NTA Level 4 • Semester 1 • PST04103

Structure and Functions of Nervous Tissues

Human Anatomy and Physiology • Source Session/Topic 9

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Session 9: Structure and Functions of Nervous Tissues

Total Session Time: 60 minutes

Prerequisites

• None

Learning Tasks

By the end of this session, students are expected to be able to:

• Define Nervous Tissue

• Identify Components of Nervous Tissue

• Distinguish Different Types of Neurons

• Distinguish Different Types of Neuroglia and their Functions

Resources Needed:

• Flip charts, marker pens, and masking tape

• Black/white board, chalk and whiteboard markers

• Overhead Projector, Transparencies, Anatomy Atlas and Models, LCD and

Computer

SESSION OVERVIEW

SESSION CONTENTS

STEP 1: Presentation of Session Title and Learning Tasks (5 minutes)

READ or ASK students to read the learning tasks and clarify

ASK students if they have any questions before continuing

STEP 2: Definition of Nervous Tissue (5minutes)

|Activity: Brainstorming (5 minutes) |

| |

|Ask students to brainstorm on the following question: |

|What is nervous tissues? |

| |

|ALLOW few students to respond |

| |

|WRITE their responses on the flip chart/ board |

| |

|CLARIFY and SUMMARISE by using the content below |

Nervous tissue or nerve tissue:

• Is the main tissue component of the two parts of the nervous system;

the brain and spinal cord of the central nervous system (CNS), and the

branching peripheral nerves of the peripheral nervous system (PNS),

which regulates and controls bodily functions and activity.

o Nervous tissue is distributed throughout the body as an integrated

communications network.

STEP 3: Components of Nervous Tissue (5minutes)

• Structurally, nerve tissue consists of two classes of cell types.

o Neurons, the nervous tissue is made up of billions of cells called

neurons that are specialized to respond to stimuli and to transmit

a signal to activate other cells.

o Glial cells or neuroglia, non-excitable supporting cells,

participate in neural activity, neural nutritional and defence

processes of the central nervous system.

• A Typical Neuron Consist of:

o Cell body, which has many radiating processes called dendrites,

which are specialized to receive signals from other neurons.

o Axon, a single long process, which is capable of generating a nerve

impulse and conducting it over a long distance to stimulate other

neurons in the CNS, or muscular or secretory cells elsewhere in the

body.

o Neurons usually receive information through dendrites; the

information is integrated in the cell body and transmitted onwards

via axons.

• STEP 4 : Types of Neuron (10 minutes)

• Unipolar neurons, these neurons have single processes, the axon arising

from the cell body.

• Unipolar neurons have no dendrites.

• Bipolar neurons, have two processes (both axons) emerging directly and

oppositely from the cell body.

• Bipolar neurons are found in the cochlear and vestibular ganglia as well

as retina and olfactory mucosa.

• Multipolar neurons, has one axon and many dozens of dendrites.

• Most neurons in the CNS are multipolar.

• Pseudo unipolar neurons, has a single short process (an axon) with a T-

shaped branching, one branch extending towards the CNS, and the other

extending to a periphery ending.

• In typical pseudo unipolar neurons, both branches are axons on both

structural and electrophysiological grounds.

Classification of Neurons according to their Functional Roles

• Motor neurons are involved in stimulating muscles or glands (effector

organs) in the periphery.

• Sensory neurons, sensory neurons receive sensory stimuli from the

environment or from tissues and organs of the body.

• Interneurons, maintain connection between neurons in the CNS, forming

complex functional chains or circuits

[pic]

Source: Strandring, (2005) Figure

9.3: A Neuron

STEP 5: Neuroglia and their Functions (25 minutes)

|Activity: Buzzing (5 minutes) |

| |

|ASK students to pair up and buzz on the question for 2 minutes |

| |

|What is neuroglia? |

|ALLOW few pairs to respond and let other pairs to add on points not |

|mentioned |

| |

|WRITE their response on the flip chart/board |

| |

|CLARIFY and SUMMARIZE by using the content below |

Neuroglia (Glial Cells)

• These are supporting cells found in the central nervous system and

peripheral nervous system

• There are six types of supporting cells

• Four are found in the CNS and two are found in the PNS

• Neuroglia found in central nervous system are

o Astrocytes

▪ Star-shaped, abundant, and versatile

▪ Guide the migration of developing neurons, they are found in large

numbers adjacent to blood vessels

They form a blood-brain barrier, i.e. the blood is separated from neurones

by capillary wall and a layer of astrocytes foot process

o Microglia

▪ Specialized immune cells that act as the macrophages of the CNS

▪ They derived from monocytes

o Ependymal Cells

▪ These cells form the epithelial lining of the ventricles of the

brain and the central canal of the spinal cord

o Oligodendrocytes,

▪ These are found in clusters around cell bodies

▪ They form and maintain the myelin, having the same functions as

schwann cells in peripheral nerves

▪ These cells have clinical importance as most tumours of the brain

are arising from them

Glia Cells Found in the Peripheral Nervous System

• Satellite cells, surround clusters of neuronal cell bodies in the PNS,

they are of unknown function

• Schwann cells, form myelin sheaths around the larger nerve fibers in the

PNS, they are for neuronal regeneration

STEP 6: Key Points (5 minutes)

• The nervous system is composed of neurons (nerve cells) and neuroglia

(protective and supporting cells)

• Neurons are sensitive to stimuli, convert stimuli into electrical signals

called action potentials (nerve impulses), and conduct nerve impulses.

• Neuroglia (Glial Cells) are supporting cells found in the central nervous

system and peripheral nervous system

STEP 7: Evaluation (5 minutes)

• What is nervous tissue?

• What are the components of nervous tissue?

• What are the types of neuron types of neurons?

• What are the types of neuroglia and their functions?

• What are the function of neuroglia?

References

Seeley, R. R., Stephens, T. D., &Tate, P. (2003). Anatomy and Physiology.

(5thed.).Boston:

McGraw-Hill.

Standring, S. (2008). Grays’s Anatomy; the anatomical basis of clinical

practice. (40th ed.).

Elservier: Churchill Livingstone.

Thibodeau, G. A., & Patton, K. T. (1999). Anatomy & Physiology. Mosby:

Hoffman

Press, Inc.

Tortora, G.J &Derrickson, B (2009). Principles of Anatomy and Physiology

12th Edition,

USA, John Wiley & Sons Inc., USA

Waugh, A., & Grant, A. (2006). Ross and Willson Anatomy and physiology in

Health and

illness. China: Churchill Livingstone Elservier.

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