Grade 9 Circulatory System Quiz

Study Notes

Known as the transport system or cardiovascular system.
Comprises blood, blood vessels, and the heart, supplying tissues with oxygen and nutrients.

Maintains a state of balance necessary for survival.
Circulatory system contributes to homeostasis by:
- Exchanging molecules.
- Controlling the chemical makeup of blood.
- Transporting substances through organs, such as the liver and kidneys.

Open Circulatory System:
- Common in invertebrates (e.g., crustaceans, spiders, grasshoppers).
- Blood pumped through open-ended vessels, diffusing out into the body.
- Requires less energy, operates at lower pressure, suitable for organisms with slow metabolism.
Closed Circulatory System:
- Found in vertebrates, consists of a heart and a network of vessels.
- Blood is contained within vessels, allowing for higher pressure and faster metabolism.

Heart:
- Functions as a double pump, pumping oxygen-poor blood to the lungs and oxygen-rich blood to the body.
- Right side manages pulmonary circuit; left side handles systemic circuit.
- Chambers: upper (atria) and lower (ventricles); septum separates right and left sides.
- Valves prevent backflow, ensuring unidirectional blood flow.
Blood Vessels:
- Types include arteries, veins, and capillaries.
- Arteries carry oxygenated blood from the heart, veins return deoxygenated blood to the heart, and capillaries facilitate nutrient and gas exchange.
Blood Components:
- Red Blood Cells (RBCs): Transport oxygen.
- White Blood Cells (WBCs): Part of the immune response.
- Platelets: Involved in clotting.
- Plasma: Liquid component containing nutrients, hormones, and waste.

Comprised of four chambers: two atria and two ventricles.
Atria receive blood while ventricles pump blood out.
Valves:
- Atrioventricular (tricuspid and bicuspid/mitral) and semilunar valves ensure proper circulation.

Oxygenated Blood:
- Bright red, rich in oxygen and nutrients, found in arteries.
Deoxygenated Blood:
- Dark red, contains carbon dioxide and waste, found in veins.

Arteries:
- Carry blood away from the heart; thick and elastic walls withstand high pressure.
- The aorta is the largest artery; arterioles are smaller arteries leading to capillaries.
Veins:
- Return blood to the heart with thinner but wider walls, equipped with one-way valves.
- Venules are the smallest veins.
Capillaries:
- Smallest blood vessels, site of nutrient and gas exchange between blood and tissues.