Nervous Tissue and Cells Flashcards by Dalton Ridley

Structural Divisions of Nervous System

Central nervous
system (CNS): Brain and spinal cord.

Peripheral nervous
system (PNS): Cranial, spinal, and peripheral nerves
conducting impulses.
Ganglia (small aggregates of nerve cells outside the
CNS).

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Functional Divisions of Nervous System

Sensory division (afferent) 
Motor division (efferent)

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Sensory division (afferent)

Somatic – Sensory input perceived consciously (e.g.,
from eyes, ears, skin, musculoskeletal structures).

Visceral – Sensory input not perceived consciously

(e. g., from internal organs and cardiovascular
structures) .

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Motor division (efferent)

Somatic – Motor output controlled consciously or
voluntarily (e.g., by skeletal muscle effectors).

Autonomic – Motor output not controlled consciously
(e.g., by heart or gland effectors).

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Nervous system cell types

Cells in both central and peripheral nerve
tissue are of two kinds:

Neurons, which typically have numerous long
processes.

Glial cells which have short processes, support
and protect neurons, and participate in many
neural activities, neural nutrition, and defense of
cells in the CNS.

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Neuron functions

Maintain ionic gradient, also called electrical potential, across cell membrane

React promptly to stimuli with a reversal of the ionic gradient (membrane depolarization)

The functional units of the PNS and CNS

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Neurotransmitters

Small molecules of a number of different types.

Released by exocytosis from terminal bouton

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Neuron parts

(1) The cell body (= perikaryon or soma) is often large, with a large, nucleus and well-developed nucleolus.
(2) Numerous short dendrites receiving input from other neurons.

(3) A long axon carries impulses from the
cell body and is covered by a myelin sheath composed of other cells.

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Axons

Most neurons have only one axon, typically longer than its dendrites.

The plasma membrane of the axon is the axolemma and its contents are the axoplasm.

Axons originate from a pyramid-shaped region of the perikaryon called the axon hillock

Each small axonal branch ends with a dilation called a terminal bouton

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Types of Neurons

Multipolar, Bipolar, Unipolar, Anaxonic

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Multipolar

A type of neuron with one axon and two or more dendrites, are the most common.

All motor neurons and CNS interneurons are multipolar

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Bipolar

A type of neuron that has one dendrite and one axon, comprise the sensory neurons of the retina, the olfactory epithelium, and
the inner ear.

One dendrite and one axon entering nerve cell body

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Unipolar

A type of neuron which include all other sensory neurons, each have a single process that bifurcates close to the perikaryon, with the longer branch
extending to a peripheral ending and the other toward the CNS.

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Anaxonic

A type of neuron that has many dendrites but no true axon, do not produce action potentials (they are non-spiking), but regulate electrical changes of adjacent CNS neurons. Found in the brain and retina.

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Interneurons

Connect sensory and motor neurons to each other, forming complex
functional networks or circuits in the CNS.
Interneurons make up 99% of all neurons in adults.

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Gray matter

Most neuronal cell bodies occur in this

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White matter

Most axons concentrated in this

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Synapses

Sites where nerve impulses are transmitted from
one neuron to another, or from neurons and other effector cells.

The structure of a synapse ensures that transmission is
unidirectional.

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Anesthetics

Most local anesthetics are low-molecular-weight
molecules that bind to the voltage-gated sodium channels, interfering with sodium ion influx and, consequently, inhibiting the action potential responsible for the nerve impulse.

