The pacemaker of the heart is normally the:
sino-atrial node
atrio-ventricular node
bundle of Hiss
mitral valve
left ventricle
In electrocardiogram (ECG) the QRS complex represents:
depolarisation of the atria
repolarization of the atria
depolarisation of the ventricles
repolarization of the ventricles
delay at the AV node
An ECG would be useful for determining a patient's:
heart murmur
stroke volume
cardiac output
blockage of conduction of electrical signals between the atria and the ventricles
none of the above
Cardiac output (C.O.) is the:
volume of blood pumped per minute by both ventricles
volume of blood flowing through the systemic circulation each minute
product of the number of heartbeats per minute and the volume pumped per beat
a and c
b and c
According to the Frank-Starling mechanism of the heart
with each systole the left ventricle ejects a larger volume of blood then the right ventricle
the intrinsic rate of the heart's pacemaker is 100 beats per minute
cardiac output increases with increased heart rate
stroke volume increases with increased venous return
both ventricles contact simultaneously
Distinguishing characteristics of the veins include the following
all veins carry deoxygenated blood
all veins carry blood towards the heart
all veins have thick elastic walls
a and b
During exercise, there is an increased flow of blood to
the brain
the kidneys
the muscles
a, b and c
Which of the following does not contribute to the increased stroke volume (SV) during exercise
increased contractility of the cardiac muscle
increased venous return
increased length of filling time during diastole
increased sympathetic stimulation of the ventricular muscle
increased end-diastolic volume
The aortic valve
prevents the backflow of blood into the aorta during ventricular diastole
prevents the backflow of blood into the left ventricle during ventricular diastole
prevents the backflow of blood into the left ventricle during ventricular ejection
prevents backflow of blood into the aorta during injection
closes when the first heart sound is heard
In humans, blood loss causes
venous constriction
decreased blood flow to the skin
a fall in the cardiac output
splenic contraction
Angiotensin ll:
as an octapeptide
is produced mainly in the lungs
causes thirst
stimulates the secretion of the antidiuretic hormone (ADH)
all of the above
Which of the following organs has the greatest blood flow per 100 g of tissue?
brain
heart muscle
skin
liver
kidney
If the heart rate is 70 beats/min, then cardiac output is closer to:
3.45 l.min-1
4.55 l.min-1
5.25 l.min-1
8.0 l.min-1
9.85 l.min-1
The ventricles are completely depolarized during which portion of the ECG?
PQ interval
QRS complex
QT interval
ST segment
T wave
Cardiac output (CO) of the right heart is what percentage of that of the left?
25%
50%
75%
100%
125%
The action potential corresponds to which portion of the ECG?
P wave
Which effects are caused by sympathetic stimulation?
increased force of heart contraction
increased heart metabolism
increased heart conductibility
decreased excitability
a, b, and c
Which are the peculiarities of the action potential in cardiac muscle?
long duration (0.3 s)
short duration (0.01 s)
high amplitude
plateau
a, and d
Excitation from SA node to AV node is conducted by:
Nodal fibers
Internodal fibers
Atrial cardiac cells
His bundle
b, and c
When are all four valves closed?
