20.1: The Circulatory System

1. 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.

2. Circulatory system • made up of 3 parts • organ • heart • tissues & cells • blood vessels • arteries • veins • capillaries • blood • red blood cells • plasma

3. 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

4. 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 bloodcells red bloodcells

5. 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

6. Hemoglobin • Protein which carries O2 • 250,000 hemoglobins in 1 red blood cell O2 O2 O2 O2

7. White blood cells: Infection fighters • Largest blood cell • play a major role in protecting your body from foreign substances. White Blood Cells

8. Platelets: Blood clotting • Smallest (fragments) • help blood clot after an injury. • Short-lived

9. Blood vessels arteries veins artery arterioles venules arterioles capillaries venules veins

10. 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

11. Major arteries aorta carotid= to head to brain & left arm to right arm to body pulmonaryartery pulmonaryartery=to lungs coronary arteries

12. Veins: Built for their job Blood flows toward heart • Veins • blood returns back to heart • 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 • in larger veins one-way valves allow blood to flow only toward heart Openvalve Closed valve

13. Major Veins superiorvena cava= from upper body pulmonaryvein= from lung pulmonaryvein = from lung inferiorvena cava= from lower body

14. Structure-function relationship • Capillaries • very thin walls • allows diffusion of materials across capillary • O2, CO2, H2O, food, waste body cell waste CO2 O2 food

15. Your Heart: The Vital Pump • Atria: upper chamber which receive blood that pump blood to • Ventricles: muscular walled chambers which pump blood from heart leftatrium rightatrium leftventricle rightventricle

16. Circulation of Blood Circulationto 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 • Circulation to body • pumps O2-rich blood to body • picks up nutrients from digestive system • collects CO2 & cell wastes lungs heart body Circulationto body

17. 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. aortalargest blood vessel in the body.

18. Heartbeat regulation • surge of blood through an artery is called a pulse. • Pacemaker: initiates heartbeat generates an electrical impulse that spreads over both atria. Sinoatrial node (Pacemaker

19. 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

20. 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

21. ATP CO2 O2 Circulatory System & Homeostasis • Homeostasis • 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 • 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 food waste

22. 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

23. Cardiovascular health bypass surgery • Risk Factors • genetics • diet • high animal fat • exercise & lifestyle • smoking • lack of exercise

24. Women & Heart Disease Death rates for heart disease per 100,000 women, 2002 • 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. Risk factors • Smoking • Lack of exercise • High fat diet • Overweight

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