Neurons: The Brain's Building Blocks

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Questions and Answers

What is the primary component of the brain?

Glial cells

Axons

Dendrites

Neurons (correct)

What is the function of dendrites in a neuron?

To produce the myelin sheath

To clean up cellular debris

To transmit messages away from the neuron

To receive sensory input signals and information from other neurons (correct)

What is the function of the cell body in a neuron?

To transmit messages away from the neuron

To receive sensory input signals and information from other neurons

To determine responses to message inputs (correct)

To produce the myelin sheath

What is the purpose of the myelin sheath?

To help in transmitting information Signup and view all the answers

What happens if the myelin sheath is damaged?

The transmission of electrical impulses along the axon may be affected Signup and view all the answers

What is the result of the progressive deterioration of the myelin sheath?

Multiple sclerosis Signup and view all the answers

What is a symptom of multiple sclerosis?

Jerky, uncoordinated movement Signup and view all the answers

What produces the myelin sheath?

Glial cells Signup and view all the answers

What is the primary function of acetylcholine in the human body?

Controlling muscle action, learning, and memory Signup and view all the answers

What happens when there is inadequate production of dopamine?

Parkinson's disease occurs Signup and view all the answers

What is the function of serotonin in the human body?

Regulating mood and controlling eating habits Signup and view all the answers

What is the function of norepinephrine in the human body?

Producing feelings of alertness and wakefulness Signup and view all the answers

What is the function of GABA in the human body?

Found throughout the brain and spinal cord Signup and view all the answers

How do most neurons interact with each other?

Through complex patterns of excitatory or inhibitory influences Signup and view all the answers

What is the basis of everything we sense, think or do?

The action potential Signup and view all the answers

What happens when the membrane potential becomes more negative at a particular spot on the neuron's membrane?

Hyperpolarization Signup and view all the answers

What travels along the membrane of the axon to the axon terminals when a neuron fires?

Action potential Signup and view all the answers

What are the small structures inside the terminal buttons that release chemicals into the synapse?

Synaptic vesicles Signup and view all the answers

What are the chemical messengers in the body that transmit signals between nerve cells?

Neurotransmitters Signup and view all the answers

What can neurotransmitters produce on the receptors?

Either excitatory or inhibitory effect Signup and view all the answers

What happens to the neurotransmitter substance after it travels across the synapse?

It is taken back for reuse in the axon terminals Signup and view all the answers

What is the function of enzymes in the synapse?

To break down neurotransmitters Signup and view all the answers

What is the function of the blood-brain barrier?

To prevent certain substances in the bloodstream from reaching the brain Signup and view all the answers

What is the region at which the axon terminals of a neuron closely approach other cells called?

Synapse Signup and view all the answers

What is the term for the slight negative charge inside the cell compared to the outside?

Resting potential Signup and view all the answers

What happens when positive ions enter the cell body?

The cell becomes more positively charged Signup and view all the answers

What is the term for a change in the electrical potential on the membrane of a nerve cell in response to a stimulus?

Graded potential Signup and view all the answers

What happens when the graded potential exceeds the threshold of the neuron?

The cell generates an action potential Signup and view all the answers

What is the term for a short-term change in the electrical potential on the surface of a nerve cell in response to stimulation?

Action potential Signup and view all the answers

What happens to the cell membrane during an action potential?

It becomes more permeable to ions Signup and view all the answers

What is the effect of abnormal levels of a certain neurotransmitter on the brain?

It can influence sleep and eating disorders Signup and view all the answers

What is the function of endorphin in the brain?

It is released in response to pain or vigorous exercise to reduce sensations Signup and view all the answers

How do drugs affect our feelings and/or behaviors?

By altering the process of synaptic transmission Signup and view all the answers

What is the effect of agonists on the body?

They combine with a receptor on a cell to trigger a physiological reaction Signup and view all the answers

What is the role of antagonists in the body?

They interfere with the physiological action of another agent Signup and view all the answers

What is an example of an agonist mentioned in the content?

Acetylcholine Signup and view all the answers

Study Notes

Neurons: Building Blocks of the Nervous System

The brain is primarily composed of neurons, with tens of billions of them.
Neurons are the building blocks of the brain and are believed to be the principal cellular elements of intelligence.

