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Cardiovascular System > 7. Electrical & Molecular Mechanisms Of The Heart And Vassculature > Flashcards

7. Electrical & Molecular Mechanisms Of The Heart And Vassculature Flashcards

1
Q

What is the cardiac output of average 70kg man?

A

5L/min

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2
Q

What happens to the concentration gradient & electrical gradient at the equilibrium potential for an ion?

A

They become equal

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3
Q

What is the resting membrane potential for cardio myocytes ?

A

-85 to -95 mV

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4
Q

How does action potential in axon and skeletal muscle last?

A

0.5-1ms

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5
Q

How long does it take for depol to occur in SA node and cardiac ventricle ?

A

100ms

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6
Q

What causes a pacemaker potential ?

Which channels are used?

How are these channels activated?

A

Funny currents

HCN channels

By hyperpolarisation/negative membrane potential (

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7
Q

What causes the upstroke in an AP of a pace maker cell?

A

L type ca2+ channels opening = ca+2 influx

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8
Q

Where in the heart is depolarisation the fastest ?

A

SA node

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9
Q

Where in the heart is there automaticity?

A

SA node and AV node

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10
Q

What do pacemakers cells do?

A

Sets the rhythm

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11
Q

What is asystole ?

A

No beating of the heart

No APs fired

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12
Q

If action potentials fire to slowly this’s it’s called..

A

Bradycardia

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13
Q

If action potentials fire too quickly this is called…

A

Tachycardia

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14
Q

If action potential firing/electrical activity in heart becomes random this is called…

A

Fibrillation

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15
Q

What is the normal range of k+ concentration ?

A

3.5-5.5 mmol.L^-1

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16
Q

In hyperkalaemia what happens to the resting membrane potential of cells?

A

It becomes more +ve - closer to threshold.

17
Q

What does hyperkalaemia do to the action potential ?

A
  • slower upstroke
  • depolarise the membrane
  • more inactivated na+ channels
  • narrowing of AP
18
Q

What can hyperkalaemia lead to ?

A

Asystole

19
Q

What is mild hyperkalaemia?

A

5.5-5.9mmol/L

20
Q

What is moderate hyperkalaemia?

A

6.0-6.4 mmol/L

21
Q

What is severe hyperkalaemia?

A

> 6.5mmol/L

22
Q

What is the treatment for hyperkalaemia?

A
  • calcium gluconate
  • Calcium chloride
  • insulin + glucose
23
Q

What does hypokalaemia do to the action potential of cardio myocytes ?

A

Increases the duration

Delays repolarisation

24
Q

What are early after depolarisations ?

When do they occur?

A

Oscillations in membrane potential

Occur when there is a delayed repolarisation

25
Q

If the action potential is prolonged what 3 things is the patient more prone to getting?

A

Arrhythmias
Early after depolarisations
VF

Cardiovascular System (9 decks)

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