CVS review Flashcards
what does the right coronary artery supply
inferior aspect of the heart and right atrium
An increase in intracellular calcium ion concentration causes contraction in cardiac myocytes. What do calcium ions bind to to initiate contraction?
Troponin C
If cells in the SA node cease to function what rhythm will likely result?
If cells of the SA node cease to fire the AV node will take over as the pacemaker. These cells fire more slowly, hence bradycardia. It will not be sinus bradycardia as this implies the sino-atrial node is driving the electrical activity.
If cells in the SA node fire too quickly what rhythm will result?
sinus tachycardia
An increase in intracellular calcium ion concentration causes contraction in vascular smooth muscle cells. What do calcium ions bind to to initiate contraction?
Calcium ions bind to calmodulin and the Ca2+-calmodulin complex activates myosin light chain kinase.
How is electrical activity in the heart initiated?
spontaneous depolarisation
In the isovolumetric phases of the cardiac cycle, which valves are open?
none
In which phase of the cardiac cycle can the first heart sound be heard?
The first heart sound is caused by the shutting of the mitral valve, and this occurs in the isovolumetric contraction phase.
What causes the second heart sound?
The snapping shut of the aortic valve in the isovolumetric stage of the cardiac cycle causes the second heart sound.
In which phase of the cardiac cycle can the QRS complex be seen on an ECG?
isovolumetric contraction
What is the correct path of the electrical impulse through the cardiac tissue?
SA node -> AV node -> Bundle of His -> Purkinje fibres
If a patient’s blood pressure is 120/75 mmHg, what is their mean arterial blood pressure?
diastolic + 1/3 (pulse pressure) = diastolic + 1/3 (systolic - diastolic) = 75 + 1/3 (120 - 75) = 75 + 1/3 (45) = 75 + 15 = 90
Where do you find the femoral pulse?
just inferior to the mid-inguinal point (this is halfway between the ASIS and the pubis)
action of adrenaline in coronary muscle, skeletal muscle and in the liver’s vasculature
At physiological (normal body) levels = vasodilation (β2 receptors)/
At pharmacological levels = vasoconstriction (α1 receptors)
The opening of which channel is responsible for the upstroke of the action potential in the ventricular myocytes?
Voltage-gated Sodium ion channels
Calcium can bind to a protein on the surface of the sarcoplasmic reticulum to cause calcium release from inside the sarcoplasmic reticulum into the cell cytoplasm. What is the name of this protein
ryanodine receptors. This is called Calcium Induced Calcium Release.
What causes the inactivation of the voltage-gated sodium channels in hyperkalaemia?
The membrane potential becoming less negative and the cell depolarising
Which of these is classified as stage 2 hypertension?
The margins for stage 2 hypertension are between 160/100 mmHg (clinic) or 150/95 mmHg (home) and 180/110 mmHg.
Which part of the brain stimulates the thirst reflex, an important accompaniment for ADH release?
hypothalamus
What is the typical resting membrane potential in ventricular myocytes?
-85mV
The cell membrane of ventricular myocytes is permeable to potassium ions at rest and there is only a very small permeability to other ions. Therefore the resting membrane potential is close to the equilibrium potential for potassium ions.
What is the effect of hyperkalaemia on the spread of action potentials though out the myocardium?
Cardiac myocytes depolarise causing inactivation of sodium channels and slowing down the spread of action potentials
Left atrial pressure is being assessed in a patient using a specialised catheter with a balloon and pressure sensor at the tip. The patient’s left atrial pressure is elevated and ranges from 5 - 20 mmHg throughout the cardiac cycle, whilst the patient’s arterial blood pressure is 140/80 mmHg. What will be the pressure in the patient’s left ventricle in diastole?
5-20
