Circulatory System Lesson

Circulatory
System
Structures

● Heart

● Blood Vessels

○ Arteries

○ Veins

○ Capillaries

● Blood

Circulatory System Function

The overall function of the circulatory
system is to transport materials
throughout the body toward and away
from particular target organs and tissues.

–Brings Oxygen & nutrients to cells

–Takes away Carbon Dioxide & waste

Two Pathways

Pulmonary Circulation

●Carries blood to lungs and back to the heart

Systemic Circulation

●Carries blood to body and back to the heart

Arteries:
Carries blood
Away from heart

Veins:
Carries blood To
the heart

● Large, elastic
● Thick-walled, Muscular
● Oxygenated blood

○ Exception: Pulmonary Artery

● Blood flows slower, low pressure
● Thin-walled with valves to prevent

backflow of blood

● De-oxygenated blood

○ Exception: Pulmonary Vein

Capillaries

● Smallest vessel

● Microscopic

● Walls- only one cell thick

● They pass between cells of all

tissues in the body

● Purpose-exchange substances

○ Oxygen/Nutrients: into cells

○ Carbon Dioxide/Waste: out

Heart:
Structure
and Function

● Keeps blood moving

● Around the size of a closed fist.

● Large organ composed of cardiac

muscle (involuntary)

● Hollow muscle with chambers &

valves.

● Beats about 100,000 times a day.

Heart:
Structure

Four chambers

● Two upper (Right & Left Atrium)

● Two lower (Right & Left Ventricle)

Four valves

● Tricuspid
● Pulmonary
● Mitral
● Aortic

Blood

● Body contains 4-6 Liters

● About 7% of body weight

● Consists of:

○ Water

○ Plasma

○ Erythrocytes (RBC)

○ Leukocytes (WBC)

○ Platelets

Erythrocytes
(RBC)

● Transporters of:

○ Oxygen

○ Carbon Dioxide

● Red blood cells (RBC): produced in

bone marrow of:

○ long bones: ex. humerus & femur

● Living cells: 100-120 days

Leukocytes
(WBC)

● White blood cells fight infection:

○ Destroy bacteria

○ Produce antibodies

● Produced in the spleen & lymph

nodes

○ Less abundant

○ Living cells

Platelets

● Help to prevent bleeding

○ Clots blood

● Cell fragments

○ Produced in bone marrow

○ Non-living cells

● Works with fibrin (sticky network of

protein fibers)

○ Form a web trapping blood cells

to create the blood clot