The document discusses the nerve supply of the lungs. The lungs receive nerve fibers from the pulmonary plexuses, including parasympathetic, sympathetic, and visceral afferent fibers. Parasympathetic fibers originate from the vagus nerves and act as bronchoconstrictors, vasodilators, and secretomotors. Sympathetic fibers originate from the thoracic spinal cord and act as bronchodilators, vasoconstrictors, and inhibit alveolar gland secretion. Visceral afferent fibers transmit reflexive and nociceptive sensory information. Abnormalities in these nerve pathways contribute to the pathophysiology of bronchial asthma.

1. RESPIRATORY SYSTEM
OBJECTIVE: TO MENTION THE NERVE SUPPLY OF LUNGS
ABIRAL WAGLE
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2. Lungs
• A pair of respiratory organs
• Primary organ of respiration, gas exchange occurs
in the alveoli
• Location:
Thoracic cavity
Right and Left lung separated by mediastinum
• Texture: Soft and spongy

4. Nerves of the lungs and visceral pleura
Derived from pulmonary plexuses
Parasympathetic, Sympathetic, and Visceral afferent
fibers
The nerve supply to the lungs is down the bronchial tree
- majority of the supply is to bronchi and bronchioles
- little signal is given to or from alveoli

5. Right vagus
nerve
Right pulmonary
plexus
Left vagus
nerve
Left pulmonary
plexus
Sympathetic
trunk
Paravertebral
ganglia of
sympathetic
trunk

6. Parasympathetic fibers
• Presynaptic fibers from the Vagus nerve (CN X)
• synapse with parasympathetic ganglion cells (cell bodies of
postsynaptic neurons) in the pulmonary plexuses
• Actions
- motor to the smooth muscle of the bronchial tree
(bronchoconstrictor)
- inhibitory to the pulmonary vessels (vasodilator),
- secretory to the glands of the bronchial tree (secretomotor)

7. Sympathetic fibers
• Postsynaptic fibers
• Their cell bodies (sympathetic ganglion cells) are in the
paravertebral sympathetic ganglia (T2-T5) of the
sympathetic trunks
• Actions
- Inhibitory to the bronchial muscle (bronchodilator)
- Motor to the pulmonary vessels (vasoconstrictor)
- Inhibitory to the alveolar glands of the bronchial tree—
type II secretory epithelial cells of the alveoli

8. Visceral afferent fibers
(Sensory impulses)
Reflexive Nociceptive
(subconscious sensations (pain impulses)
associated with reflexes)

9. Reflexive afferent fibers
• Cell bodies in sensory ganglion of the Vagus n. (CN X)
• Accompany the parasympathetic fibers
• Impulses from:
- Tactile sensation for cough reflexes
- Stretch reception of bronchial muscles
- Hering-Breuer reflexes (stretch reflex of the lungs)
- Pressor reception from pulmonary arteries
- Chemoreception (blood gas level) from pulmonary
veins

10. Nociceptive afferent fibers
• From visceral pleura and bronchi - accompany the
sympathetic fibers to sensory ganglion of upper thoracic
spinal nerves
• From the trachea - accompany the parasympathetic
fibers to the sensory ganglion of the vagus nerve (CN X).
• Impulses in response to painful/injurious stimuli
- Chemical irritants
- Ischemia
- Excessive stretch

11. Correlation with Bronchial asthma
• Bronchial asthma
- Chronic disorder of the airways
- Usually an immunologic reaction
- Marked by:
- episodic bronchoconstriction
- inflammation of bronchial walls
- increased mucus secretion
- Dysfunction of the airway innervation in asthma
leads to its pathophysiology

13. • Abnormalities in cholinergic and sympathetic
innervation
• β-Adrenergic blockers and cholinergic agonists
induce bronchoconstriction
• Mechanism:
- Activation of sensory nerves leading to reflexes
- Stimulation of receptors located on autonomic
nerves (crosstalk between these G-protein-
coupled receptors and downstream pathways
ensures normal airway function)

14. • Abnormalities in Nonadrenergic Noncholinergic
(NANC) neural pathways
• Neuromediators like bradykinin, neurokinin,
vasoactive intestinal peptide (VIP), & substance P.
• Produce features of clinical asthma involving
bronchoconstriction, mucus secretion, vascular
hyperpermeability , cough, and vasodilation, a
process called 'neurogenic inflammation‘
• The NANC system has been proposed for
bronchial hyperreactivity

15. REFERENCES
• Keith L. Moore, Arthur F. Dalley II, Anne M.R.
Agur : Moore Clinically Oriented Anatomy
• BD Chaurasia’s Human Anatomy (Volume 1:
Upper Limb and Thorax)
• https://www.ncbi.nlm.nih.gov/pubmed/

16. THANK YOU