ANS_Physiology_Summary highlighted .pptx

Ans physiology summary

1. Organization of the Nervous System • Central Nervous System (CNS): Brain and spinal cord; integration and control center. • Peripheral Nervous System (PNS): Spinal nerves (31 pairs) + cranial nerves (12 pairs). • Subdivisions: - Somatic Nervous System (SoNS): Controls voluntary skeletal muscles. - Autonomic Nervous System (ANS): Controls involuntary functions (e.g., CVS, GIT).

2. SoNS vs. ANS Comparison | Feature | SoNS | ANS | |-------------------------|-----------------------------------------|----------------------------------------| | Control | Voluntary (skeletal muscles) | Involuntary (organs, glands) | | Neurons | Single, myelinated | Pre- & post-ganglionic neurons | | Neurotransmitter (NT) | Acetylcholine (ACh) | ACh & Norepinephrine (NE) | | Effect | Always excitatory | Excitatory or inhibitory |

3. Cranial Nerves Overview • 12 pairs of cranial nerves, some sensory, motor, or mixed. • Roman numeral designations. • Parasympathetic innervation: CN III, VII, IX, X. • Functions: sensory (e.g., smell, vision), motor (e.g., eye movement), autonomic (e.g., heart, gut).

4. ANS Divisions • Sympathetic (Fight/Flight): Thoracolumbar origin; increases activity for emergencies. • Parasympathetic (Rest/Digest): Craniosacral origin; promotes maintenance. • Dual Innervation: Most organs receive both for balance and control.

5. Dual Innervation Exceptions | Organ | Sympathetic Only | Parasympathetic Only | |-------------------------|---------------------------------------|----------------------------------------| | Sweat glands | Activation | None | | Adrenal medulla | Epinephrine release | None | | Blood vessels | Constriction/Dilation | None |

6. Effect of ANS on Target Organs | Target Organ | Sympathetic Effect | Parasympathetic Effect | |---------------------|--------------------------------------|----------------------------------------| | Heart Rate | Increases | Decreases | | Bronchi | Dilates | Constricts | | Pupils | Dilates | Constricts | | GIT Motility | Decreases | Increases |

7. General Functions of Sympathetic vs. Parasympathetic • Sympathetic: Prepares the body for emergencies (e.g., increased cardiac output, dilated pupils). • Parasympathetic: Maintains homeostasis and energy conservation (e.g., slows heart rate, stimulates digestion).

8. ANS Neuron Properties | Feature | Sympathetic | Parasympathetic | |-------------------------|-------------------------------------|---------------------------------------| | Preganglionic Neurons | Short | Long | | Postganglionic Neurons | Long | Short | | NT at Ganglion | Acetylcholine | Acetylcholine | | NT at Effector | Norepinephrine | Acetylcholine |

9. Autonomic Ganglia • Paravertebral: Near spinal cord (Sympathetic). • Prevertebral: Near viscera (Sympathetic). • Terminal: Near/in organs (Parasympathetic).

10. ANS Neurotransmitters • Sympathetic: ACh (Preganglionic), NE (Postganglionic). • Parasympathetic: ACh (Preganglionic & Postganglionic). • Cholinergic (ACh) vs. Adrenergic (NE) neurons.

11. ANS Receptors | Receptor Type | Location | Action | |------------------------|-----------------------------------|---------------------------------------| | Nicotinic (N) | Ganglia | Depolarization | | Muscarinic (M) | Effector organs | Varies (M1-M5) | | Alpha (α1, α2) | Smooth muscle | Constriction or inhibition | | Beta (β1, β2, β3) | Heart, smooth muscle, lipocytes | Excitatory or inhibitory |

12. Sympathetic vs. Parasympathetic Pathways • Sympathetic: Short preganglionic, long postganglionic neurons. • Parasympathetic: Long preganglionic, short postganglionic neurons. • Origins: Thoracolumbar (Symp.), Craniosacral (Parasymp.).

13. Autonomic Reflexes • Components: Receptor, afferent neuron, integration center, efferent neuron, effector. • Examples: - Baroreceptor Reflex: Regulates blood pressure. - Micturition Reflex: Controls urination.

14. Pharmacology of ANS | Drug Type | Example | Action | |------------------------|--------------------------|---------------------------------------| | Sympathomimetic | Epinephrine, Albuterol | Stimulate adrenergic receptors | | Parasympathomimetic | Pilocarpine | Stimulate muscarinic receptors | | Adrenergic Blockers | Propranolol, Metoprolol | Block adrenergic receptors | | Cholinergic Blockers | Atropine | Block muscarinic receptors |

15. MCQ Focus: Key Concepts • Comparisons: SoNS vs. ANS, Sympathetic vs. Parasympathetic. • Neurotransmitters and Receptors. • Reflex Arcs and Examples. • Pharmacology: Sympathomimetic/Parasympathomimetic drugs.