The Role of the Nervous System What do

The Role of the Nervous System

What do you want to know? https: //www. youtube. com/watch? v=zeo 19 WVQ 47 w 2

Neurons neuron - is the functional unit of the nervous system 3 classes of neurons: 3

3 classes of neurons: afferent neurons (aka sensory neurons) - transmit stimuli from receptors to interneurons - integrate information (found in brain & spinal cord) efferent neurons - carry response signal from interneurons to effectors (muscles & glands) - motor neurons are efferent neurons that send signals to skeletal muscles 4

dendrites - receive signals and transmit them toward the cell body - “normal cell function” nerve signal - ions flowing down conc gradients axons - long part of the cell that conduct signals away from the cell body to another neuron or effector axon terminals points of transmission 5

nerve - bundle of neurons - neurons connect to each other - axon terminals connect to another cell’s dendrites 6

Accessory Cells Glial cells - provide nutrition & support to neurons eg: Schwann cells - tightly wrapped layers of myelin sheaths (plasma membrane) -electrical insulators -Nodes of Ranvier are gaps between Schwann cells -together the insulated stretches of axon & exposed gaps increase the speed of electrical impulses 7

Guillain–Barré- disorder that affects the myelin sheaths 8

Neural Circuits & Reflex Arc Neural Circuits receptor —> afferent neuron —> interneuron —> efferent neuron —> effector eg: seeing a glass of water receptor —> afferent neuron —> interneuron —> efferent neuron —> effector (eyes) (ocular nerves) (in brain) (motor neuron) (muscles of the arm) 9

Reflex Arc = simplest neural circuit receptor —> afferent neuron —> interneuron —> efferent neuron —> effector (hand) (nerves in arm) (in spinal cord) *note, additional signals sent to brain *often pain happens after reaction! (motor neuron) (muscles of arm/hand)

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You’ve Got Nerve • Lab on page 556 -7 • complete Part A-D • Answer a-I • Watch the video online 12