a Regulation of the respiratory smooth muscle by autonomIc nervous system Vagus nerve:Ach→> M receptor→ Contraction Sympathetic nerve:NE→>β2- receptor→> Relaxation Regulation of the respiratory smooth muscle by endocrine or paracrine factors Histamine, Bradykinin> Contraction NE, E, Isoproterenol ->Relaxation◼ Regulation of the respiratory smooth muscle by autonomic nervous system: – Vagus nerve: Ach → M receptor → Contraction – Sympathetic nerve: NE → 2 -receptor → Relaxation ◼ Regulation of the respiratory smooth muscle by endocrine or paracrine factors: – Histamine, Bradykinin → Contraction – NE, E, Isoproterenol → Relaxation