3.3.4.1 mass transport in animals Flashcards
describe the structure of haemoglobin
globular protein, quaternary structure with 2 heavy and 2 light polypeptide chains, each chain has a haem group with a Fe2+ ion which carries the oxygen molecule
how is oxygen loaded, transported and unloaded
- partial pressure of oxygen is high in the lungs so oxygen binds to haemoglobin forming oxyhaemoglobin
2.oxyhaemoglobin is transported in the blood in red blood cells - oxygen is unloaded to respiring cells at a low partial pressure of oxygen
- unloading of oxygen occurs when there is a high CO2 concentration
explain the oxygen dissociation curve
due to the shape of haemoglobin, it is difficult for the first oxygen molecule to bind to Hb
when Hb binds with the first molecule its shape changes making it easier for the next oxygen molecules to bind
as Hb becomes more saturated it is harder for more oxygen molecules to bind as there are less sites for the molecule to bind
what is positive cooperativity
when a haemoglobin protein changes shape making it easier for the second and third molecule to bind
describe the gradient of the oxygen dissociation curve
shallow gradient initially due to less oxygen binding
the gradient becomes steeper as more molecules bind to Hb
gradient becomes shallow again and flattens off as it is hard for oxygen to bind
describe the effect of increasing carbon dioxide concentration on the oxygen dissociation curve.
increasing conc of CO2 causes the curve to shift to the right - the bohr effect-
increase conc, decreases pH in the blood, causing the shape of Hb to change, decreasing the affinity of oxygen, increasing rate of dissociation/ unloading of oxygen
examples of left shift of the oxygen dissociation curve due to low oxygen
living in an environment with low partial pressure of oxygen ( e.g. high altitude, low altitude and foetuses) gives organisms a higher affinity for oxygen
so Hb associates with oxygen, allowing the Hb molecule to become fully saturated at a lower partial pressure
what does a closed double circulatory system mean
closed - blood is confined to blood vessels
double - blood passes through the heart twice per cycle
describe the structure of the heart
left and right atrium
left and right ventricle
atrio-ventricular valves
semi-lunar valves
function and structure of atriums
thin walled + elastic
pump blood to the ventricles
function and structure of ventricles
thick + muscular walls as they pump blood further
ventricles pump blood to the lungs and the body
what is the systemic circulatory system and explain it
when blood is pumped to the rest of the body ( not the lungs).
oxygenated blood is pumped from the left ventricle out the aorta and to body tissues.
the aorta splits into the renal artery which passes blood to the kidneys.
the renal vein takes deoxygenated blood to the heart via the inferior vena cava
what is the pulmonary circulatory system and explain it
when blood is pumped to the lungs via the pulmonary blood vessels.
deoxygenated blood is pumped from the right ventricle out the pulmonary artery to the lungs.
the oxygenated blood is sent back to the heart via the pulmonary vein
describe the first stage of the cardiac cycle
Atrial systole
1. ventricles relax and the atria contracts
2. this decreases the volume of the chambers but increasing the pressure
3. this pushes blood into the ventricle opening the AV valve
4. this increases the volume and the pressure inside the ventricle
describe the second stage of the cardiac cycle
ventricle systole
1. atria relaxes and the ventricle contracts decreasing their volume increasing their pressure
2. a higher pressure in the ventricle than the atria closes the AV valve (lub sound)
3. high pressure in the ventricle opens the SL valve forcing blood out the ventricle into the pulmonary artery and aorta
describe the third stage of the cardiac cycle
atria and ventricle diastole
1. ventricle and atria both relax
2. higher pressure in the arteries close the SL valve (dub sound)
3.atria fills with blood due to higher pressure in the veins and therefore the atria.
4. pressure of the atria is greater than the pressure of the ventricle causing the AV valve to open allowing blood to flow passively into the ventricle, restarting the cycle
structure of an artery + how its related to its function
thick muscle wall - due to high pressure
thick elastic tissue - allows them to stretch and recoil
smooth endothelium lining - reduces friction + maintains high blood pressure
narrow lumen
what are arterioles
when arteries divide into smaller vessels
they control blood flow from the arteries to the capillaries
thick muscular layer to slow down blood flow
structure of the vein + how its related to its function
thin muscle layer
thin elastic layer
wide lumen - maximise blood sent to heart
contains valves
low blood pressure
structure of capillaries + how its related to its function
permeable walls - allow for gas exchange
one cell thick - short diffusion distance + slow blood flow to allow for diffusion
what are capillary beds
network of capillaries
what is tissue fluid
fluid that surround tissues, containing water, oxygen and nutrients
how is tissue fluid formed
- high hydrostatic pressure at the arterial end. this forces fluid out of the capillary
- ultrafiltration of small molecules occurs
- hydrostatic pressure in the capillary decreases at the venule end
- proteins remaining in the capillary cause a decrease in water potential at the venule end
- water re enters the capillaries via osmosis
what happens to excess tissue fluid
drained into the lymphatic system then back to the circulatory system
describe the composition of lymph
more lymphocytes and amino acids
less oxygen and nutrients
formula for cardiac output
cardiac output = stroke volume X heart rate
