Chapter 18.2 Cardiac Muscle Tissue-Cardiovascular System

Question 1

What are characteristics of cardiac muscle tissue?

Answer 1

Cardiac muscle tissue has one or two centrally located nuclei, is striated, and contracts by sliding filament mechanism.
Additionally, they have Branching cells with intercalated discs.

Question 2

What does Intercalated discs contain?

Answer 2

Desmosomes (hold cells together)
Gap junctions (critical to heart’s ability to be electrically coupled)
Large mitochondira

Question 3

What does large mitochondria in intercalated disc do?

Answer 3

Produce energy needed / prevent fatigue

Question 4

What ability do node cells have and what is it called?

Answer 4

ability to stimulate their own action potentials which is called autorhythmicity

Question 5

What is Absolute refractory period?

Answer 5

It is 250 ms (long) and prevents tetanic contractions

Question 6

What proportion of cardiac cells do not function in contraction?

Answer 6

Approximately 1% of cardiac cells do not function in contraction

Question 7

What is relationship between conducting system of heart and cardiac muscle cells?

Answer 7

conducting system of heart is in electrical contact with cardiac muscle cells via gap junctions

Question 8

What does conducting system do?

Answer 8

It initiates heartbeat and helps spread impulse rapidly throughout heart

Question 9

What do certain cells in atria do?

Answer 9

It secrete atrial natriuretic peptide, regulate concentration of Na+ in extracellular fluid, and opposite function of aldosterone