Nervous System Overview

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Questions and Answers

What is the primary function of the sensory division of the peripheral nervous system?

Process and interpret stimuli.

Gather information from peripheral receptors. (correct)

Carry impulses from the central nervous system to muscles.

Regulate functions by secreting hormones.

How many pairs of cranial nerves are there in the human body?

14 pairs

10 pairs

15 pairs

12 pairs (correct)

What are the two main systems that regulate the functions of the body?

Central and peripheral nervous systems

Afferent and efferent divisions

Sympathetic and parasympathetic systems

Nervous and endocrine systems (correct)

What is the primary function of the Central Nervous System (CNS)?

Integrate and control body functions Signup and view all the answers

Which part of the nervous system is made up of the brain and spinal cord?

Central nervous system Signup and view all the answers

Which structure is part of the Peripheral Nervous System (PNS)?

Cranial nerves Signup and view all the answers

What is the role of motor output in the nervous system?

To produce a response based on processed stimuli. Signup and view all the answers

What is the main role of the sensory (afferent) division?

Send impulses from receptors to the CNS Signup and view all the answers

How many segments form the spinal cord?

31 segments Signup and view all the answers

Which of the following receptors belongs to the sensory division?

Visual receptors Signup and view all the answers

Which division of the nervous system is responsible for involuntary control of organs?

Autonomic nervous system Signup and view all the answers

How does the sympathetic division function in the body?

Mobilizes systems during activity Signup and view all the answers

What classification of nerves arises from the spinal cord?

Spinal nerves Signup and view all the answers

What component of the reflex arc receives stimuli and initiates the reflex action?

Receptor Signup and view all the answers

What defines a polysynaptic reflex?

It involves multiple synapses Signup and view all the answers

Which nervous system component is responsible for voluntary muscle control?

Somatic nervous system Signup and view all the answers

What neurotransmitter is released from the postganglionic neuron in the sympathetic division of the autonomic nervous system?

Norepinephrine (NE) Signup and view all the answers

Which of the following accurately describes the structure of the autonomic nervous system?

It consists of two neurons in series connecting the CNS to the effector cells. Signup and view all the answers

What is the primary role of the autonomic ganglia?

To serve as a relay point between preganglionic and postganglionic fibers. Signup and view all the answers

Which cranial nerves are involved in the parasympathetic division of the autonomic nervous system?

III, VII, IX, X Signup and view all the answers

In somatic efferent innervation, which neurotransmitter is responsible for muscle contraction?

Acetylcholine (ACh) Signup and view all the answers

What differentiates the preganglionic neurons from postganglionic neurons in the autonomic system?

Preganglionic neurons originate in the CNS. Signup and view all the answers

Which type of ganglia is associated with the sympathetic chain?

Lateral / paravertebral ganglia Signup and view all the answers

Which statement accurately describes the autonomic nervous system?

It regulates involuntary functions. Signup and view all the answers

What neurotransmitter is primarily used by postganglionic neurons in the sympathetic division?

Noradrenaline Signup and view all the answers

Where are terminal ganglia primarily located?

Near or within the innervated organs Signup and view all the answers

Which of the following correctly describes the length of preganglionic fibers in the sympathetic division?

Relatively short Signup and view all the answers

What is a function of autonomic ganglia?

To relay preganglionic fibers Signup and view all the answers

Which segment of the spinal cord contains preganglionic neurons for the sympathetic division?

Thoracolumbar segments Signup and view all the answers

What is a characteristic of postganglionic neurons in the parasympathetic division?

They are relatively short Signup and view all the answers

Which of the following statements about the chemical transmission in autonomic ganglia is true?

Acetylcholine is used for chemical transmission Signup and view all the answers

What is the primary role of collateral ganglia in the autonomic nervous system?

To relay preganglionic sympathetic fibers Signup and view all the answers

Study Notes

Introduction

The nervous system and endocrine system regulate body functions.
The nervous system is a rapid control system using nerve impulses.
The endocrine system is a slower control system using hormones.

Functions of the Nervous System

Gathers information about changes inside and outside the body (stimuli).
Processes and interprets sensory input, deciding if action is needed.
Activates muscles or glands in response to stimuli.

Organization of the Nervous System

Anatomical divisions

Central nervous system (CNS): brain and spinal cord
- Brain: cerebrum, cerebellum, brain stem (midbrain, pons, medulla oblongata)
- Spinal cord: 31 segments (8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal)
Peripheral nervous system (PNS): nerves extending from the brain and spinal cord

Divisions based on origin

Cranial nerves: 12 pairs arising from the brain.
Spinal nerves: 31 pairs arising from the spinal cord, one pair per segment.

Functional Classification of the Peripheral Nervous System (PNS)

Sensory (afferent) division: carries information from receptors to the CNS.
- Includes visual, auditory, chemoreceptors, and somatosensory (touch) receptors.
Motor (efferent) division: carries impulses from the CNS to peripheral organs.

