Lecture 9 — Autonomic Effects on Organs
Condensed source-based study notes. Consult original slides for diagrams and finer details.
Sympathetic and Parasympathetic Effects
• The autonomic nervous system regulates internal organs through sympathetic and parasympathetic divisions.
• The eye: sympathetic activation contracts the radial muscle, causing mydriasis; parasympathetic activation contracts circular muscle, causing miosis, and ciliary muscle for near accommodation.
• Sympathetic cardiac stimulation increases heart rate (positive chronotropy), contraction force (positive inotropy), and electrical conduction (positive dromotropy).
• Most vascular smooth muscle receives sympathetic noradrenergic innervation; vascular effects depend on receptor type.
• Sympathetic stimulation relaxes bronchial smooth muscle, inhibits gut motility and glandular secretion, and contracts gastrointestinal sphincters.
Metabolic and Other Responses
• Sympathetic responses include glycogenolysis, gluconeogenesis and lipolysis. Renin participates in blood-pressure regulation.
• The lecture discusses the renin–angiotensin–aldosterone system and mentions ACE inhibitors, ARBs and renin inhibitors.
• Sympathetic activity raises blood sugar, promotes bladder filling, and reduces salivary and bronchial secretions; parasympathetic activity generally supports digestion, secretion and voiding.
Cardiovascular Integration
• Stroke volume is the volume pumped by the left ventricle per beat. Increased venous tone supports venous return.
• The source discusses reflex control of cardiovascular function, including autonomic contributions to heart rate and vascular tone.
