Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Cardiovascular System > Lecture 7 - Cardiac Action Potentials; Drugs and the CVS > Flashcards

Lecture 7 - Cardiac Action Potentials; Drugs and the CVS Flashcards

1
Q

how is the cardiac resting membrane potential generated?

A

cell membrane mostly permeable to K

K move out taking positive charge with them

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

what is the cardiac resting membrane potential?

A

around -90mV

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

how is heart rate increased?

A

sns on san

noradrenaline (alpha 2 receptor) makes the pacemaker potential steeper

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

how is heart rate decreased?

A

pns on san

acetylcholine (m3 receptor) makes the pacemaker potential shallower

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

what is the role of baroreceptors?

A

role in controlling heart rate
stretch sensitive
pass information to medulla to cause pns innervation of san
slows heart rate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what are cardiovascular drugs used to treat?

A 
arrhythmias
heart failure
angina
hypertension
risk of thrombus formation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what do cardiovascular drugs alter?

A

rate and rhythm of heart
force of myocardial contraction
peripheral resistance and blood flow
blood volume

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

what are causes of arrhythmias?

A

ectopic pacemaker activity
after depolarisation
reentry loop

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

what is ectopic pacemaker activity?

A

damaged area of myocardium becomes depolarised and spontaneously active
latent pacemaker activated due to ischaemia
dominates over san

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

what are after depolarisations?

A

abnormal depolarisations after the ap
maybe caused by high intracellular Ca
longer ap
longer qt

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

what is the reentry loop?

A

conduction delay
normal spread of excitation disrupted due to damaged area
incomplete conduction damage

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

what are the four classes of anti arrhythmic drugs?

A
  1. drugs that block voltage gated Na channels
  2. antagonists of beta-adrenoceptors
  3. drugs that block K channels
  4. drugs that block Ca channels
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

describe class 1 anti arrhythmic drugs

A 
eg lidocaine
blocks open or inactive channels
dissociates rapidly in time for next ap
prevents firing of ap too close together
after depolarisations cant cause another ap
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

describe class 2 anti arrhythmic drugs

A

eg propanolol, atenolol
block sympathetic action by acting on beta 1 receptors
decreases slope of pacemaker potential
inhibits adenyl cyclase decreasing inotropy
after an am increases sns activity and reduces O2 demand of mycardium

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

describe class 3 anti arrhythmic drugs

A

prolong ap by blocking K channels which repolarise
arp is lengthened
can also be pro arrhythmic

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

describe class 4 anti arrhythmic drugs

A 
eg verapamil
decreases slope of pacemaker potential
decreases avn conduction
decreases force of contraction
coronary and peripheral vasodilation
17
Q

what is adenosine?

A 
produced endogenously
acts on A1 receptors at avn
enhances K conductance
hyperpolarises cells of conduction tissue
anti arrhythmic
18
Q

what is an inotropic drug?

A

affect force of contraction of the heart

19
Q

what does a negatively inotropic drug do?

A

reduces workload of heart
reduces o2 requirement of heart and limits further damage
eg beta blocker

20
Q

what does a positively inotropic drug do?

A

when heart needs to beat more strongly
beta-adrenoceptor agonist
eg dobutamine

21
Q

how are drugs used to treat heart failure?

A

ace-inhibitors prevent formation of angiotensin II (vasoconstrictor)
promotes vasodilation of arterioles and venous dilation
decreases afterload and preload to heart

22
Q

what does angiotensin II do?

A

promotes aldosterone release from adrenal cortex

aldosterone causes Na and water retention increasing blood volume

23
Q

what causes angina?

A

o2 supply to heart doesnt meet need ischaemia of heart causes chest pain
due to narrowing of coronary arteries

24
Q

how is angina treated?

A

reduced workload to heart
beta blockers
Ca channel blockers
organic nitrates

25
Q

what do organic nitrates do?

A

react with thiols in vascular smooth muscle to release NO2-
NO2- is reduced to NO which is a vasodilator
NO activates guanylate cyclase increasing cGMP and lowering intracellular Ca
causes relaxation of vascular smooth muscle

26
Q

what is the primary action of angina treatment?

A

acts on venous system
venodilator
lowers central venous pressure and preload
heart fills less so force of contraction lowers

27
Q

what is the secondary action of angina treatment?

A

acts on coronary arteries

improves o2 delivery to ischaemic myocardium

28
Q

which heart conditions increase risk of thrombus formation?

A

af

valve disease

29
Q

how are drugs used to treat hypertension?

A

reduce co and/or tpr

include ace inhibitors, diuretics, adrenoceptor blockers, Ca channel blockers

Cardiovascular System (15 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions