1. Ch. 11 Efferent peripheral nervous system Midterm 2 on Nov 11 th will cover chapters 8, 10, 11. Today: –Autonomic division Homeostasis Organization Neurotranmsitters and neuromodulators Receptors

2. Mixed nerves Afferent and efferent fibers Autonomic fibers (involuntary) Somatic motor fibers (voluntary)

3. Autonomic Division of the Peripheral Nervous System Sympathetic “branch” –dominates in stressful situations –In emergencies “fight or flight” –Always  blood vessel diameter Parasympathetic  “rest and digest”

4. Sympathetic and parasympathetic contributions to homeostasis Maintain the internal environment Tonic control Antagonistic control Specific receptors determine responses

5. Autonomic fibers exert tonic control of blood vessels - vasodilation or vasoconstriction - sympathetic fibers - up or down control

6. Dual antogonistic innervation

7. Cooperation between sympathetic and parasympathetic effects E.g male reproductive system: –Parasympathetic fibers  penile erection –Sympathetic fibers  ejaculation

8. Different effect with different receptor: vasodilation or vasoconstriction

9. Brain regulates autonomic function Hypothalamus, pons, medulla Heart rate, blood pressure, temp. water balance Influence from limbic system and cerebral cortex Also autonomic reflexes e.g. urination

10. Autonomic efferent pathways **divergence**

11. Blue, parasympathetic, Red, sympathetic Parasympathetic ganglia are close To the targets

12. Autonomic neurotransmitters and receptors

13. Neuroeffector junction: synaptic vesicles are in varicosites

14. Norepinephrine release from varicosity: - MAO (monoamine oxidase) metabolizes NE