(Mass Transport in Animals)

• HAEMOGLOBIN (globular protein found in red blood cells. Carries oxygen from the lungs around the body):

  • QUATERNARY STRUCTURE: Haemoglobin is a globular protein made from 4 different polypeptide chains, which give haemoglobin its quaternary structure
• HAEMOGLOBIN (globular protein found in red blood cells. Carries oxygen from the lungs around the body):

  • GLOBULAR PROTEIN: Globular= spherical structure with hydrophobic R groups facing inwards, hydrophilic R groups facing outwards (so soluble in water -> allows more hydrogen bonds with surrounding water molecules)
• HAEMOGLOBIN (globular protein found in red blood cells. Carries oxygen from the lungs around the body):

  • HAEM GROUPS: Each polypeptide chain in a haemoglobin molecule has a haem group- a prosthetic group attached to the protein. The haem groups contains an iron ion (which makes haemoglobin red)
• HAEMOGLOBIN (globular protein found in red blood cells. Carries oxygen from the lungs around the body):

  • BINDING; The process where haemoglobin binds with oxygen= loading/ associating. The process where haemoglobin releases oxygen= unloading/ disassociating
• HAEMOGLOBIN (globular protein found in red blood cells. Carries oxygen from the lungs around the body):

  • AFFINITY: Haemoglobin has a high affinity (attraction) for oxygen. When red blood cells reach the lungs, oxygen diffuses into the red blood cells and binds to haemoglobin. 4 molecules of oxygen bind to 1 molecule of haemoglobin. When oxygen binds to haemoglobin, oxyhaemoglobin is formed
• HAEMOGLOBIN (globular protein found in red blood cells. Carries oxygen from the lungs around the body):

  • DISSOCIATION: When red blood cells reach the tissues of the body eg muscle cells, oxygen is released from the oxyhaemoglobin in the process of dissociation
• HAEMOGLOBIN (globular protein found in red blood cells. Carries oxygen from the lungs around the body):

  • SHAPE CHANGE; Haemoglobin can associate & disassociate with oxygen so quickly as its shape changes in the presence of substances eg in presence of carbon dioxide -> new shape of haemoglobin binds more loosely to oxygen -> haemoglobin releases its oxygen
• HAEMOGLOBIN (globular protein found in red blood cells. Carries oxygen from the lungs around the body):

  • DIFFERENT HAEMOGLOBINS: Organisms have haemoglobins with different affinities to oxygen due to them having different amino acid sequences (-> so different tertiary & quaternary sequences too)
• PARTIAL PRESSURE (concentration of oxygen in the surrounding cells. Haemoglobin is controlled by partial pressure):

  • PARTIAL PRESSURE: Oxygen partial pressure (pO₂)= the conc of oxygen in the cells. Carbon dioxide partial pressure (pCO₂)= the conc of carbon dioxide in the cells. pO₂ is important in determining whether oxygen binds to haemoglobin
• PARTIAL PRESSURE (concentration of oxygen in the surrounding cells. Haemoglobin is controlled by partial pressure):

  • AFFINITY:  greater the conc of carbon dioxide -> more readily haemoglobin releases its oxygen. pO₂ determines the affinity of haemoglobin for oxygen. If pO₂= high, haemoglobin has a high affinity for oxygen -> oxygen binds to haemoglobin. If pO₂= low, haemoglobin has a low affinity for oxygen -> oxygen dissociates from haemoglobin
• PARTIAL PRESSURE (concentration of oxygen in the surrounding cells. Haemoglobin is controlled by partial pressure):

  • TRANSPORT OF OXYGEN:The effect of pO₂ on the affinity of haemoglobin -> allows oxygen to be transported to the cells that need oxygen the most 
• PARTIAL PRESSURE (concentration of oxygen in the surrounding cells. Haemoglobin is controlled by partial pressure):

  • TRANSPORT OF OXYGEN EG:  Oxygen is loaded quickly in the lungs (low carbon dioxide conc/ pCO₂ -> pH is raised slightly -> changes shape of the haemoglobin + high oxygen conc  -> high affinity). Oxygen is unloaded quickly in respiring tissues (high carbon dioxide conc/  pCO₂ -> pH lowers slightly -> changes the shape of the haemoglobin + low oxygen conc in muscles -> low affinity)
• (TYPES OF HAEMOGLOBIN:)

