Blood vesseles

• What is the function of arteries in the circulatory system?

  To carry blood away from the heart
• What do arterioles do in the circulatory system?

  Deliver blood to the capillaries
• What happens in the capillaries?

  Molecules diffuse between blood and body cells
• What is the central cavity of the artery called?

  The lumen
• Why is the wall of the artery relatively thick?

  To withstand high blood pressure
• What protein is rich in the outer layer of the artery wall?

  Collagen
• What role does smooth muscle play in arteries?

  Controls blood flow by contracting and relaxing changing the diameter
• How do smaller arteries differ from larger arteries?

  They contain more smooth muscle
• What happens to elastic fibers when the heart contracts?

  They stretch to accommodate high pressure
• What is the function of elastic recoil in arteries?

  Keeps blood moving smoothly forward
• What is the effect of the pulse in arteries?

  Blood is pushed down under high pressure
• How does the structure of arterioles differ from arteries?

  Arterioles have thinner collagen and elastic layers
• What is vasoconstriction?

  Contraction of smooth muscle in arterioles
• What is vasodilation?

  Relaxation of smooth muscle in arterioles
• When does vasodilation occur?

  When an organ needs more oxygen
• What are the main structural features of arteries?

  • Thick walls to withstand high pressure
  • Collagen-rich outer layer for strength
  • Smooth muscle layer for blood flow control
  • Elastic fibers for stretching and recoil
  • Lumen lined with endothelial cells to reduce friction
• What are the main structural features of arterioles?

  • Thinner collagen and elastic layers than arteries
  • Relatively thicker smooth muscle layer
  • Lower blood pressure compared to arteries
  • Involved in controlling blood flow to capillaries
• What is the process of blood flow through the circulatory system?

  1. Heart pumps oxygenated blood into arteries
  2. Arteries branch into arterioles
  3. Arterioles deliver blood to capillaries
  4. Molecules diffuse between blood and body cells
  5. Blood returns through venules and veins to the heart
• How do arteries and arterioles differ in function and structure?

  • Arteries: carry blood away from heart, thicker walls, higher pressure
  • Arterioles: deliver blood to capillaries, thinner walls, lower pressure, more smooth muscle
• What is the significance of the pulse in arteries?

  • Indicates high pressure blood flow
  • Results from heart contractions
  • Helps maintain forward blood movement
• What are the roles of vasoconstriction and vasodilation in arterioles?

  • Vasoconstriction: reduces blood flow through capillaries
  • Vasodilation: increases blood flow through capillaries
  • Regulates oxygen supply to organs
• What should you be able to describe by the end of the video?

  The structure of capillaries
• How are capillaries adapted for the diffusion of molecules?

  They have thin walls and extensive branching
• What do arteries carry from the heart?

  Oxygenated blood
• What do arterioles do?

  They carry blood to capillaries
• What is a network of capillaries called?

  Capillary bed
• What substances are exchanged in capillary beds?

  Oxygen, glucose, and waste products
• Why is the extensive branching of capillaries important?

  It provides a massive surface area for exchange
• What is the structure of capillary walls?

  Single layer of endothelial cells
• What is the role of the basement membrane in capillaries?

  It provides structural support
• How does the thin wall of capillaries affect diffusion?

  It reduces the diffusion distance
• What is the diameter of the capillary lumen compared to a red blood cell?

  Slightly greater than a red blood cell
• How does the shape of red blood cells affect their movement through capillaries?

  They travel in single file
• Why does slower movement of red blood cells benefit diffusion?

  It increases time for diffusion
• What are the small gaps in capillary walls for?

  Allow fluid and white blood cells to pass
• What is tissue fluid?

  Fluid that bathes the cells
• What essential molecules does tissue fluid provide?

  Glucose and amino acids
• What role do gaps in capillary walls play in immunity?

  Allow white blood cells to leave bloodstream
• What are the adaptations of capillaries for diffusion?

  • Extremely thin walls (single layer of cells)
  • Extensive branching for large surface area
  • Small lumen diameter for close contact with red blood cells
  • Gaps in walls for fluid and white blood cell passage
• What should you be able to describe by the end of the video?

  The structure of veins