Nervous Control of Ventilation

Question 1

Components of brain stem

Answer 1

Midbrain
Pons
Medulla
Spinal Cord

Question 2

Role of neural regulation of ventilation

Answer 2

Setting rhythm and pattern of ventilation while controlling respiratory muscles

Question 3

Why is neural regulation faster than chemical regulation

Answer 3

Neural control dependent on fast acting impulses to and from the CNS

Chemical control has to respond to chemical changes in pCO2 and pO2 which takes time

Question 4

Respiratory depression

Answer 4

Rate and/or depth of respiration is insufficient to maintain adequate gas exchange in lungs

Occurs as result on the medullary & pons centres

Question 5

Drugs and Respiratory Depression

Answer 5

Some drug side effects can cause respiratory depression (e.g. benzodiazepines, opioids)

It can be reversed by analeptics

Question 6

Dorsal Respiratory Group

Answer 6

It is associated with inspiration -
Fibres from this region innervate diaphragm and external intercostal muscles

DRG neurons switch on then off causing a rhythmic pattern

Question 7

Ventral Respiratory Group

Answer 7

Fibres from VRG innervate the abdominal muscles and internal intercostal muscles

Activity enhanced during forced expiration

Question 8

Pneumotaxic centre

Answer 8

Transmits signals to the DRG to limit inspiration

Fine tunes breathing and facilitates the rhythmic pattern

Prevents over-inflation of lungs

Question 9

Apneustic Centre

Answer 9

Responsible for prolonged inspiratory gasps (apneusis)

Prolongs DRG stimulation

Not clear on involvement in normal ventilation

Question 10

Apneusis

Answer 10

Disturbance of respiratory rhythm characterized by severely prolonged inspiratory effort

Question 11

Vagus Nerve (in ventilation)

Answer 11

Sends signals to DRG

Prevents overstimulation of DRG and thus prevents its overinflation

Question 12

Summarise the roles of:
DRG
VRG
Pneuomtaxic Centre
Apneustic Centre
Vagus Nerve

Answer 12

DRG: Inspiration
VRG: Forced Expiration
Pneuomtaxic Centre: Switch off inspiration
Apneustic Centre: Prolongs DRG stimulation (inspiration)
Vagus Nerve: Switch off inspiration

Question 13

Transection on Breathing

Answer 13

Question 14

Higher brain centres that play a role in ventilation

Answer 14

Hypothalamus and cerebral cortex

Question 15

Cerebral cortex in ventilation and its limitation

Answer 15

Associated with voluntary ventilation

Bypasses medullary centres during conscious control

Limited ability to breath hold

Question 16

Hypothalamus on ventilation

Answer 16

Strong emotions, pain and changes in temperature can alter respiratory rate and rhythm

Causes apnoea as induced by negative emotions (anger, pain) or decreases in temp

Tachypnea (rapid breathing) can be induced by excitation or increase in temperature

Think of a toddler

Question 17

Stretch Receptors - Location, sensitivity, role

Answer 17

Located in SM of trachea and bronchi

Sensitive to lung expansion

Lung Expansion –> Respiratory Centre –> Inspiration is shorter and shallower –> Prevents overinflation of the lungs

Question 18

Juxtapulmonary Receptors - Location, Stimulus, Role

Answer 18

Lie in alveolar wall between epithelia and endothelia (close to pulmonary capillaries)

Stimulated by Congestion, Oedema, Histamine - Inflammation

Activation results in Apnoea or rapid shallow breathing, bronchoconstriction and mucous secretion

Question 19

C-Fibre Receptors

Answer 19

Juxtapulmonary Receptors

Question 20

Irritant Receptors

Answer 20

Located between epithelial cells

Sensitive to irritant gases, smoke and dust

Activation results in rapid shallow breathing, cough, btonchoconstriction, mucous secretion and augmented breaths (Gasps)

Question 21

Irritant Receptors - Location, Stimulus, Effect

Answer 21

Located between epithelial cells

Sensitive to irritant gases, smoke and dust

Activation results in rapid shallow breathing, cough, bronchoconstriction, mucous secretion, augmented breaths

Question 22

Consequences of stimulating irritant receptors in:

Bronchioles, Trachea/Bronchi, Nasal Cavity

Answer 22

Bronchioles - Airways constrict (asthma)
Trachea & Bronchi - Coughing
Nasal Cavity - Sneezing