Transport

• What are the adaptations of capillaries?


  They are thin and have pores, making them permeable.
• What components are found in blood?

  Red blood cells, plasma, white blood cells, and platelets.
• What is the outer layer of arteries called?

  The tunica externa, which contains elastin and collagen.
• What is the composition of the tunica media in arteries?


  It contains smooth muscle.
• How does the tunica media of arteries compare to that of veins?


  The tunica media is thicker in arteries than in veins.
• What is the function of the thick layer of muscle and elastic fibers in arteries?


  To withstand high pressure.
• Do arteries have valves?


  No, arteries do not have valves.
• What is the direction of blood flow in arteries?


  Blood flows away from the heart.
• Where can pulse rate be measured?

  At the radial artery in the wrist and the carotid artery in the neck.
• What devices can be used to measure pulse rate?

  Smart watches or oximeters.
• What is the structure of capillaries?


  Capillaries have one layer of endothelial cells.
• What is the significance of capillaries having no tunica media or muscle and elastic fibers?


  It allows for easier material exchange.
• What are the adaptations of arteries for high pressure?


  Thick walls, collagen in the outer wall, and elastic fibers.
• How do smooth muscle and elastic fibers in arteries help maintain blood pressure?


  Smooth muscle contracts and elastic fibers stretch and recoil.
• Why is a narrow lumen important in arteries?


  It helps maintain high blood pressure.
• What is the role of smooth endothelial cells lining the lumen of arteries?


  They reduce friction in blood flow.
• What is the surface area of capillaries like?


  Capillaries have a large surface area as they are branched and have a narrow diameter.
• Why is the narrow lumen of capillaries significant?


  It is wide enough for one red blood cell, facilitating efficient exchange.
• How do the thin walls of capillaries aid in their function?


  They allow for faster diffusion of materials.
• What is the significance of the permeable walls of capillaries?


  They allow for material exchange.
• What connects arterioles to venules?


  Capillaries connect arterioles to venules.
• What is the blood flow rate in capillaries?


  Capillaries have the slowest blood flow.
• What are the adaptations of veins?


  Thin walls, wide lumen, and compression by skeletal muscles to move blood back to the heart.
• What is atherosclerosis?

  Atherosclerosis is the hardening and narrowing of arteries due to cholesterol buildup.
• What does the coronary artery supply to the heart?


  The coronary artery supplies the heart with oxygen and nutrients.
• What happens when the coronary artery is occluded?


  It can lead to death of heart tissue and chest pain due to lack of oxygen.
• What is an atheroma?


  An atheroma is a buildup of cholesterol that narrows arteries.
• What can form if the plaque in an artery ruptures?


  A thrombus can form, restricting blood flow.
• What happens if a thrombus becomes dislodged?


  It becomes an embolus and can cause a blockage at another site.
• What attracts macrophages to sites of damage in arteries?


  Macrophages are attracted to release growth factors that stimulate fibrous tissue development.
• What do macrophages do with cholesterol in arteries?


  They consume cholesterol and form a plaque.
• What is tissue fluid?


  Tissue fluid surrounds cells and allows for the exchange of materials between blood and cells.
• How does tissue fluid form?


  It forms from plasma leaking out of capillaries.
• What happens at the arterial end of a capillary?


  Fluid exits as capillary hydrostatic pressure is greater than blood osmotic pressure.
• What occurs at the mid capillary?


  There is no net movement as capillary hydrostatic pressure equals blood osmotic pressure.
• What happens at the venous end of a capillary?


  Fluid enters the capillary as capillary hydrostatic pressure is less than blood osmotic pressure.
• What is the concentration of nutrients and oxygen in tissue fluid?


  Tissue fluid has a high nutrient and oxygen concentration.
• What causes oedema?

  Oedema is swelling caused by excess tissue fluid.
• How is most tissue fluid returned to blood plasma?


  Most tissue fluid returns to blood plasma, while the rest is taken up by lymph ducts.
• What happens to lymph fluid in the lymphatic system?


  Lymph travels through the lymphatic system and returns to the blood via lymph nodes.