phys - cardio Flashcards
explain why there is pooling of blood in pulmonary vessels in left heart failure.
failure of left ventricle to pump results in more blood left in LV after systole –> less blood is able to enter from left LA from pulmonary vessels –> blood accumulate in pulmonary vessels
explain why there is SOB in LHF
increased hydrostatic pressure in pulmonary vessels –> fluid seep out into capillaries that engulf alveoli –> fluid in lungs –> decrease gaseous exchange –> SOB
what is the amount of blood ejected in one contraction of the left ventricle?
stroke volume (EDV-ESV)
what is ejection fraction?
and what is the formula?
% of EDV that is ejected into systemic circulation during ventricular contraction
ejection fraction = SV/EDV
what is cardiac output?
and what is the formula for cardiac output?
volume of blood pumped by left ventricle per minute
CO = SV x HR
what is the effect of increasing right atrial pressure on cardiac output?
increase venous return –> increase preload and EDV –> increased CO
what is the force the heart generates each time it beats?
pulse pressure
what is total peripheral resistance?
sum of vascular resistances of all tissues
why does MAP decrease when you suddenly stand up?
blood pooling in lower extremities –> decrease venous return –> decrease SV –> decrease CO –> decrease MAP
where are baroreceptors found?
arch of aorta and carotid sinus
what do baroreceptors detect?
pressure changes
john has BP of 140/70 what is his pulse pressure?
70mmHg
pulse pressure = systolic pressure - diastolic pressure
The flow rate through a vessel is 10ml/min, and the pressure difference is 50 mmHg, assuming the pressure difference remains the same and the radius increases by 2 times, what is the new flow rate?
a. 160 ml/min
b. 20 ml/min
c. 40ml/min
d. 500 ml/min
e. 80ml/min
a. 160 ml/min
flow = change in pressure / resistance
So if radius doubles, R will decrease 24=16 times
Since flow is inversely proportional to R, flow will increase 16-fold = 10x16 = 160ml/min
john’s bp is 120/80 what is his mean arterial pressure?
a. 93 mmHg
b. 100 mmHg
c. 82 mmHg
d. 105 mmHg
e. 109 mmHg
a. 93 mmHg
MAP
= 1/3 systolic pressure + 2/3 diastolic pressure
= diastolic pressure + 1/3 pulse pressure
= 80 + 1/3(40)
= 80 + 13
= 93
MAP = CO x TPR
Norepinephrine (adrenaline) binds preferentially to B2 receptors in blood vessels supplying the heart and skeletal muscle. This has the purpose of:
a. Vasodilation of arteriolar smooth muscle throughout
b. Allowing vasodilation to these tissues whilst vasoconstriction occurs elsewhere in the body
c. This serves no purpose
d. Increase metabolic rate in these
Vasoconstriction of arteriolar smooth muscle to the heart and skeletal muscle
b. Allowing vasodilation to these tissues whilst vasoconstriction occurs elsewhere in the body
Isovolumetric contraction occurs during which phase of ECG?
a. R wave
b. S-T segment
c. P wave
d. T wave
e. P-Q segment
a. R wave (depolarisation of ventricles)
P wave –> atrial depolarisation (atrial systole)
T wave –> repolarisation of ventricles (ventricular ejection and isometric ventricular relaxation)
the left interventricular valve:
a. Prevents backflow of blood from the ventricle to the atrium during diastole
b. Opens when ventricular pressure exceeds aortic pressure.
c. Closes as a result of atrial contraction.
d. Closes just before the QRS complex of the ECG begins.
e. Is closed during the period of ventricular ejection
e. Is closed during the period of ventricular ejection
a. during systole
b. referring to opening of aortic valve
SA node is the heart’s normal pacemaker because:
a. Lies in the right atrium
b. Is unaffected by circulating hormones such as adrenaline
c. Receives both sympathetic and parasympathetic innervation
d. Provides the only electrical connection between the atria and ventricles
e. Has the fastest natural rate of spontaneous action potential generation
e. Has the fastest natural rate of spontaneous action potential generation
which of the following statements regarding the conduction system of the heart is true?
