Neural Control Of Resp

Question 1

What is the major rhythm generator of RESP

Answer 1

The medulla

Question 2

What generates the breathing rhythm

Answer 2

Network of neurons called pre-botzinger complex

Pacemakers

Question 3

Where are the pre-botzinger neurons located

Answer 3

Upper end of medullary RESP centre

Question 4

What are some RESP control centres in brain stem

Answer 4

Pons RESP centres - pneumotaxic and apneustic

• pre - botzinger complex

Medullary RESP centre- dorsal RESP group and ventral RESP group

Question 5

What gives rise to inspiration

Answer 5

Dorsal RESP group neurones - for inspiration
These are activated by pre-botzinger complex
Signals from dorsal lead to contraction of insp muscles
When signals stop there is passive expiration

Question 6

What are the muscle actions involved in inspiration

Answer 6

Contraction of external intercostal muscles - elevate ribs which increase side to side dimension of thoracic cav

Lower dia - increases vertical dimension

Elevation of ribs causes sternum to move up and out increases front to back dimension

Question 7

What is the neural control of ‘active’ expiration when hyperventilating

Answer 7

Increased dorsal RESP group neurones which cause excitation of secondary centre wh it is the ventral centre

Ventral release signals which excite internal inter coastal muscles and abdominals etc causing forceful exp

Question 8

What a re the accessory muscles of insp

Answer 8

Contract only in forceful exp

• scm
• scalenus

Question 9

What are the muscles of active expiration

Answer 9

Contract during active exp

• internal intercostals
• abdominals

Question 10

What are the major insp muscles

Answer 10

Contract every insp
Relax causes passive exp
- external intercostal
-dia

Question 11

The rhythm is generated in medulla but modified in the

Answer 11

Pons neurones

Question 12

What centres modify breathing in the pons

Answer 12

Pneumotaxic - stimulation terminates inspiration inhib insp

                  - stimulated by the dorsal RESP group 
                   - without this breathing would be prolonged insp                     with brief exp APNEUSIS

Apneustic centre - impulses from neurones excite insp area of medulla
- prolong Insp, rhythm gen in medulla, rhythm modified form pons

Question 13

The RESP centres are influenced by stimuli received from

Answer 13

Higher brain centres - cerebral cortex centres

Stretch receptors - in walls bronchi - the inflation hering-breur reflex - guard against hyperventilation

Juxtapulmonary receptors - Stim by pulmonary capillary congestion and pulmonary oedema also pulmonary oedema - rapid shallow breathing

Joint receps - stimulated by joint movement

Baroreceptors - increased vent rate in response to decreased blood pressure

Central and peripheral chemoreceptors

Question 14

What are some involuntary modifications of breathing

Answer 14

Pulmonary stretch receps hering- breur reflex
Joint receps reflex in exercise
Stimulation of RESP centre by temperature, adrenaline, or impulses from cerebral cortex
Cough reflex
Sneezing reflex

Question 15

What do pulmonary stretch receps do to breathing

Answer 15

Activated by insp, afferent discharge inhibits insp - hering-breur reflex

Question 16

How do joint receps affect breathing

Answer 16

Impulses from moving limbs reflexly increase breathing

Probably continue to the increased ventilation during exercise

Question 17

What are some factors that may increase ventilation during exercise

Answer 17

Reflexes originate from body movement 
Adrenaline release 
Impulses from cerebral cortex 
Increase in body temp 
Accumulation of carbon dioxide and hydrogen ion generated by active muscles

Question 18

What is the cough reflex

Answer 18

Vital part of the body defense mechanism
Help clear airways of dust, dirt or excessive secretions
Activated by irritation of airways or tight airways
Centre in medulla
Afferent discharge stimulates - short intake of breath, followed by closure of larynx, contraction of abdominal muscle, openings larynx and expulsion of air at high speed

Question 19

What su the sneezing reflex

Answer 19

Activated by irritation of mucosa of upper RESP passages especially the nasal mucosa (dust, pollen, viruses)
Centre in medulla
Complex afferent discharge stimulates eyes, face and neck muscles, soft palate, uvula, abdominal muscle, dia, chest muscles
Result sudden forceful expulsion of air through the nose and mouth

Question 20

What is the RESP Rhythm and what does the diaphragm do

Answer 20

Inspiration followed by expiration
Inhalation - dia contracts
Expiration - dia relaxes