The Neuron

A neuron consists of three basic structures: the cell body, axon, and one or more dendrites.
Dendrites receive sensory input signals and information from other neurons.
The cell body determines responses to message inputs.
The axon carries messages away from the neuron and is insulated with a myelin sheath.

Neuron Structures: Myelin Sheath

The myelin sheath helps transmit information and is produced by glial cells.
Damage to the myelin sheath can affect transmission of electrical impulses along the axon.
Multiple sclerosis is a disease that results from progressive deterioration of the myelin sheath, leading to jerky, uncoordinated movement.

Glial Cells

Glial cells form the myelin sheath and perform basic housekeeping functions, such as cleaning up cellular debris.
They also form the blood-brain barrier, which prevents certain substances in the bloodstream from reaching the brain.

Neuron Structures

The axon divides into several small branches with small bulbs at the end, known as axon terminals.
These closely approach but do not actually touch other cells.
The region where the axon terminals of a neuron closely approach other cells is known as the synapse.

Communication Within Neurons

There are different negatively and positively charged ions in and outside of the cell.
The inside of the cell has a slight negative charge in relation to the outside of the cell, resulting in a resting potential of -70 millivolts.
When positive ions enter the cell body, the cell body works to push out the positive ions while retaining the negative ions.
Graded potentials are a change in the electrical potential on the membrane of a nerve cell in response to a stimulus.
If the graded potential exceeds the threshold of the neuron, a complex biochemical change will occur, and an action potential will be generated.

Action Potential

During an action potential, the cell membrane becomes more easily accessible, and positive ions enter the cell.
The inside of the cell becomes more positively charged than the outside of the cell.
The change in electrical potential across the cell membrane moves quickly along the neuron.
The action potential is the basis of everything we sense, think, or do.

Hyperpolarization

Hyperpolarization occurs when the membrane potential becomes more negative at a particular spot on the neuron's membrane.
Depolarization is when the membrane potential becomes less negative (more positive).

Communication Between Neurons

When a neuron fires, the action potential travels along the membrane of the axon to the axon terminals.
Inside the terminal buttons are many structures known as synaptic vesicles.
The action potential causes these vesicles to approach the cell membrane and fuse with the membrane, emptying their chemicals into the synapse.
These chemicals are called neurotransmitters.
Neurotransmitters travel across the synapse until they reach the specialized receptor cells of the other cell.

Neurotransmitters

Neurotransmitters are chemical messengers in the body that transmit signals between nerve cells.
They help regulate bodily functions ranging from heart rate to appetite.
Neurotransmitters can produce an excitatory effect on the receptors (make the neuron more likely to fire) or an inhibitor effect (make the neuron less likely to fire).
After the neurotransmitter travels across the synapse, it is either taken back for reuse in the axon terminals of the neuron that released it (reuptake) or broken down by enzymes.

Neurotransmitters Types

Acetylcholine: found at every junction between the motor and the muscle tissue, involved in muscle action, learning, and memory.
Norepinephrine: found in the automatic nervous system, involved in control or alertness and wakefulness.
Dopamine: produced in the substantia nigra, involved in movement, attention, and learning.
Serotonin: located in the neurons in the brain and spinal cord, involved in mood and in the control of eating, sleep, and arousal.
GABA (gamma-amino-butyric acid): found throughout the brain and spinal cord, a major inhibitory neurotransmitter in the brain.
Endorphin: a natural substance produced in the brain, released in response to pain or vigorous exercise to help reduce sensations that can interfere with ongoing behavior.

Drugs and Neurotransmitters

Drugs can affect our feelings and/or behaviors by altering the process of synaptic transmission.
This is as a result of the drug being similar to that of the chemical structure in the neurotransmitter.
In some cases, drugs can mimic the effects of a neurotransmitter.
In other cases, they can inhibit the effects that are normally produced by the neurotransmitter.
Some neurotransmitters are agonists, and others are antagonists.

Agonists and Antagonists

Agonist: a molecule that combines with a receptor on a cell to trigger a physiological reaction.
Antagonist: a biological structure or chemical agent that interferes with the physiological action of another.
Examples of agonists are drugs that combine with the cholinergic receptor, and examples of antagonists are drugs that bind to cell receptors that prevent the agonists from eliciting a biological response.

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Description

Learn about the biology of neurons, the building blocks of the nervous system, and their role in brain development and intelligence.