Psychology Chapter 4.1-4.2 The Nervous System Overview

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Questions and Answers

What are the primary components of the central nervous system (CNS)?

Afferent and efferent neurons

Sensory and motor systems

Brain and spinal cord (correct)

Neurons and glia

Which type of matter in the CNS is primarily composed of myelinated axons?

White matter (correct)

Gray matter

Neuronal cell bodies

Glial cells

What role do afferent neurons play within the nervous system?

They transmit sensory information to the CNS. (correct)

They send signals away from the brain.

They mediate reflex actions.

They enhance communication between interneurons.

The peripheral nervous system (PNS) is primarily concerned with which of the following?

Connecting peripheral nerves to the brain Signup and view all the answers

What are the two branches of the peripheral nervous system?

Somatic and autonomic Signup and view all the answers

Which type of neuron is responsible for carrying motor commands from the brain to the body?

Efferent neurons Signup and view all the answers

How is white matter characterized in the context of the nervous system?

Myelinated axons Signup and view all the answers

What is the primary function of the nervous system?

Regulation and coordination of body systems Signup and view all the answers

What is the primary function of the somatic nervous system?

Controlling voluntary muscular movements Signup and view all the answers

The autonomic nervous system primarily regulates which type of functions?

Involuntary, automatic bodily functions Signup and view all the answers

Which division of the autonomic nervous system is responsible for the body's 'fight or flight' responses?

Sympathetic nervous system Signup and view all the answers

How do sympathetic neurons affect the adrenal glands during a stress response?

They stimulate secretion of norepinephrine and epinephrine Signup and view all the answers

What effect does the parasympathetic nervous system have on heart rate?

It decreases heart rate Signup and view all the answers

During stress, what is a typical effect of sympathetic nervous system activation on blood vessels?

Constriction of blood vessels supplying visceral organs Signup and view all the answers

Which statement accurately describes the relationship between the somatic and autonomic nervous systems?

Somatic controls voluntary actions, autonomic handles involuntary processes Signup and view all the answers

What occurs during the 'rest and digest' phase managed by the parasympathetic system?

Promotion of energy conservation and storage Signup and view all the answers

What initiates the Action Potential (AP) in a neuron?

The opening of Na+ channels Signup and view all the answers

What happens during repolarization of a neuron?

Na+ channels inactivate and K+ channels open Signup and view all the answers

What is the absolute refractory period in relation to an AP?

The period when Na+ channels inactivate and K+ channels open Signup and view all the answers

Which factor influences the speed of AP propagation down the axon?

The diameter of the axon and myelination Signup and view all the answers

What causes the membrane potential to become more positive during the AP?

Na+ ions entering the cell Signup and view all the answers

What occurs immediately after the threshold is reached in a neuron?

Further Na+ channels open Signup and view all the answers

What role do neurotransmitters play at the synapse?

Facilitating communication between neurons Signup and view all the answers

Which ion primarily contributes to the repolarization of the membrane potential?

K+ ions Signup and view all the answers

What occurs at excitatory synapses when neurotransmitters bind to receptors on the postsynaptic neuron?

The membrane potential becomes more positive, leading to depolarization. Signup and view all the answers

Which neurotransmitter is primarily responsible for inhibition in the central nervous system?

GABA Signup and view all the answers

What determines whether ionic movement across the postsynaptic membrane results in excitation or inhibition?

The type of neurotransmitter and the postsynaptic neuron's membrane potential. Signup and view all the answers

Which of the following neurotransmitters is classified as primarily excitatory?

Glutamate Signup and view all the answers

How does an inhibitory synapse affect the postsynaptic neuron?

It makes the postsynaptic membrane potential more negative, reducing action potential initiation. Signup and view all the answers

Acetylcholine is specifically released by which type of neurons?

Somatic motor neurons Signup and view all the answers

Which of the following statements about neurotransmitters is incorrect?

GABA can enhance the likelihood of action potentials. Signup and view all the answers

What is the primary function of neurotramsitters like glutamate at synapses?

To promote postsynaptic neuron excitation. Signup and view all the answers

What is responsible for the resting membrane potential (RMP) in neurons?

High concentration of potassium ions inside and low concentration of sodium ions outside Signup and view all the answers

What term describes the electrical signal that travels down a neuron's axon?

Action potential Signup and view all the answers

When a neurotransmitter binds to receptors on a postsynaptic neuron, what effect can it have on membrane potential?

It can alter the membrane potential in either direction Signup and view all the answers

What is an excitatory postsynaptic potential (EPSP)?

A potential that increases the likelihood of an AP Signup and view all the answers

Which of the following ions primarily contribute to the resting membrane potential in neurons?

Potassium ions (K+) Signup and view all the answers

What occurs when the summed postsynaptic potentials exceed a certain threshold?

An action potential is fired Signup and view all the answers

What type of potential decreases the likelihood of an action potential?

Inhibitory postsynaptic potential (IPSP) Signup and view all the answers

Which cells are responsible for forming myelin sheaths around neurons' axons?

