Chapter 16: Circulation

Transcription

1 Section 1 (The Body s Transport System) Chapter 16: Circulation 7 th Grade Cardiovascular system (the circulatory system) includes the heart, blood vessels, and blood carries needed substances to the cells (nutrients from digested foods, glucose, and oxygen) carries waste products away from the cells. (such as CO 2 from cellular respiration) also helps to fight disease (blood contains diseasefighting blood cells) 1. closed system Examples: 2 types of circulatory systems: the blood moves only within a connected network of tubes called blood vessels as it delivers oxygen and nutrients to the cells in the body. Vessels leaving the heart and vessels returning to the heart are connected. birds, fish, amphibians, reptiles, mammals 2. open system Blood leaves the blood vessels and sloshes around inside the body. Delivers oxygen and nutrients to the cells much more slowly than a closed system. (It takes longer for the blood to make it around the body.) Examples: the heart pumps blood into open spaces in the body, and the blood is not contained in vessels all the time. clams, snails, crayfish, lobsters Heart septum The Heart: Each side has two chambers, an upper chamber (atrium) and a lower chamber (ventricle) atrium (plural is atria) the two upper chambers on each side of the heart that receives blood into the heart ventricle has a separate right and left side separated by a wall of tissue (called a septum) a wall of tissue that separates the left side of the heart from the right side a lower chamber on each side of the heart that pumps blood out of the heart The right side: (pumps blood to the lungs to get oxygen) right atrium right ventricle receives oxygen-poor blood (or CO 2 -rich blood) from the body. pumps blood into the right ventricle pumps oxygen-poor blood out of the heart to the lungs (to get rid of CO 2 and pick up oxygen) 1

2 The left side: left atrium left ventricle (pumps blood to the rest of the body) receives oxygen-rich blood from the lungs. pumps blood into the left ventricle pumps oxygen-rich blood to parts of the body (to deliver oxygen and pick up CO 2 from the cells) pumps with greater force than the right ventricle (needs to send blood much farther) pacemaker valve a group of cells in the right atrium that sends out signals that make heart muscle contract and regulates heartbeat rate. a flap of tissue in the heart that prevents blood from flowing backward located between the atrium and ventricle on both sides of the heart artery any blood vessel that is carrying blood away from the heart They carry blood out of the heart to the lungs, or to the body Artery walls are very thick and flexible (to withstand the higher blood pressure in them) From the arteries, blood flows into capillaries. capillary a tiny blood vessel where substances are exchanged between the blood and the body cells Capillaries weave between the cells in the body. Oxygen is dropped off, and CO 2 and other wastes are picked up. (by diffusion) Diffusion is possible because capillary walls are very thin. From the capillaries, blood (now oxygenpoor) flows into veins. vein a blood vessel that carries blood back to the heart They carry blood back from the lungs, or back from the body have thinner walls than arteries (Veins are under less pressure.) Since blood in veins is under less pressure, skeletal muscles help push the blood along by contracting around the vein. Larger veins have valves in them to keep the blood flowing in the right direction. Loop 1 Loop 2 Blood flows in 2 loops through the body: blood leaves the heart (in an artery), travels to the lungs, then back to the heart (in a vein) blood leaves the heart (in arteries), travels throughout the body, then back to the heart (in veins) 2

3 Order of Blood Flow in the Body: 1. Oxygen-rich blood leaves the lungs. 2. Enters left atrium through. veins 3. Enters left ventricle through a. valve 4. Leaves left ventricle through. arteries 5. Travels to smaller arteries throughout the body. 6. Travels to capillaries throughout the body. 7. Blood goes to the cells and trades oxygen & nutrients for waste products and carbon dioxide (CO 2 ). 8. Leaves capillaries and enters smaller veins (blood is now oxygenpoor) 9. Enters larger veins. 10. Enters right atrium through. veins 11. Enters right ventricle through a. valve 12. Pumped to the lungs through an. artery aorta the largest artery in the body that carries blood out of the left ventricle to the rest of the body Smaller arteries branch off the aorta to carry blood to the capillaries. coronary arteries small arteries that branch off the aorta and carry blood to the cells in the heart. (The heart is made of cells and these need oxygen and nutrients as well.) pulse the expansion and relaxation of an artery wall as blood is pumped through it. Each time your heart beats a spurt (or surge) of blood expands your arteries. When you feel your pulse, you are not feeling your heartbeat! blood pressure the force that is exerted by the blood against the walls of blood vessels caused by the ventricles contracting and forcing blood out of the heart As blood moves farther from the heart, blood pressure decreases. (Blood pressure is greatest right out of the heart.) Section 2 (Blood and Lymph) Parts of Blood: 1. plasma 2. red blood cells 3. white blood cells 4. platelets plasma the liquid part of blood Plasma is 90% water. Plasma carries nutrients (such as glucose), fats, vitamins, and minerals Plasma carries away waste products from cell processes. red blood cells take up oxygen in the lungs and deliver it to the cells in the body. Red blood cells are produced in bone marrow. Red blood cells are made mostly of hemoglobin to help it carry oxygen. Red blood cells are formed with a nucleus, but lose their nucleus as they mature. Red blood cells live about 120 days. (They have no nucleus to reproduce themselves.) Red blood cells are the most numerous cell type in the body. hemoglobin an iron-containing protein in red blood cells that binds (attaches) to oxygen molecules Hemoglobin in red blood cells picks up oxygen in the lungs and drops it off to cells that need it as blood travels through capillaries. Oxygen attaches to iron in the hemoglobin. (important to have iron in your diet) white blood cells a blood cell that fights disease Less numerous than red blood cells Are much larger than red blood cells White blood cells have a nucleus. 3

