animal transport Flashcards
How are the valves prevented from being forced inside out
Valves are attached to the tedinous cords
how long does one heat beat last (cardiac cylce)
0.7-0.8 seconds
what does myogenic muscle mean
It contracts and relaxes automatically, it doesnt have to receive impulses from the nerves
Describe how changes in ratio have influenced the need for transport systems in plants and animals
Small SA:V means the diffusion distance increases and the available SA for diffusion decreases. Organisms with larger volumes have higher energy demands.
Define double circulation
The blood goes to the heart twice in one cycle around the whole body
An advantage of a double circulatory system
Maintains a high blood pressure carrying substances faster through the body
Why is the wall of the left ventricle thicker than the wall of the right atrium
The ventricles need to develop more force to contract to push the blood of the heart around the body, which a longer distance than that required of the atria. The ventricle have more muscle, to push with greater force at a higher pressure.
Explain how pressure changes in the heart bring about the closure of the atrioventricular valve
During VENTRICULAR SYSTOLE
pressure in VENTRICLES IS HIGHER THAN ATRIA
PRESSURE PUSHES UP AGAINST CUSPS OF THE VALVE AND FORCES IT SHUT
How the action of the heart is co-ordinated
The SA node acts as a pacemaker and creates an electrical signal, WAVE OF EXCITATION SPREADS OVER THE ATRIA
atria contract
the blood is delayed from passing into the ventricles by the AVN, until all the atria are filled with blood
it travels down the septum by the bundle of hiss and purkyne fibres
reaches apex and stimulates purkyne tissue
ventricles contract
progresses from the apex
Type of muscle found in the heart wall and the process that creates pressure in heart
cardiac muscle
muscle contraction
How is the walls of the artery’s different from that of the vein
They contain more collagen
more elastic tissue
no valves
How is hydrostatic pressure generated in the heart
VENTRICULAR SYSTOLE
whY does hydrostatic pressure drop as it moves away from the heart
As blood moves further from the heart, the vessel decreases in size from an artery to a capillary
the resistance to blood flow decreases
vessels have a larger lumen
What happens to blood plasma when it arrives at the capillary
Hydrostatic pressure forces it out of capillary and into extracellular spaces, forming tissue fluid
plasma proteins remain in the capillaries too large to pass through wall
Hydrostatic pressure is greater than water potential
Why is fetal oxyhaemoglobin on the left of the curve of adult oxyhaemogloblin
1 placenta has low pO2 ;
2 adult (oxy)haemoglobin will, release O2 / dissociate, (in, low pO2 / placenta) ;
3 fetal haemoglobin has higher affinity for oxygen /
described ;
4 fetal haemoglobin, is (still) able to take up
(some) oxygen, in placenta / at low(er) pO2 ;
WHy does the pressure fluctuate as blood flows along the aorta
Systole and diastole means contractions increase pressue, and relaxation decreases pressure
How does increasing permeability of capillary membrane affect surrounding tissues
More plasma proteins through
more WHite blood cells
more tissue fluid formed
increased pressure in surrounding tissues
Why is the sino atrial node described as a pacemaker
Sets up an electrical impulse that starts a heart beat
Why does atrial fibrillation decrease the efficiency of the heat
Atria doesn’t beat in a synchronised pattern
chambers are unable to flll properly
heart doesn;t pump right amount of blood at each beat
3 ways in whch carbon dioxide is transported
5% dissolve in plasma
10% react with haemoglobin, form carbohaemoglobin
85% transported as hydrogen carbonate ions
How is CO2 converted in HCO3 ions
Co2 enters RBS aand reacts with water to form carbonic acid (H2CO3) catalysed by the enzyme carbonic anhydrase
this dissociates forming HCO3 ions and H ions
Why is the chloride shift needed
When the negatively charged hydrogen carbonate ions leave, CL- ion replace them to return cell to neutral charge
How does CO2 reduce the affinit of haemoglobin for oxygen
H ions from dissociation displace the oxygen molecules, if there are more hydrogen ions than more oxygen will be released of Hb
WHat is the Bohr SHift
The change of shape in the oxyhaemoglobin curve, when CO2 is present
causing the oxyhaemoglobin to release oxugen more readily
