heart + haemoglobin Flashcards
structure of haemoglobin
- large protein with quaternary structure
- 4 polypeptide chains
- each chain has a haem group, that contains an iron ion each
oxygen binds to haemoglobin to make oxyhemoglobin
reversible reaction - can dissociate
in high pO2
haemoglobin has a high affinity
more oxygen loaded to form oxyhaemoglobin
blood is saturated with oxygen
eg in the lungs
in low pO2
haemoglobin has a low affinity
more oxygen unloaded
low saturation of oxygen in blood
eg in repairing tissues
Bohr Effect
curve shifts right in high pCO2
- saturation of blood with oxygen lower for a given pO2
- cells release CO2 when they respire, increases partial pressure of CO2
- oxygen increases rate of unloading, more O2 released
- allows respiring cells to get more oxygen
why is the curve s shaped?
when haemoglobin combines with first oxygen, it alters shape
makes it easier for other molecules to join
but when the haemoglobin gets more saturated, it’s harder for oxygen to bind
creates shallow curve at each end, steep in the middle where its easiest to bind
organisms living in low concentrations of O2
haemoglobin has a higher affinity for oxygen - more loading
curve shift left
blood in more saturated with O2 for a given partial pressure than human
organisms with high O2 demand (eg active)
haemoglobin has lower affinity for oxygen
curve shifts right
blood less saturated for a given partial pressure than humans
more unloaded for cells to respire
Adaptations of arteries
Carry blood from heart - body
Oxygenated except pulmonary
Thick muscular walls and elastic tissue - maintain high pressure
Endothelium folded - can stretch, maintain pressure
Adaptations of veins
Carry blood back to heart
Deoxygenated except pulmonary
Wide lumen
Little muscular tissue - blood under low pressure
Valves to stop back flow
Flow helped by contraction of muscles surrounding
Adaptations of arterioles
Arteries divide into arterioles
Form a network
Carry blood to capillaries
Elastic walls - changes in pressure
Muscular walls - can constrict or relax to divert blood flow
Adaptations of capillaries
Allow for exchange of molecules between blood and cells
Make up capillary beds
Adapted for efficient diffusion
One cell thick walls - short diffusion distance
Close to cells
Many of them - large surface area
leaky - allow fluid out
Formation of tissue fluid
Arteriole end - higher hydrostatic pressure
Forces fluid out of leaky capillaries (into spaces around cells)
Fluid loss lowers hydrostatic pressure
Venule end - lower hydrostatic pressure
Loss of fluid = lower water potential at venule end (higher concentration of plasma proteins)
Some fluid moves back in by osmosis
Excess fluid drained by lymphatic system and dumped back into the circulatory system
Adaptations of the heart
Left ventricle thicker (more muscular tissue)
- needs to pump blood around body (right just to lungs)
Ventricles thicker then atria
- pump blood out of heart not just to ventricles
Atrioventricular valve- stop back flow into atria
Semilunar valves - stop back flow in heart (in arteries)
How do valves work?
Determined by pressure
Means blood flows in one direction
Higher pressure behind = opened
Higher pressure in front = closed
Cardiac cycle
Blood enters atria
Atria contract - decreasing volume
Pressure in atria increases
Forces atrioventricular valve open - blood flows into ventricles
Atria relax and ventricle contract
Decreases volume and increase pressure
Pressure higher in ventricles so AV valve shuts
Pressure higher then aorta and pulmonary artery - SL valves open
Blood forced into arteries
Higher pressure in arteries closed SL valves
Atria and ventricles relax
Blood enters again through vena cava and pulmonary vein
