Neurons Classification Quiz

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Questions and Answers

What type of fibers secrete acetylcholine?

Adrenergic fibers

Postganglionic fibers

Cholinergic fibers (correct)

Preganglionic fibers

Which enzyme is responsible for the destruction of acetylcholine after its secretion?

Norepinephrine oxidase

Acetylcholinesterase (correct)

Choline acetyltransferase

Catechol-O-methyltransferase

Where does the synthesis of norepinephrine begin?

In the synaptic cleft

In the mitochondria of nerve endings

In the axoplasm of terminal nerve endings (correct)

In the secretory vesicles

How long does acetylcholine persist in the tissue after being secreted?

A few seconds Signup and view all the answers

What are the fibers that secrete norepinephrine called?

Adrenergic fibers Signup and view all the answers

What type of neuron is primarily found in the retina, olfactory mucosa, and cochlear and vestibular ganglia?

Bipolar neurons Signup and view all the answers

Which of the following correctly describes the primary function of sensory neurons?

Receive stimuli from receptors Signup and view all the answers

What structure of a neuron is responsible for sending impulses to effector organs?

Axon Signup and view all the answers

Which type of motor nerves is under voluntary control?

Somatic motor nerves Signup and view all the answers

What is the primary purpose of transmitter vesicles in the presynaptic terminal?

Contain neurotransmitters Signup and view all the answers

What separates the presynaptic terminal from the postsynaptic neuron?

Synaptic cleft Signup and view all the answers

Which type of neuron is typically associated with nerve fibers found in the spinal ganglia?

Pseudounipolar neurons Signup and view all the answers

What is a major part of the typical anterior motor neuron?

Soma Signup and view all the answers

What is the origin of the secretory cells in the adrenal medullae?

Derived from nervous tissue Signup and view all the answers

Which cranial nerves are primarily involved in the parasympathetic nervous system?

III, VII, IX, X Signup and view all the answers

Where are the postganglionic neurons of the parasympathetic nervous system typically located?

In the wall of the organ being controlled Signup and view all the answers

What percentage of parasympathetic nerve fibers are found in the vagus nerves?

75 percent Signup and view all the answers

What type of neurons do preganglionic sympathetic fibers connect with in the adrenal medullae?

Postganglionic neurons Signup and view all the answers

Which of the following organs is NOT primarily supplied by the vagus nerve?

Kidneys Signup and view all the answers

What happens to preganglionic fibers in the parasympathetic nervous system before reaching their target organs?

They do not synapse, but travel directly to the organ Signup and view all the answers

Which structure does NOT have a connection to the parasympathetic nervous system?

Adrenal glands Signup and view all the answers

What percentage of norepinephrine is typically transformed into epinephrine in the adrenal medulla?

80 percent Signup and view all the answers

Which process accounts for the removal of 50 to 80 percent of secreted norepinephrine?

Reuptake into adrenergic nerve endings Signup and view all the answers

What is the primary mechanism of action for muscarinic receptors?

G protein signaling Signup and view all the answers

How long does norepinephrine generally remain active in tissues?

A few seconds Signup and view all the answers

What are nicotinic receptors primarily classified as?

Ligand-gated ion channels Signup and view all the answers

Which enzyme is NOT involved in the destruction of norepinephrine?

Dipeptidyl peptidase Signup and view all the answers

What type of receptors does muscarine specifically activate?

Muscarinic receptors Signup and view all the answers

Which of the following statements about acetylcholine is incorrect?

Muscarinic receptors are ligand-gated ion channels. Signup and view all the answers

Which two major classes of adrenergic receptors are identified?

Alpha and beta receptors Signup and view all the answers

What percentage of secretion from the adrenal medulla is epinephrine on average?

80% Signup and view all the answers

Which receptor type does norepinephrine primarily excite?

Alpha receptors Signup and view all the answers

What occurs during a mass discharge of the sympathetic nervous system?

