Cardiology Flashcards

1
Q

Blood pressure

A

hydrostatic force exerted against blood vessel walls by blood

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2
Q

Systolic arterial pressure

A

force exerted on aorta and systemic arteries by blood when the heart contracts

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3
Q

Diastolic arterial blood pressure

A

force exerted on walls of the aorta and systemic arteries by blood when the heart relaxes

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4
Q

Pulse pressure

A

difference between systolic and diastolic blood pressure

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5
Q

Mean arterial blood pressure

A

average arterial blood pressure during a single cardiac cycle

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6
Q

When calculating MAP, which value is doubled and why

A

Diastolic blood pressure
As the diastolic portion of the cycle is twice as long as the systolic portion

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7
Q

Average systolic value (resting)

A

90-120

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8
Q

Average resting diastolic blood pressure (resting)

A

60-80

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9
Q

Average pulse pressure

A

30-50

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10
Q

Average (resting) map

A

70-105

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11
Q

What are baroreceptors used for

A

relaying information derived from blood pressure within the autonomic nervous system

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12
Q

What happens when blood pressure increases (3)

A

walls of blood vessels stretch more
Baroreceptors are activated
Signals are sent to the medulla

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13
Q

what does the brain do in response to increased baroreceptor firing (2)

A

Parasympathetic activity increases
Sympathetic activity decreases

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14
Q

What is the result of the brain’s response to increased baroreceptor firing (3)

A

Decreased cardiac output
Decreased vascular resistance
Decreased blood pressure

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15
Q

What happens when blood pressure decreases (3)

A

walls of the blood vessels stretch less
Baroreceptors detect less stretch
Signalling to the brain decreases

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16
Q

what is the brain’s response to decreased baroreceptor signalling (2)

A

increased sympathetic activity
Decreased parasympathetic activity

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17
Q

What is mean arterial blood pressure a product of (2)

A

Cardiac output and systemic vascular resistance

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18
Q

what is cardiac output the product of (2)

A

heart rate and stroke volume

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19
Q

What is cardiac output

A

Volume of blood pumped by each ventricle per minute

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20
Q

How does the sympathetic nervous system increases heart rate

A

releasing noradrenaline

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21
Q

How does the parasympathetic nervous system decrease heart rate

A

Releasing acetylcholine

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22
Q

What is stroke volume

A

volume of blood pumped by each ventricle per heart beat

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23
Q

What happens if sympathetic nerves innervate ventricular myocardium (2)

