THE CARDIOVASCULAR THE CARDIOVASCULAR SYSTEMSYSTEM

VITAL FUNCTIONSVITAL FUNCTIONS

• pumps 7000 liters of blood / day

• beats ~2.5 billion times

• to carry O2 from the lungs to the body’s cells

• to carry nutrients from the digestive system to the cells

• to remove cellular waste

• to form clots / to coagulate (an anticoagulant prevents clotting)

YOUR BLOOD: YOUR BLOOD: FLUID TRANSPORTFLUID TRANSPORT

• blood is a tissue made of

fluid, cells, & fragments of cells– fluid = plasma, 55% of the total volume of blood– cells = red & white blood cells suspended in plasma

• usually 45% of the total volume of blood• this percentage is called the hematocrit (HCT)

– fragments = platelets suspended in plasma

YOUR BLOOD: YOUR BLOOD: FLUID TRANSPORTFLUID TRANSPORT

• red blood cells (RBC’s): erythrocytes– round, disk-shaped cells – make up 44% of the total volume of blood– produced in the red bone marrow of the ribs,

humerus, femur, sternum, and other long bones

red blood cells (RBC’s): Erythrocytesred blood cells (RBC’s): Erythrocytes

– only have a nucleus in the early stages of development

– active about 120 days, then broken down in the spleen & liver by macrophages via phagocytosis

– contain hemoglobin, an iron-rich protein molecule that binds to O2

– oxygenated RBC’s carry oxygen from the lungs to the body’s cells

Anemia:Anemia:

= too few RBC’s or too little hemoglobin. Person is pale & lacks energy. Caused by low iron intake.

carbon dioxide in the blood:carbon dioxide in the blood:

– 70% of the CO2 combines with water in plasma to form bicarbonate (affects the pH of blood)

– 30% is attached to hemoglobin or dissolved in plasma

white blood cells (WBC’s): leukocytes:white blood cells (WBC’s): leukocytes:

– infection fighters– play a major role in protecting you from

foreign substances, and from invading bacteria

– make up 1% of total blood volume– they are larger than RBC’s & they have a

nucleus

blood clotting:blood clotting:

– platelets help blood to clot by linking together a sticky network of protein fibers called fibrin

– this forms a web over the wound to catch escaping RBC’s

– platelets are produced in bone marrow & last only 1 week

ABO BLOOD GROUPSABO BLOOD GROUPS

• blood surface antigens determine blood group– antigen = substances that stimulate an

immune response– antigens are on the

surface of certain RBC’s– 2 types of antigens:

A & B

– blood plasma contains antibodies that are shaped to correspond with the different blood surface antigens

– the antibodies react with the matching antigen if they are brought together, resulting in clumped blood

– you don’t have

antibodies for your

own antigen type

– type A blood has A antigens and anti-B antibodies

– type B blood has B antigens and anti-A antibodies

Rh factor = Rhesus factor:Rh factor = Rhesus factor:

– another antigen which may be present (Rh+) or absent (Rh-)

– Rh factor is an inherited characteristic – only 15% of the U.S. population is Rh-

– may complicate pregnancies• an Rh- mother that is pregnant with a Rh+

baby will make anti-Rh+ antibodies when their blood mixes at birth

• if she gets pregnant again with another Rh+ baby, her anti-Rh+ antibodies will destroy RBC’s in the fetus

• prevention: mom is treated with a substance to prevent the production of antibodies in her blood at 28 weeks & again shortly after the birth of the first baby

YOUR BLOOD VESSELS: YOUR BLOOD VESSELS: PATHWAYS OF CIRCULATIONPATHWAYS OF CIRCULATION

• 3 main types: arteries, veins, capillaries + venules & arterioles

• 62,000 miles of blood vessels in your body!

arteries:arteries:

– large, thick walled,

muscular, elastic

blood vessels– carry blood away

from the heart

under great pressure– main arteries divide into smaller arteries that

divide into arterioles which eventually branch into capillaries

capillaries:capillaries:

– microscopic blood vessels only 1 cell thick– enables nutrients & gases to diffuse easily

between blood cells & surrounding tissue cells– form a dense network that reaches virtually

every cell in the body– join to form venules as

blood leaves tissues

veins:veins:– venules merge to form veins– carry blood from the tissues

back to the heart– less pressure than the arteries– blood travels against gravity in

some veins, so they are equipped with valves to prevent blood flowing backward

YOUR HEART: YOUR HEART: THE VITAL PUMPTHE VITAL PUMP

• the heart– a large organ made of cardiac muscle cells

rich in mitochondria– main function = to keep blood moving

constantly thru the body

• Myocardium = thick layer of muscle in the walls of the heart

• Pericardium = serous membrane that encloses the heart

all mammalian hearts have 4 chambers:all mammalian hearts have 4 chambers:

