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 ;
