Grade 9 Circulatory System Quiz

Circulatory System Overview

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

Objectives of Study

• Compare the two basic types of circulatory systems.
• Describe the parts of the circulatory system and their functions.
• Outline components of blood and their roles in the circulatory system.

Homeostasis

• 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.

Types of Circulatory Systems

• 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.

Parts of the Circulatory System

• 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.

Heart Structure

• 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.

Blood Types

• Oxygenated Blood:

  • Bright red, rich in oxygen and nutrients, found in arteries.

• Deoxygenated Blood:

  • Dark red, contains carbon dioxide and waste, found in veins.

Blood Vessel Types

• 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.