Enhanced ability to perform vigorous muscle activity Signup and view all the answers

What is the result of stimulating the adrenal medullae?

Release of epinephrine and norepinephrine into the blood Signup and view all the answers

Which type of tone reflects the ongoing activity of the sympathetic nervous system?

Sympathetic tone Signup and view all the answers

Which of the following is a characteristic of the hormones epinephrine and norepinephrine once released into circulation?

Their effects may last 2 to 4 minutes Signup and view all the answers

What is the primary role of the sympathetic and parasympathetic systems in the body?

They manage the balance between increase and decrease of activity in organs Signup and view all the answers

Study Notes

Neuron Classification

Neurons are classified by the number of processes extending from the cell body.
Most neurons are multipolar; they have multiple dendrites and one axon.
Bipolar neurons are located in the retina, olfactory mucosa, and inner ear, involved in the senses of sight, smell, and balance.
Pseudounipolar neurons are found in spinal ganglia and most cranial ganglia.
Sensory neurons (afferent) receive stimuli from body receptors.
Motor neurons (efferent) transmit impulses to effector organs, such as muscles and glands.

Functional Subdivisions of Nervous Components

Somatic motor nerves are voluntary and innervate skeletal muscles.
Autonomic motor nerves control involuntary functions including glands, cardiac muscle, and smooth muscle.
Interneurons connect other neurons, forming complex circuits in the CNS and retina.

Structure of Motor Neuron

Composed of three major parts:
- Soma: main body of the neuron.
- Axon: extends from soma into peripheral nerves, transmitting impulses.
- Dendrites: numerous branching projections extending from the soma.

Chemical Synapse Structure

The presynaptic terminal connects to the postsynaptic neuron via a synaptic cleft (200-300 angstroms wide).
Contains transmitter vesicles with neurotransmitters and mitochondria for energy.

Sympathetic Nerve Endings and Hormones

Preganglionic sympathetic fibers reach adrenal medullae without synapsing.
They end on modified neuronal cells that secrete epinephrine and norepinephrine into the bloodstream.
Secretory cells are derived from nervous tissue and have remnants of nerve fibers.

Parasympathetic Nervous System

Parasympathetic fibers exit through cranial nerves III, VII, IX, and X, and some sacral spinal nerves.
Vagus nerve (cranial nerve X) contains about 75% of parasympathetic fibers. It innervates major organs in the thoracic and abdominal regions.
Has both preganglionic and postganglionic neurons, with postganglionic neurons located within the walls of the organs they control.

Neurotransmitter Functions

Cholinergic fibers secrete acetylcholine, while adrenergic fibers secrete norepinephrine.
Acetylcholine synthesized in nerve endings and has a brief action time, broken down by acetylcholinesterase.
Norepinephrine synthesis starts in nerve endings; 80% converted to epinephrine in adrenal medulla.

Acetylcholine Receptor Types

Muscarinic receptors: use G proteins, located on effector cells of the parasympathetic and sympathetic systems.
Nicotinic receptors: ligand-gated ion channels at synapses between preganglionic and postganglionic neurons.

Adrenergic Receptors

Divided into alpha and beta receptors.
Norepinephrine predominantly excites alpha receptors while epinephrine activates both types equally.

Sympathetic and Parasympathetic Stimulation

Sympathetic stimulation can lead to excitation or inhibition depending on the organ.
Adrenal medullae release hormones which amplify sympathetic effects and prolong actions for 2-4 minutes.

Nervous System Tone

The sympathetic and parasympathetic systems maintain a baseline activity level known as tone.
Tone allows for fine control in increasing or decreasing organ activity as needed.

Alarm or Stress Response

Mass discharge of the sympathetic nervous system enhances the body’s ability for vigorous physical activity during stressful situations.

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Description

Test your knowledge on the classification of neurons based on their processes. This quiz covers multipolar, bipolar, and pseudounipolar neurons along with their locations and functions in the body. Perfect for students studying neuroanatomy or neuroscience.