Structure and Functions of the Autonomic Nervous System – PST04103 Human Anatomy and Physiology

NTA Level 4 • Semester 1 • PST04103

Structure and Functions of the Autonomic Nervous System

Human Anatomy and Physiology • Source Session/Topic 35
Full source-text version: all educational wording from the extracted learning source is retained; only presenter/tutor metadata and web-layout noise are removed, while formatting is improved for readability.

Session 35: Structure and Functions of the Autonomic Nervous System

Total Session Time: 120 minutes

Prerequisites

• Session 34; Structure and Functions of the Central Nervous System

Learning Tasks

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

• Define the Autonomic Nervous System
• Explain the Divisions of the Autonomic Nervous System
• State the Functions of Autonomic Nervous System at Different Organs

Resources Needed:

• Flip charts, marker pens, and masking tape
• Black/white board and chalk/whiteboard markers
• Overhead projector (OHP) and computer

SESSION OVERVIEW

|Step |Time |Activity/ |Content |

| | |Method | |

|1 |05 minutes |Presentation |Introduction, Learning Tasks |

|2 |10 minutes |Presentation |Definition of the Autonomic Nervous |

| | |Brainstorming |System |

|3 | |Presentation |Divisions of the Autonomic Nervous |

| |45 minutes |Small Group |System |

| | |Discussion | |

|4 | |Presentation |Functions of the Autonomic Nervous |

| |50 minutes |Small Group |System at Different Organs |

| | |Discussion | |

|5 |05 minutes |Presentation |Key Points |

| 6 |05 minutes |Presentation |Evaluation |

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 Autonomic Nervous System (10 minutes)

|Activity: Brainstorming (5 minutes) |

| |

|Ask students to brainstorm on the following question: |

| |

|What is autonomic nervous system? |

| |

|ALLOW few students to respond |

| |

|WRITE their responses on the flip chart/ board |

| |

|CLARIFY and SUMMARISE by using the content below |

• Autonomic nervous system (ANS) is a part of peripheral nervous system and

consists of motor parts of spinal nerves and cranial nerves

• The peripheral nervous system relays information to and from the central

nervous system

• Autonomic nervous system is made up of visceral motor neurons to the

smooth muscles, cardiac muscles and glands of which muscles will either

contract or relax and glands will either increase or decrease secretions

STEP 3: Divisions of the Autonomic Nervous System (45 minutes)

|Activity: Small Group Discussion ( 30 minutes) |

| |

|DIVIDE students into small manageable groups |

| |

|ASK students to discuss on the following question |

|What are the divisions of the autonomic nervous systems? |

| |

|ALLOW students to discuss for 15 minutes |

| |

|ALLOW few groups to present and the rest to add points not mentioned |

| |

|CLARIFY and SUMMARIZE by using the contents below |

• The ANS has two divisions which are sympathetic and parasympathetic.

o Often, they function in opposition to each other.

• Sympathetic division

o The sympathetic division brings about widespread responses in many

organs.

o The sympathetic division is dominant in stressful situations, which

include anger, fear, or anxiety, as well as exercise.

o There are synapses between preganglionic and postganglionic neurons

o One preganglionic neuron often synapses with many postganglionic

neurons to many effectors. This anatomic arrangement has physiological

importance.

• Parasympathetic division

o The parasympathetic division dominates in relaxed (non-stress)

situations to promote normal functioning of several organ systems.

o In the parasympathetic division, one preganglionic neuron synapses

with just a few postganglionic neurons to only one effector. With this

anatomic arrangement, much localized (one organ) responses are

possible.

• In autonomic pathways there are two synapses: one between preganglionic

and postganglionic neurons, and the second between postganglionic neurons

and visceral effectors.

o Acetylcholine is the transmitter released by all preganglionic

neurons, both sympathetic and parasympathetic and is inactivated by

cholinesterase in postganglionic neurons.

o Parasympathetic postganglionic neurons all release acetylcholine at

the synapses with their visceral effectors.

o Most sympathetic postganglionic neurons release the transmitter

norepinephrine at the synapses with the effector cells.

o Norepinephrine is inactivated by either catechol-Methyltransferase

(COMT) or monoamine oxidase (MAO), or it may be removed from the

synapse by reuptake.

STEP 4: Functions of the Autonomic Nervous System at Different Organs

(50 minutes)

|Activity: Small Group Discussion ( 30 minutes) |

| |

|DIVIDE students into small manageable groups |

| |

|ASK students to discuss on the following question |

|What are the functions of autonomic nervous system to different body |

|organs? |

| |

|ALLOW students to discuss for 15 minutes |

| |

|ALLOW few groups to present and the rest to add points not mentioned |

| |

|CLARIFY and SUMMARIZE by using the contents below |

|Organ |Sympathetic response |Parasympathetic |

| | |response |

|Heart (cardiac muscle) |Increase rate |Decrease rate (to |

| | |normal) |

|Bronchioles (smooth |Dilate |Constrict (to normal) |

|muscle) | | |

|Iris (smooth muscle) |Pupil dilates |Pupil constrict (to |

| | |normal) |

|Salivary glands |Decrease secretion |Increase secretion to |

| | |normal |

|Stomach and intestine |Decrease peristalsis |Increase peristalsis |

|(smooth muscle) | |for normal digestion |

|Stomach and intestine |Decrease secretion |Increase secretion for|

|(glands) | |normal digestion |

|Internal anal sphincter |Contracts to prevent |Relaxes to permit |

| |defecation |defecation |

|Urinary bladder (smooth |Relaxes to prevent |Contracts for normal |

|muscle) |urination |urination |

|Internal urethral |Contracts to prevent |Relaxes to permit |

|sphincter |urination |urination |

|Liver |Changes glycogen to |None |

| |glucose | |

|Pancreas |Secrete glucagon |Secrete insulin and |

| | |digestive enzymes |

|Sweat glands |Increase secretion |None |

|Adrenal glands |Increase secretion of|None |

| |epinephrine and | |

| |norepinephrine | |

STEP 5: Key Points (5 minutes)

• Autonomic nervous system (ANS) is a part of peripheral nervous system and

consists of motor parts of spinal nerves and cranial nerves.

• The sympathetic division is dominant in stressful situations while

parasympathetic division dominates in relaxed (non-stress) situations

• In their functions, sympathetic and parasympathetic always oppose each

other.

STEP 6: Evaluation (5 minutes)

• What is autonomic nervous system
• What are the divisions of the autonomic nervous systems?
• Which neurotransmitter is inhibited by cholinesterase?

References

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

(5th ed.).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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