – Can live for months or even years Platelets • Platelets are cell fragments that play an important role in forming blood clots Forming Clots • When a vessel is cut, platelets collect and stick around the cut. • Platelets release a chemical that leads to the production of a protein called fibrin. – Fibrin makes a net of fibers across the wound. • This net traps blood cells. – As more and more of the platelets and cells get caught in the fibrin net, a clot forms. » A scab is a dried blood clot on the skin’s surface Blood Types • Four major blood types: A, B, AB, O • Types are determined by the proteins known as marker molecules that are on RBCs – A has the A marker, B has the B marker, AB has both A and B, O has no markers on it Blood Types • Plasma has proteins that recognize cells with foreign markers and they make those cells clump together – A has anti-B proteins – B has anti-A proteins – AB has no anti- proteins – O has both anti-A and anti-B proteins Why is Blood Type Important? • Your blood type determines what type of blood you can safely receive in a blood transfusion. – If you are A, you can receive A and O blood – If you are B, you can receive B and O blood – If you are AB, you can receive, A, B, AB, and O • “Universal recipients” – If you are O, you can only receive O blood • “Universal donors” Rh factor • The Rh factor is another protein that is found in the blood. • You are either Rh+ or Rh- • Rh factor is named for the Rhesus monkey, which was the first organism recognized to have the Rh factor The Lymphatic System • As blood travels through the circulatory system, some of the fluid leaks out. – The fluid moves through the walls of the capillaries and into the tissues. • The fluid carries materials the cells in the tissues need. • After bathing the cells, the fluid moves into the body’s drainage system, the lymphatic system. – A network of vein-like vessels that returns the fluid to the bloodstream Lymph • Once inside the lymphatic system, the fluid is called lymph. • Lymph is made of water and dissolved materials; it also has some white blood cells in it. • The lymphatic system has no pumps, so lymph moves very slowly. • The lymphatic vessels connect to large veins in the chest. – Lymph empties into these veins and the fluid becomes part of the plasma again. Lymph Nodes • Lymph nodes are pieces of tissue that filter lymph, trapping bacteria and other disease-causing microorganisms in the fluid. Lymph Nodes • When the body is fighting infection, the lymph nodes enlarge. • Sometimes referred to as “swollen glands.” Cardiovascular Diseases • Cardiovascular disease is the leading cause of death in the U.S. today. Atherosclerosis • Atherosclerosis is a condition in which an artery wall thickens as a result of the buildup of fatty materials such as cholesterol. – This reduces the flow of blood in the affected artery. Atherosclerosis • When atherosclerosis develops in the coronary arteries, the heart muscle receives less blood (less oxygen), which can lead to a heart attack. – Heart attacks occur when the blood flow to part of the heart muscle is blocked. • Cells die in the part of the heart that does not receive blood and oxygen. This permanently damages the heart Treating Atherosclerosis • Low-fat diet and exercise for mild cases. • Some medications can be prescribed. • Severe cases may lead to angioplasty, where a small balloon is inserted into the blocked artery to help open it up. • When arteries are completely blocked, a bypass operation may be performed. – In a bypass, a vein from the leg is used to create an alternate path for blood to flow into the heart muscle. Hypertension • Hypertension is high blood pressure. • A person will have hypertension if their blood pressure is consistently greater than 140/90. • High blood pressure makes the heart work harder to pump blood through the body, possibly damaging the walls of the blood vessel. • Because most people have no obvious signs of the disease it is called the “silent killer”. Treating High Blood Pressure • Closely related to atherosclerosis. • As arteries narrow, the blood pressure increases. • Diet and exercise help • Limit intake of salt • Sometimes given medications that lower blood pressure Measuring Blood Pressure • Blood pressure is measured by a device called a sphygmomanometer • The first number in a blood pressure reading is the measurement of the blood pressure when the ventricles contract. • The second number, which is lower, is the blood pressure when the ventricles relax. • The blood pressure is given as a fraction with the contraction pressure, or systolic, over the relaxation pressure, or diastolic. – A healthy blood pressure is 120/80 or lower.
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