Cardiovascular/Circulatory System

Consists of….

•Blood vessels

•Blood

•Heart

Blood Vessels

• Two pathways:

–Pulmonary Circulation•Carries blood to lungs and back

–Systemic Circulation•Carries blood to body and back

Capillaries of head and arms

Capillaries of abdominal organs and legs

Inferior vena cava

Pulmonary vein

Capillaries of right lung

Superior vena cava

AortaPulmonary artery

Capillaries of left lung

Pathway of Circulation-3 Types of Vessels

– Arteries- carries blood Away from heart

• Large• Thick-walled,

Muscular• Elastic• Oxygenated blood

– Capillaries• Smallest vessel• Microscopic• Walls one cell thick• Nutrients and gases

diffuse here

– Veins• Carries blood

that contains waste and CO2

• Blood not under much pressure

• Carries deoxygenated blood

BLOOD!

• Body contains 4-6 L (Depending on size)• Consists of

– Water– Red Blood Cells– Plasma– White blood cells and platelets

• It is a tissue

What’s in Blood?Liquid Portion Carries

• Blood cells

–Erythrocytes (RBC - red blood cells)

–Leucocytes (WBC - white blood cells)

• Platelets (non cellular particles)

More About What's In Blood

• Proteins

–Enzymes

–Hormones – Endocrine System

• Nutrients - Digestive System

• Gases - Respiratory System

RBCs

• Transporters of– Oxygen– Carbon Dioxide

• RBC– Lack a nucleus– Contain hemoglobin– Disk-shaped

RBCs

• RBC are produced in red bone marrow of ribs, humerus, femur, sternum

• Lives for 120 days• Old RBC are destroyed in liver and spleen

WBCs

• Fight infection

• Larger size

• Less in number

• Most live for a few days, but can live for months

• Several types

• All contain nuclei

Infection

Platelets

• PLATELETS are for CLOTTING blood

• Cell fragments

• Produced in bone marrow

• Short life span (1 week)

Blood Clotting

Break in Capillary Wall

Blood vessels injured.

Clumping of Platelets

Platelets clump at the site and release thromboplastin. Thromboplastin converts prothrombin into thrombin..

Clot Forms

Thrombin converts fibrinogen into fibrin, which causes a clot. The clot prevents further loss of blood..

The Heart

• At REST, the heart pumps about 5 QUARTS of blood a minute.

• During EXTREME EXERTION (exercise) it can pump 40 quarts a minute.

• Composed of – Cardiac muscle– Mitochondria – Enclosed in a sac (Pericardium)

Heart Structure

• Four chambers – Two upper (Atria)

• Walls thinner• Less muscular

– Two lower (Ventricles)• Walls thicker• More muscular• Do more work

Path Through The Heart

• Both Atria fill at same time– Right atrium receives oxygen POOR blood

from body from vena cava– Left atrium receives oxygen RICH blood from

lungs through four pulmonary veins

• After filled with blood atria contract, pushing blood into ventricle

More on the Path

• Right ventricle contracts and pushes oxygen-poor blood toward lungs

• against gravity, through pulmonary arteries

• Left Ventricle contracts and forces oxygen rich blood

• out of heart through aorta (largest vessel)

Heart Wall• Epicardium – visceral layer of the serous

pericardium• Myocardium – cardiac muscle layer forming

the bulk of the heart• Fibrous skeleton of the heart –

crisscrossing, interlacing layer of connective tissue

• Endocardium – endothelial layer of the inner myocardial surface

The Structures of the Heart

Right Ventricle

Right Atrium

Left Atrium

Inferior Vena Cava

Tricuspid Valve

Pulmonary Valve

Pulmonary Veins

Superior Vena CavaAorta

Pulmonary Arteries

Aortic Valve

Mitral Valve

Left Ventricle

Septum

Physiology of the Heart

• Pulmonary Valve: Keeps blood from flowing back into the right ventricle

• Bicuspid Valve: Prevents blood from flowing back into the left atrium, A.K.A. Mitral valve

• Left Atrium: Receives oxygen rich blood from the pulmonary veins

• Pulmonary Trunk: Transfers blood through the pulmonary arteries to the lungs

More Physiology • Tricuspid Valve: Prevents backflow of blood

to the right atrium

• Aorta: Blood flows from the aorta throughout the entire body

• Left Ventricle: Pumping chamber which forces blood through the aortic valve, more muscular than the right ventricle

• Right Atrium: Collecting chamber, Receives blood from the superior and inferior vena cava

More Physiology

• Inferior Vena Cava: Vein that brings oxygen-poor blood from the lower part of the body to the right atrium

• Aortic Valve: Prevents blood from going back into the left ventricle

• Interventricular Septum: Separates the pumping chambers of the heart

• Right Ventricle: Receives blood from the right atria

Heart Valves• Heart valves insure unidirectional blood flow

through the heart• Atrioventricular (AV) valves lie between the atria

and the ventricles• AV valves prevent backflow into the atria when

ventricles contract• Chordae tendineae anchor AV valves to papillary

muscles

Heart Valves

Figure 19.9

Heart Valves

• Aortic semilunar valve lies between the left ventricle and the aorta

• Pulmonary semilunar valve lies between the right ventricle and pulmonary trunk

• Semilunar valves prevent backflow of blood into the ventricles

Heart Valves

Figure 19.10

Blood Pressure

Blood against the blood vessel’s walls (Systole – contraction of heart muscle, Diastole – relaxation of heart muscle)–The systolic pressure refers to

• the pressure recorded while the ventricles pump the blood.

–The diastolic pressure refers to • the pressure recorded as the ventricles fill with

blood.

• A normal blood pressure is 120/80

Disorders

• Atherosclerosis• Hypertension• Heart Attack• Stroke• Endocarditis • Pericarditis • Deep Venous Thrombosis (DVT)• Varicose Veins