Mass transport in animals Flashcards
how do you know haemoglobin is a protein
Has 4 polypeptide chains (quaternary structure) each associated with a haem group (contains iron) which combines with 1 oxygen molecule
describe the binding of oxygen and haemoglobin
- 1 haemoglobin has 4 polypeptide chains so can combine with 4 oxygen molecules
- Binding of first oxygen causes a change in shape which makes further binding easier
- Binding of last oxygen is less likely so requires a higher p.O2
when does haemoglobin load O2
• Associates at high p.O2 in the lungs
Haemoglobin has high affinity for O2
when does haemoglobin unload O2
Dissociates at low p. O2 when there is a higher concentration of CO2 as it reduces haemoglobin affinity for O2
how are there different types of haemoglobin
sequence of amino acids determines shape
type of haemoglobin in active animals
• Active animals have haemoglobin which readily release oxygen to respiring cells
o Lower affinity for oxygen = shift to the right
type of haemoglobin in small animals
• Small animals have large surface area to volume ratio
o Lower affinity for oxygen = shift to the right
o Lose heat faster so have greater rate of respiration
o Enough O2 for respiring tissues
type of haemoglobin in animals living in high altitudes
• Animals at high altitudes (where oxygen is scarce) have haemoglobin which readily combine with oxygen
o Higher affinity for oxygen = shift to the left
o Low partial pressure of O2 in the lungs
o Haemoglobin is able to load more oxygen at same O2 partial pressure
o Enough O2 for respiring tissues but difficult to dissociate
partial pressure
how much oxygen is available to be taken up
how does CO2 affect haemoglobin
Respiring cells make CO2 that dissolve in plasma to form carbonic acid
More CO2 dissolves with H2O to increase H+ ion concentration so lower pH
More acidic means lower affinity (attraction) of O2 to haemoglobin
Changes shape of haemoglobin
Oxygen is free to dissociate to and diffuse into respiring cells
Bohr effect
oxygen dissociation curve shifts to the right when more CO2 or H+ ions are present
explain the foetus haemoglobin being different to the mother’s
Foetus has ODC shifted to the left of mother so foetal haemoglobin has a higher affinity for oxygen so oxygen can move from mother to foetus respiring cells
pulmonary circulation
from heart to lungs to pick up oxygen
systemic circulation
take oxygenated blood to the rest of the body
arteries (3)
No valves and normally carry oxygenated blood (except PA) away from heart
Thick layer of muscle allows constriction and dilation
Thick elastic layer allows stretch and recoil to withstand high pressures
arterioles (2)
Pressure decreases so have fewer elastic fibres
Circular muscle fibres: vasoconstriction and vasodilation
capillaries (3)
One cell thick (short DP) for rapid exchange between blood and cells
Many and highly branched increases surface area
Endothelial cells have spaces for white blood cells to pass through
veins (3)
Normally carrying deoxygenated blood (expect PV) back to the heart
Thin muscle and elastic layer
Low pressure blood so has valves for one directional flow
systole
heart contraction
diastole
heart relaxation
myogenic
Coronary arteries supply cardiac muscle with oxygen and is able to contract without nervous stimulation
compare the left ventricle with the right one
Left ventricle as thicker muscle so stronger/ more contractions causing higher blood pressure
what would occur if there was a hole between the left and right side of the heart
oxygenated blood and deoxygenated blood mix so lower volume of oxygenated blood leaves left ventricle
cardiac cycle
- Diastole:
- Ventricles are relaxed so blood enters atria and pressure rises
- When pressure in the atria is higher than in the ventricles, atrioventricular valves open allowing blood into the ventricles - Atrial systole:
- Atrial walls contract to force blood into ventricles - Ventricular systole:
- Ventricular walls contract increasing pressure
- Atrioventricular valves close preventing blood from re-entering atria
- When pressure in ventricles are higher than in the arteries, semi-lunar valves open and blood is forced out of the heart
cardiac output
volume of blood pumped in 1 minute
stroke volume
volume of blood pumped in 1 beat on one side of the heart
equation connecting cardiac output, stroke volume and heart rate
Cardiac output=stroke volume x heart rate
how is heart beat controlled
- Sinoatrial node in right atrium acts as a pace maker
- Generates action potential which spreads across the atria causing it to contract - Action potential passes through the atrioventricular node (patch of tissue) into the ventricles (septum does not conduct impulses)
- Passes down a group of fibres called purkinje fibres (collectively, Bundle of His)to the base of the ventricles
- Ventricles start contracting from the bottom so there is no blood trapped at the bottom of the ventricles
maintaining one-way flow (2)
Contractions in certain areas of the heart lead to high pressure in that area
Valves prevent backflow of blood
hydrostatic pressure
pressure of blood created by the heart which forces fluid out and stronger than osmotic pressure, decreases in pressure the further away from the heart
water potential
pressure exerted by dissolved substances in the tissue fluid which draws water back into the blood
how tissue fluid forms
• Blood has higher hydrostatic pressure than water potential so tissue fluid e.g. water and small molecules are forced out
o Proteins and red blood cells are not lost to tissue fluid – too big
• Hydrostatic pressure decreases along capillary (loss of water, further away from heart)
o Water potential outside capillary is greater than inside - presence of protein and loss of water in capillary
o Water enters blood by osmosis
lymph vessels
drains remaining tissue fluid and large molecules, which are too large to enter capillaries
how does smoking cause cardiovascular disease
CO binds to haemoglobin instead of O2
- Reduces O2 capacity of blood, heart needs to work harder, increase blood pressure
- Insufficient supply of O2 to heart muscle during exercise
how does having high blood pressure cause cardiovascular
Heart works harder to pump blood in arteries
- More likely to develop an aneurysm which can burst causing a haemorrhage