A

increases force of contraction
Which increases stroke volume

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24
Q

What is systemic vascular resistance

A

sum of resistance in all vasculature of the systemic circulation

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25
What regulates systemic vascular resistance
Contraction and relaxation vascular smooth muscles
26
What is meant by vasomotor tone
Vascular smooth muscles are partially contracted even at rest
27
What is vasomotor tone caused by
tonic discharge of sympathetic nerves
28
What does tonic discharge of sympathetic nerves result in
Continuous release of noradrenaline
29
Describe autorhythmicity
the heart is capable of beating in the absence of stimuli
30
Where does excitation of the heart originate
Pacemaker cells in the sino-atrial node
31
Sinus rhythm meaning
when the heart is driven by the sino-atrial node
32
What exists in place of a stable resting membrane potential in pacemaker cells of the sino-atrial node
Generation of regular and spontaneous pacemaker potentials
33
Describe the pacemaker potential
Slow depolarisation of the pacemaker membrane to a threshold
34
What causes the pacemaker potential (3)
funny current Decreased potassium ion efflux Calcium ion influx
35
What is the funny current
depolarising cation current caused by influx of sodium ions through HCN channels
36
Once a threshold is reached for pacemaker cells, what happens(2)
rising phase Falling phase
37
Describe the rising phase of an action potential in a pacemaker cell (2)
caused by opening of L-type calcium ion channels Calcium ion influx occurs
38
Describe the falling phase of the action potential in pacemaker cells (2)
Caused by inactivation of L-type calcium ion channels and activation of potassium ion channels Potassium ion efflux occurs
39
How does cell to cell spread of excitation occur
via gap junctions
40
What is the result of the slow conduction velocity within the atrioventricular node (2)
Conduction is delayed So atrial systole precedes ventricular systole
41
What allows rapid spread of action potentials to the ventricles (2)
bundle of HIs Purkinje fibres
42
What is the sole point of electrical contact between t he atria and ventricles
atrioventricular node
43
What is the resting membrane potential of contractile cardiac muscle cells
-90mV
44
Describe phase 0 of action potentials in contractile cardiac muscle cells (2)
there is rapid sodium ion influx The membrane potential is reversed to +20mV
45
Describe phase 1 of action potentials in contractile cardiac muscle cells (2)
sodium ion channels close There is transient potassium ion efflux
46
Describe phase 2 of action potentials in contractile cardiac muscle cells
there is influx of calcium ions via L-type calcium ion channels
47
Describe phase 3 of action potentials in contractile cardiac muscle cells (2)
L-type calcium ion channels close Potassium ion efflux occurs
48
What is phase 4 of action potentials in contractile cardiac muscle cells
The resting membrane potential is restored
49
Describe the plateau phase
When the membrane potential do contractile myocytes is maintained near the peak of the action potential for a few hundred milliseconds
50
What is the main cause of the plateau phase in contractile myocytes
Influx of calcium ions via L-type calcium channels (phase 2)
51
What are the ECG waves (3) and what events cause them
P wave caused by atrial depolarisation QRS wave caused by ventricular depolarisation T wave caused by ventricular repolarisation
52
Is the vagus nerve part of the sympathetic or parasympathetic nervous system
Parasympathetic nervous system
53
What dominates under normal resting conditions
Vagal tone caused by continuous influence of the vagus nerve on the sino-atrial node
54
What is the importance of vagal tone
it slows intrinsic heart rate from roughly 100 bpm to a normal resting heart rate
55
What is supplied by the vagus nerve (2)
sino-atrial node Atrioventricular node
56
What is the effect of vagal stimulation (3)
slower rate of firing of the sino-atrial node Increased atrioventricular node delay Decreased heart rate
57
Describe the neurotransmitter action involved in vagal stimulation (2)
acetylcholine Acting at muscarinic M2 receptors (G-protein coupled)
58
What is supplied by cardiac sympathetic nerves (3)
sino-atrial node Atrioventricular node Myocardium
59
What is the effect of cardiac sympathetic nerve stimulation (3)
Increased rate of firing of the sino-atrial node Decreased atrioventricular node delay Increased force of contraction
60
Describe the neurotransmitter action involved in cardiac sympathetic nerve stimulation (2)
noradrenaline Acting at β1 adrenoceptors (g protein coupled)
61
Summarise RAAS effect (2)
increases systematic vascular resistance Increases plasma volume
62
Summarise Natriuretic peptides (3)
opposes RAAS system Reduces blood volume Reduces blood pressure
63
Summarise ADH (3)
Increase systemic vascular resistance Increases blood pressure Regulates extracellular fluid volume and osmolality to manage fluid load/deficit
64
What is renin
an enzyme found in plasma
65
When is renin released (3)
Due to sympathetic stimulation of renal nerves Due to decreased blood flow to the kidneys Due to reduced salt delivery to the kidneys
66
what is the sequence of events that occurs in the renin angiotensin aldosterone system (4)
Renin is released from kidneys Angiotensinogen is converted to angiotensin 1 ACE converts angiontensin I to angiotensin II Angiotensin II causes vasoconstriction and stimulates the release of aldosterone from the adrenal cortex
67
What is the effect of aldosterone (2)
increases renal absorption of plasma and water Increases plasma volume
68
When are natriuretic peptides release (2)
in response to cardiac distension In response to neurohormonal stimuli
69
What is the effect of natriuretic peptides (6)
decrease renin release Vasodilation Excretion of salt and water in kidneys Reduce blood volume Decrease blood pressure Decrease SVR
70
What are the two types of natriuretic peptides
atrial natriuretic peptides Brain-type natriuretic peptides
71
Where is ADH made and stored (2)
a peptide hormone made by the hypothalamus Stored in the posterior pituitary
72
What stimulates secretion of ADH (2)
reduced extracellular fluid volume Increased plasma osmolarity
73
Effects of ADH (6)
increase reabsorption of water in kidney tubules Vasoconstriction Increases plasma volume Increases cardiac output Increases blood pressure Increases SVR
74