6a/b - Mass Transport in Animals Flashcards
Define ‘oxygenated blood’
high in oxygen and low in carbon dioxide
Define ‘deoxygenated blood’
Low in oxygen and high in carbon dioxide
Describe diastole
The heart relaxes, atria fill with blood from vena cava and pulmonary veins.
Semi - lunar valves closed as pressure higher in arteries than ventricles
Describe atrial systole
Blood fills the atria from vena cava and pulmonary vein.
Atrial muscles contract causing pressure to increase in ventricles.
The pressure forces av valves open, blood flows into ventricles
Describe ventricular systole
Ventricle muscles contract causing volume in vs to decrease and pressure to increase.
Causes av valces to close and semi-lunar to open.
Blood flows into aorta and pulmonary vein
Define stroke volume
The volume of blood pumped out of one ventricle during each contraction
Define cardiac output
Total volume pumped from one ventricle per minute
How do you calculate the cardiac output
CA = Stroke volume x Heart rate
Describe the structure of arteries
Very thick walls
Walls have an inner coar of a single layer of endothelium
Thick middle coat of smooth muscle and elastic fibres
Outer coat of collagen fibres
Describe the structure of veins
Very thin walls
Have valves
Thin middle coat of smooth muscle and elastic fibres
Outer coat of collagen fibres
Describe the structure of capillaries
Tiny pores so highly permeable Single layer of endothelium Large SA:Vol ratio Short diffusion pathway Slow rate of blood so more time for diffusional exchange
At the arteriole end of the capillary the hydrostatic pressure of the blood is high. What causes this?
The contraction of the left ventricle in the ventricular systole
How is tissue fluid formed and reabsorbed?
The high blood pressure forces out water, salts (small solutes) and nutrients.
The soluble plasma proteins in blood, which reduce the water potential of the blood. This creates a water potential gradient, which exerts a pulling force, opposing loss of this fluid
Why is water drawn back into the capillaries at the venule end?
Water potential of the blood at end of capillary is low, tissue fluid is high. This creates a large inward osmotic pull which is greater than blood pressure. Water drawn back in by osmosis down a wp gradient
How is tissue fluid drained away from cells?
By lymph vessels and is returned to the circulation near the heart
Describe the function of haemoglobin
Has high affinity for oxygen
Loads oxygen when O2 conc. high
Dissociates from (unloads) O2 where O2 conc. low
Where in the body would O2 conc. be:
a) high
b) low
a) lungs
b) respiring tissue
Define the term ‘conjugated’
The protein is bound to a non-protein group (e.g.iron)
Define ‘affinity’
The binding potential of molecules
Define ‘cooperative binding’
As more O2 molecules bind to haemoglobin the tertiary structure and shape of haemoglobin changes, making it easier for next O2 to bind - increases affinity
What shape is the oxygen dissociation graph?
Sigmoidal
What happens to the dissociation graph when there is an increase in temperature, acidity and CO2 conc.?
Shifts right - Bohr shift
When is it likely that there will be an increase in temperature, acidity and CO2 conc.?
During exercise - faster cellular respiration, more heat and CO2 produces. CO2 dissolves to form a weak acid
What happens to the affinity of haemoglobin when the curve shifts right?
Affinity for O2 decreases so unloading of O2 to tissues is increased
