1. The Nervous System Introducion

2. Overview Functions Organization Protection

3. Functions Monitor activities of body parts - sensory neurons Communicate between body parts - associative neurons Command necessary action - motor neurons

4. Functions The nervous system is a fast acting control center; it gathers, integrates, stores and recalls information, and acts upon that information to ensure survival.

5. Organization: Divisions of the Nervous System Central Nervous System (CNS) -brain -spinal cord

6. Organization: Divisions of the Nervous System Peripheral Nervous System (PNS) -cranial nerves -spinal nerves Has two subdivisions: somatic & autonomic

7. Organization: Divisions of the Nervous System - PNS Somatic nervous system - voluntary, contains sensory & motor neurons; stimulates skeletal muscle

8. Organization: Divisions of the Nervous System - PNS Autonomic nervous system - involuntary; controls action of cardiac and smooth muscle as well as glands Two subdivisions: sympathetic & parasympathetic

9. Organization: Divisions of the Nervous System - PNS Sympathetic system = “fight or flight” response activated during times of stress = increased heart rate, blood pressure, etc. Also referred to as the “E” system for exercise, excitement, emergency, & embarrassment

10. Organization: Divisions of the Nervous System - PNS Parasympathetic system = “housekeeping” in effect most of the time; maintains homeostasis Also referred to as the “D” system for digestion, defecation, and diuresis (urination)

11. Protection of the Nervous System Bones - skull protects brain; vertebrae protect spinal cord Cerebrospinal Fluid (CSF) - watery fluid formed from plasma that circulates through the central nervous system and function as a shock absorber

12. Protection of the Nervous System Blood-Brain Barrier - made of the least permeable capillaries in the body, keeps neurons separated from many substances in the body to help prevent uncontrolled neural activity

13. Protection of the Nervous System Blood-Brain Barrier - keeps out metabolic wastes such as urea, toxins, proteins, and most drugs -also keeps out nonessential amino acids and potassium -does allow essential amino acid, water and glucose

14. Protection of the Nervous System

15. Meninges - 3 layered connective tissue membranes that cover & protect the brain and spinal cord Layers in order of outermost to innermost: Dura mater, Arachnoid membrane, and Pia mater

16. Meninges Dura mater = “tough mother”, leathery and made up of two layers that forms the outer covering of the brain as well as the periosteum of the skull

17. Meninges Arachnoid membrane - middle layer with threadlike extensions giving a cobweb like appearance. Has subarachnoid filled with CSF

18. Meninges Pia mater = “gentle mother”, innermost layer, delicate and highly vascularized (rich blood supply)

19. The End!