during isovolumetric ventricular contraction
during isovolumetric ventricular relaxation
during ventricular systole
during atrial diastole
a, and b
Effects of hypokalaemia:
short PQ interval
ventricular extrasystoles
elevated ST segments
long QRS interval
long QT interval
Hyperkalaemia:
causes a prolonged QT interval
prolongs the QRS
causes ST segment elevation
potentiates digoxin toxicity
causes loss of P wave
Left ventricular end-diastolic volume is:
10 - 30 ml
30 - 50 ml
50 - 70 ml
70 - 100 ml
100 - 130 ml
Local metabolic control is most important in determining flow to the:
lungs
skeletal muscles
kidneys
The atrial component of ventricular filling is:
5%
10%
30%
80%
The lowest intrinsic discharge activity resides in the:
SA node
AV node
Bundle branches
Purkinje fibers
Ventricular fibers
Slowest conduction (velocity) occurs in the:
Atrium
Bundle of His
Ventricular muscle
Which one of the following causes vasodilatation:
TXA2
Serotonin (5-HT)
Endothelin
Neuropeptide Y
VIP
The highest oxygen extraction is found in the:
carotid body
heart
The fastest conduction velocity is found in the:
Atrial muscle
AV-node
Ventricular conduction system (Purkinje system)
Oxygen consumption at rest is the highest in the:
Coronary blood flow is:
dominant in the left coronary artery in 60% of people
better supply to subendocardium during systole
better supply to subendocardium during diastole
better supply to left ventricle during systole
left > right during systole
The velocity of blood flow is greatest in:
capillaries
pulmonary vein during diastole
small arteries
inferior vena cava
the aorta
Arterial baroreceptor afferents:
reach the spinal cord via sympathetic nerves
utilize glycine as a neurotransmitter
primary synapse in C1 area of the medulla
activate GABA inhibitory interneurons
excite autonomic efferents in the anterolateral horn
Isovolumetric contraction is associated with:
immediate increase in heart rate due to cardiac sympathetics
cardiac output increased/unchanged
increased systolic blood pressure and decreased diastolic blood pressure
does not work
decrease stroke volume
Baroreceptors are not located in:
carotid sinus
right atrium
aortic arch
large veins
The volume of blood is the greatest in the:
systemic capillaries
the liver
the lungs
The standard ECG setting is:
speed 50 mm.s-1 50 mm/mv
speed so mm.s-1 25 mm/mV
speed 25 mm.s-1 25 mm/mV
speed 25 mm.s-1 50 mm/mV
Long term control of tissue blood flow includes:
adenosine
nitric oxide
change in tissue vascularity
oxygen tension at the precapillary sphincter
aldosterone
Turbulence is more likely with:
small tube diameter
high density fluid
increased tube length
increased viscosity
The following would directly increase heart rate
sympathetic stimulation
parasympathetic stimulation
decreased blood pressure
At any given time the largest amount of blood in the body is carried by:
veins
capillary beds
arterioles
aorta
vena cava
The pacemaker of the heart is:
AV bundle
None of the above
The T wave in an ECG indicates:
Resting potential
Atrial depolarization
SA node excitation
Ventricle repolarization
Purkinje excitation
End diastolic volume in human is about
140 ml
50 ml
70 ml
100ml
200ml
Major functions of the lymphatic system are?
provide route for return of extracellular fluid
act as drain off for inflammatory response
render surveillance, recognition , and protection against foreign materials via lymphocytes, phagocytes, and antibodies
a, and c
Blood pressure is the measure of:
pressure exerted by the blood on the walls of the blood vessels
pressure exerted by the blood on the arteries
pressure exerted by the blood on the veins
pressure exerted by the blood on the aorta
Systolic Pressure is:
an average of 120 mm Hg
lowers steadily during ventricle systole
the highest when blood is being pumped out of the left ventricle into the aorta
an average of 80 mm Hg
The working myocardium:
is a functional syncitium
is comprised of cells whose cytoplasm communicates
plays the role of pacemaker of the heart
is comprised of cells, connected by structures that impede the ion flow
reacts to threshold irritants with different number of excited fibers
The heart rate at rest is:
100 - 140 beats.min-1
40 - 60 beats.min-1
approximately 50 beats.min-1
60-90 beats.min-1
20-40 beats.min-1
The full compensatory pause is typical of:
the atrial extrasystoles only
both the atrial and the ventricular extrasystoles
the ventricular extrasystoles only
extrasystoles during atrial fibrillation
extrasystoles during atrial flutter
The duration of the cardiac cycle depends on:
the time one systole to occur
the time one diastole to occur
the heart rate
the cardiac paused
The rhythm of the heart is determined by:
the bundle of His
the atrioventricular node
the sinus node
the Purkinje fibers
the Ieft and right bundle branches
The increased heart rate is called:
tachipnoe
bradycardia
atrial fibrillation
atrial flutter
tachycardia
When the rhythm is determined by the AV node, the heart rate is:
approximately 75 beats.min-1
40-60 beats.min-1
8-120 beats.min-1
Automaticity is characteristic of:
the cardiac muscle only
the striated muscles
some neurons and smooth muscle cells
all excitable tissues
the smooth muscle cells only
The action potential of the cardiomyocytes passes through:
slow depolarization and quick repolarization
rapid depolarization and slow repolarlzation
