The conduction system

Question 1

The heart is described as myogenic because…

Answer 1

• the beat starts inside the heart due to an electrical impulse within the SA node.
• this electrical signal sparks a wave of excitation

Question 2

The factors which affect the change in rate of the conductions system are…

Answer 2

• HR, increases during exercise to allow for working muscles to get more O2
• the heart, generates own impulses from SAN.
  The rate of which the impulses are fired is controlled by the neural control mechanism.

Question 3

What is part of the neural control mechanism?

Answer 3

• Sympathetic NS (increases HR) and Parasympathetic NS (decreases HR)
• Controlled by cardiac control centre

Question 4

Chemoreceptors in the neural control mechanism

Answer 4

• chemorecep–> detect increase in blood CO2–> CCC–> symp NS–> SAN–> HR increase

Question 5

Proprioceptors in the neural control mechanism

Answer 5

• propriorecep–> detect increase in muscle length–> CCC–> symp NS–> SAN–> HR increase

Question 6

Baroreceptors in the neural control mechanism

Answer 6

• Barorecep–> detect increase in blood pressure–> CCC–> parasymp NS –>SAN–> decrease HR

Question 7

How does the Hormonal control mechanism work?

Answer 7

• Hormonal control = release of adrenaline during exercise
• adrenaline= stress hormone released by Sympathetic NS
• Stimulates SAN to increase speed + force of contraction to get more blood to working muscles