Mass transport Flashcards
structure of Haemoglobin molecules
- primary structure: sequence of amino acids in the four polypeptides chain
- secondary: each chain is coiled into a helix
- tertiary: each chain is folded in a specific shape to carry oxygen
- quarternary: four polypetides are linked to form an almost spherical molecule
Loading and unloading oxygen
- when haemoglobin releases its oxygen is called unloading or dissociating
- when haemoglobin bind with oxygen is called loading or associating
The role of haemoglobin
its role is to transport oxygen
Haemoglobin must:
- readily associate with oxygen at the surface where gas exchange takes place
- readily dissociate from oxygen at those tissues requiring it
- haemoglobin changes it’s affinity for oxygen under different conditions
- it changes its shape in the presence of carbon dioxide
- in the presence of carbon dioxide, haemoglobin binds to oxygen more loosely so it then releases it
Why are there different haemoglobins?
- each species produces a haemoglobin with slightly different amino acid sequence
- each species’ haemoglobin has different tertiary and quarternary structure so thus has different binding properties
Effects of carbon dioxide concentration
- haemoglobin has a reduced affinity for oxygen in the presence of carbon dioxide
- the greater the concentration of carbon dioxide, the more readily the haemoglobin releases it oxygen
Loading, transport and unloading of oxygen
- at the gas- exchange surface carbon dioxide is constantly being removed
- the pH is slightly raised due to low concentration of CD
- the higher pH changes the shape of haemoglobin into one that enables it to load oxygen readily
- the shape also increases the affinity for haemoglobin for oxygen so its not released
- in the tissues, CD is produced by respiring cells
- CD is acidic in solution so the pH of the blood within the tissues is lowered
- the lower pH changes the shape of haemoglobin into one with a lower affinity for oxygen
- Haemoglobin releases its oxygen into the respiring tissues
The more active a tissue the more oxygen is unloaded:
- the higher the rate of respiration –> the more CD the tissues produce –> the lower the pH –> the greater the haemoglobin change –> the shape change –> the more readily oxygen is unloaded –> the more oxygen is available for respiration,
Lugworm
- oxygen diffuses into the lugworm’s blood from the water and it uses haemoglobin to transport oxygen
- dissociation curve shifted far to the left of that of a human meaning the haemoglobin is fully loaded with oxygen
Llama
- it lives in high altitudes so the atmospheric pressure is lower and so the partial pressure is lower so its difficult to load haemoglobin with oxygen. Llama also have a type of haemoglobin that has a higher affinity for oxygen than human one so it has shifted to the left on the curve
plants rely on natural, passive processes such as the evapouration of water:
- a mechanism to maintain the mass flow movement in one direction for example valves
- a means of controlling the flow of the transport medium to suit the changing needs of different parts of the organism
- a mechanism for the mass flow of water or gases e.g intercoastal muscles and diaphragm during breathing
Circulatory systems in mammals
- they have a closed, double circulatory system in which blood is confined to vessels and passes twice through the heart for each complete circuit
- the blood is passed through the lungs and its pressure is reduced
- blood is returned to the heart to boost its pressure before being circulated to the rest
- so that’s why mammals have a high temperature and metabolism
The vessels that make up the circulatory system of a mammal are divided into three types:
- artieries
- veins
- capillaries
Each pump has two chambers
- atrium: thin walled and elastic so as it stretches it collects blood
- ventricle: has a much thicker muscular wall as it has to contract strongly to pump blood some distance to either lungs or rest
Right ventricle pumps blood to where
- only to the lungs because it has a thinner muscular wall
The left ventricle pumps blood to where
- it has a thicker muscular wall allowing it to contract to contract to create enough pressure to pump blood to the rest of the body