  • ANIMALS LIVING AT HIGH ALTITUDES: & birds have haemoglobin which has a high affinity for oxygen- an advantage as air at high altitudes has a lower partial pressure than at sea level
  • ANIMALS WITH HIGH METABOLIC RATES:  have haemoglobin that dissociates with oxygen easily, which allows oxygen to be quickly & easily supplied to the cells for respiration
• DISSOCIATION CURVES:

  • LOW pO₂: low partial pressure->  haemoglobin has a low affinity for oxygen
  • FIRST OXYGEN: first oxygen binds -> the protein undergoes a conformational change
  • POSITIVE COOPERATIVITY; shape change -> other O₂ molecules to bind to haemoglobin more easily (positive cooperativity)
  • INCREASING pO₂: As pO₂ increases, -> affinity of haemoglobin for oxygen increases slightly
  • PLATEAU IN PERCENTAGE SATURATION: large amount of O₂ bind to haemoglobin -> more difficult for more O₂ to bind (majority of binding sites occupied) -> plateau
• DISSOCIATION CURVE first oxygen:

  • The shape of the haemoglobin makes it hard for the first oxygen to bind on the polypeptide subunits as they are closely united
• DISSOCIATION CURVES: Percentage saturation

  • LOW pO₂: When partial pressure= low ->  haemoglobin has a low affinity for oxygen. The percentage saturation of haemoglobin is low as oxygen dissociates from the haemoglobin
  • INCREASING pO₂: As pO₂ increases, -> affinity of haemoglobin for oxygen increases slightly. Positive cooperativity -> percentage saturation of haemoglobin increases quickly
• DISSOCIATION CURVES:

  • S-SHAPED CURVE: The increasing affinity of haemoglobin with increasing pO₂ in this way creates an S-shaped curve (=the dissociation curve)
• THE BOHR EFFECT: 

  • HIGH pCO₂: Respiring cells use oxygen in respiration & produce carbon dioxide. (low pO₂, high pCO₂). When pCO₂ is high, the rate of oxygen dissociation increases
  • BOHR EFFECT: The increased dissociation of oxygen -> curve shifts right (oxygen will dissociate from haemoglobin at a lower pO₂ than normal)
  • CURVE PLACEMENT: Curve to the left= greater affinity of oxygen (haemoglobin loads oxygen easily but unloads less easily).Curve to the right= lower affinity of oxygen (haemoglobin unloads oxygen easily but loads less easily).
• (FEATURES OF TRANSPORT SYSTEMS:)

  • WHY DO LARGE ORGANISMS HAVE TRANSPORT SYSTEMS?: because of their SA to vol ratio & how active it is
  • MEDIUM: to carry materials that's usually water based (water can easily dissolve substances & move easily) eg blood but can also be gas eg air in lungs
  • MASS TRANSPORT: more rapid than diffusion that moves the medium far in bulk eg evaporation in plants or muscle contraction in animals 
  • CLOSED SYSTEM OF TUBULAR VESSELS:  contains the transport medium & forms a network
• THE CIRCULATORY SYSTEM : 

  • CLOSED, DOUBLE CIRCULATORY SYSTEM IN MAMMALS: When blood is passed through the lungs-> it's pressure is reduced -> slower movement throughout body (so instead it passes through the heart again)
• THE CIRCULATORY SYSTEM : 

  • HEART: Is the centre of the circulatory system. Mammals have a double circulatory system (blood flows through the heart twice in one circuit). Deoxygenated blood is pumped to the lungs, oxygenated blood is pumped throughout the body
• THE CIRCULATORY SYSTEM : 

  • PULMONARY ARTERY & VEIN; Deoxygenated blood is pumped out the heart to the lungs via the pulmonary artery. Oxygen diffuses into the deoxygenated blood in the lungs -> the blood becomes oxygenated. Oxygenated blood flows into the heart from the lungs via the pulmonary vein
• THE CIRCULATORY SYSTEM : 

  • AORTA & VENA CAVA: Oxygenated blood is pumped out of the heart around the body via the aorta. Blood in the aorta= very high pressure (so the blood can be pumped to all tissues). Oxygen dissociates from the blood at respiring cells -> the blood becomes deoxygenated. Deoxygenated blood flows into the heart from the body via the vena cava
• THE CIRCULATORY SYSTEM : 

  • RENAL ARTERY & VEIN: Oxygenated blood flows out of the aorta to the kidneys -> Oxygenated blood enters the kidneys through the renal artery -> Oxygen diffuses out of the blood to be used in kidney cells -> the blood becomes deoxygenated -> deoxygenated blood flows out of the kidneys via the renal vein
• ARTERIES & VEINS (arteries usually cary oxygenated blood, veins usually carry deoxygenated blood):

