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The nervous system controls and coordinates functions throughout the body, allowing us to feel pain and respond to internal and external stimuli. It consists of the brain, spinal cord, nerves, and sense organs. Neurons carry electrical messages called impulses. Reflexes protect the body before the brain processes information. The central nervous system includes the brain and spinal cord, while the peripheral nervous system consists of sensory and motor divisions.
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The Nervous System www.assignmentpoint.com
The Nervous System Electrical Communication www.assignmentpoint.com
The Nervous System Main Function: This communication system controls and coordinates functions throughout the body and responds to internal and external stimuli. Our nervous system allows us to feel pain. www.assignmentpoint.com
The Nervous System Consists of:brain, spinal cord, nerves and sense organs www.assignmentpoint.com Sense Organs: Eyes, Skin, Ears, Nose & Tongue
The Nerve A nerveis an organ containing a bundle of nerve cells calledneurons. Neurons carryelectricalmessages calledimpulsesthroughout the body. Picture shows hundreds of severed neuron axons www.assignmentpoint.com
dendrite muscle tissue Axon cell body TYPICAL MOTOR NEURON synapse Impulse in a Neuron cell body www.assignmentpoint.com
Because neurons never touch, chemical signalers calledneurotransmittersmust travel through thespace calledsynapsebetween two neurons. Neurotransmitters (pink spheres) The message is transferred whenRECEPTORSreceive neurotrans-mitters. Synapse (gap) www.assignmentpoint.com
1 2 3 Parts of a Neuron • Cell body:contains nucleus & most of the cytoplasm • Dendrites:projections that bring impulses into the neuron to the cell body. • Axon:long projection that carries impulses away from cell body www.assignmentpoint.com
Types of Neurons Sensory Neuron Interneuron Synapse Synapse Motor Neuron Interneuron Synapse Muscle Contracts Motor Neuron Sensory Neuron www.assignmentpoint.com
Sensory Neuron carry impulses from sense organs to spinal cord & brain Fun Fact: Where can the largest cells in the world be found? The giraffe’s sensory and motor neurons! Some must bring impulses from the bottom of their legs to their spinal cord several meters away!! www.assignmentpoint.com
Interneuron • processes impulses in brain and spinal cord • - connect sensory and motor neurons www.assignmentpoint.com
Axon End Motor Neurons carry impulses from the brain & spinal cord to muscles & glands Axons branching out to muscle fibers www.assignmentpoint.com
Communication with Neurons • Nerves work together with muscles for movement. Animpulsebegins when one neuron is stimulated by another neuron or by the sense organs. • Theimpulsetravels down the axons ofSensory neuronsto the brain cells calledInterneurons. • The brain will then send animpulse throughmotor neuronsto the necessary muscle or organs, telling it to contract. www.assignmentpoint.com
A reflexis an involuntary response that is processed in thespinal cordnot the brain. Reflexes protect the body before the brain knows what is going on. Reflex Arc www.assignmentpoint.com
Cerebrum brain Cerebellum Medulla Oblongata Spinal Cord Central Nervous System Consists of: Brain and Spinal Cord www.assignmentpoint.com
Central Nervous System www.assignmentpoint.com
Peripheral Nervous System Consists of:Sensorydivision andMotor division -includes all sensory neurons, motor neurons, and sense organs www.assignmentpoint.com