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Common neurotransmitters

Acetylcholine

Amino acids: Glutamate, Gamma-aminobutyric acid (GABA)

Monoamines: Serotonin or 5-hydroxytryptamine (5-HT), Dopamine, Norepinephrine, Epinephrine (adrenaline)

Neuropeptides: Cholecystokinin (CCK), Beta-endorphin

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Actylcholine

A type of neurotransmitter that binds to ACh receptors in PNS to open ion channels in postsynaptic membrane and stimulate muscle contraction

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Serotonin or 5-hydroxytryptamine (5-HT)

Has various functions in the brain related to sleep, appetite, cognition (learning, memory), and mood; modulates actions of other neurotransmitters

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Dopamine

important roles in cognition (learning, memory), motivation, behavior, and mood

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Norepinephrine (noradrenaline)

Neurotransmitter in PNS and specific CNS regions

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Epinephrine (adrenaline)

Has various effects in the CNS

Cholecystokinin (CCK)

Stimulates neurons in the brain to help mediate satiation and repress hunger

Beta-endorphin

Prevents release of pain signals from neurons and fosters a feeling of well-being

Glial Cells

Support neuronal survival and activities, and are 10x more abundant than neurons in the mammalian brain. Like neurons, most glial cells develop from the embryonic neural plate.

Neuropil

Any area in the nervous system composed of mostly unmyelinated axons, dendrites and glial cell processes that form a synaptically dense region containing a relatively low number of cell bodies. The most prevalent anatomical region of neuropil is the brain.

Different Neuroglial (Glial) Cells

Oligodendrocytes, Astrocytes, Ependymal Cells, Microglia, Schwann Cells, Satellite cells (of ganglia)

Oligodendrocytes

Origin: Neural Tube Location: CNS Functions: Myelin production, electric insulation

Astrocytes

Most abundant glial cells of the CNS Origin: Neural Tube Location: CNS Functions: Structural and metabolic support of neurons, especially at synapses; repair processes

Ependymal Cells

Origin: Neural Tube Location: Lining of brain ventricles and central canal of CNS Functions: Aid in production and movement of CSF

Microglia

Origin: Bone Marrow (monocytes) Location: CNS Functions: Defense and Immune-related activities

Schwann Cells

Origin: Neural Crest Location: Peripheral nerves Functions: Myelin production, electrical insulation

Satellite cells (of ganglia)

Origin: Neural Crest Location: Peripheral nerves Functions: Structural and metabolic support for neuronal cell bodies Insulate, nourish, and regulate the microenvironments of neurons in PNS

Which neurotransmitter is used at neuromuscular junctions?

Acetylcholine

The Central Nervous System (CNS) has the following type(s) of nerve fibers:

Both sensory and motor

Neural plasticity, which occurs during embryonic brain development and underlies adaptation, learning, and memory postnatally, depends critically on changes in

Dendritic spines

The possible effect(s) of a neurotransmitter on the postsynaptic membrane is to

Either depolarize or hyperpolarize, depending on the type of synapse.

Are glial cells excitable?

Somatic sensory nerve fibers receive information from

Skeletal muscle

Glial cells with myelin sheathes, found in the CNS

Oligodendrocytes

Cells whose processes are reinforced by glial fibrillary acid protein

Astrocytes

The most numerous type of glial cell in the brain

Astrocytes

Function as part of the blood-brain barrier

Astrocytes

These cells line the ventricles of the brain

Ependymal cells

Facilitate movement of CSF

Ependymal cells

These cells migrate and remove damaged synapses

Microglia

The only glial cell derived from blood cells.

Microglia

Produce myelin sheathes in the PNS

Schwann cells

Cells that support or nourish the neurons of ganglia

Satellite cells

What is an example of a low-molecular-weight molecule that bind to the voltage-gated sodium channels of the nerve cell membrane and inhibit the action potential that produces the nerve impulse.

Local anesthetics

The voltage difference between the exterior and interior of the cell, across the cell membrane is called the membrane potential. In certain types of cells, the voltage fluctuations frequently take the form of a rapid upward spike followed by a rapid fall. This fluctuation is called the

Action potential, Depolarization wave, Nerve impulse

Which functional part of the nervous system transmits impulses from the CNS to muscles and glands?

Motor

The Peripheral Nervous System (PNS) has which type(s) of nerve fibers?