• 2 upper chambers = L & R atria

• 2 lower chambers = L & R ventricles

• the atrial walls are thinner & less muscular than the ventricles because they perform less work

• the L ventricle works harder than the R, so it’s bigger making the heart lopsided

• a solid septum separates the whole R side from the L, so blood never mixes

Valves of the heart:Valves of the heart:

- the tricuspid valve sits between the R atrium & the R ventricle & it permits blood to flow thru while preventing backflow

– the bicuspid (mitral) valve sits between the L atrium & the L ventricle, & does the same job as the tricuspid

– the bicuspid & tricuspid valves are called atrioventricular

– the pulmonary & aortic valves are called semilunar because their cusps are shaped like half moons

– the aortic valve sits at the entrance to the aorta & prevents backflow into the L ventricle

– the pulmonary valve sits at the entrance to the pulmonary trunk & prevents backflow into the R ventricle

blood’s path through the heart:blood’s path through the heart:

– blood enters the heart thru the atria & leaves thru the ventricles

– both atria fill up at the same time– the R atrium receives O2 poor - CO2 rich

blood from the head & body via 2 large veins, the vena cava

blood’s path through the heart:blood’s path through the heart:

– the L atrium receives O2 rich blood from the lungs via 4 pulmonary veins (the only veins to carry oxygen-rich blood)

– after the atria fill with blood, they contract & push it into the ventricles

– after the 2 ventricles

are full, they contract

simultaneously

– the R ventricle pushes O2 poor blood out of the heart & towards the lungs thru the pulmonary arteries (the only arteries to carry oxygen-poor blood)

– the L ventricle pushes O2 rich blood out of the heart thru the aorta (the largest blood vessel in the body) to the arteries

PATH OF BLOOD:PATH OF BLOOD:

• Vena cava (superior / inferior) * Pulmonary veins

• Right atrium * Left atrium• Tricuspid valve * bicuspid valve• Right ventricle * left ventricle• Pulmonary semi-lunar valve * aortic semi-lunar• Pulmonary arteries * aorta • Capillaries of lungs * all body cells

the heart acts as 2 separate pumps, the heart acts as 2 separate pumps,

following 2 pathwaysfollowing 2 pathways ::

– pulmonary circulation = the right side of the heart pumps blood from the heart to the lungs

– systemic circulation = the left side of the heart pumps blood from the heart to the rest of the body

heartbeat regulationheartbeat regulation

– each heartbeat causes a surge of blood to flow from the L ventricle into the aorta & then into the arteries = pulse

– best felt in the arm’s radial artery or the neck’s carotid artery

heartbeat regulationheartbeat regulation

– heart rate is set by the pacemaker in the top of the R atrium

• sends an impulse to the atria

• triggers another impulse to contract the ventricles

– electrocardiograph = a machine

that measures & records these

electrical signals

heartbeat regulationheartbeat regulation

– electrocardiogram = the reading produced by this machine

– the ECG is an important tool used to diagnose abnormal heart rhythms & patterns

blood pressureblood pressure

= the force that the blood exerts on the blood vessels

– it rises & falls as the heart contracts & relaxes

– it rises sharply when the ventricles contract = systolic pressure / systole

– it drops dramatically as the ventricles relax = diastolic pressure / diastole

blood pressureblood pressure

• hypertension = high blood pressure = persistently elevated arterial pressure. Can be caused by kidney disease, high sodium intake, obesity, psychological stress, or arteriosclerosis (hardening of the arteries)

control of the heartcontrol of the heart

– the medulla oblongata regulates the rate of the pacemaker

– sensory cells in the arteries become stretched when the heart beats too fast which sends a signal to the medulla oblongata

control of the heartcontrol of the heart

• if the heart slows too much, blood pressure drops which signals the medulla oblongata to speed up the pacemaker

RELEVANT VOCABULARY:RELEVANT VOCABULARY:

• Pericarditis = inflammation of the pericardium• Pulmonary circulation = a circuit transporting blood

between the heart & lungs• Systemic circulation = a circuit transporting blood

between the heart & body tissues• Myocardial infarction = a heart attack• Tachycardia = rapid heart rate (100+ beats / min)• Bradycardia = abnormally slow heart rate (<60)

• Heart murmur = abnormal or unusual heart sounds, can be due to valve incompetence

• Cardiac output = the volume of blood pumped out by each side of the heart in 1 min

• Stroke volume = the volume of blood pumped out a ventricle with each heartbeat

• Congestive heart failure = a progressive condition occurring when the pumping efficiency of the heart is depressed so that circulation is inadequate to meet tissue needs

• Pulmonary edema = blood vessels leak fluid into the air sacs and tissues of the lungs

• Atherosclerosis = fatty deposits / plaque clogs the blood vessels, leads to arteriosclerosis (hardening of the arteries)

• Leukemia = cancer of the white blood cells