Nervous Tissue and Neuron Anatomy

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What role do glial cells serve in the nervous system?

They provide structure and support to neurons. (correct)

They transmit signals between neurons.

They facilitate muscle contractions.

They replicate and communicate like neurons.

Which part of the neuron is primarily responsible for sending signals to other neurons?

Axon (correct)

Cell body

Nucleus

Dendrites

What is the primary characteristic of neurons regarding replication?

Neurons can replicate under certain conditions.

Neurons replicate constantly.

Neurons replicate during any stage of life.

Neurons do not replicate. (correct)

Where in the body is the central nervous system located?

In the cranial and vertebral cavities. Signup and view all the answers

What function does the endoplasmic reticulum serve in a neuron?

Manufactures proteins. Signup and view all the answers

Which division of the nervous system is responsible for the 'rest and digest' response?

Parasympathetic division Signup and view all the answers

What are neurotransmitters?

Chemicals that transmit signals between neurons. Signup and view all the answers

Which part of the neuron receives signals from other neurons?

Dendrites Signup and view all the answers

What neurotransmitter is primarily responsible for inhibitory signaling in the nervous system?

Gamma-aminobutyric acid Signup and view all the answers

What process is primarily responsible for the elimination of neurotransmitters from the synapse?

Reuptake Signup and view all the answers

Which neurotransmitter is linked to the mood regulation and organ function?

Norepinephrine Signup and view all the answers

Selective serotonin reuptake inhibitors (SSRIs) are primarily used to treat which conditions?

Anxiety and depression Signup and view all the answers

What type of neurons release glutamate?

Glutamatergic neurons Signup and view all the answers

What is the primary function of the sodium/potassium pump in neurons?

To create a concentration gradient of ions. Signup and view all the answers

What is the resting membrane potential of a neuron?

-70 mV Signup and view all the answers

What is the primary role of the sodium-potassium pump in neurons?

To maintain the resting membrane potential Signup and view all the answers

Which ions are primarily involved in generating action potentials in neurons?

Sodium and potassium Signup and view all the answers

What triggers the opening of ligand-gated channels?

Binding of a specific molecule Signup and view all the answers

Where do graded potentials primarily occur in a neuron?

Along dendrites and the cell body Signup and view all the answers

How does the ionic movement contribute to the action potential in neurons?

It allows sodium to enter the neuron, reversing the charge. Signup and view all the answers

What occurs during hyperpolarization of a neuron?

An exit of potassium ions from the cell Signup and view all the answers

What occurs to the membrane potential when a neuron is depolarized?

The charge difference decreases. Signup and view all the answers

What causes repolarization in a neuron after depolarization?

Exit of potassium ions Signup and view all the answers

What is meant by the term 'polarized membrane' in relation to neurons?

The interior of the neuron is more negative compared to the exterior. Signup and view all the answers

What is a characteristic of graded potentials?

They vary in size based on the strength of the stimulus Signup and view all the answers

What triggers the release of neurotransmitters in neurons?

The generation of action potentials. Signup and view all the answers

Which of the following channels opens in response to mechanical pressure?

Mechanically-gated channels Signup and view all the answers

What role do negatively charged proteins play inside the neuron?

They help establish resting membrane potential. Signup and view all the answers

What are the types of membrane ion channels mentioned?

Ligand-gated and mechanically-gated channels Signup and view all the answers

What is the threshold voltage that must be reached to generate an action potential?

-55 mV Signup and view all the answers

Which ions are primarily involved in the depolarization of the neuron during an action potential?

Sodium and potassium Signup and view all the answers

What happens during the absolute refractory period?

No action potential can be generated Signup and view all the answers

How does the sodium-potassium pump affect membrane potential after an action potential?

It restores resting membrane potential Signup and view all the answers

What is the nature of propagation of an action potential down a myelinated axon?

Saltatory conduction Signup and view all the answers

What must the membrane potential be to allow a second action potential to occur during the relative refractory period?

It must be at least -55 mV Signup and view all the answers

What is primarily responsible for the rapid entry of sodium ions into neurons when the threshold is reached?

