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
Between each atrium are valves that prevent the backflow of blood into the atria when the ventricles, such as:
- left atrioventricular valve
- right atrioventricular valve
Roles of chambers and ventricles and atria
- each 4 chambers is connected to large blood vessels that carry blood towards or away from heart
- The ventricles pump blood away from heart and into arteries
- atria recieve blood from veins
Vessels connected to four chambers:
- aorta is connected to left ventricle which carries oxygenated blood to rest of body not lungs
- vena cava is connected to right atrium and brings deoxygenated blood back from tissues of the body
- pulmonary artery: is connected to right ventricle and carries deoxygenated blood to lungs where CD is removed from blood
- pulmonary vein is connected to left atrium and brings oxygenated blood back from lungs
Coronary arteries
the heart is supplied by its own blood vessels called coronary arteries which branch off the aorta shortly after it leaves the heart
- blockages of these artieries e.g by blood clot leads to myocardial infarction e.g heart attach where an area of the heart is deprived of blood
Relaxation of the heart
- blood returns to the atria of the heart through pulmonary vein (from the lungs) and the vena cava (from the body)
- Diastole, in the cardiac cycle, period of relaxation of the heart muscle, accompanied by the filling of the chambers with blood. … Initially both atria and ventricles are in diastole, and there is a period of rapid filling of the ventricles followed by a brief atrial systole
Contraction of the atria (atrial systole)
- the contraction of atrial walls along with the recoil of the relaxed ventrical walls, forces the remaining blood into the ventricles from the atria
- throughout this stage the muscle of the vetricle walls remains relaxed
Contraction of the ventricles (ventricular systole)
the contraction, or period of contraction, of the heart, especially of the ventricles, during which blood is forced into the aorta and pulmonary artery.
- Systole, period of contraction of the ventricles of the heart that occurs between the first and second heart sounds of the cardiac cycle
cardiac output
= heart rate x stroke volume
Structure of blood vessels
- arteries carry blood away from the heart and into arterioles
- arterioles are smaller arteries that control blood flow from arteries to capillaries
- capillaries are tiny vessels that link arterioles to veins
- veins carry blood from capillaries back to the heart
Arteries, Arterioles and Veins all have the same basic layer structure
- tough fibrous out layer: which resists the pressure from both within and out
- muscle layer: that can contract and so control the flow of blood
- elastic layer: helps maintain blood pressure by stretching and springing back
- Inner lining (endothelium) which is smooth to reduce friction and thin to allow diffusion
- Lumen is not an actual layer but the central cavity of the blood vessel through which blood flows
Artery structure and function:
- muscle layer is thick com
pared to veins meaning smaller arteries can be constricted and dilated in order to control the volume of blood passing through them - elastic layer is relatively thick compared to veins because blood pressure in arteries is kept high
- Overall thickness of the wall is great: resists the vessel bursting under pressure
- There are no valves because blood is under constant pressure
