Control Of Breathing

Question 1

What are the two types of stretch receptors involved in protective interruption of respiratory rhythm?

Answer 1

• Slowly adapting pulmonary stretch receptors
• Rapidly adapting pulmonary stretch receptors

Question 2

Where are slowly adapting pulmonary stretch receptors found and what do they do?

Answer 2

• Located within airway smooth muscle

• Only active when tidal volume approaches physical limitations of lung tissue for expansion

• Hering-Breuer reflex protects the lungs by initiating a signal that inhibits inspiration

Question 3

Where are rapidly adapting pulmonary stretch receptors found and what do they do?

Answer 3

• Dense in the trachea and large airways

• Respond to stimuli (e.g, cigarette smoke, inhaled particles and cold air) by initiating reflexes such as coughing and sneezing by causing bronchoconstriction

Question 4

What is the difference between central and peripheral chemoreceptors?

Answer 4

• Central chemoreceptors respond only to changes in PaCO2 (through changes in concentration of H+, not directly to CO2)

• Peripheral chemoreceptors respond to changes in PaO2 (mainly, but PaO2 and H+ also stimulate them)

Question 5

Describe phase 1 of control of ventilation in steady state exercise

Answer 5

Ventilation increases abruptly and as early as in the first breath after exercise has commenced (thought to be controlled by neural mechanisms)

Question 6

Describe phase 2 and 3 of control of ventilation in steady state exercise

Answer 6

• Phase 2 - ventilation increases gradually

• Phase 3 - steady state is achieved