Sodium voltage-gated channels Signup and view all the answers

What role does excess potassium play during the generation of action potentials?

It exits, causing hyperpolarization Signup and view all the answers

Study Notes

Nervous Tissue

Nervous tissue is composed of two types of cells: neurons and glial cells.
Neurons are responsible for communication within the nervous system.
Glial cells provide structure and support to neurons, but cannot communicate.

Neuron Anatomy

Cell Body houses organelles such as the nucleus, nucleolus, ribosomes, and endoplasmic reticulum.
Dendrites receive signals from other neurons.
Axon begins at the axon hillock and sends signals to other neurons.

Nervous Systems

The Central Nervous System (CNS) includes the brain and spinal cord, which are housed within the cranial cavity and vertebral cavity.
The Peripheral Nervous System (PNS) comprises the nerves outside the brain and spinal cord, lacking bony protection.

Communication within the Nervous System

Communication depends on electrical signaling which occurs due to the movement of ions.
Ion movements generate action potentials, leading to the release of neurotransmitters.

Membrane Potentials

The cell membrane acts as a barrier to ionic movement.
This difference in charge is called the resting membrane potential
Resting membrane potential of a neuron is -70 mV.

Maintaining Resting Membrane Potential

Sodium-Potassium Pump: pumps 3 sodium ions out of the cell and 2 potassium ions into the cell, creating a relatively negative internal environment.
Unequal Distribution of Ions: Sodium ions are more concentrated outside the cell, while potassium ions are more concentrated inside the cell.
Leak Channels: Potassium ions exit the cell through leak channels, further contributing to the negative charge inside the cell.

Changes in Resting Membrane Potential

Depolarization: The charge difference decreases, making the interior of the cell less negative.
Hyperpolarization: The charge difference increases, making the interior of the cell more negative.
Repolarization: A return to a polarized state after depolarization occurs.

Membrane Channels

Ligand-Gated Channels: Open and close due to the binding of a molecule (ligand).
Mechanically-Gated Channels: Open and close in response to pressure or distortions in cell membranes.

Graded Potentials

Small changes in the resting membrane potential that vary in size.
Caused by mechanically-gated and ligand-gated membrane channels.
Occur along dendrites and the cell body.
May hyperpolarize when excess potassium exits.
Sodium-Potassium pumps restore the membrane potential back to -70mV.

Action Potentials

Occur when a threshold of -55mV is reached.
Triggered by opening voltage-gated sodium and potassium channels.
Sodium ions rapidly enter the neuron, depolarizing it.
Potassium ions exit the neuron, repolarizing it.

Refractory Period

Occurs after an action potential is generated.
Absolute Refractory Period: No new action potential can be generated.
Relative Refractory Period: A new action potential can be generated only with a stronger stimulus.

Propagation of an Action Potential

Action potential travels down the axon in a sequence.
Sodium ions enter one section of the axon, depolarizing it, and triggering the depolarization of the next section.

Myelinated Axons

Myelinated axons are wrapped in a myelin sheath, which speeds up the conduction of action potentials.
This is called saltatory conduction.

Neurotransmitters

Chemicals that relay messages from neurons.
Examples include:
- Glutamate: Learning and memory
- GABA: Principal inhibitory neurotransmitter
- Glycine: Spinal cord
- Dopamine: Reward system
- Norepinephrine: Mood and regulation of organ function
- Epinephrine: Adrenaline
Neurotransmitters have specific receptors on the postsynaptic neuron.
They are eliminated from the synapse via reuptake.

Serotonin

Serotonin reuptake inhibitors (SSRIs) are used to treat anxiety and depression.
SSRIs block the reuptake of serotonin, increasing its concentration in the synapse.

Studying That Suits You

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

Description

This quiz explores the structure and function of nervous tissue, focusing on neurons and glial cells. It covers neuron anatomy, including the cell body, dendrites, and axon, and distinguishes between the central and peripheral nervous systems. Test your knowledge of how communication within the nervous system occurs through electrical signaling.