Topic 4

• Diffusion is the movement of particles from a high to low concentration, until evenly distributed
• what can diffuse? (properties)

  lipid soluble, non-polar, small
• increasing rate of diffusion:

  • size
  • diffusion distance
  • temperature
  • surface area
  • concentration gradient
• facilitated diffusion allows water-soluble, large, charged proteins to cross across the plasma membrane
• protein channels are hydrophilic. they only open in the presence of a specific ion
• carrier proteins change shape what a particular molecule binds to it - which then releases a molecule onto the other side of the membrane
• osmosis is the movement of water molecules from high to low concentration over a semi-permeable membrane
• a hypotonic solution has a higher water concentration, so water will move into a cell. May burst the animal cell.
• a hypertonic solution has a low water concentration, so water moves out of cell, and shrivels. cytoplasm looses structure. (animal cells)
• an isotonic solution has the same water concentration as the cells
• in plant cells, water moves in so cell becomes turgid
• in plant cells when water moves out, cell is plasmolysed
• water potential = turgor pressure + osmotic potential
• Active transport is the moment from low to high concentration, with energy (ATP)
• Protien pumps are carrier proteins. A molecules goes into the enzyme, ATP binds, enzyme changes shape and the molecule is released from the other side
• endocytosis is cells taking in molecules by engulfing them. eg phagocytosis
• exocytosis is cells releasing stuff by secreting vesicles
• factors effecting rate of active transport:

  • rate of respiration
  • atp avaliability
  • number and speed of carrier proteins
• where is the tricuspid valve?

  right atrium ventricle
• where is the bicuspid valve?

  left atrium ventricle
• vena cava brings deoxygenated blood from your body. Superior from head/chest, inferior from lower body.
• aorta takes oxygenated blood from heart to the rest of your body
• pulmonary vein brings oxygenated blood from the lungs. It goes out the aorta
• The pulmonary artery takes deoxygenated blood to the lungs, in order to get oxygen.
• aorta —> body —> vena cava —> pulmonary artery —> lungs —> pulmonary vein —> aorta
• Myoglobin stores oxygen at low partial pressures to be used as a ’last resource’ when oxygen levels are low during respiration
• high pp of CO2 cause a lower affinity of oxygen. easier to unload oxygen in respiring tissue
• low pp of CO2 means increased affinity of oxygen, in alveoli to load more oxygen
• cooperative bonding is when its hard for the first oxygen to bind to haemoglobin, but then the shape changes slightly so it’s easier for the other oxygens to bind
• fetal haemoglobin has a higher affinity for oxygen, because it gets oxygen from mother haemoglobin, so needs to have a higher affinity than adults.
• at high altitudes, theres low pp of oxygen. animals have to have a higher affinity of oxygen, so they can still load oxygen even at lower pp oxygen