2 Functions of the Nervous System To receive (in the brain) information (stimuli) from sensory receptorsRECEPTORS = Specialized cells that receive information from the environmentEx: rods and cones in the retina of your eyeSENSE ORGANS = Organs containing special receptor cellsEx: EyesSENSORY RECEPTORSSENSE ORGAN
3 Functions of the Nervous System To interpret (make sense of) sensory impulsesThis happens when signals go from the sensory receptors to the brainTo send out impulse instructions (response) to muscles and glandsThe brain sends instructions for action to musclesThe brain sends instructions to glands to release hormones
4 THOUGHT QUESTION…Which cell organelle most closely corresponds to the nervous system?The nucleus because the nucleus controls the cell and the nervous system controls the body.
6 The Nervous System has two parts CNSCentral Nervous SystemBrain makes all the decisionsSome voluntary, some involuntaryDecisions are sent out to spinal cordPNSPeripheral Nervous SystemNetwork of nerve pairsBrain signals are delivered by spinal cordMost nerves branch off of spinal cordSends signals to brain for decision making
7 The Central Nervous System is made up of the BRAIN and the SPINAL CORD.
8 CENTRAL NERVOUS SYSTEM Organ - Brain Main organWeighs about 3lbsProtected by craniumCovered by a tough membraneContains different structures that perform different functions
10 CENTRAL NERVOUS SYSTEM Organ – Spinal Cord Connects the brain to the nerves in the whole bodyNerves branch off of the spinal cord at different levels to go to the bodyProtected by the bony spinal column of vertebrae
11 The Peripheral Nervous System is made of a network of nerves that Connect the brain and spinal cord tothe rest of the body.
12 PERIPHERAL NERVOUS SYSTEM Tissue- Nerves Long fibers that lead to all parts of the body from the spinal cordFibers may be in the form of bundles like a rope made of smaller fibers
14 THOUGHT QUESTIONS… What is the main organ of the nervous system? The brain What makes up the CNS?The brain and spinal cordWhat makes up the PNS?The network of nerves that connect the brain and spinal cord to the rest of the body
15 Nerve Cells are called NEURONS -long cells-cell body on one end-nucleus in cell body-dendrites branch off-long part is axon-shaped like a hand!
16 How Neurons Work Together You have many neurons, all over your body.
17 The neurons are lined up, dendrite end to axon end. Each dendrite is very close to the axon end of another neuron.This forms a complex network.
18 There are tiny spaces between the neurons, called SYNAPSES. Electrochemical signals or impulses travel through thenetwork and have to ‘jump’ across these little spaces.
19 Neurons pass impulses to each other and form a network all through the body.
20 Sensory Receptors Types of sensory receptors Types of sensory organs TouchPainHeatColdPressureSmellTasteTypes of sensory organsEyesEarsNoseSkinTongue
22 THOUGHT QUESTIONS What are the tissues of the nervous system? NervesWhat are nerve cells called?NeuronsWhat are the structures that make up a nerve cell?Axon, cell body, dendriteWhat is the gap between neurons called?SynapseHow do impulses travel through neurons?Electrochemical signals are picked up by the dendrites, travel to the cell body and then away from the cell body through the axon. The signal jumps across the synapse to the dendrites of another neuronWhat kinds of neurons are there?Sensory neurons, interneurons and motor neurons
23 Sensory ReceptorsNeurons in different parts of your body receive signals from sensory receptor neurons… called STIMULIThose signals are sent to the spinal cord and brain by the network of neurons.The brain has interneurons that process the information and decide on a reaction, called a RESPONSE that is sent out through motor neurons
26 Stimuli and Response (Cause and Effect) SENSORYRECEPTORSBRAIN’SDECISIONSTIMULUSRESPONSESkin senses coldGoosebumps help warm you upNose smells good foodHunger prompts you to eatSkin senses pain from an insect biteWhite blood cells rush to the scene
29 THOUGHT QUESTIONSWhat is the proper term for something that CAUSES a change?StimulusWhat is the proper term for the EFFECT of a stimulus?ResponseWhat are the five sensory organs?Eyes, ears, tongue, nose, skin
30 Check for Understanding What is the name of a nerve cell?What shape is a neuron?On your ‘hand’ neuron, where is the nucleus?Where are the dendrites?Where is the axon?How are neurons connected?What is the ‘gap’ between neurons called?What are the organs of the central nervous system?What is the major decision maker?What is the function of the spinal cord?Describe the peripheral nervous system.What is the proper term for something that CAUSES a change?What is the proper term for the EFFECT of a stimulus?What are the five sensory receptors?