Nervous System

 1. Function – Receives and sends out info from and to the outside and inside your body

 2. Two parts of the Nervous System A. Central (CNS) – Brain and Spinal Cord A. Central (CNS) – Brain and Spinal Cord B. Peripheral (PNS) – All of the other nerve cells B. Peripheral (PNS) – All of the other nerve cells

3.Neurons (Nerve Cells)  A. Cell Body – Contains the nucleus  B. Dendrite – Receives nerve impulse  C. Axon – Sends the nerve impulse away

 D. Myelin – Protects the axon. Allows the nerve impulse to move very fast

 D. Node of Ranveir – places between the myelinated Schwann cells where action potential takes place Action Potential: tial+in+neurons tial+in+neurons

 4. Synapse – Gap in between to neurons

 5. Nerve Impulse – Signal that moves through the Nervous System.  A. Travels in 2 Ways  1. Electrical – As it moves through the neuron.  2. Chemical – As it moves across a synapse

6. The Pathway  A. Receptor Cells – Special cells that detect the stimulus from inside or outside your body  1. Found everywhere in your body.  2. Some are connected to your 5 senses

 B. Sensory Neurons – Receive the impulse from the receptor cells and pass it on to the inter-neurons

 C. Interneurons – Neurons found in the spinal cord and brain

 D. Motor Neurons – Carry the response impulse away from spinal cord to an effector

 E. Effector – A muscle or a gland that receives the response impulse

7.Reflex Arc  Response to a stimulus that does not come from the brain. It comes from the Spinal Cord

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You can see in the magnified box that the axon is a bundle of little fibers and the myelin is actually wrapped around it several times liked a rolled up carpet. Myelin serves some incredibly important functions. It protects the axon. It allows an impulse to get from one neuron to another, and it allows that impulse to move very, very fast

1. Sensory Receptors - structures that detect changes in external & internal environment modified neurons or epithelial cells that have evolved to respond to stimuli (eye, ear, nose, muscles)

Motor Neuron Action Potential

Interneuron

 Classes of Sensory Receptors chemo-receptors: chemicals sense solutes in solvents, taste, smell chemo-receptors: chemicals sense solutes in solvents, taste, smell osmo-receptors: of hypothalmus which monitors blood osmotic pressure osmo-receptors: of hypothalmus which monitors blood osmotic pressure photo-receptors: light - eye, eyespots, infrared receptors of snakes, etc... photo-receptors: light - eye, eyespots, infrared receptors of snakes, etc... thermo-receptors: radiant (heat) energ thermo-receptors: radiant (heat) energ phono-receptors: sound waves electro-receptors: detect electric currents... electric eels, etc.. noci-receptors: pain receptors... naked dendrites of skin (epidermis) mechano-receptors: mechanical forces - stretching alters membrane permeability phono-receptors: sound waves electro-receptors: detect electric currents... electric eels, etc.. noci-receptors: pain receptors... naked dendrites of skin (epidermis) mechano-receptors: mechanical forces - stretching alters membrane permeability

Link: parts of the neuron parts of the neuronparts of the neuron   In turn, these pathways can be divided according to the direction in which they conduct stimuli:   Afferent system by sensory neurons, which carry impulses from a receptor to the CNSsensory neurons   Efferent system by motor neurons, which carry impulses from the CNS to an effectormotor neurons   Relay system by relay neurons (also called interneurons), which transmit impulses between the sensory and motor neurones.relay neurons