Lesson 8.1 Outline of Nervous SystemFunctions: Communication Coordination Control Gathering information
Differences betweenhuman and animal NS:1. Language2. Judgment3. Problem solving4. Creativeness5. Passing along heritage
Neurobiologist –biologist who studiesthe nervous system.Neurologist – physicianwho specializes indisorders of the NS.
Two Divisions of NS: 1. Central nervous system(CNS) – brain and spinalcord/nerves
Two Divisions of NS: 1. Central nervous system (CNS) – brain and spinal cord/nerves2. Peripheral nervous system(PNS)nerves that branch from theCNS.
CNS Composed of:1. Brain •protected by cranium •has high levels thought •major organ of NS •Message center •Uses info to formulate ideas •Makes decisions •Communicates to body
CNS Composed of:1. Brain2. Spinal Cord Thick bundle nerve fibers within spinal cavity How brain communicates with most of body Ends at first lumbar
PNS Composed of:1. Cranial nerves Nerves that come from brain 12 pairs Branch from brain stem Transmits messages from/to eyes, ears, mouth, face and scalp
PNS Composed of:1. Cranial nerves2. Spinal Nerves Nerves that come from spinal cord 31 pairs Transmit signals to and from the rest of the body
Brain and spinal cord covered by a triple layer of protective tissue called Meninges.
Cerebrospinal fluid –bathes the brain andruns through fibers ofmiddle meninge tocushion brain.
Nerves are made ofbundles of nerve cellscalled neurons.
Three parts of neurons1. cell body• contains the nucleus, found only in spinal cord and brain.
Three parts of neurons1. cell bodyA mass of cell bodies is called aganglion.Large mass of ganglion called aplexus.Nerve center – plexus that has acertain function.
Three parts of neurons1. cell body2. dendrites – short, branchedextensions of cell body thatreceive nerve impulses andconduct them toward the cellbody.
Three parts of neurons1. cell body2. dendrites3. axon – one long extensionwhich carries impulses toother neurons or cells
Nerve impulses travel from the dendrite to cell body to axon.Axon branchesat terminal end.
GLIAL CELLS – also foundin the nervous systemare cells that SUPPORTAND INSULATE notfunctional.
Gray Matter vs. White MatterGray matter – within spinal cordand brain composed of cellbodies not wrapped by myelinWhite matter – made up ofdendrites and axons wrapped inmyelin.
Myelin•An insulating material that formsa layer, the myelin sheath, usuallyaround only the axon of a neuron.•It is essential for the properfunctioning of the NS.•Myelin is an outgrowth of a glialcell.
3 Types of neurons:1. Sensory neurons – transmit from sense organs to CNS2. Motor neurons – transmit from CNS to other part of body3. Interneurons – neurons withinthe CNS that connect sensory andmotor neurons with each other.
Sciatic Nerve – one of thelongest nerves of the body.Branches from spinal cord oflower back and goes to theleg.
PNS Types of Nerve fibers:1. Mixed – both sensory and motor neurons. Go from sense organ to spinal cord and send message back.2. Sensory3. Motor
Divisions of the PNS1. Somatic – skeletal musclecontrol2. Autonomic – responsiblefor all routine body activitiesfreeing the mind toconcentrate on biology class.
Two divisions ANS:Sympathetic –stimulates whendanger, stress, or activeex. Increases heart rate whenscaredParasympathetic – stimulateswhen at rest, or brings things backto normal. Ex. Decreases heart rateafter scare is over.