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The CIRCULATORY system connects all other systems. This
system performs four (4) principal functions:

• Transportation of oxygen and carbon dioxide
• Distribution of nutrients and transportation of wastes
• Maintenance of body temperature
• Circulation of hormones

Three general components:

• FLUID (blood) in which materials are transported
• System of BLOOD VESSELS in which the fluid moves in
• PUMP – (heart) that pushes fluid throughout system

The cardiovascular system = heart + blood vessels + blood

CIRCULATORY SYSTEM:

a) Pulmonary circuit: blood from RIGHT side (low OXYGEN) pumped
to LUNGS to pick up oxygen (release CO2)

b) Systemic circuit: blood from LEFT side (high OXYGEN) pumped
through body


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Heart Structure:

HEART: a double pump

a) RIGHT: pulmonary circuit

b) LEFT: systemic circuit



A large MUSCLE called the SEPTUM separates both sides.

The heart is divided into four (4) chambers:

• ATRIA: top two chambers, thin walls, RECEIVE blood
• VENTRICLES: bottom two chambers, thick walls, PUMP blood

VALVES: these are found between atria and ventricles and where ventricles empty into arteries that leave the heart ex. Atrioventricular valves: a) bicuspid valve- between RA and RV

tricuspid valve- between LA and LV
Semilunar valves: found between ventricles and arteries




Function of Valves:

• to ensure blood flows in ONE DIRECTION only
• prevents blood from going the wrong way

BLOOD VESSELS

There are THREE main types of blood vessels:




ARTERIES

• carry blood AWAY from the heart
• THICK walls (extra muscle)
• blood under high pressure
• largest called the AORTA
• most have HIGH amounts of OXYGEN except pulmonary artery (low O2 – goes to lungs)
• ARTERIOLES: small arteries

CAPILLARIES:

• smallest blood vessels
• where exchange of materials between blood and cells occurs
• one cell thick

VEINS:

• carry blood BACK to the heart
• THIN walls (less muscle)
• blood under LOW pressure
• contain VALVES to keep blood moving in one direction

BLOOD CELLS:


WBC: - white blood corpuscles

• -many types, called LEUKOCYTES
• -function: protect the body from invading microorganisms and toxins
• -cells have a nucleus

RBC: -red blood corpuscles

• -contain hemoglobin: an iron-containing protein which helps blood carry OXYGEN and CARBON DIOXIDE
• -with oxygen the blood is bright red
• -with carbon dioxide blood is dark red
• -cells do NOT have a nucleus

PLATELETS: - small cell fragments (not really true cells)
- job: help blood CLOT by working with SERUM proteins