CIRCULATORY SYSTEM
Dec 22, 2015
Function
The function of the circulatory system is to transport substances such as gases (O2, CO2), nutrients/wastes, hormones, immune system. It is also used to regulate body temperature.
Blood Pathways
There are 3 paths that blood travels: Systemic circuit: to the body and
back Pulmonary circuit: to the lungs and
back Cardiac circuit: to the heart and
back
Arteries/Arterioles
thick muscular walls, carry blood away from heart, propelled by blood pressure (heart)
Veins/Venules
Thinner walls, carry blood towards the heart, blood propelled by muscle contractions, have valves to control flow of blood
The Heart
1. aorta 2. pulmonary artery 3. pulmonary vein 4. left atrium 5. AV (mitral) valve 6. left ventricle 7. semi-lunar (aortic)
valve 8. right ventricle 9. AV (tricuspid) valve 10. right atrium 11. vena cava
The Heart
The heart is a muscular organ consisting
of 4 chambers. The atria receive blood and the ventricles pump blood.
Right Side of Heart
The right side of the heart receives blood from body and pumps it to lungs. The left side of the heart receives blood from lungs and pumps it to the body.
Left Side of Heart
The blood in the right side of the heart is de-oxygenated (does not have oxygen) while the blood in the left side of the heart is oxygenated (has oxygen).
A-V Valves
Atrio-ventricular (AV) valves prevent blood from flowing from the ventricle to the atrium.
The tricuspid valve is on the right side while the bicuspid (mitral) valve is on the left.
Semi-Lunar Valves
The semi-lunar valves prevent blood from flowing from the arteries to the ventricles.
They are also known as the pulmonary and aortic valves.
Blood
55% of blood is plasma which is mostly water and dissolved proteins, gases, glucose, hormones and ions.
Platelets are involved in blood clotting.
Red Blood Cells
The remaining 45% is mostly red blood cells with a few white blood cells.
Red blood cells have no nuclei. They contain the protein hemoglobin
which is used to carry oxygen.
White Blood Cells
White blood cells are part of the immune system.
They protect the body from infections by engulfing foreign bacteria and producing antibodies.
Circulatory Disorders
Atherosclerosis: hardening of the arteries Heart disease: cardiac vessels are
blocked, weakening heart Stroke: blood vessels in the brain burst
causing brain damage Hemophilia: blood does not clot properly Sickle-cell anemia: Reduced number of
red blood cells due to abnormal hemoglobin