Sensory and motor fibers

Which type of fibers innervates skeletal muscle, causing muscles to contract?

Somatic Motor

\_\_\_\_\_\_\_\_ are sites where action potentials are transmitted from one neuron to another.

Synapses

The visceral sensory fibers of the nervous system receive information from the

Esophagus, stomach, intestines

Somatic Sensory nervous system

Receives sensory information from skin, fascia, joints, skeletal muscles, and special senses

Visceral Sensory nervous system

Receives sensory information from viscera (intestines)

Somatic Motor nervous system

Transmits information to skeletal muscles. "Voluntary" nervous system: innervates skeletal muscles

Autonomic Motor nervous system

Transmits information to cardiac muscle, smooth muscle, glands "Involuntary" nervous system: innervates cardiac muscle, smooth muscle, glands

# Reversed prompt Central nervous system (CNS): Brain and spinal cord. Peripheral nervous system (PNS): Cranial, spinal, and peripheral nerves conducting impulses. Ganglia (small aggregates of nerve cells outside the CNS).

Structural Divisions of Nervous System

# Reversed prompt ``` Sensory division (afferent) Motor division (efferent) ```

Functional Divisions of Nervous System

# Reversed prompt Somatic – Sensory input perceived consciously (e.g., from eyes, ears, skin, musculoskeletal structures). Visceral – Sensory input not perceived consciously (e. g., from internal organs and cardiovascular structures) .

Sensory division (afferent)

# Reversed prompt Somatic – Motor output controlled consciously or voluntarily (e.g., by skeletal muscle effectors). Autonomic – Motor output not controlled consciously (e.g., by heart or gland effectors).

Motor division (efferent)

# Reversed prompt Cells in both central and peripheral nerve tissue are of two kinds: Neurons, which typically have numerous long processes. Glial cells which have short processes, support and protect neurons, and participate in many neural activities, neural nutrition, and defense of cells in the CNS.

Nervous system cell types

# Reversed prompt Maintain ionic gradient, also called electrical potential, across cell membrane React promptly to stimuli with a reversal of the ionic gradient (membrane depolarization) The functional units of the PNS and CNS

Neuron functions

# Reversed prompt Small molecules of a number of different types. Released by exocytosis from terminal bouton

Neurotransmitters

# Reversed prompt (1) The cell body (= perikaryon or soma) is often large, with a large, nucleus and well-developed nucleolus. (2) Numerous short dendrites receiving input from other neurons. (3) A long axon carries impulses from the cell body and is covered by a myelin sheath composed of other cells.

Neuron parts

# Reversed prompt Most neurons have only one axon, typically longer than its dendrites. The plasma membrane of the axon is the axolemma and its contents are the axoplasm. Axons originate from a pyramid-shaped region of the perikaryon called the axon hillock Each small axonal branch ends with a dilation called a terminal bouton

Axons

# Reversed prompt Multipolar, Bipolar, Unipolar, Anaxonic

Types of Neurons

# Reversed prompt A type of neuron with one axon and two or more dendrites, are the most common. All motor neurons and CNS interneurons are multipolar

Multipolar

# Reversed prompt A type of neuron that has one dendrite and one axon, comprise the sensory neurons of the retina, the olfactory epithelium, and the inner ear. One dendrite and one axon entering nerve cell body

Bipolar

# Reversed prompt A type of neuron which include all other sensory neurons, each have a single process that bifurcates close to the perikaryon, with the longer branch extending to a peripheral ending and the other toward the CNS.

Unipolar

# Reversed prompt A type of neuron that has many dendrites but no true axon, do not produce action potentials (they are non-spiking), but regulate electrical changes of adjacent CNS neurons. Found in the brain and retina.

Anaxonic

# Reversed prompt Connect sensory and motor neurons to each other, forming complex functional networks or circuits in the CNS. Interneurons make up 99% of all neurons in adults.

