BPK 105 Study Guide - Final Guide: Respiratory Center, Respiratory Minute Volume, Tidal Volume
27 Apr 2018
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Module 10 - Review Questions - Part 5
9. Describe the rhythmic control of ventilation. Describe the phases of change in
ventilation during exercise. How does exercise training affect ventilation at rest and
during exercise? [8 marks]
GENERATION OF RHYTHMIC BREATHING
- The medullary respiratory center generates the basic pattern of spontaneous, rhythmic
breathing. Although the precise mechanism is not well understood, the generation of
rhythmic breathing involves the integration of stimuli that start and stop inspiration.
1. Starting inspiration
.
- The neurons in the medullary respiratory center that promote inspiration are continuously
active.
- The medullary respiratory center constantly receives stimulation from many sources,
such as receptors that monitor blood gas levels and the movements of muscles and
joints.
- In addition, stimulation can come from parts of the brain concerned with voluntary
respiratory movements and emotions.
- When the inputs from all these sources reach a threshold level, somatic nervous system
neurons stimulate respiratory muscles via action potentials, and inspiration starts.
2. Increasing inspiration.
- Once inspiration begins, more and more neurons are activated.
- The result is progressively stronger stimulation of the respiratory muscles, which lasts for
approximately 2 seconds (s).
3. Stopping inspiration.
- The neurons stimulating the muscles of respiration also stimulate the neurons in the
medullary respiratory center that are responsible for stopping inspiration.
- The neurons responsible for stopping inspiration also receive input from the pontine
respiratory neurons, stretch receptors in the lungs, and probably other sources.
- When the inputs to these neurons exceed a threshold level, they cause the neurons
stimulating respiratory muscles to be inhibited.
- Relaxation of respiratory muscles results in expiration, which lasts approximately 3 s.
- The next inspiration begins with step 1.
EFFECT OF EXERCISE ON BREATHING
The mechanisms by which breathing is regulated during exercise are controversial, and no
single factor can account for all the observed responses. Breathing during exercise can be
divided into two phases:
1. Breathing increases abruptly.
- At the onset of exercise, the rate of breathing immediately increases.
Document Summary
Module 10 - review questions - part 5: describe the rhythmic control of ventilation. Describe the phases of change in ventilation during exercise. The medullary respiratory center generates the basic pattern of spontaneous, rhythmic breathing. Although the precise mechanism is not well understood, the generation of rhythmic breathing involves the integration of stimuli that start and stop inspiration: starting inspiration . The neurons in the medullary respiratory center that promote inspiration are continuously active. The medullary respiratory center constantly receives stimulation from many sources, such as receptors that monitor blood gas levels and the movements of muscles and joints. In addition, stimulation can come from parts of the brain concerned with voluntary respiratory movements and emotions. When the inputs from all these sources reach a threshold level, somatic nervous system neurons stimulate respiratory muscles via action potentials, and inspiration starts. Once inspiration begins, more and more neurons are activated.
