CIRCULATORY SYSTEM

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.

Components

Blood Vessels Blood Heart

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

Blood Vessels

There are three types of blood vessels: Arteries Capillaries Veins

Arteries/Arterioles

thick muscular walls, carry blood away from heart, propelled by blood pressure (heart)

Capillaries

Very thin walls, only one cell thick, site of nutrient/gas exchange

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).

Valves

Different valves stop blood from flowing in the wrong direction.

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.

Blood

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