Cardiac Conduction system

Question 1

What are the two cardiac muscle cells?

Answer 1

Myocardial conduction cells (1%)

Myocardial contraction cells (99%)

Question 2

Contraction cells have a resting membrane of __ mV when, the cell is said to be p____.

Answer 2

Contraction cells have a resting membrane of -90mV when, the cell is said to be polarised.

Question 3

How is a contraction cell stimulated?

Answer 3

By an adjacent cell

Question 4

How are contraction cells stimulated?

Answer 4

Ion channels open and close in set pattern

causes ionic influx- depolarisation/repolarisation

Question 5

What type of muscle cell is specialised?

Answer 5

Conduction cell

Question 6

Conduction cells are able to s_______ generate and e____ i______ , this is termed a______.

Answer 6

Conduction cells are able to spontaneously generate and electrical impulse, this is termed automaticity.

Question 7

What can conduction cells initiate?

Answer 7

Action potentials at regular intervals

Question 8

The sinoatrial node is located where?

Answer 8

posterior wall of right atrium

Question 9

How big is the SA node?

Answer 9

20mm by 4mm

Question 10

True or false the SA node membrane potential is stable?

Answer 10

False

Question 11

What is the blood supply to the SA node?

Answer 11

RCA 59%
CFx 38%
both 3%

Question 12

The AV node is a mass of cells and c_____- t_____. Located in the l____ p______ region of the i____-a___ s_____ (IAS)

Answer 12

The AV node is a mass of cells and connective tissue. Located in the lower posterior region of the inter-atrial septum (IAS)

Question 13

What is the blood supply of the AV node?

Answer 13

90% RCA

10% LCx

Question 14

How long is the electrical impulse delayed for at the AV node/ what is the delay caused by?

Answer 14

100ms

due to complex local circuitry and
small diameter of the cells- allowing

Question 15

Why is there a delay at the AV node?

Answer 15

Allow atria to contract fully - efficient ventricular filling

Protection mechanism