Cardiovascular homeostasis I Flashcards
What is Pulmonary circulation
Blood is pumped from the heart to the lung, short distance and the pressure requirements are low
What is systemic circulation?
Blood pumped from the heart to the rest of the body, long distance with high aortic pressure
What is the main function of the heart?
To pump blood at a pressure high enough that it is able to circulate throughout the entire body and reach all the target organs
What does a P wave show?
Depolarisation of the atria
What does the QRS complex show?
Depolarisation of the ventricles
What does a T wave show?
Repolarisation of the ventricles
What sound does the closure of the AV valves make?
A ‘lubb’ sound, it is long and deep
Which valves vibrate as they close?
the AV valves (tricuspid and mitral)
What is the ‘second sound’?
Fast Closure of the pulmonary/ aortic valve as the ventricles relax- it is a higher pitched and shorter sound
Where is information sent to either increase or decrease rate of firing?
Information is sent to the SA node
What system controls the regulation of the heart rate?
The nervous system (specifically the autonomic)
What receptors on the heart stimulate the sympathetic system?
Beta-1-adrenoreceptors
What receptors on the heart stimulate the parasympathetic system?
M2 Muscarinic receptors (inhibit/s low down heart rate)
Why is the resting heart rate low in animals?
The parasympathetic system is dominating
What effect does the stretching of cardiovascular muscle have on the ventricles?
The force exerted due to the stretch further increases pressure inside the ventricle
this is called isovolumetric contraction
What is isovolumetric contraction?
When left ventricle pressure rises above the atrial pressure causing the mitral valve to close
this produces the first ‘lub’ heart sound
What occurs to the LV muscles as blood starts to leave the LV
the LV muscles start to shorten which aids in expelling blood
When do the aortic valves close during the cardiac cycle and what is the significance?
The aortic valves close once the LV pressure falls below the aortic pressure- this helps to prevent backflow and helps propel the blood
When do the left atrioventricular (bicuspid/mitral) valves re-open?
Once the LV pressure is below the atrial pressure
Why is atrial contraction actually only neccesary during exercise?
atrial contraction only adds around 25% of the blood volume
Why would the atrial pressure increase when the ventricle contracts?
There is a bulging of the AV valve into the atria
What can be used as a surrogate marker to measure left atrial pressure?
Pulmonary capillary wedge pressure
What is the ST segment?
Time during which the ventricles are contracting and emptying
What is the TP interval?
Time during which the ventricles are relaxing and filling
What is the ‘third heart sound’
heard immediately after the second heart sound shows changing in filling speed
What is the ‘fourth heart sound’
It is heard immediately before the 1st heart sound contraction of the atria causes vibration of the ventricles
What would a cardiac cycle be defined as?
the events occuring from the start of one beat to the start of another
What hormones have an effect on the sympathetic innervation of the heart?
Adrenaline/ noradrenaline
What hormones have an effect on the parasympathetic innervation of the heart?
acetylcholine (vagus nerve stimulation)
