L45. CVS Cardiac Cycle/Blood Pressure Flashcards
What are heart muscle cells called?
Cardiomyocytes
Describe the differences in myocardium between the left and right ventricle.
Right ventricle - thinner myocardium
Left ventricle - thicker myocardium
Name 2 AV valves and give their location.
Right atrium to right ventricle - tricuspid valve
Left atrium to left ventricle - bicuspid valve
Name 2 semilunar valves and give their location.
Right ventricle to pulmonary artery - pulmonary valve
Left ventricle to aorta - aortic valve
Is heart valve movement active or passive?
Passive
What is systole?
Ventricular contraction
What is diastole?
Ventricular relaxation
Name the muscles that are connected to the valve cusps. What do they do?
Papillary muscles
Prevent backflow by limiting valve movement
What causes the “lub” sound?
AV valves closing
What causes the “dub” sound?
SL valves closing
Give the definition of stroke volume.
Volume of blood ejected per heartbeat.
What is the end diastolic volume?
Volume in ventricle before contraction.
What is the end systolic volume?
volume in the ventricle after ejection.
Is all blood ejected from the ventricle in each heartbeat?
No
How is stroke volume calculated?
End diastolic volume - end systolic volume
How is heart rate determined in terms of anatomy?
The rate that the cardiac pacemaker (sino-atrial node - top of right atrium) fires action potentials.
Which nervous system determines action potential firing, thus heart rate?
Autonomic nervous system
Which nerves release noradrenaline?
Sympathetic nerves
Which nerves release acetylcholine?
Parasympathetic nerves (vagus nerve)
Name 2 neurotransmitters and their effects on heart rate.
Noradrenaline increases heart rate
Acetylcholine decreases heart rate
Name 2 types of adrenoreceptors and the main type of adrenoreceptor in the heart.
Alpha and beta adrenoreceptors
Heart contains mostly beta-1 receptors.
Briefly describe how action potentials cause the heart to contract.
Action potentials spread as a wave of depolarisation from the SA node through the cardiac conduction system. This triggers the heart to contract.
What does bradycardia mean?
Heart rate is too slow.
How is cardiac output calculated?
stroke volume x heart rate
Describe what is outlined in “Starling’s Law”.
As the heart chambers become increasingly filled, the force of muscle contraction increases.
Describe systolic blood pressure.
Pressure in the aorta during contraction.
Describe diastolic blood pressure.
Pressure in the aorta during relaxation.
How is pulse pressure calculated?
systolic BP - Diastolic BP.
How is mean arterial blood pressure calculated?
Diastolic BP + 1/3 pulse pressure
What equipment is used to measure arterial blood pressure?
Inflatable blood pressure cuff and stethoscope
What do mechanoreceptors in the heart do?
Detect the degree of stretch in blood vessel walls.
What innervates the carotid sinus?
Nerve of hering ( a branch of the glossopharyngeal nerve)
What is the Valsalva manoeuvre and what does is result in?
attempting to expire on a closed glottis.
Increases blood pressure
Give the values for hypertension.
140mmHg systolic / 90mmHg diastolic or higher
Name 2 drugs used to treat hypertension.
clonidine and alpha methyldopa
Give the values for hypotension.
90 mmHg systolic / 60 mmHg diastolic
What is postural hypotension?
Abnormal drop in blood pressure after standing up.
