Electrical and Mechanical Components of the Heart

Question 1

The heart has two components:

Answer 1

Electrical and mechanical

Question 2

How does the mechanical component operate?

Answer 2

• the heart’s pump - - ejects blood from the hearts chambers during contraction
• allows for refilling during relaxation

Question 3

What does the electrical component of the heart do?

Answer 3

• powers the hearts pump

- electrical stimulation is followed by mechanical contraction but sometimes is not

Question 4

What are the types of cardiac cells?

Answer 4

mechanical and electrical

Question 5

What is the other name for electrical cells?

Answer 5

pacemaker cells

Question 6

what are the three properties of electrical cells?

Answer 6

• automaticity - spontaneous generation and discharge of electrical impulse
• excitability - ability to respond to an impulse
• conductivity - ability to transfer an impulse

Question 7

what are the two phases of electrical cells?

Answer 7

depolarization - activation of stimulus

repolarization - recovery post stimulus

Question 8

what are the two properties of mechanical cells?

Answer 8

contractibility - cell filaments shorten and then return to their regular length

extensibility - heart filaments stretch

Question 9

how do mechanical cells perform the work of the heart?

Answer 9

systole - contraction of the heart

diastole - relaxation of the heart

Question 10

why is the cell membrane considered “polarized”?

Answer 10

RESTING CELL

outside the cell - more positively charged ions

inside the cell - more negatively charged ions

Question 11

what causes electrical impulses in the heart?

Answer 11

rapid flow of ions back and forth across a semi-permeable cardiac cell membrane

Question 12

What is depolarization?

Answer 12

when cardiac cells receive a stimulus, the cell membrane becomes more permeable to ions and the inside of the cells becomes positive

Question 13

Where does depolarization start?

Answer 13

• stimulus starts in the pacer cells of the heart’s sinoatrial node
• a wave of depolarization travels down the heart’s conduction system until all cells are depolarized

Question 14

What is repolarization?

Answer 14

• rest period
• cardiac cells start to recover
• inside of cell returns to it’s normal negative resting states

Question 15

what is a cycle of depolarization and repolarization called?

Answer 15

cardiac action potential

Question 16

What is excitation-contraction coupling?

Answer 16

• electrical cells coordinate the electrical activity (depolarization) and stimulate mechanical cells to contract (pump)