Nervous System Overview Quiz

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Which part of the autonomic nervous system is responsible for mobilizing body systems during activity?

Somatic nervous system

Visceral sensory division

Sympathetic division (correct)

Parasympathetic division

What is the primary function of the parasympathetic division of the autonomic nervous system?

Conserves energy and promotes housekeeping functions (correct)

Activates the skeletal muscles

Initiates sensory impulses to the CNS

Increases heart rate

Which type of nerve fibers conducts impulses from the CNS to cardiac muscles?

Afferent sensory fibers

Motor nerve fibers

Somatic motor fibers

Visceral motor fibers (correct)

What defines the difference between the somatic nervous system and the autonomic nervous system?

The somatic nervous system is voluntary, while the autonomic nervous system is involuntary. Signup and view all the answers

Which part of the nervous system includes the brain and spinal cord?

Central nervous system (CNS) Signup and view all the answers

What type of nerve fibers are included in the sensory division of the peripheral nervous system?

Somatic and visceral sensory nerve fibers Signup and view all the answers

Which division of the autonomic nervous system is primarily active during rest?

Parasympathetic division Signup and view all the answers

In which division of the nervous system would you find motor fibers conducting impulses to effectors?

Efferent division Signup and view all the answers

Which muscles are directly innervated by the fibers of the sympathetic division of the autonomic nervous system?

Smooth muscles, cardiac muscles, and glands Signup and view all the answers

Which part of the nervous system is chiefly responsible for communication between the CNS and the rest of the body?

Peripheral nervous system (PNS) Signup and view all the answers

What characteristic distinguishes the axon hillock from the dendrites?

It conveys signals away from the cell body. Signup and view all the answers

Which of the following correctly describes the function of Nissl bodies in the nerve cell body?

They are primarily involved in biosynthesis. Signup and view all the answers

What is true about myelinated axons in the central nervous system (CNS) compared to those in the peripheral nervous system (PNS)?

They are known as tracts in the CNS and nerves in the PNS. Signup and view all the answers

Which of the following statements best describes the functional role of dendrites in a neuron?

They receive incoming signals and direct them to the cell body. Signup and view all the answers

Which of the following statements about the nerve cell body is NOT true?

It has centrioles to support cell division. Signup and view all the answers

Which cell type is primarily responsible for maintaining the blood-brain barrier?

Astrocytes Signup and view all the answers

What is the primary role of oligodendrocytes in the central nervous system?

To insulate and myelinate nerve fibers Signup and view all the answers

Which type of neuroglia acts as phagocytes that keep an eye on neuron health?

Microglia Signup and view all the answers

Which of the following is NOT a function of astrocytes?

Insulating nerve fibers Signup and view all the answers

What distinguishes Schwann cells from oligodendrocytes?

Schwann cells myelinate fibers in the PNS, oligodendrocytes do so in the CNS Signup and view all the answers

Which type of neuroglia is capable of regulating the environment around neuron cell bodies in the ganglia?

Satellite cells Signup and view all the answers

What happens to the myelin sheath in Multiple Sclerosis?

It is destroyed and replaced by hardened tissue called scleroses. Signup and view all the answers

Which of the following statements regarding neuroglia is true?

Neuroglia support, segregate, and guide neurons. Signup and view all the answers

What occurs during the depolarization phase of an action potential?

Na+ gates open and K+ gates close, leading to a rapid increase in membrane potential. Signup and view all the answers

What is the primary function of the sodium-potassium pump during the action potential?

It restores the resting ionic conditions of the neuron after repolarization. Signup and view all the answers

Which statement accurately describes the process of repolarization?

Sodium inactivation gates close, reducing Na+ permeability and allowing K+ to exit. Signup and view all the answers

What distinguishes continuous propagation from saltatory propagation in action potentials?

Saltatory propagation involves the jumping of action potentials between nodes of Ranvier. Signup and view all the answers

What primarily generates the resting membrane potential in a neuron?

The differential permeability of the neurilemma to sodium and potassium Signup and view all the answers

Which statement is correct regarding the sodium-potassium pump's function?

It maintains concentration gradients for both sodium and potassium by utilizing ATP. Signup and view all the answers

How does an electrochemical gradient influence ion movement?

Ions are repelled by like charges and attracted to opposite charges. Signup and view all the answers

Why is the inside of a neuron negatively charged during resting potential?

Negatively charged proteins and the greater concentration of potassium contribute to this state. Signup and view all the answers

Which of the following describes voltage-gated channels?

They respond to the changes in membrane potential. Signup and view all the answers

What is the role of mechanically gated channels in neurons?

They open in response to physical deformation of receptors. Signup and view all the answers

What determines the resting membrane potential value in neurons?

The ions' concentration difference and permeability across the membrane. Signup and view all the answers

What is the significance of the negative sign in the resting membrane potential value?