quick de- and repolarizations
slow de- and repolarizations
period of current electrical activity, expressed as slow waves and spike potentials
P wave of the electrocardiogram reflects:
depolarization of the ventricles
depolarization of the atria
hyperpolarization of the atria
the time necessary for the impulse originating in SA. node to reach the Purkinje fibers
Asynchronic contraction of the ventricles:
is a phase of the ventricular systole
is a phase of the ventricular diastole
begins with closing the S.L. valves
begins with opening the S.L. valves
begins with opening the A.V. valves
In the complete atriovenrticular block:
the conductivity at the bundle of His is fully interrupted
there is a complete independence of the atrial and ventricular ECG stages
the atrial waves indicate normal heart rate, but the rate of ventricular ones is 20-40 beats.min-1
the duration of PQ interval is 0.12-0.20 s
The stroke volume of the heart at rest is:
60 - 90 beats.min-1
approximately 70 ml
5.2 l
0.500 I
100-140 mmHg
The electrical axes of the heart is determined by:
the vectorial sum of QRS complexes in the standard leads
the vectorial sum of QRS complexes in the precordial leads
the vector's direction of the electrical forces of the ventricular muscle tissue
the supine or straight position of the body
the vector's direction of the electrical forces of the atrial muscle tissue
The augmented unipolar leads are
1st, 2nd and 3rd
aVR, aVL and aVF
answers a, and b
V1, V2, V3, V4, V5 and V6
b, and d
The auscultation of the mitral valve is performed at:
2nd sternal intercostal space, right of the sternum
5th intercostal space, 2 cm inside of the medioclavicular line
4th sternal intercostal space, right of the sternum
2nd sternal intercostal space, left of the sternum
3rd sternal intercostal space, left of the sternum
The phase 'plateau' of the cardiomyocytes action potentials is due to:
outflow of K+ from the cells
inflow of Na+ into the cells
inflow of K+ into the cells
slow inflow of Ca2+ into the cells
inflow of Na+ into the cells and outflow of K+ from the cells
The extrasystoles are:
increased heart rate of 250-230 imp-min-1
disturbances in conductivity
disturbances in excitability
extraordinary, only currently interrupting the cardiac rhythm, contractions of the cardiac muscle
c, and d
The electrical axes of the heart is of the indifferent type when the angle with the isoelectric line is:
+60 to +90 degrees
+30 to +60 degrees
from -90 degrees upward
+30 to -30 degrees
from -30 degrees downwards
Which of the following is not a vasoconstrictor:
norepinephrine
epinephrine
serotonin
angioitensin II
kinins
At rest the diastolic arterial pressure is:
90-95 mmHg
140-160 mmHg
60-90 mmHg
75 mmHg
Which of the following doesn't affect blood pressure:
cardiac output (C.O.)
minute respiratory volume
viscosity of blood
total peripheral vessel resistance
the volume of blood
Throughout the isovolumetrtc relaxation of the ventricles:
A.V. valves are opened, S.L. valves - opened
A.V. valves are closed, S.L. valves - opened
A.V. valves are opened, S.L. valves - closed
A.V. valves are closed, S.L. valves - closed
The first heart sound is:
systolic, result of the ventricular contractions
systolic, result of the A.V. valves closing
systolic, result of the S.L valves closing
diastolic, result of the A.V. valves closing
Cardiac output (C.O.) depends on:
vital capacity (VC)
stroke volume (SV)
heart rate (HR)
the preload and afterload
b, c and d
The intracardial regulation of the heart is carried out by:
integrated reflexes
neural regulatory mechanisms
humoral factors
adaptation to changes in venous return or resistance in the aorta
the automaticlty
The heart stops in diastole because of:
increased level of Ca2+ in the extracellular fluid
increased levels of catecholamines
increased levels of glucocorticoids
increased concentration of K+ the extracellular fluid
increased secretion of T3 and T4
The peripheral chemoreceptors trigger:
pressor and depressor reflexes
pressor reflexes only
the quick regulation of arterial blood pressure
depressor reflexes only
Hering-Breuer reflex
The pulse pressure is:
closer in value to the systolic than to the diastolic pressure
mean arithmetic of systolic and diastolic pressures
closer in value to the diastolic than to the systolic pressure
the difference between systolic and diastolic pressure
one third of the mean arterial pressure
The cardiovascular center is situated in:
hypothalamus
mesencephalon
the cortex
medulla oblongata
C8 - Th1-2 spinal cord segments
In the pulmonary circulation blood leaves the:
right ventricle and goes directly to the aorta
right ventricle and moves to the lungs
right atrium and goes directly to the left ventricle
right atrium and goes directly to the lungs
left ventricle and moves to the lungs
In the systemic circulation, blood leaves the:
left ventricle and goes directly to the aorta
lungs and moves to the left atrium
The cardiac cycle includes all of the following events except:
the movement of impulses from the SA node to all regions of the heart wall
the closing and opening of the heart valves during each heart beat
the number of times the heart beats in one minute
the changes in pressure gradients in all chambers of the heart
the changes in blood volume in all chambers of the heart
Which of the following chemicals does not regulate blood pressure?
