Neuron Teacher Key 5-17-16

...where molecules become real TM

Teacher Key

Big Idea Different types of neurons compose the nervous tissue that forms the communication system within the body.

Introduction to Neurons An individual’s survival and reproductive success depends upon the ability to sense, respond and adapt appropriately to changes in the environment. The nervous system links sensation to response. Nerve cells (neurons) in the nervous system are the structural units principally used in transmitting information. Many different types of neurons with specialized structures enable them to conduct messages effectively from one part of the body to another. Modeling Neurons and Neuronal Structures

1. Draw your mental image of a neuron in the space below. (Various.)

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2. What are two characteristics that distinguish nerve cells from other cells? ______Nerve cells are unique in that they transmit signals and utilize chemical communication.

3. What is the difference between a nerve cell and a nerve? ______A nerve cell is a specialized excitable cell for the transmission of electrical signals ______over long distances while a nerve is a fiber composed of a bundle of axons of nerve ______cells.

4. Label these major parts of the large neuron model: dendrites, axon, soma/cell body, nucleus, myelin sheath, Schwann cell, axon hillock, synaptic knob.

Synaptic Knob Axon Hillock Dendrites

Axon Soma / Cell Body

Nucleus Schwann Cell

Myelin Sheath Nucleus

5. With an arrow, indicate the direction of the movement of information through the above nerve cell. (Noted in red on the diagram above.)

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6. Sketch and identify the types of neurons modeled in the Neuron Modeling Set© in the space below.

Bipolar Unipolar Multipolar Interneuron

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7. Where are these neurons found in the body? How do they function? Complete the chart below.

Type of Neuron Based on Location Functional Class Abundance Structure most abundant/ multipolar PNS/CNS motor/efferent major CNS neuron

special sense bipolar most sensory rare organs

commonly found unipolar chiefly PNS most sensory in spinal cord and cranial nerves

Conducts impulses most abundant interneuron CNS from afferent to (over 100 billion) motor neurons

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8. Identify the function of each of the following:

motor neuron - ______a nerve cell that transmits signals from the brain or spinal ______cords (CNS) to muscels or glands

interneuron - ______a nerve cell within the CNS that forms synapses with ______sensory and/or motor neurons and integrates sensory ______input and motor output sensory neuron - ______a nerve cell that receives information from internal or external ______environments and transmits signals to the CNS

9. What is the myelin sheath? ______The myelin sheath is a coat of cell membranes from Schwann cells or ______oligodendrocytes that are wrapped around the axon of a neuron.

10. What is the function of myelin sheath? ______The membranes of the cells forming the myelin sheath are composed mostly of lipids, ______which are poor conductors of electrical current and provide good insulation.

11. Label the neuron, oligodendrocyte, and Schwann cell.

Neuron Oligodendrocyte

Schwann Cell Neuron

Peripheral Nervous System Central Nervous System

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12. Is the large neuron model a part of the PNS or the CNS? How do you know? ______The neuron is part of the PNS because the myelin sheath is composed from Schwann ______cells instead of oligodendrocytes.

13. What is a synapse? Identify where synapse junctions may occur in the body. ______A synapse is the junction where a neuron communicates with another cell across a ______narrow gap. a nerve cell that receives information from internal or external 14. Identify where synapse junctions may occur in the body. environments and transmits signals to the CNS ______Synapses may occur between nerve cells, between a nerve cell and a muscle cell or ______between a nerve cell and glandular cell.

Neuronal Neuro- muscular

Neuro- glandular

Teacher Key

15. To illustrate the structural diversity among neurons, identify the types of synapses shown in the diagram to below (axodendritic, axoaxonic, axosomatic).

Using the neurons in the kit, model each of these synapse types.

Axodendritic Axoaxonic

Axosomatic