It indicates the inside of the neuron is negatively charged compared to the outside. Signup and view all the answers

Which statement about unmyelinated axons is accurate?

They conduct nerve impulses slowly. Signup and view all the answers

What primarily composes gray matter?

Dendrites and glial cells. Signup and view all the answers

Which neuron type is the most abundant in the central nervous system?

Multipolar neurons. Signup and view all the answers

What is the primary function of sensory (afferent) neurons?

Transmit impulses toward the CNS. Signup and view all the answers

What characterizes the action potentials in neurons?

They are always the same regardless of the stimulus. Signup and view all the answers

Which of the following statements about ion channels is incorrect?

Chemically gated channels respond to changes in voltage. Signup and view all the answers

What is the primary role of oligodendrocytes in the CNS?

They form myelin sheaths around axons. Signup and view all the answers

What distinguishes a unipolar neuron from other types?

It has a short process that branches into two. Signup and view all the answers

Study Notes

Nervous System Objectives

Describe the divisions of the nervous system and their characteristics.
Identify the structures and functions of a typical neuron.
Describe the location and function of neuroglia.
Describe resting membrane potentials.
Discuss the events in the generation and propagation of an action potential.
Define the structure and function of a synapse.

Nervous System

The master controlling and communicating system of the body.
Functions:
- Sensory input - stimuli goes to the CNS.
- Integration - interpretation of sensory input.
- Motor output - response to stimuli coming from the CNS.

Terminology

Input (Sensory):
- Receptors monitor changes.
- Changes are called stimuli.
- Information is sent by afferent nerves.
Integration:
- Information is processed.
- A decision is made about what should be done.
Output (Motor):
- Effector organs (muscles or glands) are activated.
- Effected by efferent nerves.

Organization of the Nervous System

Central nervous system (CNS):
- Brain and spinal cord.
- Integration and command center.
Peripheral nervous system (PNS):
- Paired spinal and cranial nerves.
- Carries messages to and from the spinal cord and brain.

Peripheral Nervous System (PNS): Two Functional Divisions

1. Sensory (afferent) division:
- Somatic sensory fibers - carry impulses from skin, skeletal muscles, and joints to the brain.
- Visceral sensory fibers - transmit impulses from visceral organs to the brain.
2. Motor (efferent) division:
- Carries impulses from the CNS to effector organs (muscles and glands).

Motor Division: Two Main Parts

1. Somatic Nervous System:
- Voluntary - carry impulses from the CNS to skeletal muscles.
2. Autonomic Nervous System (ANS):
- Involuntary - carry impulses from the CNS to smooth muscle, cardiac muscle, and glands.

ANS Division: Two Main Parts

Sympathetic and Parasympathetic.

Histology of Nerve Tissue

The two principal cell types of the nervous system are neurons and neuroglia (glial).
- Neurons: Excitable cells that transmit electrical signals.
- Neuroglia (glial): Cells that surround and wrap neurons (supporting cells).

Supporting Cells: Neuroglia

Provide a supportive scaffolding for neurons.
Segregate and insulate neurons.
Guide young neurons to the proper connections.
Promote neuron health and growth.
Six types: 4 in CNS, 2 in PNS.

Neuroglia of the CNS

Astrocytes:
- Most abundant, versatile, and highly branched glial cells.
- Maintain blood-brain barrier.
- Cling to neurons and their synaptic endings.
- Wrap around capillaries, regulating their permeability.
- Provide structural framework for the neuron.
- Guide migration of young neurons.
- Control the chemical environment.
- Repair damaged neural tissue
Microglia: Small, ovoid cells with spiny processes.
- Phagocytes that monitor the health of neurons.
Ependymal cells: Range in shape from squamous to columnar.
- Line the central cavities of the brain and spinal column.
Oligodendrocytes: Branched cells with myelin.
- Myelin: Wraps oligodendrocyte processes around nerve fibers
- Insulates nerve fibers.

Neuroglia of the PNS

Schwann cells (neurolemmocytes):
- Myelin: Wraps itself around nerve fibers, insulating them.
Satellite cells: Surround neuron cell bodies in ganglia, regulating the environment around the neurons.

Myelin in the Peripheral and Central Nervous Systems

Myelin sheaths can either be formed by Schwann cells (PNS), or by oligodendrocytes (CNS).

Action Potentials (APs)

Brief reversal of membrane potential, only generated by muscle cells and neurons.
Do not decrease in strength over distance.
Principal means of neural communication.
An action potential in the axon of a neuron is a nerve impulse.

Action Potential: Resting State

Na+ and K+ channels are closed.

Action Potential: Depolarization Phase

Na+ permeability increases, membrane potential reverses. Na+ gates open; K+ gates close.
Threshold: critical level of depolarization (-55 to -50 mV). Depolarization becomes self-generating at threshold.

Action Potential: Repolarization Phase

Sodium inactivation gates close; membrane permeability to Na+ declines to resting levels.
Voltage-sensitive K+ gates open; K+ exits the cell.
Internal negativity of the resting neuron is restored.