  • PULMONARY ARTERY: The only artery that carries deoxygenated blood. Deoxygenated blood is carried from the heart to the lungs
  • PULMONARY VEIN: The pulmonary vein is the only vein that carries oxygenated blood. Oxygenated blood is carried from the lungs to the heart
• HEART STRUCTURE (a muscular organ containing 4 chambers):

  • ATRIUM & VENTRICLE: Atrium= thin walled & elastic to stretch as it collects blood. Ventricle= thick muscular wall to contract to pump blood
• HEART STRUCTURE (a muscular organ containing 4 chambers):

  • RIGHT ATRIUM: Deoxygenated blood flows into the right atrium. Vena cava= the vein that pumps deoxygenated blood into the right atrium. The right atrium= the first chamber that deoxygenated blood flows through
• HEART STRUCTURE (a muscular organ containing 4 chambers):

  • RIGHT VENTRICLE: Has thinner walls than the left to pump blood to lungs. When the walls of the atrium contracts -> deoxygenated blood flows into the right ventricle. The atrioventricular valves prevent blood from flowing back into the atria from the ventricles -> then the walls of the right ventricle contracts, blood is pumped from the pulmonary artery to the lungs. The semilunar valves prevent blood from flowing back into the right ventricle from the pulmonary artery
• HEART STRUCTURE (a muscular organ containing 4 chambers):

  • LEFT ATRIUM: Oxygenated blood flows into the left atrium from the lungs. Pulmonary vein= the vein that pumps oxygenated blood into the left atrium
• HEART STRUCTURE (a muscular organ containing 4 chambers):

  • LEFT VENTRICLE: Thick muscular wall to pump blood around organism. When the walls of the left atrium contracts -> oxygenated blood flows into the left ventricle. The atrioventricular valves prevent blood from flowing back into the atria from the ventricles. The walls of the left ventricle are considerably thicker than the right ventricle (the left ventricle has to transport blood all away around the body but the right only has to transport blood to the lungs)
• HEART STRUCTURE (a muscular organ containing 4 chambers):

  • AORTA: Connected to left ventricle & carries oxygenated blood to all of the organism except lungs. When the left ventricle contracts -> blood is pumped out  of the heart to the rest of the body. Oxygenated blood leaves the heart through the aorta. The semilunar valves prevent blood from flowing back into the left ventricle from the aorta
• HEART STRUCTURE (a muscular organ containing 4 chambers):

  • VALVES: Atrioventricular valves prevent backflow of blood into the atria when ventricles contract= the left atrioventricular (bicuspid) valve & the right atrioventricular (tricuspid) valve. Semi lunar valves prevent backflow into the ventricles. Pocket valves are in veins and ensure when veins are squeezed, blood travels to the heart (rather than away)
• THE CARDIAC CYCLE

  
• THE CARDIAC CYCLE (Diagram)

  
• The Cardiac Cycle

  1. Systole/Relaxation

  2. Atrial Diastole/Contraction

  3. Ventricular Contraction
• THE CARDIAC CYCLE: 1)Systole/Relaxation

  Both the ventricles & the atria are relaxed and the atrioventricular valves open. Blood flows into the ventricles and the atria from the pulmonary vein & vena cava
• THE CARDIAC CYCLE: 2)Atrial Diastole/Contraction

  Blood from the lungs flows into the left atrium & blood from the body flows into the right atrium simultaneously. The atria contract -> increases pressure in the atria. Blood in the atria is forced through the ventricles. The ventricles are relaxed & fill with blood
• THE CARDIAC CYCLE: 3)Ventricular Contraction

  The atria relax & the ventricles start to contract. Contraction of the ventricles -> pressure inside the ventricles increases -> The pressure shuts the atrioventricular valves (so the blood doesn't flow back into the atria). The blood in the ventricles is forced out the ventricles & out of the heart through the pulmonary artery or the aorta
• INTERPRETING DATA:

  • PRESSURE IN THE ATRIA: When the atria contract -> pressure in the atria increases. When the atria relax & the ventricles contract -> pressure in the atria decreases. When both the atria & the ventricles relax, there's a slight increase as the atria fills with blood again
• INTERPRETING DATA:

  • PRESSURE IN THE VENTRICLES: When the atria contract -> the pressure in the ventricles is relatively low, there's a slight increase as the ventricles fill with blood. When the ventricles contract -> pressure increases dramatically. The pressure increases more than when the atria contract. When both the atria & the ventricles relax, there's a slight increase as the ventricles fill with blood again