Electric properties of the heart

Question 1

What are the the physical connections called between heart cells?

Answer 1

-Desmosomes

Question 2

What are the electrical connections called between heart cells?

Answer 2

Gap junctions

Question 3

What forms intercalated discs?

Answer 3

Gap junctions and desmosomes

Question 4

How long is cardiac muscle action pot?

Answer 4

250 msec

Question 5

How long is average contraction of muscle cells?

Answer 5

2 msec

Question 6

What does the long refractory cause?

Answer 6

-stops tetanus

Question 7

What regulates contraction?

Answer 7

Ca2+ entry from outside cells

Question 8

Does Ca2+ saturate tropinin?

Answer 8

NOPE ca2+ can there for be used to regulate the strength of contraction

Question 9

What is the “resting potential” for pacemaker cells?

Answer 9

Around -55/60mv

Question 10

What causes the resting pot in non pacemakers?

Answer 10

-High resting Pk+

Question 11

What causes initial depolarisation in non pacemaker cells?

Answer 11

In crease in Pna+

Question 12

What causes the plateau in non pacemaker cells?

Answer 12

Increase in Pca+ and decrease in Pk+

Question 13

What causes repolarisation in non pacemaker cells?

Answer 13

Decrease in PCa2+ (l type) and increase Pk+

Question 14

What does L type ca2+ mean?

Answer 14

Large type ca2+

Question 15

What cause the action pot for pacemaker cells?

Answer 15

Increase in Pca2+ (l type)

Question 16

What causes the pacemaker pot (prepotential)

Answer 16

• Gradual decrease in Pk+
• early increase in PNA+
• Late Increase in PCa2+ (t type)

Question 17

how does temperature affect electrical activity?

Answer 17

Increase -10beats/min/0C

Question 18

How does hyperkalemia effect EA?

Answer 18

-Fibrillation & heart attack

Question 19

How does hypokalemia effect EA?

Answer 19

-Fibrilation and heart block (anomalous)

Question 20

How does Hypercalcemia affect EA?

Answer 20

increased HR& force of contraction