1. The Nervous System Part I “Not to be confused with Anxiety!” Physiology Standards 9 a-e “Coordinated structures and systems within the body help it to maintain homeostasis despite the changes in the outside environment (homeothermic)”

2. Physiology Standards 9 a-e a) Know how major body systems compliment each other to provide the body with Oxygen and nutrients while removing waste and Carbon Dioxide b) Know how the nervous system allows different parts of the body to communicate and receive information from the outside environment c) Know how the nervous and endocrine systems regulate conditions in the body using feedback loops

3. Physiology Standards 9 a-e d) Know the functions of the nervous system and the role of neurons in transmitting impulses e) Know the role of sensory neurons, interneurons, and motor neurons in sensation, thought, and response

4. The Nervous System controls and coordinates functions throughout the body and “responds” to internal and external stimuliThe Nervous System controls and coordinates functions throughout the body and “responds” to internal and external stimuli –“Your nervous system is how your body communicates within itself and with the outside world” Stimulus – (pl. stimuli ) is a change in environment such as a smell or a noise that is “detected” by an organismStimulus – (pl. stimuli ) is a change in environment such as a smell or a noise that is “detected” by an organism

5. Neurons The nervous system is made up of millions of cells called neurons Messages carried by the nervous system are chemical and electrical signals called impulses The cell that transmits impulses is called a neuron

6. Neurons three types of neuronsThere are three types of neurons: –Sensory neurons carry impulses from the sense organs to the spinal cord and the brain –Motor neurons carry impulses from the brain and spinal cord to muscles and glands –Interneurons connect sensory and motor neurons and carry impulses between them

7. Neurons The largest part of a typical neuron is called the cell body –Contains the nucleus –Where most metabolic activity takes place Spreading out from the cell body are short, branched extensions called dendrites –Detect impulses from the environment to the cell body

8. Neuron Structure

9. Neurons The long fiber that carries impulses away from the cell body is the axon –Ends in a series of small areas called axon terminals –Some axons have an insulating membrane called the myelin sheath The sheath leaves exposed parts of the axon called nodes where a nerve impulse can “jump” from one node to the next

10. Neuron Structure Axon terminals Nodes Myelin sheath Cell body Axon Nucleus Dendrites

11. The Synapse At the end of an axon the nerve impulse reaches the axon terminal The space between two neurons is called the synapse A vesicle releases a neurotransmitter that communicates the message to the next neuron Neurotransmitter Axon terminal Axon Direction of Impulse Vesicle

12. The Synapse

13. Nervous System Divisions Central Nervous System: “ CNS” –Composed of the Brain and the Spinal Cord Peripheral Nervous System: “ PNS” –Composed of all of the nerves that run throughout the body –Responsible for gathering stimuli to be sent to the CNS Brain Spinal cord Peripheral Nerves