The Nervous System The human nervous system 1

The Nervous System

The human nervous system…. 1. 2. 3. 4. Receives Processes Stores Transmits - stimulus from inter/exter. environ. - message sent - brain remembers stimulus - brain sends reactive message …. information that comes from the various parts of the body (internal) and the external world.

The Nervous System has 2 main parts The Peripheral Nervous System (PNS) _________ Which is made up of Sensory Motor Nerves (All over your body) The Central Nervous System (CNS) ________ Which is made up of: The Brain and The Spinal Cord

What is the Nervous System made of? Neurons! (Nerve Cells) – All of the organs and nerves of the nervous system are made of approximately 100 billion Neurons. Ø Neurons are special cells that can send, receive and transmit electrical Messages called nerve impulses Ø Each neuron is made of: – Dendrites – A Cell Body – An Axon – Axon Terminals

Neurons

Real Neuron Images

Anatomy of a Neuron n Dendrites: these are “branched” processes are specialized to receive input and carry information toward the cell body. n The Cell Body: - is the metabolic center of the neuron (where energy is made). - contains the nucleus (center) of the cell - most proteins needed for functioning are made here - incoming signals from dendrites meet here.

Anatomy of a Neuron n Axon: • is larger in diameter than dendrites. is specialized to carry information away from the cell body. may be very long, up to 1 meter! n Axon Terminals • • the end of the axon. Sends the signal on to other neurons.

Draw your own picture of a neuron here and label the 4 parts

Characteristics of Neurons 1) Neurons can be stimulated: they react to chemical signals by transforming them into electrical signals. 2) Neurons are conductive: they transmit nerve impulses to other cells. 3) Neurons are needy: they require great amounts of glucose and oxygen to function (20% of body’s energy goes to cells. Neurons will die within minutes without oxygen).

Neurotransmission

How do neurons communicate? • • Neurons interact with other neurons through synapses. The axon terminals of one neuron will end near (but do not touch) the dendrites of another neuron. • Presynaptic neuron: sends out information • Postsynaptic neuron: receives information n Note: There is no physical connection between the two neurons! Synapse and Neurotransmitter Intro Video

Nerve Impulses When a neuron registers an internal stimulus (from another neuron or a hormone) or an external stimulus (such as a sound, touch, heat, electrical shock, pain, odour) it will produce an electric current known as a nerve impulse or an action potential (AP). The nerve impulse travels down the axon to the axon terminals at speeds up to 430 km/h. Delay reaction Ruler Test: Delay from sight to brain to finger muscles.

Fill in the blanks with the following words: Relayed, Received, Transmitted, or Processed, Nerve impulses are: 1) 2) 3) 4) ___Received ___by the dendrites; __Processed____ by the cell body; __Transmitted__ through the axon; ___Relayed___ by the axon terminals.

Review Questions 1) What is the main function of the nervous system? 2) What are the 2 main parts of the nervous system and how do they differ? 3) What is the nervous system made up of? 4) What are the 4 main parts of the neuron and what are their specialized functions?

5) What is a synapse? 6) Draw a picture of a synapse including pre and postsynaptic neurons. Make sure to label all structures in your diagram. 7) What are two names for the electric current that travels down a neuron? 8) What is the name of the chemical messengers found at inside the axon terminal? 9) What part of the neuron receives the nerve impulse?

Question Answers

Answers to HW Review Questions 1) What is the main function of the nervous system? The nervous system receives, processes, stores and transmits information that comes from parts of the body and the external world. 2) What are the 2 main parts of the nervous system and how do they differ? The central nervous system is composed of the brain and the spinal cord. The peripheral nervous system is composed of the nerves (motor and sensory) all over your body.

3) What is the nervous system made up of? The nervous system is composed of more than a billion nerve cells or neurons. 4) What are the 4 main parts of the neuron and what are their specialized functions? Dendrites: receive inputs from other neurons and carry messages to towards the cell body. Cell Body: Makes energy and proteins for the neuron, processes the inputs from the dendrites. Axon: transmits the nerve impulse away from the cell body. Axon Terminals: relays (passes on) the nerve impulse to another neuron.

5) What is a synapse? The connection between 2 neurons rough which they interact. 6) Draw a picture of a synapse including pre and postsynaptic neurons. Make sure to label all structures in your diagram.

7) What are two names for the electric current that travels down a neuron? -Nerve impulse, action potential (AP) 8) What is the name of the chemical messengers found at inside the axon terminal? -Neurotransmitters 9) What part of the neuron receives the nerve impulse? - the dendrite Mouse Party Interactive