Nervous Tissue and Cells Flashcards
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).
Functional Divisions of Nervous System
Sensory division (afferent) Motor division (efferent)
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) .
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).
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.
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
Neurotransmitters
Small molecules of a number of different types.
Released by exocytosis from terminal bouton
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.
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
Types of Neurons
Multipolar, Bipolar, Unipolar, Anaxonic
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
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
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.
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.
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.
Gray matter
Most neuronal cell bodies occur in this
White matter
Most axons concentrated in this
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.
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.
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
Actylcholine
A type of neurotransmitter that binds to ACh receptors in PNS to open ion channels in postsynaptic membrane and stimulate muscle contraction
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
Dopamine
important roles in cognition (learning, memory), motivation, behavior, and mood
Norepinephrine (noradrenaline)
Neurotransmitter in PNS and specific CNS regions
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?
No
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