transport in animals

• features of a good transport system

  -circulating fluid to carry materials around the body

  -muscular pump that created pressure to push fluid around the body

  -vessels to carry fluid

  -exchange surfaces

  -2 circuits
• single circulatory system (fish)


  -blood passes through heart 1 per full circuit of body

  -low blood pressure

  -high pressure would damage capillaries in gills

  -limits speed of blood flow to rest of body- limits speed of oxygen and nutrient delivery

  -fish aren't as active as mammals, ectothermic, need less energy from respiration
• double circulatory system


  -humans and other mammals

  -pulmonary circuit carries deoxygenated blood to lungs where its oxygenated

  -systemic circuit carries blood to organs to supply them with oxygen

  -blood passes through heart 2 per full circuit of the body
• pulmonary circulation


  -blood to lungs

  -low pressure prevents damage to capillaries in the lungs
• systemic circulation


  -blood to body organs

  -high pressure- blood needs to travel a great distance
• open circulation


  -blood not enclosed in vessels

  -flows freely in body cavity

  -insects and other invertebrates
• closed circulation


  -blood enclosed in blood vessels

  -arteries veins and capillaries

  -all vertebrates
• open circulation


  -no tissue fluid- cells and tissues bathed in blood

  -action of muscles pumps blood

  -heart has many chambers and chambers pumps blood forward by peristalsis

  -blood enters heart via a series of valves called ostia
• hydrostatic pressure

  -created when blood is pumped along arteries into arterioles and into the capillaries

  -pressure forces blood out of the capillaries
• tissue fluid

  -composed of substances small enough to leave through the gaps in the capillary walls

  -acted on by osmotic pressure which pushed some of the fluid back into the capillaries
• tissue fluid has a less negative water potential than the blood (the blood contains more solutes). this causes water to move down the water potential gradient into the blood from the tissue fluid via osmosis
• lymphatic system

  -remaining tissue fluid not pushed back into the capillaries is carried in the lymphatic system

  -lymph contains less oxygen and nutrients than tissue fluid

  -carries waste products

  -lymph nodes help filter out bacteria and foreign materials
• cardiac output= heart rate x stroke volume