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Presentation on theme: "NERVOUS SYSTEM."— Presentation transcript:


2 Functions of the Nervous System
To receive (in the brain) information (stimuli) from sensory receptors RECEPTORS = Specialized cells that receive information from the environment Ex: rods and cones in the retina of your eye SENSE ORGANS = Organs containing special receptor cells Ex: Eyes SENSORY RECEPTORS SENSE ORGAN

3 Functions of the Nervous System
To interpret (make sense of) sensory impulses This happens when signals go from the sensory receptors to the brain To send out impulse instructions (response) to muscles and glands The brain sends instructions for action to muscles The 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.

5 Nervous System ORGANS Brain Spinal Cord TISSUES = Nerves
CELLS = Neurons (nerve cells) Dendrite Axon Synapse

6 The Nervous System has two parts
CNS Central Nervous System Brain makes all the decisions Some voluntary, some involuntary Decisions are sent out to spinal cord PNS Peripheral Nervous System Network of nerve pairs Brain signals are delivered by spinal cord Most nerves branch off of spinal cord Sends signals to brain for decision making

7 The Central Nervous System is made up of
the BRAIN and the SPINAL CORD.

Main organ Weighs about 3lbs Protected by cranium Covered by a tough membrane Contains different structures that perform different functions


Connects the brain to the nerves in the whole body Nerves branch off of the spinal cord at different levels to go to the body Protected 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 to the rest of the body.

Long fibers that lead to all parts of the body from the spinal cord Fibers may be in the form of bundles like a rope made of smaller fibers

13 How the CNS and PNS fit together in the body

14 THOUGHT QUESTIONS… What is the main organ of the nervous system?
The brain  What makes up the CNS? The brain and spinal cord What 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 the network 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
Touch Pain Heat Cold Pressure Smell Taste Types of sensory organs Eyes Ears Nose Skin Tongue

21 3 TYPES OF NEURONS Muscle Fiber

22 THOUGHT QUESTIONS What are the tissues of the nervous system?
Nerves What are nerve cells called? Neurons What are the structures that make up a nerve cell? Axon, cell body, dendrite What is the gap between neurons called? Synapse How 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 neuron What kinds of neurons are there? Sensory neurons, interneurons and motor neurons

23 Sensory Receptors Neurons in different parts of your body receive signals from sensory receptor neurons… called STIMULI Those 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


25 Path of an Impulse

26 Stimuli and Response (Cause and Effect)
SENSORY RECEPTORS BRAIN’S DECISION STIMULUS RESPONSE Skin senses cold Goosebumps help warm you up Nose smells good food Hunger prompts you to eat Skin senses pain from an insect bite White blood cells rush to the scene

27 Different sensory receptors have different shapes!


29 THOUGHT QUESTIONS What is the proper term for something that CAUSES a change? Stimulus What is the proper term for the EFFECT of a stimulus? Response What 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?

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