Control Of Respiration - Physiology

Question 1

What is the hierarchy of control

Answer 1

1.Brainstem automatic
2.Brainstem responsive to stimuli
3.Higher Brainstem
4.Learned responses
5.Voluntary
6.Input from multiple sources
7.Different stimuli causes responses with different time delays

Question 2

Where is the major rhythm generator

Answer 2

Medulla oblongata

Question 3

What happens to ventilation if
1.section cut above medulla
2.section cut below medulla

Answer 3

1. Fairly normal ventilation
2. Ventilation ceases

Question 4

Which network of neurones generates the breathing rhythm

Answer 4

Pre-Botzinger complex

They fire in bursts, each burst leads to contraction of inspiratory muscles (inspiration) and when and firing stops passive expiration

Question 5

During inspiration what happens to
1. Diaphragm
2. External intercostal muscles

Answer 5

1. Contraction of diaphragm flattens out its dome shape - innervated by phrenic nerve c3,4,5
2. Contraction of external intercostal muscles lifts ribs and moves out sternum - bucket Handle mechanism

Question 6

What do neurones do in active expiration during hyperventilation

Answer 6

Ventral respiratory group neurones excite internal intercostals for forceful expansion

In normal quiet breathing ventral neurones do not activate expiratory muscles

Question 7

What affects medullary centres

Answer 7

Neurotransmitters
Including glutamate, glycine, GABA, Opiods, Substance P 5HT
Pontine and higher centres
Input from cranial nerves IX and X
Chemo-ceptors
Stretch receptors in the lungs and chest wall
MUCH, MUCH more

Question 8

How is rhythm modified by pneumotaxic centre in pons

Answer 8

The pneumotaxic centre is stimulated when dorsal respiratory neurones (excited by pre-botzinger complex) fire , terminates inspiration when stimulated

Without pneumotaxic centre inspiration is prolonged with brief expiration - APNEUSIS