Neurons and Glial Cells Overview

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Questions and Answers

Which statement accurately describes substance dependence?

It entails a casual use of substances without any repercussions.

It involves no withdrawal symptoms or tolerance to the substance.

It is characterized by an individual's ability to control their use of substances.

It is defined by a persistent loss of control over substance use, even when facing negative consequences. (correct)

Which type of neuron is specialized to transmit commands from the central nervous system to muscles and glands?

Motor neuron (correct)

Bipolar neuron

Sensory neuron

Interneuron

What distinguishes addiction from mere substance use?

Addiction results in a compulsive craving for drugs, more about 'wanting' than 'liking'. (correct)

Addiction is characterized by infrequent, non-compulsive use of substances.

Addiction leads to a gradual decrease in substance tolerance.

Addiction leads to prolonged periods of substance abstinence.

What type of neuron has more than two processes extending from its cell body?

Multipolar neuron Signup and view all the answers

Which class of drugs is primarily associated with increased brain activity?

Stimulants, such as caffeine and amphetamines. Signup and view all the answers

What is the process known as tolerance?

The need for increased amounts of a drug to achieve the same effect. Signup and view all the answers

What is the role of interneurons in the nervous system?

Act as connectors between sensory and motor systems Signup and view all the answers

What describes the resting potential of a neuron?

The electrical potential when a neuron is inactive Signup and view all the answers

Which of the following drugs is classified as a hallucinogen?

Ecstasy Signup and view all the answers

What occurs during the depolarization of a neuron?

The internal charge becomes more positive Signup and view all the answers

Which component prevents most toxins from entering the brain?

Blood-brain barrier Signup and view all the answers

What principle states that a neuron transmits an impulse of the same strength each time it fires?

All-or-none principle Signup and view all the answers

What does the process of polarization in a neuron achieve?

Prepares the neuron for firing Signup and view all the answers

What is the primary function of hormones in the body?

To regulate growth, metabolism, and behaviors Signup and view all the answers

Which of the following hormones is NOT regulated by the pituitary gland?

Thyroxin Signup and view all the answers

What is the role of melatonin secreted by the pineal gland?

To help regulate the sleep-wake cycle Signup and view all the answers

What effect do anabolic steroids typically have on individuals?

Enhance athletic performance Signup and view all the answers

Which type of drug blocks a neurotransmitter's action?

Antagonist Signup and view all the answers

What characterizes psychoactive drugs?

They are administered for specific psychological effects Signup and view all the answers

What condition results from a deficiency of thyroxin?

Hypothyroidism Signup and view all the answers

How do adrenal cortical steroids primarily affect the body?

They increase resistance to stress Signup and view all the answers

What primarily triggers the release of neurotransmitters at the synapse?

A shift in electric potential caused by ion flow Signup and view all the answers

How do excitatory neurons influence other neurons?

By causing other neurons to fire Signup and view all the answers

Which method does not contribute to the deactivation of neurotransmitters?

Reuptake by the postsynaptic receptor Signup and view all the answers

What is a key characteristic of most neurotransmitters?

They elicit a specific observable effect on postsynaptic cells. Signup and view all the answers

What distinguishes electrical synapses from chemical synapses?

Electrical synapses rely on the direct movement of ions. Signup and view all the answers

What role do synaptic vesicles play in neurotransmission?

They store neurotransmitters in the axon terminals. Signup and view all the answers

Which of the following describes the refractory period in neurons?

The time during which a neuron cannot fire again. Signup and view all the answers

What is the primary function of receptor sites on dendrites?

To receive specific neurotransmitters Signup and view all the answers

What is the primary function of astrocytes in the nervous system?

Support the activities of neurons and transfer nutrients Signup and view all the answers

Which part of a neuron is primarily responsible for receiving information from other neurons?

Dendrites Signup and view all the answers

What distinguishes neurons from glial cells in the nervous system?

Neurons transmit information over long distances Signup and view all the answers

What is the role of the myelin sheath in relation to neuron function?

To insulate axons and speed up signal transmission Signup and view all the answers

Which transport mechanism involves the movement of materials from the axon terminal back to the cell body?

Retrograde transport Signup and view all the answers

What mainly composes the neural membrane of a neuron?

A two-molecule thick layer of phospholipids Signup and view all the answers

What specifically provides means for transporting materials within a neuron?

Microtubules Signup and view all the answers

Which structure of the neuron is primarily involved in carrying signals to other neurons?

Axon Signup and view all the answers

Study Notes

Neurons and Synapses

Neurons are specialized cells in the nervous system for information processing and communication.
They receive and transmit information to other cells.
Glia (or neuroglia) are cells that support neurons' activities.
Glia do not transmit information long distances like neurons do.

Cells of the Nervous System

The cerebral cortex and its associated areas contain 12 to 15 billion neurons.
The spinal cord has 1 billion neurons.
The cerebellum has 70 billion neurons.
Obtaining an exact neuron count is difficult due to their small size and varying density.

Types of Glia

Astrocyte: Structural and nutritional support for neurons, synapse isolation, debris cleanup, blood-brain barrier participation, and chemical signaling. Located in the central nervous system.
Oligodendrocyte: Myelination of axons in the central nervous system.
Schwann cell: Myelination of axons in the peripheral nervous system.
Microglia: Debris cleanup in the central nervous system.
Astrocytes help transport nutrients to neurons and block toxic movement. They also hold neurons in place.

Structure of Neurons

Neurons have a cell body (soma) containing organelles.
Dendrites receive information from other neurons.
The axon carries signals to other neurons.
The synapse is the junction between two neurons, where information transfer occurs.
Myelin sheath is fatty insulation around many axons.

