Autonomic Nervous System and Special Senses Overview

Cholinergic Receptors:

• Natural Agonist: Acetylcholine
• Types:
• Nicotinic:
  • Agonist: Nicotine (prolonged effects)
  • Antagonist: Curare
• Muscarinic:
  • Agonist: Muscarine (from mushrooms)
  • Antagonist: Atropine

Adrenergic Receptors:

• Natural Ligands: Norepinephrine, Epinephrine
• Types/Subclassifications:
• Alpha 1, Alpha 2
• Beta 1, Beta 2, Beta 3
• Locations:
• Alpha 1: Heart
• Alpha 2: Lungs
• Beta 3: Adipose

Sympathetic Nervous System:

• Postganglionic neurons: Adrenergic receptors
• Exception: Sweat glands (cholinergic control)

Drug Classifications:

• Example: Albuterol (asthma) - Beta 2 agonist
• Beta-blockers (e.g., Propranolol) - decrease sympathetic activity

Acetylcholinesterase Inhibitors:

• Function: Prolong acetylcholine action by blocking breakdown
• Examples: Neostigmine, Sarin

Sympathetic vs. Parasympathetic:

• Sympathetic: Fight or flight (generalized effects)
• Parasympathetic: Rest and digest (localized effects)

Comparison of Effects:

• Pupil: Dilated (sympathetic), constricted (parasympathetic)
• Heart Rate: Increased (sympathetic), decreased (parasympathetic)
• Lungs: Dilate (sympathetic), constrict (parasympathetic)
• Digestion: Decrease (sympathetic), increase (parasympathetic)

Central Control of ANS:

• Hypothalamus: Main regulator for homeostasis and ANS control
• Brainstem: Midbrain, pons, and medulla part of control mechanism

Special Senses Overview:

• Focus on vision, hearing, olfaction (taste), equilibrium
• Photoreceptors in the retina respond to light stimulus
• Understanding of the electromagnetic spectrum necessary for understanding vision
• Eye anatomy: Fibrous, vascular, and retinal tunics; aqueous vs vitreous humor