module 3 bits Flashcards
what is tachycardia?
Increased heart rate
What is brachycardia?
Decreased heart rate
What is fibrillation?
Uncoordinated contraction of atria and ventricles
What is an ectopic heartbeat?
Extra or early beat of the ventricles
In an ECG what does the P wave mean?
Atria contraction
In an ECG what does the QRS wave mean?
Excitation of ventricles
In an ECG what does the T wave mean?
Diastole
Calculation for cardiac output?
Stroke volume x heart rate
4 bullet points of the coordination of the cardiac cycle?
- SAN triggers atria to contract
- Band of non-conductive fibres stops depolarisation reaching ventricles straight away
- AVN conducts impulse down septum of heart to bundle of His
4.Depolarisation spread across ventricles by purkinje fibres- ventricles contract
What vessel does deoxygenated blood enter the right atrium?
Vena cava
What vessel does oxygenated enter the left atrium in?
Pulmonary vein
What chamber does oxygenated blood enter the heart in
left atrium
What vessel does oxygenated blood exit the heart in?
Aorta
What vessel does deoxygenated blood exit the heart in?
Pulmonary artery
Does foetal Hb have a higher or lower O2 affinity?
Higher
Describe how CO2 ends up being breathed out in the lungs
- CO2 diffuses into blood cell
- Combines with water to form carbonic acid
- Carbonic anhydrase enzyme converts this to hydrogencarbonate ion
- Hydrogencarbonate ion diffuses out of RBC and Cl- diffuses in to balance charges
- Some CO2 will bind directly to Hb creating carbaminohaemoglobin and will be carried in the blood back to the lungs
- The H+ that dissociated from the carbonic acid binds to Hb to form haemoglobonic acid
- Blood to lungs
- H+ dissociates from Haemoglobonic acid and binds with hydrogencarbonate ion (transported in tissue fluid) to form CO2 and H2O
Describe the Bohr shift
At high CO2 concs…
Increased H+ from CO2 changes shape of Hb
Reduces O2 affinity to Hb
Causes more oxygen to dissociate from Hb to respiring site
Describe how O2 conc. effects affinity to Hb
At low concentrations, O2 has low affinity for Hb.
This causes more O2 to dissociate from Hb
At high concentrations, O2 has high affinity for Hb. This causes more O2 to dissociate from Hb
What wave will look funny in fibrillation?
The P wave
