Text book - Transport in animals Flashcards
Why is there low pressure in the capillaries
The lungs are very delicate and high pressure would cause damaging and bleeding
-flow in the capillaries must be low to allow full exchange of gase
Open CS
blood is not kept in vessels leaves to surround the tissues
4) How do the tissues in the artery walls reduce fluctuations in blood pressure
Wall of artery stretches (dilates), so that pulse of blood is accommodated; the collagen in the wall prevents over stretching; the elastic tissue recoils to return the wall to original size, helping to maintain pressure as blood flows on
How does constricting the blood at the arterioles in the digestive system can cause blood to be diverted to the muscles
5) Constriction reduces the diameter of the blood vessel, this increases resistance to flow and less blood can flow to the digestive system. This means there is more blood available to be directed towards the muscles where the arterioles dilate to reduce resistance to flow.
Where is hydrostatic pressure created
The ventricles
What substances contribute to the oncotic pressure
- Dissolved solutes such as mineral ions, sugars and proteins.
How does O2 diffuse out
Oxygen diffuses out of the red blood cells into the plasma. The plasma moves by mass flow from the capillary into the tissue fluid that surrounds the tissues.
Tendinous cords
They stop the flaps of the atrioventricular valves turning inside out and prevent blood flow back to the atria.
Why cords are at cross bridges
Help to conduct the wave of excitation all over the muscle, also help to create squeezing action, rather than contraction in one direction.
Process
2) Atria fill → ventricles start to fill → atria contract → ventricles fill completely → atrioventricular valves shut → ventricles contract → semi lunar valves open → blood flows into aorta → semilunar valves close → atrioventricular valves open
What causes the fluctuations in pressure from the aorta and the arteries
Rhythmic contraction of the ventricle walls.
Pulse
The dilation of the arteries caused by rhythmic contraction of the ventricle walls
Waves
The P wave is associated with contraction of the atria. The QRS complex is contraction of the ventricles – there is much more muscle involved, so the excitation wave is stronger
Atrial fibrillation
the atria contract more frequently than the ventricles. Atria do not fill and contract properly, so ventricles do not fill accordingly.
- Patient feels two beats for each atrial contraction - so heart rate doubles. The ventricles do not have time to fill properly so less blood is pumped and less oxygen delivered to tissues.
Ectopic heartbeat
a longer delay before the next beat starts – this feels as if a beat has been missed.
