Movie: Nervous System (27:00min) The Nervous System Movie: Nervous System (27:00min)

The Nervous System The body’s command system. Functions: Communicates information throughout the body and controls the body’s response to stimuli. Stimuli – any change that happens inside the body or in the surrounding environment. Functions: Takes in and processes information about the environment. Coordinates the actions of the body’s skeletal muscles. Allows communication Regulates all activities the body can perform.

Organization of the Nervous System Made up of nervous tissue Main organs: Brain Spinal cord Sensory organs; eyes, ears, nose, tongue, and skin Has two divisions: Central nervous system (CNS) Peripheral nervous system (PNS)

Nervous Tissue Made up of cells called Neurons Message carrying cells Dendrites Cell Body Nucleus Axon Axon Terminals Synapse

Characteristics of a Neuron Neurons can NEVER be replaced! Parts of the Neuron: Dendrites Carry impulses toward the cell body Cell body Contains the nucleus Controls all the activities of the cell Axon Carry impulses away from the cell body Axon Terminal Ends of an axon Pass a message on to the neighboring neuron’s dendrites Synapse Space separating the axon terminal of one neuron and the dendrites of the neighboring neurons.

Nerve Impulse The message being carried throughout the body by nerves - Nerve Impulse. ONLY travesl in one direction Travels as fast as 120 m/sec Carried as both electrical and chemical messages Messages come in from different stimuli and trigger electrical impulses At the end of the axon it is changed into a chemical message so it can cross over the synapse – neurotransmitters.

Nerve Impulse Synapse Dendrites Cell Body Nucleus Axon Axon Terminals Come in as electrical signals Changed to Chemical Signals Dendrites Cell Body Nucleus Axon Axon Terminals Synapse

Types of Neurons 3 Types of Neurons: Sensory Neuron – picks up stimuli from the internal and external environments. Location where the stimuli is received - Receptor. Interneurons – carry nerve impulses from one neuron to another. Brain interprets the message and determines appropriate reaction. Motor Neuron – Send an impulse to the muscle resulting in a response to the stimuli. Muscle tissue responds to the impulse - Effector

1 ____ Receptors in your ear hear the phone. ____ Receptors trigger nerve impulses in sensory neurons. ____ Nerve impulses pass to interneurons in the brain. ____ Your brain interprets the impulses from many interneurons and you realize the phone is ringing. Your brain also decides that you should answer the phone. ____ Impulses travel along motor neurons to the muscles. ____ Muscles in the arm carry out the response and you reach to pick up the phone - effector. 2 3 4 5 6

Central Nervous System (CNS) Brain Made up of the brain and spinal cord. Forms the largest part of the nervous system. Responsible for communication, memory and thought. Spinal Cord

Peripheral Nervous System (PNS) Connects the brain and spinal cord to the rest of the body. Made up of: 12 pairs of cranial nerves 31 pairs of spinal nerves 2 divisions: Somatic Controls voluntary actions jogging Autonomic Controls involuntary actions Breathing & digestion Spinal Nerves