ADH
Atrial natriuretic peptide
Angiotensin II
Nitric acid
Epinephrine
Exchange of nutrients and gases between the blood and tissue cells is the main function of:
arteries
venules
Arterial blood pressure increases in response to all but which of the following?
increasing stroke volume
increasing heart rate
rising blood volume
falling blood volume
The inferior vena cava brings blood from the lower regions of the body empties into the:
left atrium
right ventricle
The pacemaker of the heart is the;
The bundle branches
The tricuspid valve is located between the:
right and left atria
right and left ventricles
right atrium and right ventricle
left atrium and left ventricle
right ventricle and the aorta
When the mitral valve closes, it prevents the backflow of blood from the:
left atrium into the left ventricle
left ventricle into the left atrium
right atrium into the right ventricle
left ventricle into the aorta
right ventricle into the pulmonary trunk
The vessels that carry oxygen to the myocardial cells are called:
aortic arteries
pulmonary arteries
pulmonary veins
coronary veins
coronary arteries
The myocardium functions as a functional syncytium due to:
the presence of striations in the myocardium
branching of myocardlal cells
the presence of gap junctions
the presence of desmosomes
higher concentration of Ca2+
Autorhythmic cardiac cells are found In all the following location except the:
Interatrial septum
Purkinje cells
Coronary blood flow to the left ventricle increases during:
early systole
myocardial hypoxia
hypothermia
stimulation of parasympathetic nerves in the heart
AV block
Local metabolic activity is the chief factor determining the rate of blood flow to the:
glands
lung
The pressure:
drop along large veins is similar to that along large arteries
drop across the hepatic penal bed is similar to that across the splenic vascular bed
in the hepatic portal vein exceeds that in the inferior vena cava
drop across the vascular bed in the foot is greater when a subject is in the vertical than when he is in the horizontal position
in foot veins is higher when walking than when standing still
The second heart sound differs from the first heart sound in that it is
related to turbelence set up by valve closure
longer lasting than the first sound
higher in frequency
occasionally in split
heard when the ventricles are contracting
Pulmonary vascular resistance is
is equal to that offered by the systemic circuit
decreased when alveolar oxygen pressure fails
expressed in units of volume flow per unit time per unit pressure gradients
decreased during exercise
regulated reflexvely by sympathetic vasoconstrictor nerves
Veins:
contain most of the blood volume
have a histaminergic vasodilator innervation
receive nutrition from vas vasorum arising from their lumen
respond to distension by dilation of their smooth muscle
do not contain valves
In the heart:
the left atrial wall is about three times thicker than the right atrial wall
systolic contraction normally begins in the left atrium
excitation spreads directly from atrial muscle cells to ventricular muscle cells
atrial and ventricular muscle contracts simultaneously in systole
the contracting ventricles shorten from apex to base
When measuring blood pressure by the auscultatory method:
the sounds that are heard are generated in the heart
the cuff pressure at which the first sounds are heard indicate systolic pressure
the cuff pressure at which the loudest sounds are heard indicate diastolic pressure
systolic pressure estimations tend to be lower than those made by the palpatory method
wider cuff's are required for smaller arms
The absolute refractory period in the ventricles:
is the period when the ventricles are completely still excitable
corresponds to the period of ventricular depolarization
corresponds approximately to the period of ventricular relaxation
is shorter than the corresponding period in atrial muscle
decreases during parasympathetic stimulation of the heart
Vascular resistance:
increases by 50 per cent When the vascular radius is halved
is related to the thickness of the wall of the vessel
is related to the vessel’s length
is affected by blood Hb concentration
is greater in the capillary bed than in the arteriolar bed
Sympathetic drive to the heart is increased:
in exercise
in relaxed position
in normotension
when parasympathetic drive is decreased
during a vasovagal attack
Hyperaemia in skeletal muscle during exercise is normally associated with:
release of sympathetic vasoconstrictor tone in the exercising muscles
capillary dilation due to relaxation of capillary smooth muscle
a fall in arterial pressure
reflex vasoconstriction in other vascular beds
an increase in venous pressure
Sinuatrial node cells are:
found in both atria
innervated by the somatic nerves
unable to generate impulses when completely denervated
connected to the AV node by fine bundles of purkinje tissue
able to generate impulses because their membrane potential is unstable