Glial cells Signup and view all the answers

Study Notes

The Nervous System

The nervous system controls and manages all bodily functions
The nervous system receives and processes information from both inside and outside the body
The nervous system then coordinates and activates responses to the information it receives
The nervous system is divided into two major branches: the central nervous system (CNS) and the peripheral nervous system (PNS)
The PNS is composed of neurons and glia located outside the brain and spinal cord
The CNS contains the brain and spinal cord and integrates information from the PNS

The Central Nervous System

The CNS is composed of white matter and gray matter
Gray matter is comprised of unmyelinated axons, neuronal cell bodies, and dendrites
White matter consists primarily of myelinated axons that allow for long-distance communication between neurons
White matter can be classified as afferent or efferent
Afferent neurons send signals to the brain
Efferent neurons carry messages away from the brain

The Peripheral Nervous System

The peripheral nervous system (PNS) consists of neurons located outside of the CNS
The PNS is divided into two branches: The somatic nervous system and the autonomic nervous system
The somatic nervous system includes sensory neurons that carry information to the CNS, and motor neurons that relay commands from the CNS to the body
Somatic sensory neurons transmit impulses from receptors in the skin muscles and joints to the spinal cord
Somatic motor neurons transmit impulses from the spinal cord to the skeletal muscles, allowing individuals to consciously move their bodies
The autonomic nervous system controls subconscious, automatic functions that are not subject to voluntary control
The autonomic nervous system regulates the activity of glands, smooth muscles, and cardiac muscles
The autonomic nervous system is further divided into the sympathetic nervous system and the parasympathetic nervous system

The Sympathetic Nervous System

The sympathetic nervous system mobilizes the body for action during stress
The sympathetic nervous system helps prepare the body for "fight or flight" responses
The sympathetic nervous system increases heart rate, dilates airways, and constricts blood vessels to the visceral organs, glands, and skin

The Parasympathetic Nervous System

The parasympathetic nervous system promotes energy conservation and storage when stress is low
The parasympathetic nervous system helps facilitate "rest and digest" responses
The parasympathetic nervous system decreases heart rate, decreases airflow through the lungs, increases blood flow to the visceral organs, and promotes digestion
The parasympathetic nervous system is suppressed during times of stress

Neural Communication

Communication between neurons involves an electrical signal called an action potential (AP) that travels down a neuron's axon
The properties of the neuronal membrane and the ion concentrations inside and outside of the cell enable the AP
Action potential propagation is driven by an uneven concentration of charged ions between the inside and the outside of all living cells, which is known as the membrane potential
Ion movement across the membrane leads to either postsynaptic depolarization (excitation) or hyperpolarization (inhibition)
Exogenous neurotransmitters can increase or decrease the likelihood of an action potential, depending on the type of channel and environmental conditions
Excitatory postsynaptic potential (EPSP) brings the membrane potential closer to the threshold and increases the likelihood of an AP
An inhibitory postsynaptic potential (IPSP) brings the membrane potential further from the threshold and decreases the likelihood of an AP

The Action Potential

The action potential (AP) results in the transmission of an electrical signal down the axon
The neuron membrane potential changes due to the opening and closing of sodium (Na+) and potassium (K+) ion channels
The cell membrane potential becomes more positive during the AP, as Na+ ions enter the cell
When the threshold is reached, additional Na+ channels open rapidly increasing the depolarization of the membrane
Repolarization occurs as Na+ channels inactivate and K+ channels open, K+ rushes out of the cell to restore the charge potential
The K+ and Na+ channels close to fully restore the resting membrane potential (RMP)
Another AP cannot occur during the repolarization stage, this time is referred to as the absolute refractory period.
The rate at which an AP travels down the axon is influenced by axon size and myelination
Larger diameter axons and myelinated axons transmit neural impulses faster than smaller and unmyelinated axons

Neurotransmitter Release

When an AP reaches the axon terminal of the presynaptic neuron, neurotransmitters are released from synaptic vesicles, where they are stored, into the synaptic cleft
Neurotransmitters travel across the synaptic cleft and some bind to receptors on the postsynaptic cell membrane
When a neurotransmitter binds to its receptor on the postsynaptic neuron, ions can move into or out of the postsynaptic neuron and alter the neuron's RMP
The type of receptor and the postsynaptic neuron's membrane potential determine whether ionic movement results in postsynaptic excitation (depolarization) or inhibition

Synaptic Classifications

Synapses are classified as excitatory (promoting AP initiation) or inhibitory (inhibiting AP initiation)
Excitatory synapses promote the membrane potential of the postsynaptic neuron to become more positive (depolarization)
Inhibitory synapses result in a more negative charge potential, inhibiting AP initiation

Neurotransmitter Classifications

Neurotransmitters are classified as excitatory or inhibitory depending on their effects on the postsynaptic neuron
Excitatory neurotransmitters make the postsynaptic neuron more likely to have an AP
Inhibitory neurotransmitters make the postsynaptic neuron less likely to have an AP

Neurotransmitter Examples

The amino acid neurotransmitters include gamma-aminobutyric acid (GABA), glutamate, and glycine
GABA is the principal inhibitory neurotransmitter of the CNS
Glycine is also a primarily inhibitory neurotransmitter found in the CNS.
Glutamate is the primary excitatory neurotransmitter of the CNS.
Acetylcholine is the neurotransmitter released by somatic motor neurons at the neuromuscular junction.

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Description

Explore the functions and structure of the nervous system in this quiz. Learn about the roles of the central and peripheral nervous systems, including the distinctions between gray and white matter. Test your knowledge on how the nervous system processes information and coordinates bodily responses.