The Nervous System

Key Concepts Muscle Motor Neuro n Interneuron Skin receptors Sensory Neuron Brain Know the function and divisions of the nervous system (CNS & PNS) Know the function and divisions of the nervous system (CNS & PNS) Describe the structure of a neuron Describe the structure of a neuron Identify and know the function of the three types of neurons and the describe neurotransmission Identify and know the function of the three types of neurons and the describe neurotransmission Know the main parts of the brain and explain their functions Know the main parts of the brain and explain their functions Identify the lobes of the cerebral cortex Identify the lobes of the cerebral cortex

Funtion of the Nervous System Receive information externally and internally Receive information externally and internally Respond to stimuli Respond to stimuli Maintain stable internal conditions. Maintain stable internal conditions.

Neurons Neurons are the cells that carry nerve impulses through your nervous system Neurons are the cells that carry nerve impulses through your nervous system There are 3 kinds of neurons There are 3 kinds of neurons Interneuron -connects motor and sensory neurons; what the brain is mostly made of Interneuron -connects motor and sensory neurons; what the brain is mostly made of Sensory – picks up stimuli from internal and external sources Sensory – picks up stimuli from internal and external sources Motor – sends message to muscle to produce an action or movement Motor – sends message to muscle to produce an action or movement

Neuron Structure A neuron is made up of 3 main parts Cell body – where the nucleus and organelles are found Dendrites – extensions that pick up nerve impulses and carry to the cell body Axon – carries the nerve impulse away from the cell body and to another neuron Nerve impulses travel in only ONE direction

Neurotransmission 1. Message travels form the dendrites through the cell body and to the end of the axon. 2. The message causes chemicals, neurotransmitters, to be released from the end of the axon into the space between the axon of one neuron and the dendrites of another 3. The neurotransmitters then travel across the synapse on the receptors on the dendrites of another neuron. 4. Once the neurotransmitters have attached to the receptors the impulse is passed on. 5. The neurotransmitters are released from the receptors.

Divisions of the Nervous System Central Nervous System (CNS) Central Nervous System (CNS) Brain Brain Spinal cord Spinal cord Peripheral Nervous System (PNS) Peripheral Nervous System (PNS) All of the nerves located OUTSIDE of the CNS (senses) All of the nerves located OUTSIDE of the CNS (senses)

Main Parts of the Brain Cerebrum Cerebrum Cerebellum Cerebellum Brain Stem Brain Stem

Peripheral Nervous System Consists of a network of nerves that branch out from the CNS. Consists of a network of nerves that branch out from the CNS. Somatic system – control voluntary actions Somatic system – control voluntary actions Autonomic system – controls involuntary actions Autonomic system – controls involuntary actions

Reflex Automatic response that occurs very rapidly without conscious control Automatic response that occurs very rapidly without conscious control Nerve impulse goes to spinal cord but NOT the brain; helps to speed up the reaction Nerve impulse goes to spinal cord but NOT the brain; helps to speed up the reaction