The first heart sound corresponds in time with:
closure of the aortic and pulmonary valves
the P wave of the electrocardiogram
a decline in atrial pressure
a rise in ventricular pressure
the A wave in central venous pressure
The velocity of blood flow:
in capillaries is low because they offer high resistance to flow
in veins is greater than in venules
can fall to zero in the ascending aorta during systole
is lower towards the centre of large blood vessels than at the periphery
in the circulation falls as the haematocrit falls
The strength of contraction of left ventricular muscle increases when:
end-diastolic ventricular filling pressure
serum potassium levels rise
blood calcium levels fall
blood magnesium levels fall
peripheral resistance is decreased
During isometric ventricular contraction:
the entry and exit valves of the ventricle are closed
pressure in the aorta rises
pressure in the atria falls
left coronary blood flow is going up
the rate of rise in pressure is greater in the right than in the left ventricle
Cardiac output:
is normally expressed as the output of one ventricle in liters/minute
is about 2.0 l at rest
is about 10.0 l at rest
rises in a cold environment
does not increase in exercise following denervatlon of the heart
In the brachial artery:
Pulse waves travel at the same velocity as blood
Pulse pressure falls with decreasing elasticity of the wall
Pressure rises markedly when the artery is occluded distally
Pressure falls when the arm is raised above head level
Pulse pressures have a smaller amplitude than aortic pulse pressures
Arterioles offer more resistance to flow than other vessels since they have:
thicker muscular walls
richer sympathetic innervation
smaller internal diameters
a smaller total cross-sectional area
a greater pressure drop along their length
In the denervated heart, left ventricular stroke work increases when:
the end-diastolic length of the ventricular fibres increase
peripheral resistance decreases
blood volume falls
right ventricular output decreases
the veins dilate
With increasing distance from the heart, arterial:
walls contain relatively more smooth muscle than elastic tissue
flow has a greater tendency to be turbulent
mean pressure tends to decrease slightly
pulse pressure tends to increase slightly
pO2 falls appreciably
In the estimation of cardiac output using the Fick principle:
pulmonary blood flow is measured
the pO2 of arterial and mixed venous blood are measured
oxygen uptake is estimated from alveolar pO2 measurements
pulmonary arterial blood is sampled to measure the oxygen in venous blood
pulmonary venous blood is sampled to measure the oxygen in arterial blood
Systemic hypertension may be caused by:
hypoxia due to chronic respiratory failure
excessive secretion of aldosterone
excessive secretion of insulin
myocardial thickening (hypertrophy) of the left ventricle
the rapid cardiac action of ventricular fibrillation
Peripheral differs from central circulatory failure in that:
hypovolaemia is unusual
it leads to underperfusion of the tissues
cardiac output is usually normal
central venous pressure is high
ventricular function is usually normal
In atrial fibrillation:
the electrocardlagram shows no evidence of atrial activity
ventricular rate is lower than atrial rate
respiratory sinus arrhythmia can usually be seen
the ventricular rate is higher than atrial rate
the QRS complexes have an abnormal configuration
Pain due to poor coronary blood flow (angina) may be relieved by:
Cutting the parasympathetic nerve trunks supplying the heart
Infecting CaCl2
Providing the patient with a cold environment
β-adrenoceptor stimulating drugs
Drugs causing peripheral vasodilation
Aortic valve incompetence may cause:
increase in arterial pulse pressure
systolic murmurs in the aortic valve area
hypertrophy of right ventricular muscle
decreased myocardial blood flow
right ventricular failure
Ventricular extrasystoles:
are usually associated with a normal QRS complex
from the same focus have similar QRS complexes
usually occur following a compensatory pause
can‘t be detected by ECG
indicate serious heart disease
Pulmonary embolism (blood clots impacting in lung blood vessels) usually decreases:
pulmonary vascular resistance
left atrial pressure
right atrial pressure
ventilation to perfusion ratios in the affected lung
pO2 in pulmonary venous blood
Hardening of the arterial walls tends to raise:
Arterial compliance
Systolic arterial pressure
Diastolic arterial pressure
Peripheral resistance
The frequency of breathing
Left ventricular failure tends to cause an increase in:
Ieft ventricular ejection fraction
pulmonary capillary pressure
lung compliance
pulmonary oedema when the patient stands up
In otherwise healthy people, local tissue death follows obstruction of:
an internal carotid artery
a renal artery
a femoral artery
a brachial artery
the hepatic portal vein
The part of the circulation pumping blood to and from the lungs is known as the _____ circulation.