Interneurons

# Reversed prompt Most neuronal cell bodies occur in this

Gray matter

# Reversed prompt Most axons concentrated in this

White matter

# Reversed prompt Sites where nerve impulses are transmitted from one neuron to another, or from neurons and other effector cells. The structure of a synapse ensures that transmission is unidirectional.

Synapses

# Reversed prompt Most local anesthetics are low-molecular-weight molecules that bind to the voltage-gated sodium channels, interfering with sodium ion influx and, consequently, inhibiting the action potential responsible for the nerve impulse.

Anesthetics

# Reversed prompt Acetylcholine Amino acids: Glutamate, Gamma-aminobutyric acid (GABA) Monoamines: Serotonin or 5-hydroxytryptamine (5-HT), Dopamine, Norepinephrine, Epinephrine (adrenaline) Neuropeptides: Cholecystokinin (CCK), Beta-endorphin

Common neurotransmitters

# Reversed prompt A type of neurotransmitter that binds to ACh receptors in PNS to open ion channels in postsynaptic membrane and stimulate muscle contraction

Actylcholine

# Reversed prompt Has various functions in the brain related to sleep, appetite, cognition (learning, memory), and mood; modulates actions of other neurotransmitters

Serotonin or 5-hydroxytryptamine (5-HT)

# Reversed prompt important roles in cognition (learning, memory), motivation, behavior, and mood

Dopamine

# Reversed prompt Neurotransmitter in PNS and specific CNS regions

Norepinephrine (noradrenaline)

# Reversed prompt Has various effects in the CNS

Epinephrine (adrenaline)

# Reversed prompt Stimulates neurons in the brain to help mediate satiation and repress hunger

Cholecystokinin (CCK)

# Reversed prompt Prevents release of pain signals from neurons and fosters a feeling of well-being

Beta-endorphin

# Reversed prompt Support neuronal survival and activities, and are 10x more abundant than neurons in the mammalian brain. Like neurons, most glial cells develop from the embryonic neural plate.

Glial Cells

# Reversed prompt Any area in the nervous system composed of mostly unmyelinated axons, dendrites and glial cell processes that form a synaptically dense region containing a relatively low number of cell bodies. The most prevalent anatomical region of neuropil is the brain.

Neuropil

# Reversed prompt Oligodendrocytes, Astrocytes, Ependymal Cells, Microglia, Schwann Cells, Satellite cells (of ganglia)

Different Neuroglial (Glial) Cells

# Reversed prompt Origin: Neural Tube Location: CNS Functions: Myelin production, electric insulation

Oligodendrocytes

# Reversed prompt Most abundant glial cells of the CNS Origin: Neural Tube Location: CNS Functions: Structural and metabolic support of neurons, especially at synapses; repair processes

Astrocytes

# Reversed prompt Origin: Neural Tube Location: Lining of brain ventricles and central canal of CNS Functions: Aid in production and movement of CSF

Ependymal Cells

# Reversed prompt Origin: Bone Marrow (monocytes) Location: CNS Functions: Defense and Immune-related activities

Microglia

# Reversed prompt Origin: Neural Crest Location: Peripheral nerves Functions: Myelin production, electrical insulation

Schwann Cells

# Reversed prompt Origin: Neural Crest Location: Peripheral nerves Functions: Structural and metabolic support for neuronal cell bodies Insulate, nourish, and regulate the microenvironments of neurons in PNS

Satellite cells (of ganglia)

# Reversed prompt Receives sensory information from skin, fascia, joints, skeletal muscles, and special senses

Somatic Sensory nervous system

# Reversed prompt Receives sensory information from viscera (intestines)

Visceral Sensory nervous system

# Reversed prompt Transmits information to skeletal muscles. "Voluntary" nervous system: innervates skeletal muscles

Somatic Motor nervous system

# Reversed prompt Transmits information to cardiac muscle, smooth muscle, glands "Involuntary" nervous system: innervates cardiac muscle, smooth muscle, glands

Autonomic Motor nervous system