Transport in animals

• effect of nicotine on the heart

  increase stickiness of platelets

  thrombosis causes the release of adrenaline

  this restricts the arterioles which restricts further blood flow to the body
• effect of CO on the body

  combines permanently with haemoglobin to form carboxyhaemoglobin

  reduces the bloods carrying capacity for oxygen

  heart rate increases to pump more blood around the body to equivalate to the same amount of oxygen delivery

  damages the endothelium of blood vessels

  causing atherosclerosis which increases cardiovascular disease risk
• open circulatory system

  haemolymph is pumped directly into haemocoel

  not contained in vessels

  low pressure
• closed system


  blood contained in vessels

  gases and small molecules leave by diffusion

  oxygen transported as oxyhaemoglobin
• arteries

  thicker walls of smooth muscle -> contract and dilate to control blood pressure

  elastic layer -> stretch and recoil

  collagen -> structural support under high pressure to maintain shape and volume
• arteriole 


  smooth muscle -> thicker than arteries as it has to greatly restrict flow into the capillaries

  elastic fibers -> higher in arteries to lower the pressure

  thinner collagen layer as it is under lower pressure than arteries
• capillaries


  no smooth muscle, elastic fibers, or collagen

  one red blood cell thick

  short diffusion distance

  small -> form a network to increase surface area
• venules

  thin smooth muscle -> under low pressure

  no elastic fibers or collagen
• tissue fluid

  high hydrostatic pressure at the arteriole end

  forces water and small molecules out of the capillaries

  proteins remain in the capillaries as they are too large to cross the membrane

  these decrease water potential and increase oncotic pressure

  water moves in by osmosis as a result

  after water equilibrium is achieved the remaining water gets absorbed by the lymph nodes and drained into the lymphatic system
• structure of the heart

  myogenic

  supplied with blood from the coronary arteries

  surrounded by a pericardial membrane that prevents it from filling with blood
• why is the left ventricle thicker

  contracts with more force at a higher pressure as blood has to reach the entire body
• diastole

  where the atria and ventricles relax
• atrial systole

  blood enters the atrias via the vena cava and pulmonary vein under high pressure

  the atrias contract and the atrioventricular valves open
• ventricular systole

  as blood enters the ventricles pressure increases

  the atrioventricular valve closes

  the ventricles contract from the bottom and the semi lunar valves open forcing blood into the aorta and pulmonary artery
• cardiac output equation

  heart rate x stroke volume
• control of the heart cycle

  1. SAN releases a wave of depolarisation causing the atria to contract
  2. a non-conductive layer prevents the depolarisation wave from reaching the ventricles
  3. AVN releases another wave of depolarisation that is delayed that is forced down the septum and purkyne fibers causing the ventricles to contract from the bottom upwards
  4. the cells then repolarise and cardiac muscle relaxes
• haemoglobin graph

  • oxygen binds in areas of high partial pressure of oxygen such as in the alveoli
  • it dissociates at low partial pressure of oxygen such as in respiring tissues
  • 1 molecule of oxygen is hard to bind but haemoglobin undergoes conformational change to make it easier
  • the graph levels off at the end as only 1 binding site is available giving a 1 in 4 successful chance at binding
• bohr effect


  when in areas of high CO2 concentrations such as in respiring cells the oxyhaemoglobin curve shifts to the right decreasing the affinity of haemoglobin for oxygen
• why is it important not to let CO2 build up

  increases acidity causing the binding sites of haemoglobin to change
• ppCO2 in the alveoli

  low in the alveoli

  curve shifts to the left

  increased affinity of haemoglobin for oxygen

  causing oxygen to bind
• ppCO2 in respiring tissues

  high in respiring tissues

  causes curve to shift to the right

  this decreases the affinity of haemoglobin for oxygen

  causing oxyhaemoglobin to dissociate
• fetal haemoglobin graph

  curve shifts to the left

  higher affinity for oxygen

  causing oxygen to bind
• lama haemoglobin

  live in high altitudes so they have a higher affinity
• bird haemoglobin

  lower affinity as they have a faster metabolism for rapid muscle contraction
• earth worm haemoglobin

  higher affinity

  little oxygen available underground
• ways of transporting carbon dioxide

  1. haemoglobinic acid -> blood plasma
  2. carbaminohaemoglobin
  3. HCO3- in the cytoplasm of red blood cells
• chloride shift

  H2O and CO2 combine in the blood plasma to form H+ and HCO3-

  this reaction is catalysed by carbonic anhydrase

  the HCO3- moves out of the cell making it overall acidic due to the H+ ions

  this causes Cl- to move in to equilibrate
• differences between a closed system in fish vs mammals

  fish:

  • blood only pumped through heart once
  • only a single system
• why do large mammals need a transport system

  high metabolic demand -> larger oxygen supply

  diffusion distance too far to maintain a steep concentration gradient

  low surface area to volume ratio

  toxic waste metabolites like CO2 need to be removed from the body quickly so they don't build up
• differences between fish and mammals

  single system vs double system

  2 chambers vs 4 chambers

  lower pressure vs maintained high pressure

  lower metabolic demand vs higher metabolic demand
• veins 


  thinner elastic layer -> no stretch and recoil

  valves -> prevent backflow of blood

  more collagen than arteries -> carry large volumes of blood