systemic
pulmonary
coronary
respiratory
hepatic
The plateau phase of the action potential in contractile myocardiocytes is due to:
the slow movement of Na+ across the cell membrane
the influx of Ca2+
the increased membrane permeability to K+
the increased membrane permeability to Na+
a decrease in Ca2+ diffusing across membrane
The valve between the right ventricle and the vessel that leaves it is the _____ valve.
tricuspid AV
bicuspid AV
mitral
pulmonary semilunar
aortic semilunar
If the connections between the parasympathetic division of the ANS and the heart were cut, then
heart rate would decrease
stroke volume would decrease
cardiac output would decrease
heart rate would increase
heart activity would remain unchanged
Fenestrated capillaries:
have pores in their walls
are located in most tissue
permit only one-way exchange of materials
have a layer of smooth muscle in their walls
are found in the liver and kidneys
Absolute refractory period in the heart:
corresponds to the duration of relaxation
lasts till half of cardiac contraction
shorter than refractory period in skeletal muscle
lasts till cardiac contraction
last only 10 ms
First heart sound occurs during the period of:
isometric relaxation
isotonic relaxation
isovolumetric contraction
isovolumetric relaxation
Which of these vessels does not have sympathetic control:
cerebral
splanchnic
cardiac
cutaneous
muscle
Blood brain barrier is made up of:
astrocytes
oligodendrocytes
oligodendroglia
microglia
others
Positive bathmotropic effect on heart is produced by:
stimulation of vagus nerve
stimulation of sympathetic nerves
atropin
sectioning of vagus
K+
Which of the following conducting systems has the slowest conducting velocity:
Purkinje fibres
Hiss bundle
In heart, within physiological limits the force of contraction is directly proportional to the:
Pacemaker activity
AV nodal delay
Initial length of the cardiac muscle
Respiratory rate
ST-segment
The diacrotic notch on aortic pressure curve is caused by:
closure of mitral valve
closure of tricuspid valve
closure of atrial valve
closure of pulmonary valve
opening the atrial valve
The PR interval of ECG corresponds to:
ventricular repolarization
atrial repolarization and conduction through AV node
repolarization of AV node and bundle of His
depolarization of SA node
Increased vagal tone causes:
hypertension
increase in cardiac output
increase in stroke volume
Which of the following is not increased during exercise;
total peripheral resistance
systolic BP
heart rate
muscle blood flow
Which of the following takes longest time to return to normal after 1L of blood is removed from a normal individual:
number of RBC in peripheral blood
plasma volume
renin secretion
blood pressure
number of WBC in peripheral blood
In a patient with mitral stenosis one would expect to hear:
continuous murmur
a systolic murmur loudest over the base of heart
a diastolic murmur loudest over the apex of heart
a diastolic murmur loudest over the base of heart
systolic murmur over the apex of heart
The ‘S' wave in ECG is below isoelectric line because of:
repolarization of ventricles
change in direction of the impulse when the base of the ventricles are getting depolarised
depolarisation of apex of heart
repolarisation of apex of heart
depolarisation of atria
Lymph flow from the foot is:
increased when an individual rises from the supine to standing position
increased by massaging the foot
increased when capillary permeability is decreased
decreased by exercise
decreased by massaging the foot
The "T" wave in ECG is above the isoelectric line because of:
depolarisation of ventricles
depolarisation of bundle of His
change in the direction of repolarisation from the wave of depolarization of the ventricles
repolarisation of purkinje fibres
Restoration of the blood volume after haemorrhage is aided by:
contraction of venous reservoirs
a fall in capillary pressure in certain vascular beds
arteriolar vasodilation
mobilization of intracellular fluid into the circulation
in increase in the osmotic pressure of the plasma proteins