Mass Transport In Animals Flashcards
What does haemoglobin consist of?
Consists of 4 polypeptide chains each containing a haem group including an iron ion
What type of structure is haemoglobin?
Quaternary
How many molecules of oxygen can each haemoglobin molecule transport?
4
What is another word for carbon dioxide or oxygen concentration?
Partial pressure
What does association mean?
When haemoglobin binds with oxygen
What does dissociation mean?
Haemoglobin releases oxygen
Where must haemoglobin readily associate or dissociate?
Readily associate where ppo2 is high in the lungs and readily dissociate where ppo2 is pow in respiring tissues
What is special about different haemoglobins?
Different affinity
What is the shape of the oxygen dissociation graph?
Curve
Why is the gradient at the start of the oxygen dissociation curve so shallow?
Shape of haemoglobin makes it hard for first o2 to bind as polypeptide subunits are very closed
What does the binding of the first oxygen molecule do?
Changes the quaternary structure
Why does the gradient steepen on the oxygen dissociation curve?
1st molecule changes quaternary structure so 2nd and 3rd can bind more easily called cooperative binding
Why does the gradient of the oxygen dissociation curve level off?
Harder to bind fourth oxygen molecule as less likely to find an empty oxygen site
What does it mean when the curve shifts right?
Lower affinity for oxygen loads o2 less readily but unloads more easily
What does it mean when the curve shifts to the left?
Higher affinity for oxygen loads oxygen more readily but unloads less easily
How is the heart supplied with oxygen?
Coronary arteries
What can happen if a coronary artery is blocked?
Cause myocardial infraction or heart attack
What are some risk factors of cardiovascular disease?
Smoking, high blood pressure, blood cholesterol has high density or low density lipoproteins, diet high salt or saturated fat
How can smoking cause cardiovascular disease?
CO combines with hb not o2
Nicotine stimulates adrenaline increases heart rate raises blood pressure
Makes platelets sticky higher risk of thrombosis
What are the 3 stages of the cardiac cycle?
- Relaxation of heart- diastole
- Contraction of atria - atria systole
- Contraction of ventricles- ventricular systole
What happens in diastole of the heart?
- Blood returns to the atria from the pulmonary veins and vena cava so pressure rises causing atrioventricular valve to open so blood flows into the ventricle
- Muscular walls and ventricle walls relax causing them to recoil reducing the pressure in the ventricle so semi lunar valve closes causing dub sound of heartbeat
What happens in atria systole?
- Contraction of atria walls recoil forcing remaining blood into ventricle from atria
- Muscle walls in ventricle remain relaxed
What happens in ventricular systole?
- After a short delay to allow ventricles to fill with blood the ventricle and atria walls contract simultaneously increasing pressure so atrioventricular valves shut lub sound
- Blood forced into aorta and pulmonary artery when thick ventricle walls contract to pump blood around the body
What is the double pump system and why is it needed?
Where blood is transported around the body then returned to the heart to boost the pressure to get around the whole body
Why does the heart have two sides?
So oxygenated and deoxygenated blood doesn’t mix and a steep concentration gradient so all blood is circulated
Why does the heart contain arteries with valves?
Prevents backflow
What is the difference in pressure of arteries and valves?
Arteries carry blood away at high pressure veins carry blood to the heart at low pressure
How is the heart supplied with oxygen?
Coronary arteries
What is the mammal circulatory system?
Closed double circulatory system
How is blood transported in mammals?
In vessels
What are the 3 types of vessels?
Veins, arteries and capillaries
How is oxygen finally moved into cells?
By diffusion
Why do mammals need a transport system?
Smaller sa to vol ratio cant be met by surface alone need specialist surface or pump
What are 4 features of a transport system?
- Suitable medium to carry materials
- Mass transport
- Closed system of tubes
- Pressure difference
What is the bohr effect?
The greater the concentration of co2 the more readily the haemoglobin unloads oxygen so curve shifts to the right
What happens to the affinity in the presence of co2?
Reduced affinity of oxygen
What does co2 do to the ph?
Makes it more acidic
What happens to the curve at the lungs and what does that mean
Low ppco2 shift to left increased affinity so increased uptake of oxygen and releases oxygen less readily
What happens to the curve at respiring tissues?
High ppco2 so shift to right so reduced affiniy increased release of oxygen to tissues more readily releases o2 to tissues
What does cardiac output equal?
Heart rate x stroke volume
How do valves control blood flow?
Keep blood flowing in one direction prevents backflow
What are the two types of valves in the heart?
Atrioventricular valves and semi lunar valves
What are the valves called in the veins?
Pocket valves
What do arteries do?
Carry blood away from the heart
What do capillaries do?
Tiny vessels that link arterioles to veins
What do veins do?
Carry blood away from the capillaries to the heart
What is special about the structure of the artery?
- Thicker elastic layer blood pressure is high so it can stretch and recoil maintaining pressure and smoothing surges of heart beat
- Thicker muscle to dilate and contract and control blood flow
- Very thick wall resists bursting under pressure
- Smooth endothelial lining reduces friction thin and short diffusion pathway
What is special about the structure of the veins?
- Thin elastic layer low pressure causes it to recoil
- Thin muscle layer dont need to control blood flow by constriction and dilation
- Thin walls lower pressure less risk of bursting can flatten red blood cells easily
- Valves ensure blood only flows in one direction prevents backflow
What is special about the structure of a capillary?
- Layer of epithelial cells thin so diffusion is more rapid
- Narrow diameter permeate no cell far from capillary short pathway
- Narrow lumen blood cells flattened reduces diffusion pathway
- Highly branched large surface area for gas exchange
What is special about the structure of arterioles?
- Smaller can control blood flow
How can tissue fluid leave capillaries?
Spaces in endothelial cells
How is tissue fluid formed?
- Pumping of heart creates high hydrostatic pressure at arterial end of capillary causes tissue fluid to move out
- This is opposed by the hydrostatic pressure of tissue fluid outside and lower water potential in blood but doesn’t win
- Forces small molecules out of the capillaries called ultrafiltration forming tissue fluid
Why is hydrostatic pressure lower at the venule end?
Loss of water
How is tissue fluid reabsorbed?
- Reduced hydrostatic pressure lower at venous end than outside
- Plasma has lost water so lower water potential than tissue fluid
- Water leaves tissue and moves back into capillary by osmosis down a water potential gradient
- Remainder 10% carries via lymphatic system
What happens in control of the heart?
- Wave of electrical excitation spreads from SAN across the atria causing them to contract
- Enters AVN and after a short delay to allow ventricles to fill it contracts and passes along the purkyne fibres making up the bundle of his
- Conducted to base and released then ventricles contract from bottom of heart upwards