Neuron Membranes

The neural membrane is a two-molecule thick phospholipid layer.
Ion channels and pumps are embedded in the membrane and allow chemical transport.

Neural Cytoskeleton

The neural cytoskeleton supports the neuron and transports substances.
Microtubules transport materials within a neuron.
Anterograde transport is the movement of materials from the cell body to the axon terminal.
Retrograde transport moves materials from the axon terminal back to the cell's body.
Neurofilaments provide structural support, and microfilaments may play a role in learning.

Functional Variations in Neurons

Sensory neurons receive information from the external environment.
Motor neurons send commands from the central nervous system to muscles and glands.
Interneurons connect sensory and motor neurons.

Types of Neurons

Sensory neurons (afferent) receive information from the environment.
Interneurons (associative) connect other neurons.
Motor neurons (efferent) transmit information to muscles and glands.

Classification of Neurons

Unipolar neurons have one process extending from their cell body.
Bipolar neurons have two processes extending from their cell body.
Multipolar neurons have more than two processes extending from their cell body.
Interneurons have short axons or no axons at all.

Blood-Brain Barrier

The blood-brain barrier prevents toxins from entering the brain.
It consists of an unbroken wall of cells surrounding brain blood vessels.

Neural Impulse

A neural impulse is the electrochemical discharge of a neuron.
Polarize a neuron to ready for firing creating an internal negative charge.
Resting potential is the electrical potential across the neural membrane when not responding to other neurons.
Depolarize to reduce resting potential of a cell membrane.
Action potential is the conduction of neural impulses along axons.

Firing: Neuron to Neuron

Neuron fires when incoming messages reach a threshold strength.
All-or-none principle describes a neuron firing with the same strength, or not at all.
Refractory period is the recovery time period between firings.

Synapse

Synapse is a junction between the axon terminals of one neuron and the dendrites or cell body of another neuron.
Neurotransmitters are chemical substances that communicate from one neuron to another.
Synaptic vesicles contain neurotransmitters in axon terminals.
Receptor sites are tailored locations on dendrites to receive neurotransmitters.
Excitatory neurons cause other neurons to fire.
Inhibitory neurons prevent other neurons from firing.

Chemical and Electrical Synapse

Chemical synapse uses neurotransmitters to transmit messages between neurons.
Electrical synapse directly transmits information via ion flow.

Synaptic Transmission

Neurotransmitters are synthesized, packaged, and released into the synaptic cleft after an action potential.
Neurotransmitters bind to receptors on the postsynaptic membrane and trigger a response.
Transmission is terminated by the removal of neurotransmitters from the synaptic cleft.

Methods for Deactivating Neurotransmitters

Deactivation occurs through diffusion away from the synapse, action of special enzymes, or reuptake.

Neurotransmitters

Neurotransmitters are chemical messengers that communicate across synapses.
Most produce either excitation or inhibition.

Summary Table of Neurotransmitters

Specific neurotransmitters are linked to distinct functions and locations.

Hormones

Hormones are chemicals secreted by cells and conveyed by the blood to influence other cells.
They coordinate long-lasting changes in multiple body parts.
They regulate growth, metabolism, and some behaviors.
Maintain homeostasis.

Hormones Regulated by Pituitary Gland

Pituitary gland is the "master gland" regulating several hormones.
Hormones like growth hormone, prolactin, vasopressin, and oxytocin have various functions.

Endocrine Glands

Pineal gland secretes melatonin, regulating the sleep-wake cycle.
Thyroid gland produces thyroxin affecting metabolism; hypothyroidism and hyperthyroidism represent deficiencies and excesses respectively.
Adrenal glands are located above the kidneys increasing stress resistance and promoting muscle development.
Testes and ovaries produce testosterone (androgens) and estrogen/progesterone, responsible for sex characteristics.

Steroids, Behavior, and Mental Processes

Steroids increase muscle mass, resist stress, and increase the body's energy supply.
Anabolic steroids enhance athletic performance but may have negative impacts on behaviour and cognitive functions.

Drugs and Behavior

Drugs can either facilitate or inhibit neurotransmitter transmission.
Antagonists block neurotransmitters; agonists increase their effects.
Drug effectiveness and side effects vary among individuals.

Psychoactive Drugs

Psychoactive drugs are administered to cause psychological effects.
These drugs frequently bypass the blood-brain barrier.

Drugs: Dependence and Abuse

Substance abuse is persistent substance use despite causing problems in daily life.
Substance dependence is loss of control over substance use.

Drugs: Addiction

Addiction is a compulsive craving for drug effects.
Some addictive drugs increase dopamine activity to create a reinforcing experience.
Tolerance occurs when more of a drug is needed to produce the same effect.
Withdrawal symptoms occur when a drug use is discontinued.

Types of Drugs

Stimulants speed up the central nervous system (e.g., caffeine, nicotine, amphetamines).
Depressants slow down the central nervous system (e.g., alcohol, opiates).
Hallucinogens alter the user's state of consciousness (e.g., LSD, marijuana).

Summary Table: Drugs and Effects

Different drugs produce various effects, having unique mechanisms of action and impacting the body in distinct ways.

St. John's Wort and Hallucinogenic Mushroom

Information about these specific drugs and their effects, including images of the plants.

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Description

Explore the fascinating world of neurons and glial cells in the nervous system. This quiz covers their functions, types, and the structural differences between various neurons and supporting cells. Test your knowledge on how these cells contribute to neural communication and overall brain health.