4 platelets fibrin cell fragments in blood that helps form clots to stop bleeding from cuts When a blood vessel is cut, platelets stick together to seal it off. Platelets then release a chemical that produces a protein called fibrin. The blood clot dries to form a scab. New cells form under the scab and eventually push it off the skin. a protein produced by platelets in the blood after a vessel is cut Fibrin forms a net of tiny fibers to stop blood flow from a cut. blood transfusion Blood types: 1. type A 2. type B 3. type AB 4. type O the transfer of blood from one person to another If the wrong blood type is put into a person the red blood cells will clump together, clog capillaries and may lead to death. marker molecules proteins on red blood cells that determine blood type Type A blood has the A marker. Type B blood has the B marker. Type AB blood has both A and B markers. Type O blood has neither A nor B markers. Marker molecules on your red blood cells determine the type of blood you can safely receive. clumping proteins proteins in blood plasma that recognize foreign markers (markers that are not naturally found in your body) Example: Clumping proteins make foreign red blood cells clump together. If you have Type A blood, and you receive Type B blood from someone else, the Type B cells will clump together and not flow freely. Rh factor another protein on red blood cells that can cause clumping of blood Rh positive blood type with the Rh marker on their red blood cells (Most people are Rh positive.) Rh negative you do not have the Rh marker on your red blood cells Rh positive blood mixed with Rh negative blood will cause clumping. Blood types in the U.S: Type O most common Type A 2nd most common Type AB rarest blood type Rh + is more common than Rh -- in each blood type Lymphatic system lymph a network of vein-like vessels that returns fluid to the blood that leaked out of blood vessels the fluid that the lymphatic system collects and returns to the blood Lymph vessels throughout the body empty lymph into large veins in the chest to return materials to the blood. lymph node a small knob of tissue in the lymphatic system that filters lymph to trap bacteria and other microorganisms that cause disease. When the body is fighting an infection (illness), the lymph nodes swell. 4

5 Section 3 (Cardiovascular Health) Atherosclerosis a condition in which an artery wall thickens from a buildup of fatty materials This reduces the blood flow through the artery. Oxygen and nutrients cannot be delivered as well through a blocked artery. Blocking of the coronary arteries can lead to a heart attack. Cholesterol white waxy substance found in many of the things we eat. ( egg yolk, saturated fats or animal fats ) 1. Cholesterol reacts with calcium in our blood to cause atherosclerosis and forms a fatty or waxy lining in blood vessels. Normal artery Start of waxy buildup atherosclerosis heart attack a condition in which blood flow to part of the heart muscle is blocked, causing heart cells to die from lack of oxygen and nutrients. Blood flow High blood pressure 2. This leads to hardening of the arteries where vessels become less elastic and have less blood flow 3. This leads to higher blood pressure behind the clogged area. 4. If coronary arteries become completely clogged heart attack hypertension (high blood pressure) a disorder in which a person s blood pressure is consistently higher than normal makes the heart work harder to get oxygen to all the cells through the clogged artery. People with hypertension need to limit the amount of sodium in their diet and exercise. To prevent atherosclerosis and hypertension: 1. Exercise regularly to build up heart muscle and increase lung volume Strong hearts can pump more blood per beat so the heart does not have to beat as often to give the cells what they need. 2. Eat the right foods limit foods high in cholesterol (red meat, eggs, cheese in small amounts) limit foods high in saturated fats (animal fats) (butter, whole milk, ice cream) limit foods high in trans fats (margarine, potato chips, doughnuts) Exercise increases the size of the lungs so more oxygen can be diffused with each breath. 5

6 3. Don t smoke smokers are twice as likely to have a heart attack Tar from smoking builds up in the lungs and reduces the amount of air they can hold. This means less oxygen can diffuse into the blood stream for the body cells. The cells still need oxygen, so the heart beats faster to make sure they get enough. (overworks the heart) 6