Action Potential: Hyperpolarization

Potassium gates remain open, causing an excessive efflux of K+.
This efflux causes hyperpolarization of the membrane (undershoot).
The neuron is insensitive to stimulus and depolarization during this time.

Action Potential: Role of the Sodium-Potassium Pump

Restores resting electrical conditions of the neuron, but does not restore the resting ionic conditions.

Propagation of an Action Potential:

Continuous and Saltatory Propagation
Continuous: Unmyelinated axons, current flows across the entire membrane.
Saltatory: Myelinated axons, current jumps between Nodes of Ranvier.
Action potential only generated at the Nodes of Ranvier.

Types of Stimuli

Threshold Stimulus: Strong enough to bring the membrane potential to a threshold voltage, causing an action potential.
Subthreshold Stimulus: Weak stimuli that cause depolarization (graded potentials), but not action potentials.

Coding for Stimulus Intensity

Action potentials are all-or-none; strong stimuli generate action potentials more often than weaker ones.
The CNS determines stimulus intensity by the frequency of impulse transmission.

Absolute Refractory Period

Time from Na+ activation gates opening to inactivation gates closing.
Prevents the neuron from generating another action potential ensuring separate action potentials.
Enforces one-way transmission of nerve impulses.

Relative Refractory Period

Interval following the absolute refractory period; Sodium gates are closed, potassium gates are open, and repolarization is occurring.

Synapse

The means by which adjacent neurons communicate.
Most synapses occur between the axon of one neuron and the dendrites of another (axodendritic) or between the axon of one neuron and the cell body of another (axosomatic).
The presynaptic neuron sends information, and the postsynaptic neuron receives it.
Neurons may have 1000 to 10000 axonal terminals making synapses.

Grey and White Matter

Grey Matter: Consists of unsheathed nerve fibers, cannot be regenerated if damaged (in cortex or surface layer).
White Matter: Makes up the internal structures and consists of myelinated nerve fibers. The brain and spinal cord receive impulses, process the information, and respond with the appropriate action.

Electrical Synapses

Less common than chemical synapses.
Correspond to gap junctions found in other cell types.
Very fast propagation of action potentials.
Important in the CNS for arousal from sleep, mental attention, emotions, and memory.
Important for ion and water homeostasis.

Chemical Synapses

Specialized for the release and reception of neurotransmitters.
Composed of presynaptic and postsynaptic neurons.
Presynaptic Neuron: Contains synaptic vesicles, which release neurotransmitters across the synaptic cleft to the postsynaptic neuron.
Postsynaptic Neuron: Receptors are located on dendrites and soma.

Chemical Synapses: Other Features

Synaptic cleft: Fluid-filled space separating the neurons; transmission is a chemical event, unlike the electrical one.
Synaptic cleft: Information Transfer: Nerve impulses reach the axon terminal of the presynaptic neuron, open Ca2+ channels. Neurotransmitter is released into the synaptic cleft via exocytosis. Neurotransmitter crosses the synaptic cleft and binds to receptors on the postsynaptic neuron; postsynaptic membrane permeability changes, causing excitatory or inhibitory effect.

Termination of Neurotransmitter Effects

Neurotransmitter bound to a postsynaptic neuron produces a continuous postsynaptic effect, blocking reception of additional messages. Must be removed from its receptor.

Postsynaptic Potentials

Neurotransmitter receptors mediate changes in membrane potential according to the amounts of neurotransmitter released and the time the neurotransmitter is bound to receptors.
Types:
- EPSPs: Excitatory postsynaptic potentials. Cause depolarization, increasing likelihood of action potential.
- IPSPs: Inhibitory postsynaptic potentials. Cause hyperpolarization, reducing likelihood of action potential.

Terminology for Quiz

Neuron: nerve cell
Neuroglia: supporting cell
Nerve fiber: long axon
Nerve: collection of axons in PNS
Tract: collection of axons in CNS
Nucleus: cluster of cell bodies in CNS
Ganglia: cluster of cell bodies in PNS
Unilateral: one side
Ipsilateral: same side
Contralateral: opposite side
CNS: Central Nervous System
PNS: Peripheral Nervous System
Input/sensory: afferent; to brain
Output/motor: efferent; from brain

Examine Yourself

Neurons: inside/outside CNS
Structures concerned with CSF formation: arachnoid villi, choroid plexus, subdural space, dural venous sinus
Peripheral nervous system involves: spinal ganglia, spinal cord, brain, tracts
Lateral ventricle lies in: cerebrum, diencephalon, midbrain, cerebellum

References

Information was compiled from multiple referenced sources; it is impossible to identify all sources.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge on the autonomic and somatic nervous systems with this quiz. Explore the roles of different divisions, nerve fibers, and their functions within the human body. Perfect for students studying physiology or related fields.