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
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
- 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
