Heart & Haemoglobin Flashcards
How does heart beat? Blood flow
Blood enters atrium
Atrium wall contracts
Increases pressure in atrium
Causes atrioventricular valves to open
Blood passes into ventricle
Ventricle contracts increasing pressure
Atrioventricular valve closes when pressure greater than atrium
When ventricle has higher pressure than aorta semilunar valve open
After contraction higher pressure in aorta than ventricle cause semilunar valve to close
Artery adaptations
Blood under high pressure
Thick muscular wall so wall recoils
Contains elastic tissues so artery can stretch as pulse of blood passes Thick muscular wall so wall recoils after pulse of blood passes
Vein adaptations
Blood under low pressure
Walls thinner than artery
Very little muscular or elastic tissue Valves prevent backflow of blood
Capillaries adaptations
Permeable capillary wall
Single cell walls, reduces diffusion distance
Flattened endothelial cells, reduces diffusion distance
Narrow lumen, reduces flow rate giving more time for diffusion
Tissue fluid formation
Hydrostatic pressure of blood high at arterial end of capillary bed Due to contraction of left ventricle
Fluid (containing solutes) forced out of capillary wall
Proteins and large molecules remain in blood
Water potential of blood becomes more negative
Water moves back into venous end of capillary by osmosis Lymph system collects excess tissue fluid and returns to vein
Formation of oxyhemoglobin
Haemoglobin – a protein with a quaternary structure. Binds with oxygen to form oxyhaemoglobin
At lungs oxygen binds to haemoglobin
Difficult for first oxygen to bind.
Binding causes a change in the tertiary/quaternary structure of protein Exposes another oxygen binding site
Further oxygen molecules bind to haemoglobin more easily.
What is the Bohr effect
Increased rate of respiration
Increase of carbon dioxide in blood.
Increase carbonic acid/decrease in pH.
Changes quaternary/tertiary structure of haemoglobin Oxygen dissociates more rapidly
Delivers more oxygen to respiring tissues.
