Body Systems: Circulatory and Heart

Body Systems (Circulatory)

• The circulatory system includes arteries, capillaries, and veins.
• Arteries carry blood from the heart; veins carry blood back to the heart.
• Capillaries facilitate the exchange of materials between blood and cells.
• Blood flow cessation, even temporarily, leads to irreversible cell death.

The Heart

• The heart has two sides (right and left).

• It has four chambers: two atria and two ventricles.

• The left ventricle has more muscle than the right ventricle to pump blood throughout the body.

• The heart has valves to ensure one-way blood flow (atrioventricular and semilunar valves).

• The "lub-dub" sound of the heart is created by these valves closing.

Cardiac Muscle and Pacemaker

• Specialized tissue (pacemaker/SAN) in the right atrium initiates electrical signals.
• These signals trigger atrial and ventricular contractions.
• Cardiac muscle allows for coordinated contractions.
• The pace of the pacemaker can be adjusted, for example, during exercise.

Coronary Heart Disease (CHD)

• Fatty deposits (plaque) build up inside arteries.
• This narrowing reduces elasticity and narrows arteries.
• Reduced blood supply may occur.
• A blood clot (thrombosis) can completely block an artery.
• Deprived heart muscle cells die, leading to a heart attack.

Comparing Arteries, Capillaries, and Veins

• Arteries have thick walls with elastic fibers to withstand high pressure.

• Veins have thin walls with valves to prevent backflow.

• Capillaries have thin walls for efficient material exchange.

• Blood pressure is higher in arteries than veins.

• Capillaries form an extensive network.

• Capillaries have a large surface area to facilitate the exchange of materials.

• Veins have a low-pressure system and require valves to prevent backflow.

• Blood flow within capillaries requires minimal resistance to flow.