Transport in Animals - 3 Flashcards
What is an open circulatory system
No/very few blood vessels
What is a closed circulatory system
Contain blood vessels
What is a double circulatory system
Blood flows through
the heart twice for one
complete circulation of
the body
What happens in diastole
Walls of atria and ventricles relax
Blood flows into the heart
Pressure forces Av valves open
Blood moves from atria to ventricles
SL valves are closed
What happens in atrial systole
Walls of left and right
atrium contract together.
Increases pressure in
atria.
Forces all blood into
ventricles.
What happens in ventricular systole
Once full, the ventricle walls start
to contract (millisecond later).
This causes AV valves to shut.
Momentarily all valves closed.
Walls of ventricles contract,
starting at the apex.
Pressure forces blood out of the
ventricles and into the arteries and
SL valves open.
How is the heart initiated and coordinated
The Sinoatrial node generates electrical impulses called action potentials. This creates a wave of excitation
The excitation spreads over the atria walls causing them to contract
A band of non-conducting tissue stops the contraction spreading to the ventricles
The excitation is picked up by the atrio-ventricular node, which delays the excitation
The excitation passes down the septum via the bundle of His to the base of the heart and over the purkinjie fibres
This causes the ventricles to contract upwards
What does P represent in an electrocardiogram
Excitation of atria
What does QRS represent in an electrocardiogram
Excitation of the ventricles
What does T represent in an electrocardiogram
Diastole
What is tachycardia
Heartbeat is still regular, but faster than usual
Happens as a result of exercise, emotion or fever
What is bradycardia
Regular heartbeat but slower than usual
Happens as a result of hypothermia or drugs
What is Fibrillation
Chaotic rhythm, heart stops beating properly
Will result in death
What is an ectopic heartbeat
An ectopic heartbeat is when the heart either skips a
beat or adds an extra beat.
How are arteries adapted to withstand pressure
Thick walls
Lots of collagen
Folded endothelium
How are arteries adapted to maintain pressure
Elastic fibres can stretch and recoil
- Vasoconstriction
What features help blood return to the heart in veins
Skeletal muscle pump
Valves
Gravity
residual pressure
What is the equation for the formation of oxyhaemoglobin
Hb + 4O2 -> HbO8
What is association
When oxygen attaches to Hb in the lungs
What is dissociation in haemoglobin
When Hb releases oxygen to cells for respiration
Why is the oxygen dissociation curve S-shaped
The first oxygen group finds it difficult to attach to a haem groups
Once it attaches there is a conformational change
This means the second and third haems oxygens can attach more easily
This leads to another conformational change
Then the fourth oxygen finds it hard to attach
Why does foetal haemoglobin have a higher affinity for oxygen
Placenta has a low partial pressure of oxygen
Foetal haemoglobin has a higher affinity for O2 than maternal Hb
At low partial pressure the adult Hb will dissociate and foetal Hb takes up the oxygen
What are the three ways CO2 is transported
Blood plasma
As carbaminohaemoglobin
As hydrogen-carbonate ions
How is CO2 converted into HCO3-
CO2 diffuses into RBC and combines with H2O to form carbonic acid
This is catalysed by carbonic anhydrase
The carbonic acid dissociates to release hydrogen ions and hydrogen-carbonate ions
Hydrogen-carbonate ions diffuse out of the blood cell into the plasma
This leads to chloride shift
Hydrogen ions are taken up by Hb to produce haemoglobonic acid
This displaces O2 into the plasma
