CHAPTER 23 Circulation It transports O 2 and nutrients to cells It takes away CO 2 and other wastes Artery and vein, cross-sectionBlood smear

Circulatory system made up of 3 parts  organ heart  tissues & cells blood vessels  arteries  veins  capillaries blood  red blood cells  plasma

The circulatory system associates intimately with all body tissues  Capillaries are microscopic blood vessels They form an intricate network among the tissue cells Capillary Red blood cell

The circulatory system associates intimately with all body tissues II No substance has to diffuse far to enter or leave a cell Diffusion of molecules INTERSTITIAL FLUID Capillary Tissue cell

The cardiovascular system has two circuits  The pulmonary circuit conveys blood between the heart and gas-exchange tissues  The systemic circuit carries blood between the heart and the rest of the body

 2 part system Circulation to lungs(pulmonary)  blood gets O 2 from lungs  drops off CO 2 to lungs  brings O 2 -rich blood from lungs to heart Circulation to body(systemic)  pumps O 2 -rich blood to body  picks up nutrients from digestive system  collects CO 2 & cell wastes Circulation of Blood heart lungs body Circulation to lungs Circulation to body

The human heart  4-Chambered heart atria (atrium)  thin wall  collection chamber  receive blood ventricles  thick wall pump  pump blood out right atrium left atrium right ventricle left ventricle

AV SL AV Lub-dub, lub-dub  4 valves in the heart flaps of connective tissue prevent backflow  Heart sounds closing of valves “Lub”  force blood against closed AV valves “Dub”  force of blood against semilunar valves  Heart murmur leaking valve causes hissing sound blood squirts backward through valve

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.

Blood vessels arteries arterioles capillaries venules veins artery arteriolesvenules 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 pulmonary artery pulmonar y artery = to lungs aorta carotid = to head to brain & left arm to right arm coronary arteries to body

Veins: Built for their job  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 Open valve Blood flows toward heart Closed valve

Major Veins pulmonary vein = from lung superior vena cava = from upper body pulmonary vein = from lung inferior vena cava = from lower body

Structure-function relationship  Capillaries very thin walls allows diffusion of materials across capillary  O 2, CO 2, H 2 O, food, waste body cell O2O2 food waste CO 2

The heart contracts and relaxes rhythmically  Diastole Blood flows from the veins into the heart chambers  Systole The atria briefly contract and fill the ventricles with blood Then the ventricles contract and propel blood out

The pacemaker sets the tempo of the heartbeat  The SA node (pacemaker) generates electrical signals that trigger the contraction of the atria  The AV node then relays these signals to the ventricles heart pumping controlled by electrical impulses signal also transmitted to skin = EKG electrocardiogram

Connection: What is a heart attack?  A heart attack is damage that occurs when a coronary feeding the heart is blocked Aorta Left coronary artery Blockage Dead muscle tissue Right coronary artery

Cardiovascular diseases are the leading cause of death in the United States  Blood vessel blockage is usually due to blood clots  Atherosclerosis: Growths called plaques develop in the inner wall of the arteries, narrowing their bore  In some cases, plaques also become hardened by calcium deposits, leading to arteriosclerosis, commonly known as hardening of the arteries Plaque Epithelium Smooth muscle Connective tissue

Women & Heart Disease  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 Death rates for heart disease per 100,000 women, 2002

Blood exerts pressure on vessel walls  Blood pressure depends on cardiac output resistance of vessels  Pressure is highest in the arteries It drops to zero by the time the blood reaches the veins Systolic pressure Diastolic pressure Relative sizes and numbers of blood vessels

Three factors keep blood moving back to the heart muscle contractions breathing one-way valves

Connection: Measuring blood pressure can reveal cardiovascular problems  Blood pressure is measured as systolic and diastolic pressures  Hypertension is persistent systolic pressure higher than 140 mm Hg and/or diastolic pressure higher than 90 mm Hg  It is a serious cardiovascular problem

STRUCTURE AND FUNCTION OF BLOOD  Blood consists of cells suspended in plasma  Plasma is an aqueous solution of various substances

Blood Cell production ribs, vertebrae, breastbone & pelvis  Stem cells  “parent” cells in bone marrow  differentiate into many different types of cells white blood cells red blood cells white blood cells

Blood & blood cells  Blood is a tissue of fluid & cells plasma  liquid part of blood  dissolved salts, sugars, proteins, and more cells  red blood cells (RBC) transport O 2 in hemoglobin  white blood cells (WBC) defense & immunity  platelets blood clotting

Red blood cells  transport oxygen  Small round cells produced in bone marrow 5 liters of blood in body 5-6 million RBC in drop of human blood last 3-4 months (120 days)  filtered out by liver  ~3 million RBC destroyed each second

Hemoglobin  Protein which carries O 2 250,000 hemoglobins in 1 red blood cell O2O2 O2O2 O2O2 O2O2

White blood cells help defend the body  White blood cells (leukocytes)  function both inside and outside the circulatory system They fight infections and cancer

Blood clots plug leaks when blood vessels are injured  When a blood vessel is damaged, platelets respond They help trigger the formation of an insoluble fibrin clot that plugs the leak

Connection: Stem cells offer a potential cure for leukemia and other blood cell diseases  All blood cells develop from stem cells in bone marrow Such cells may prove valuable for treating certain blood disorders

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