a. The SA node is the only pace making region in the heart
b. The cardiac AP is conducted through the atria via Purkinje fibres
c. The spread of cardiac excitation speeds up through the AV node
d. The Purkinje fibres are specialised cardiac myocytes linked by gap junctions
e. Between APs, the cells of the SA node have a steady resting potential
d. The Purkinje fibres are specialised cardiac myocytes linked by gap junctions
a. also have AV, Purkinje fibres
b. via Bachmann’s bundle
c. slows through AV node
e. unstable resting potential (funny Na+ current)
during excitation-contraction coupling in cardiac muscle cells:
a. A single action potential always releases the same amount of calcium
b. Gap junctions close during the AP to prevent calcium leaving the cell
c. Calcium released directly from the sarcoplasmic reticulum is triggered when the AP spreads over the transverse tubules
d. Contraction will not occur unless calcium enters the cell from the extracellular space
e. The AP is over before the contraction actually begins
d. Contraction will not occur unless calcium enters the cell from the extracellular space
c. case of skeletal muscle
Which of the following best explains the underlying reason for shortness of breath seen in left heart failure?
a. increased pressure in the right atrium
b. increased volume of blood entering the left atrium
c. reduced oncotic pressure in the pulmonary capillaries
d. decreased volume of blood in the pulmonary circulation
e. increased end diastolic pressure in the left ventricle
c. reduced oncotic pressure in the pulmonary capillaries
what statement is true?
a. Blood flows in parallel through the systemic and pulmonary circulations.
b. The total resistance of the pulmonary circulation is much less than the systemic circulation.
c. Blood within the pulmonary veins flows directly to the lungs.
d. Blood flowing in all the veins of the body has a low oxygen content.
e. The volume of blood flowing into the aorta per minute is much larger than that flowing into the pulmonary artery per minute.
b. The total resistance of the pulmonary circulation is much less than the systemic circulation.
During exercise there is an increase in stroke volume due to:
a. decreased venous return
b. sympathetic activation of the veins
c. an increase in heart rate
d. adrenaline acting on the sinoatrial node
e. parasympathetic activation of the arterioles
b. sympathetic activation of the veins
diastole increases as SNS activity increases
true or false
false
diastole decreases as HR increases
which of the following increases blood vessel compliance?
a. increase tone of smooth muscle surrounding blood vessels
b. increase pressure in blood vessels
c. alpha adrenoreceptor agonists
d. increase elasticity of vessels
d. increase elasticity of vessels
a, c –> constriction of smooth muscle around vessels –> less compliant
which of the following does not explain why there is a delay in AV conduction?
a. allow time for ventricular filling
b. fewer gap junctions
c. fewer fast Na+ channels
d. current takes time to spread to left atrium before it can move to AV node
d. current takes time to spread to left atrium before it can move to AV node
(this occurs through interatrial pathway, nothing to do with internodal pathway)
which of the following explains why the plateau phase occurs?
a. reduce risk of tetanus
b. increase likelihood of charge summation
c. increase force of contraction
d. occurs due to imbalance of K+ and Ca2+ ions
a. reduce risk of tetanus
prevents mV from getting too high –> summation capacity reached –> heart is non stop contracted at full force –> spasm known as tetanus
which phases of non-nodal (ventricular) cardiac action potential are not present in nodal cardiac action potential?
phase 1: initial repolarisation
phase 2: plateau
which action potential has transient Ca2+ channels?
a. nodal
b. non-nodal
c. both
d. neither
a. nodal
where would ACh bind to in the heart?
muscarinic receptors in the atria
when does isovolumetric relaxation occur
diastole or systole?
diastole when semilunar valves close and ventricles relax
the first heart sound is heard during
a. isovolumetric contraction
b. isovolumetric atrial contraction
c. isovolumetric atrial relaxation
d. closure of aortic valve
a. isovolumetric contraction
active hyperaemia exists:
a. pathology in which blood vessels are too dilated
b. pathology in which blood vessels are too constricted
c. increase blood flow during cardiac arrest
d. increase blood flow during exercise
d. increase blood flow during exercise
Selamat has ischaemic heart disease.
Endothelial function in Selamat’s coronary arteries would MOST LIKELY be characterised by …
a. impaired production of endothelin
b. increased production of prostacyclin
c. reduced bioavailability of nitric oxide
d. reduced bioavailability of superoxide anions
c. reduced bioavailability of nitric oxide
