Nervous Tissue Characteristics Flashcards

Questions and Answers

Which of the following is NOT a characteristic of nervous tissue?

Extensive integrated communication network

Contains a large extracellular matrix (correct)

Derived from neural ectoderm

Cells chemically linked to form circuits

What embryonic layer gives rise to nervous tissue?

Ectoderm

Which of the following is NOT a function of nervous tissue?

Senses changes in environment

Stores nutrients (correct)

Transmits stimuli

Generates behavior patterns

What are the three categories of neurons?

Motor, sensory, interneurons Signup and view all the answers

What characteristics do neurons have?

Irritable and conductive Signup and view all the answers

Name three components in the cell body of a nerve cell.

Prominent nucleolus, abundant rough endoplasmic reticulum, polyribosomes Signup and view all the answers

The diameter of an axon can change.

False Signup and view all the answers

In which direction do action potentials travel?

Away from the cell body Signup and view all the answers

How many axons and dendrites does a typical neuron have?

1 axon, variable number of dendrites Signup and view all the answers

What are conducted down dendrites toward the cell body of a neuron?

Graded potentials Signup and view all the answers

What is the function of bipolar neurons?

Special sensory Signup and view all the answers

Where are bipolar neurons located?

Cochlear and vestibular ganglia of inner ear, olfactory mucosa, retina of eye Signup and view all the answers

What is the function of pseudounipolar neurons?

General sensory Signup and view all the answers

Which of the following are considered general senses?

Pain Signup and view all the answers

The peripheral process of a pseudounipolar neuron conducts toward the which part?

Cell body Signup and view all the answers

The central process of a pseudounipolar neuron conducts toward what?

Central nervous system Signup and view all the answers

Where are the cell bodies of pseudounipolar neurons located?

Dorsal root ganglia Signup and view all the answers

What is the function of multipolar neurons?

Motor Signup and view all the answers

Where are multipolar neurons located?

Cerebrum, lateral/ventral horns of spinal cord, cerebellum Signup and view all the answers

Which type of neuron is the most numerous?

Multipolar motor neurons Signup and view all the answers

What are the contact points or effectors for synapses?

Other neurons Signup and view all the answers

What do synapses help maintain?

Unidirectional transmission of nerve impulse Signup and view all the answers

What are the two types of synapses, and which is more common?

Chemical (more common) and Electrical Signup and view all the answers

How are nerve impulses conducted by electrical synapses?

Gap junctions; direct flow of electrical current Signup and view all the answers

How are nerve impulses conducted by chemical synapses?

Release of neurotransmitters from synaptic vesicles Signup and view all the answers

What are the three sites of synapse on a neuron?

Dendrite, soma, axon Signup and view all the answers

Which cells support the central nervous system?

Glial cells Signup and view all the answers

Neuroglia are more numerous than neurons.

True Signup and view all the answers

Why are glial cells more likely to become cancerous than neurons?

Glial cells undergo mitosis, neurons don't (permanent G0 phase) Signup and view all the answers

What are the four types of glial cells?

Astrocytes, oligodendrocytes, microglia, ependymal cells Signup and view all the answers

Which glial cells are the most numerous?

Astrocytes Signup and view all the answers

What is the difference between fibrous and protoplasmic astrocytes in terms of processes?

Fibrous: few long processes; Protoplasmic: many short processes Signup and view all the answers

Where are fibrous astrocytes and protoplasmic astrocytes located?

Fibrous: white matter of CNS; Protoplasmic: grey matter of CNS Signup and view all the answers

What are the functions of astrocytes?

Help form blood-brain barrier Signup and view all the answers

Study Notes

Characteristics of Nervous Tissue

Originates from the neural ectoderm.
Comprised mostly of cells with minimal extracellular matrix.
Cells are chemically interconnected, forming complex circuits.
Functions as a vast, integrated communication network.
Contains excitable neurons capable of conducting stimuli.

Embryonic Origin

Nervous tissue is derived from the ectoderm layer.

Functions of Nervous Tissue

Detects environmental changes.
Transmits stimuli to effectors for responses.
Stabilizes internal conditions or produces behavioral patterns.

Types of Neurons

Motor Neurons: Transmit impulses from the central nervous system (CNS) to effectors.
Sensory Neurons: Carry signals from sensory receptors to the CNS.
Interneurons: Facilitate communication between different neurons.

Characteristics of Neurons

Neurons are irritable, conductive, and post-mitotic (do not divide).

Components of Nerve Cell Body

Prominent nucleolus indicates active synthesis.
Rich in rough endoplasmic reticulum for protein production.
Contains polyribosomes, known as Nissl substance, for ribonucleic acid synthesis.

Axon Characteristics

The diameter of an axon remains constant and does not change.
Action potentials travel away from the neuron’s cell body.

Neuron Structure

Each neuron has one axon and a variable number of dendrites (pseudounipolar, bipolar, multipolar).
Graded potentials are conducted down dendrites toward the cell body.

Bipolar Neurons

Serve special sensory functions.
Found in the cochlear and vestibular ganglia, olfactory mucosa, and retina.

Pseudounipolar Neurons

Function in general sensory processing.
Convey signals related to pain, temperature, touch, and proprioception.
Peripheral process leads to the cell body, while the central process carries signals to the CNS.

Multipolar Neurons

Primarily involved in motor functions.
Located in key brain regions such as the cerebrum, spinal cord (lateral/ventral horns), and cerebellum.

Neuron Distribution

Multipolar motor neurons are the most abundant type.

Synapses and Impulse Transmission

Synapses contact muscles, glands, and other neurons.
They ensure unidirectional transmission of nerve impulses.

Types of Synapses

Electrical Synapses: Utilize gap junctions for direct electrical current flow.
Chemical Synapses: More common, rely on neurotransmitter release from synaptic vesicles.

Synapse Sites on Neuron

Dendrite (axodendritic), soma (axosomatic), axon (axoaxonic) as potential connection sites.

Supporting Cells in CNS

Neuroglia (glial cells) are present in greater numbers than neurons.
Glial cells are prone to cancer due to their ability to undergo mitosis, unlike neurons.

Types and Functions of Glial Cells

Astrocytes: Most numerous, support neuron function, maintain the microenvironment, and help form the blood-brain barrier.
Oligodendrocytes: Provide insulation to axons in the CNS.
Microglia: Act as immune defenders in the CNS.
Ependymal Cells: Line the cavities of the CNS and help circulate cerebrospinal fluid.

Astrocyte Characteristics

Fibrous astrocytes: Fewer long processes and located in white matter of the CNS.
Protoplasmic astrocytes: Numerous short processes found in gray matter of the CNS.

Functions of Astrocytes

Anchor neurons to capillaries.
Maintain environment around neurons.
Form scar tissue in damaged areas.
Contribute to the blood-brain barrier’s integrity.

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Description

Test your knowledge on the characteristics and origins of nervous tissue with these flashcards. Learn about its cellular structure, communication networks, and embryonic development. Perfect for students studying biology or anatomy.