Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Cardiology: Key Information > Physiology > Flashcards

Physiology Flashcards

(89 cards)

Start Studying
1
Q

define autorhythmicity

A

the heart is capable of beating rhythmically in the absence of external stimuli

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

define sinus rhythm

A

a heart controlled by the SA node

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

does the SA node have a stable resting membrane potential?

A

no

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what does the SA node generate?

A

regular spontaneous pacemaker potentials (phase 4)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what produces the pacemaker potentials in the SA node?

A
  • decrease in K+ efflux
  • funny current (Na+ and K+ influx through HCN channels)
  • transient Ca2+ influx through T-type channels
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is phase 0 due to in the pacemaker cells?

A

Ca2+ influx through L-type channels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is phase 3 due to in pacemaker cells?

A

inactivation of L-type channels and activation K+ channels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what cell junction does electrical excitation spread through

A

gap junctions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what does the AV node do to the conduction velocity

A

AV cells have a small diameter so slow conduction velocity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what does slowed conduction in the AV node allow?

A

atrial systole to precede ventricular systole

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

phase 4 of myocytes?

A

resting potential due to K+ efflux via Na+/K+ ATPase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is the mV resting membrane potential in myocytes?

A

-90mV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

role of ivabradine

A

blocks HCN slowing the HR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

role of digoxin

A

inhibits Na+/K+ ATPase causing the membrane to depolarise slightly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

phase 0 in myocytes

A

upstroke due to Na+ influx

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

membrane potential in phase 0

A

+20mV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

phase 1 in myocytes

A

early repolarisation due to transient K+ efflux

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

phase 2 in myocytes

A

plateau due to Ca2+ L-type influx which balances K+ efflux

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what does durgs that block the K+ channel cause?

A

increase ventricular action potential (can lead to acquired long QT syndrome)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

phase 3 in myocytes

A

final repolarisation due to closure of Ca2+ channels and K+ efflux

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

difference in atrial myocytes

A

another outward K+ channel (ultra-rapid delayed rectifier) so phase 2 is less evident

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

sympathetic innervation of the heart

A

sympathetic nerves act on B1-adrenoceptors using NA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

parasympathetic innervation of the heart

A

vagus nerve acts on M2 muscarinic receptors using ACh decreasing HR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what dominates control of HR in resting conditions?

