The Nervous System Introducion
Overview Functions Organization Protection
Functions Monitor activities of body parts - sensory neurons Communicate between body parts - associative neurons Command necessary action - motor neurons
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.
Organization: Divisions of the Nervous System Central Nervous System (CNS) -brain -spinal cord
Organization: Divisions of the Nervous System Peripheral Nervous System (PNS) -cranial nerves -spinal nerves Has two subdivisions: somatic & autonomic
Organization: Divisions of the Nervous System - PNS Somatic nervous system - voluntary, contains sensory & motor neurons; stimulates skeletal muscle
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
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
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)
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
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
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
Protection of the Nervous System
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
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
Meninges Arachnoid membrane - middle layer with threadlike extensions giving a cobweb like appearance. Has subarachnoid filled with CSF
Meninges Pia mater = “gentle mother”, innermost layer, delicate and highly vascularized (rich blood supply)
The End!