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20.1: The Circulatory System Section Objectives: Distinguish among the various components of blood Trace the route blood takes through the body and heart. Explain how heart rate is controlled. Circulatory system made up of 3 parts organ heart tissues & cells blood vessels arteries veins capillaries blood red blood cells plasma Your Blood: Fluid Transport Blood is a tissue of fluid & cells transports O2 and nutrients to cells takes away CO2 and other wastes Aids in fighting disease Helps maintain body temp. Blood composition: Plasma: 55% (liquid part) Blood cells: 45% (red, white, & platelets Blood Cell production ribs, vertebrae, breastbone & pelvis Stem cells “parent” cells in bone marrow differentiate into many different types of cells white blood cells white blood cells red blood cells Red blood cells: Oxygen carriers Bioconcave disc shaped, most numerous No nucleus when mature, last 120 days 5-6 million RBC in drop of human blood Produced in red marrow of long bones contain hemoglobin Hemoglobin enables the transport of O2 Hemoglobin Protein which carries O2 250,000 hemoglobins in 1 red blood cell O2 O2 O2 O2 White blood cells: Infection fighters Largest blood cell play a major role in protecting your body from foreign substances. White Blood Cells Platelets: Blood clotting Smallest (fragments) help blood clot after an injury. Short-lived Blood vessels arteries veins artery venules arterioles arterioles capillaries venules veins Arteries: Built for their job Arteries blood flows away from heart thicker walls provide strength for high pressure pumping of blood elastic & stretchable maintains blood pressure even when heart relaxes Major arteries aorta carotid = to head to brain & left arm to right arm to body pulmonary artery pulmonary coronary arteries artery = to lungs Veins: Built for their job Veins Blood flows toward heart blood returns back to heart Open valve thinner-walled blood travels back to heart at low speed & pressure why low pressure? far from heart blood flows because muscles contract when we move squeeze blood through veins valves in large veins Closed valve in larger veins one-way valves allow blood to flow only toward heart Major Veins superior vena cava = from upper body pulmonary vein = from lung pulmonary vein = from lung inferior vena cava = from lower body Structure-function relationship Capillaries very thin walls allows diffusion of materials across capillary waste body cell O2, CO2, H2O, food, waste CO2 O2 food Your Heart: The Vital Pump Atria: upper chamber which receive blood that pump blood to Ventricles: muscular walled chambers which pump blood from heart left atrium right atrium right ventricle left ventricle Circulation of Blood Circulatio to lungs 2 part system Circulation to lungs blood gets O2 from lungs drops off CO2 to lungs brings O2-rich blood from lungs to heart lungs heart Circulation to body pumps O2-rich blood to body picks up nutrients from digestive system collects CO2 & cell wastes body Circulatio to body Blood’s path through the heart 1. vena cavae 2. right atrium 3. valve 4. right ventricle 5. valve 6. pulmonary artery (to lungs) 7. pulmonary veins 8. left atrium 9. valve 10. left ventricle 11. valve 12. aorta largest blood vessel in the body. Heartbeat regulation surge of blood through an artery is called a pulse. Sinoatrial node (Pacemaker Pacemaker: initiates heartbeat generates an electrical impulse that spreads over both atria. Blood pressure the force that the blood exerts on the blood vessels. Blood pressure is measured as systolic (ventricles contract) and diastolic (ventricles relax) pressures Control of the heart A portion of the brain called the medulla oblongata regulates the rate of the pacemaker, speeding or slowing its nerve impulses. If the heart beats too fast, the medulla oblongata, sends signals that slow the pacemaker. If the heart slows down the medulla oblongata sends signals to speed up the pacemaker and increase the heart rate. Medulla oblongata Circulatory System & Homeostasis Homeostasis ATP keeping the internal environment of the body balanced need to balance food & O2 in need to balance energy (ATP) production need to balance CO2 & waste out Exercise heart beat faster food O2 CO waste need more ATP bring in more O2 & food; remove more CO2 & waste out Disease poor lung or heart function = heart beat faster need to work harder to bring in O2 & food & remove wastes Cardiovascular disease Atherosclerosis & Arteriosclerosis deposits inside arteries (plaques) develop in inner wall of the arteries, narrowing their channel increase blood pressure increase risk of heart attack, stroke, kidney damage normal artery hardening of arteries Cardiovascular health Risk Factors genetics diet high animal fat exercise & lifestyle smoking lack of exercise bypass surger Women & Heart Disease Death rates for heart disease per 100,000 women, 2002 Risk factors Smoking Lack of exercise High fat diet Overweight Heart disease is 3rd leading cause of death among women aged 25–44 years & 2nd leading cause of death among women aged 45–64 years. 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