Central Nervous System (CNS)

Structure: Brain and spinal cord
Function: Integrative and control centers

Peripheral Nervous System (PNS)

Structure: Cranial nerves and spinal nerves
Function: Communication lines between the CNS and the rest of the body

Sensory (afferent) Division

Structure: Somatic and visceral sensory nerve fibers
Function: Conducts impulses from receptors to the CNS

Motor (efferent) Division

Structure: Motor nerve fibers
Function: Conducts impulses from the CNS to effectors (muscles and glands)

Autonomic Nervous System (ANS)

Structure: Visceral motor (involuntary)
Function: Conducts impulses from the CNS to cardiac muscles, smooth muscles, and glands

Sympathetic Division

Function: Mobilizes body systems during activity ("fight or flight").

Parasympathetic Division

Function: Conserves energy, promotes "housekeeping" functions during rest.

Somatic Nervous System

Structure: Somatic motor (voluntary)
Function: Conducts impulses from the CNS to skeletal muscles.

Physiological divisions

Somatic nervous system: controls voluntary skeletal muscle movements.
Autonomic nervous system: regulates involuntary visceral functions (heart, lungs, kidneys, GIT, bladder, sexual organs, glands).

Structural and Functional Unit of the Nervous System

Neuron: the structural unit of the nervous system.
Reflex action (arc): the functional unit of the nervous system.
- An involuntary, inborn response to a stimulus.

Reflex Arc

Polysynaptic Reflex: involves more than one synapse.

Components

Receptor: sensitive structure responding to changes in internal/external environments.
Afferent neuron: carries impulses from receptors to the CNS.
Center: located within the CNS.
Efferent neuron: conducts impulses from the CNS to the effector organ.
Effector organ: skeletal muscle, smooth muscle, cardiac muscle, or gland.

Somatic Efferent Innervation

Single myelinated nerve fiber travels from CNS to the effector organ.
Neurotransmitter: acetylcholine (ACh), causing muscle contraction.

Autonomic Efferent Innervation

Two neurons involved:
- Preganglionic neuron: originates in the CNS, travels to an autonomic ganglion.
- Postganglionic neuron: originates in the autonomic ganglion, travels to the effector organ.
Preganglionic neurotransmitter: always acetylcholine (ACh).
Postganglionic neurotransmitter: varies depending on the division:
- Sympathetic: norepinephrine (NE).
- Parasympathetic: acetylcholine (ACh).

Autonomic Nervous System

Two neurons in series connect the CNS and effector cells.
Synapse occurs in autonomic ganglia, outside the CNS.
Preganglionic fibers: between CNS and ganglia.
Postganglionic fibers: between ganglia and effector cells.

Divisions of the Autonomic Nervous System

Sympathetic nervous system (Thoracolumbar outflow): arises from T1-L2 spinal cord segments.
Parasympathetic nervous system (Cranio-sacral outflow): arises from cranial nerves III, VII, IX, X, and sacral segments S2-S4.

Autonomic Ganglia

Group of neuron cell bodies outside the CNS.
Site of contact between pre and postganglionic fibers.

Types

Lateral/paravertebral ganglia (sympathetic chain):
- Lie on either side of the vertebral column.
- Relay sympathetic fibers to the head, neck, and thoracic viscera.
Prevertebral/collateral ganglia:
- Lie between the sympathetic chain and the organ of supply.
- Relay preganglionic sympathetic fibers to the abdomen and pelvis.
- Examples: celiac, superior mesenteric, inferior mesenteric ganglia.
Terminal ganglia (parasympathetic):
- Near or within the innervated organs.
- Relay all parasympathetic fibers.

Functions of Autonomic Ganglia

Relay preganglionic fibers from the CNS.
Distribute signals: each preganglionic axon diverges to many postganglionic neurons.
Neurotransmitter: acetylcholine (ACh).

Table: Comparison of Sympathetic and Parasympathetic Divisions

Feature	Sympathetic Division	Parasympathetic Division
Location of preganglionic neuron	Thoracolumbar spinal cord	Cranial nerve nuclei and sacral spinal cord
Location of postganglionic neuron	Away from target organ	Near or in the target organ
Length of preganglionic fibers	Short	Long
Length of postganglionic fibers	Long	Short
Preganglionic neurotransmitter	Acetylcholine	Acetylcholine
Postganglionic neurotransmitter	Noradrenaline	Acetylcholine

Comparison of Somatomotor and Autonomic Nervous Systems

Somatomotor: Single neuron from spinal cord to effector organ.
Autonomic: Synapse between neuron leaving spinal cord and effector organ (except adrenal medulla).
All neurons leaving the CNS release acetylcholine (ACh).

Conclusion

The autonomic nervous system plays a crucial role in regulating vital bodily functions.
Understanding the ANS is essential for comprehending physiological processes such as heart rate, blood pressure, digestion, and breathing.

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Description

Explore the fundamentals of the nervous system, including its rapid control mechanisms and organization. Learn about the central and peripheral nervous systems, their anatomical divisions, and functions. This quiz will test your understanding of how the nervous system operates and its critical role in regulating body functions.