Transport in Animals

• Outline the features of a good transport system:

  • A fluid or medium to carry nutrients and oxygen around the body (blood)
  • A pump to create pressure that will push the fluid around the body (heart)
  • Exchange surfaces
  • Tubes to carry the blood (vessels)
  • A double circulatory system
• Define Single Circulatory System:

  Where blood flows through the heart once as it travels through one circuit
• Define Double circulatory system:

  Where blood flows through the heart twice as it travels through two circuits.
• Define Closed circulatory system:

  Where blood pumped by the heart is contained within blood vessels. The blood does not come into direct contact with the cells.
• Define Open circulatory system:

  Where blood pumped by the heart is not contained within blood vessels, but moves freely. The blood comes into direct contact with the cells.
• What type of circulatory system do fish have?

  closed single
• What type of circulatory system do insects have?

  open
• List the route the blood takes in the fish's closed single circulatory system:

  1. heart
  2. capillaries ⇛ body tissues
  3. gills
  4. heart
• List the route the blood takes in mammals' closed double circulatory system:

  1. heart
  2. body tissues
  3. heart
  4. lungs
  5. heart
• Define Pulmonary circulation:

  The circuit that carries deoxygenated blood from the heart to the lungs
• Define Systemic circulation:

  The circuit that carries oxygenated blood around the body from the lungs to tissues
• All vertebrates besides fish have a closed double circulatory system
• In amphibians and most reptiles there is some mixing of oxygenated and deoxygenated blood in the heart as it is not completely divided.
• What are the two types of closed circulatory systems:

  • single
  • double
• Name two features of an insect's circulatory system:

  • ostia
  • tubular heart
• Define Ostia in insects:

  Pores on the heart that allow the uptake of blood fluid (haemolymph)
• Describe the location of the tubular heart in insects.

  stretched across the dorsal surface
• Small organisms do not need a circulatory system, as they have a large surface area to volume ratio, diffusion allows the adequate exchange of gases, nutrients, and waste
• The capillaries are surrounded by body cells and tissue fluid
• Describe the circulatory system in fish:

  • closed single circulatory system
  • two chambers = one atrium, one ventricle
  • low blood pressure
  • rate of blood flow is low
  • blood travels through two sets of capillaries after being pumped out of the heart
  • capillaries are close to the surface of the lamellae of the gills
  • the rate of exchange is limited

  Route:

  1. heart
  2. capillaries ⇛ body tissues
  3. gills
  4. heart
• Fish are not metabolically active as mammals, they do not maintain their body temperature ∴ they need less energy for activity and heat from food
• The systemic circulation carries blood at a higher pressure than the pulmonary circulation
• Mammals are metabolically active animals, they maintain their body temperature ∴ they need more energy for activity and heat from food
• What two processes create a lot of heat for mammals?

  respiration and high metabolism
• In open circulatory systems, circulation is affected by body movements
• State the three major blood vessels:

  • arteries
  • veins
  • capillaries
• Define Vein:

  A type of blood vessel that carries deoxygenated blood from around the body to the heart under low pressure
• Where in the circulatory system do veins form?

  when venules join up
• Veins

  • Large lumen = 10mm diameter, maximises the volume of deoxygenated blood flowing to the heart, acts as a reservoir of blood, moves against gravity
  • thin walls = low pressure
  • Found between skeletal muscles = when contracted, adds pressure causing blood to flow
  • Collagen fibers = provides support, maintains shape
  • Thin layer of smooth muscle = allows vasoconstriction and vasodilation
  • Little elastic fibres = no pulse of blood, no need to stretch and recoil
  • semi-lunar valves = ensures blood flows in one direction, prevents backflow
  • Endothelium = lines the lumen, reduces friction
• Define Capillaries:

  The smallest type of blood vessel that forms a large network to connect the arterioles to the venules. They are the site of exchange of substances between the blood and body tissues.
• Describe the structure of the capillaries:

  • narrow lumen = 7μm diameter, erythrocytes must squeeze through in a single file, closer to the walls, more efficient diffusion
  • large network = provides large surface area, more efficient diffusion
  • rate of flow is slow = allows more time for substances to diffuse
  • permeable walls = small gaps
  • Endothelium = one cell thick, made of squamous epithelial cells, short diffusion distance, reduces friction
• Define Artery:

  A type of blood vessel that carries oxygenated blood from the heart to body tissues under high pressure
• Name the three layers of the artery wall:

  • Tunica Intima
  • Tunica media
  • Tuncia adventitia
• What does the tuncia adventitia layer of the artery wall contain?

  collagen and elastic tissue
• State what each of the layers of the artery wall contain:

  • Tunica Intima = elastic tissue and endothelium
  • Tunica media = smooth muscle
  • Tuncia adventitia = collagen and elastic tissue
• List all the blood vessels:

  • arteries
  • veins
  • capillaries
  • arterioles
  • venules
• Blood passes through the heart twice in each complete circuit.
• State the two types of circulation:

  • systemic
  • pulmonary
• Define Arteriole:

  A type of blood vessel that connects the arteries and the capillaries
• Define Venule:

  A type of blood vessel that connects the capillaries and the veins