A

vagal tone exerts a continuous influence of the SA and AV nodes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
define chronotropic
change in heart rate
26
define inotropic
force of contraction
27
define lusitropic
rate of myocardial relaxation
28
define dromotropic
conduction speed
29
define ECG
record of depolarisation and repolarisation cycle of cardiac muscle obtained from the skin surface
30
P wave
atrial depolarisation
31
QRS complex
ventricular depolarisation (masks atrial repolarisation)
32
T wave
ventricular repolarisation
33
PR interval
AV node delay
34
ST segment
ventricular systole
35
TP interval
diastole
36
QT interval
ventricular depolarisation and repolarisation
37
role of desmosomes between intercalated discs in cardiac cells
ensure tension is transmitted from one cell to the next
38
what must happen for myocardial contraction to happen?
Ca2+ must bind with troponin to expose the actin binding site for cross-bridge formation
39
what does the refractory period prevent?
tetanic contraction
40
what state are the Na+ channels in during the refractory period
inactivated
41
define stroke volume
volume of blood ejected from each ventricle per heartbeat
42
define EDV
volume of blood in each ventricle at the end of diastole
43
what determines EDV
venous return
44
what influences venous return?
- venomotor tone - skeletal muscle pump - respiratory pump (inspiration causes increased intraabdominal pressure) - blood volume
45
Starling's Law
the more the ventricle is filled with blood during diastole the greater the volume of blood ejected
46
define afterload
resistance into which the heart is pumping
47
what is after load determined by
radius of blood vessel and blood viscosity
48
what does after load increase the risk of?
hypertrophy
49
intrinsic control of SV
change in diastolic length and stretch of fibres (increases affinity for Ca2+)
50
extrinsic control of SV
nerves (parasympathetic has no effect on force of cardiac contraction)
51
75bpm diastole and systolic time
systole 0.3sec | diastole 0.5sec
52
five phases of the cardiac cycle
1. passive filling 2. atrial contraction 3. isovolumetric ventricular contraction 4. ventricular ejection 5. isovolumetric ventricular relaxation
53
describe passive filling
blood flows into the ventricles (80%)
54
describe atrial contraction
completes EDV
55
describe isovolumetric ventricular contraction
AV valves shut causing pressure to rise
56
what does the AV valves shutting indicate?
lub- S1 | beginning of systole
57
describe ventricular ejection
ventricular pressure falls below aortic/pulmonary it causes the valves to shut
58
what does the aortic valve shutting cause?
valve vibration produces the dicrotic notch
59
describe isovolumetric ventricular relaxation
closure of semi-lunar valves causes tension to fall
60
what does shutting of the aortic/pulmonary valves indicate?
dub- S2 | beginning of diastole
61
why does arterial pressure not fall to zero during diastole?
elastic recoil
62
what does the JVP indicate?
central venous pressure
63
define MAP
average arterial blood pressure during a single cardiac cycle
64
how to calculate MAP
DBP + 1/3 Pulse Pressure | [(2x diastolic pressure) + systolic pressure]/ 3
65
normal range of MAP
70-105mmHg
66
is diastole twice as long as systole?
yes
67
describe the baroreceptor reflex in postural hypotension
- standing causes venous return to decrease (gravity) - MAP decreases - reduced firing from baroreceptors causes vagal tone to decrease and sympathetic tone to increase
68
define postural hypotension
failure of the baroreceptor reflex to response to gravitational shifts
69
positive result of postural hypotension (by 3 minutes)
- systolic of at least 20mmHg | - diastolic of at least 10mmHg
70
what does extracellular fluid consist of?
plasma volume | interstitial volume
71
three systems that affect the extracellular fluid?
1. RAAS 2. NPs 3. ADH
72
RAAS
- renin is released from the kidney - converts angiotensinogen from the liver into angiotensin I - ACE from the lungs converts this to angiotensin II - activates the adrenal cortex to form aldosterone
73
NPs
cause excretion of salt and water
74
ADH synthesis
made in the hypothalamus and stored in the posterior pituitary
75
action of ADH
acts on kidney tubules causing reabsorption of water and vasoconstriction
76
extrinsic control of vascular smooth muscle
nerves and hormones
77
nervous control of vascular smooth muscle
vasomotor tone | no parasympathetic innervation
78
hormones on vascular smooth muscles
- adrenaline on alpha-receptors causes vasoconstriction (skin, gut, kidney) - adrenaline on beta2 causes vasodilation (cardiac and skeletal muscle) - angiotensin II vasoconstrition - ADH vasoconstriction
79
intrinsic control of vascular smooth muscle
- chemical local metabolites - chemical local humoral agents - temperature - myogenic response - sheer stress
80
local humoral vasodilators
- histamine - bradykinin - NO
81
local humoral vasoconstrictors
- serotonin - thromboxane A2 - leukotrienes - endothelin
82
describe the myogenic response
if MAP rises, vessels constrict
83
describe sheer stress on vascular smooth muscle
dilates arteries
84
define shock
abnormality of the circulatory system resulting in inadequate tissue perfusion and oxygenation leads to anaerobic metabolism and accumulation of waste products and cellular failure
85
define hypovolaemic shock
loss of blood volume
86
define cardiogenic shock
decreased cardiac contractility causing sustained hypotension
87
define obstructive shock (tension pneumothorax)
increased intrathoracic pressure causes decreased venous return
88
define neurogenic shock
loss of sympathetic tone causing decreased HR (unlike other types of shock)
89
define vasoactive shock
release of vasoactive mediators

Cardiology: Key Information (42 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions