Brainscape's Knowledge GenomeTM

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


See full index

Drugs and diseases-2106 > Cardiac muscle > Flashcards

Cardiac muscle Flashcards

1
Q

What are some diseases of the heart?

A
  • Hypertension-(Inc Cardiac output(CO=HRxForce of contr))
  • Ischeamic HD(angina, MI)
  • Chronic heart failure-(Red CO)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How to target these diseases + arrhythmias?

A
  • Hypertension-Red CO-B-blockers
  • Ischaemic HD-Red HR-B-blockers
  • Chronic heart failure-stimulate contraction-digoxin
  • Arrhythmias-cont HR-ion channel modulators
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the structure of cardiac muscle?

A
  • Striated like Skeletal muscle
  • But, cardiac cells are extensively connected by gap junctions like smooth muscle
  • Gap junctions: allow AP to travel from cell to cell
  • Contracts as a unit.

See PP fo diag

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

Are cardiac AP long or short>

A
  • Broad on graphs
  • Long, last for hundreds of milliseconds
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the refractory period?

A
  • AP last almost as long as contraction
  • Long refractory period prev a 2nd cont too soon
  • Allows heart to relax fully and therefore fill up with blood again before next cont
  • Even when AP freq is high & sp heart beating fast, RP allows heart to fill
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How many phases of cardiac AP are there?

A
  • 5- 0,1,2,3,4
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is phase 0 of Cardiac AP?

A
  • Rapid depolarisation-Mem pot reaches critical level (-60mV) at which inward Na+ current becomes large enough to generate all or nothing depolarisation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is phase 1 of Cardiac AP?

A
  • Partial repolarisation-Na+ channels close
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is phase 2 of Cardiac AP?

A
  • Plateau-inward calcium current
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is phase 3 of Cardiac AP?

A
  • Repolarisation-Ca2+ channels close and the outward K+ current kicks in-delayed outwardly rectifying K+ current
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is phase 4 of Cardiac AP?

A
  • Pacemaker potential-gradual depolarisation up to -60mV when Na+ current activated again
  • Only found in pacemaker cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What cells initiate a Cardiac AP?

A
  • Pacemaker cells
  • Heart muscle cells in SAN and AVN exhibit pacemaker activity-can generate an AP
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How is heartbeat triggered?

A
  • Heartbeat is triggered by APs generated by pacemaker cells NOT neural input-
  • Why heart beats when removed from body-myogenic
  • (although Autonomic NS regulates freq and force of contr)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How is a cardiac AP conducted?

A
  • Conductance of AP across atria=atrial contraction
  • Delay (0.1s) at A-V node
  • AP passes down purkinje fibres down to bottom of ventricles, then up the sides
  • Contraction of ventricles starts from the bottom
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the relationship of AP to contraction? (atrial)

A
  1. During cardiac relaxation, venous blood flows into atria.
  2. AV valves open, allowing blood to flow into ventricles.
  3. On contraction of atria, rest of blood in atria squeezed into ventricles.
  4. AV delay allows complete filling before ventr contr.
    5.(Atrial fibrillation-impaired contr of atria. some blood stays in atria-stasis-clotting.)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the relationship of AP to contraction? (ventricular)

A

1.AP travels quickly down bundles of His & then throughout ventricles via purkinje fibres
2.Ventricles contract. Inc Pressure closes AV valves prev blood entering atria
3.Rapid transmission of AP through ventricles allows cells to contract “as one”
4.(ventricular fibrillation-Uncoordinated contraction of ventricular cardiac muscle cells. Blood not pumped out of heart-death)

Defibrillation?

17
Q

Effect of Autonomic nerves on function of heart.

A
  • Parasymp innervation-Vagus nerves innervates atrium, SA and AV nodes.
  • Symp innervation-atria, SA and AV nodes and richly innervate ventricles
18
Q

Explain Parasympathetic innervation on the heart?

A
  • SA node:ACh reduces rate of closure of K+ channels
    ->Get inc repol, therefore takes longer to depo & hence stim next contr
    ->Red HR
  • AV node- red conduction, delaying contraction of ventricles
  • Dec contr of atria
19
Q

Explain sympathetic Innervation on the heart?

A
  • SA node- NA inc K+ channels closing. Inc rate of depolarisation. Red time betw contractions (phase 4)
    ->Inc HR
  • A-V node-Inc conduction
  • Cardiac muscle cells: Inc Ca2+ influx inc force of contraction of atria and ventricles

Sympathetic innervation- inc HR & force NB also adrenaline in circulation.

20
Q

What are B-blockers?

A
  • Used in treatment of hypertension and angina
  • Block B1-adrenoceptors in heart
  • Results in Dec Hr (SA node & AV node)
  • Dec force of contr (ventricles)
  • Red cardiac output (dec bp)
    1. BP=CO X resistance
  • Inc diastolic period- allows blood to muscle angina

Drugs and diseases-2106 (38 decks)

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