Electrical And Molecular Mechanisms Flashcards Preview

The Cardiovascular System > Electrical And Molecular Mechanisms > Flashcards

Flashcards in Electrical And Molecular Mechanisms Deck (26)
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1
Q

Which ion is responsible for the resting membrane potential of a cell?

A

K+ ions

2
Q

What are the concentrations of K+ on the inside and outside of the cell?

A
Inside = 150mM
Outside = 5mM
3
Q

What is the resting membrane potential of a cell?

A

Around -90 mV

4
Q

Define equilibrium in regards to an ions movement.

A

Where it’s concentration gradient and electrical gradients are matched

5
Q

What is the first step in a ventricular action potential?

A

The opening of voltage-gated Na+ channels

6
Q

What happens to a voltage-gated Na+ channel after it has opened?

A

It becomes inactivated

7
Q

What ion is responsible for the plateau phase of a cardiomyocyte action potential?

A

Entry of Ca2+ ions

8
Q

What type of Ca2+ ions are found in ventricular cardiomyocytes?

A

L-type Ca2+ voltage-gated channels

9
Q

What ion is responsible for repolarisation of a cardiomyocyte?

A

Entry of K+ ions

10
Q

Define sinus rhythm.

A

Any cardiac rhythm where depolarisation begins at the SA node

11
Q

What part of the heart is quickest to depolarise?

A

Cardiomyocytes at the SA node

12
Q

What is the resting membrane potential of cardiomyocytes at the SA node?

A

They don’t have one

13
Q

What can the depolarisation of the Na+ channels be described as?

A

Slow - the funny current

14
Q

What is the slow depolarisation of Na+ channels at the SA node called?

A

The pacemaker potential, or the funny current

15
Q

From what voltage does depolarisation of Na+ channels at the SA node begin?

A

-60mV

16
Q

What type of Na+ channels are located at the SA node?

A

HCN channels

17
Q

Are the HCN channels at the SA node voltage-gated?

A

No

18
Q

What activates the HCN channels at the SA node?

A

Hyperpolarisation

19
Q

How does increasing negativity at the SA node affect the HCN channels?

A

Increasing negativity causes an increase in the number of HCN channels that open

20
Q

Why does the SA node set the rhythm of the heart?

A

It is the quickest to depolarise

21
Q

What does the Nernst equation describe?

A

The equilibrium potential of a particular ion (I think)

22
Q

What term describes action potentials that fire too quickly?

A

Tachycardia

23
Q

What term refers to action potentials firing too slowly?

A

Bradycardia

24
Q

What range is extracellular K+ concentration kept within?

A

3.5-5-5mmol/L

25
Q

What term describes electrical activity that has become random?

A

Fibrillation

26
Q

Why are cardiomyocytes so sensitive to changes in K+ concentrations?

A

Cardiomyocytes have a negative resting membrane potential close to the equilibrium potential of K+