Structure Of Cardiac Muscle And Cardiac Output

Question 1

Describe the structure of cardiac muscle

Answer 1

• only found in the heart
• striated like skeletal muscle
• less wide than skeletal muscle fibres
• myogenic contraction occurs without stimulation by central nervous system
• branched to allow for faster signal propagation
• consists of a network of Y shaped interconnected cells joined by an intercalated disk containing cytoplasm to enable a swift transmission of impulses bw cells
• shape allows a wave of depolarisation to pass thru cells so cells contract as one, calcium ions are needed for this
• more mitochondria as they rely on aerobic respiration
• tissue doesnt become fatigued allowing for longer continous contractions to maintain a functionally stable heartbeat

Question 2

Define cardiac output

Answer 2

The volume of blood pumped out of left ventricle per minute

Question 3

What is the equation for cardiac output?

Answer 3

CO = SV x HR

Question 4

What does SV stand for in cardiac output equation?

Answer 4

Stroke volume - volume of blood expelled from left ventricle in one cardiac muscle

Question 5

What does HR stand for in cardiac output equation?

Answer 5

Heart rate - number of cardiac cycles per minute

Question 6

What is the units for cardiac output?

Answer 6

Dm3 min -1