Nervous tissue: quilt Flashcards
Euchromatin
lightly packed DNA
-often but not always under active transcription
Heterochromatin
darker staining
-dense DNA found in the nucleus of cells
T or F: Neuron nuclei can contain multiple nucleolus.
True
Nissl Substance
RER cisternae + free ribosomes in alternating pattern
Do Nissl substances stain acidophilic or basophilic?
Basophilic
Lipofuscin
product of lysosomes, brown pigment of undigested material that typically increases with age
T or F: The axon hillock contains Nissl substance.
false
Neurotubules
microtubules located in the neuron
T or F: Golgi can be extremely large in the cell body of neurons.
true
Neurofibrils
Clusters of neurofilaments
Neurofilaments
neuron-specific intermediate filaments
Actin
Microfilament commonly seen in the neural cell body
Two other names for a neuron cell body
perikaryon and soma
T or F: Neurons can divide
False
T or F: Since neurons can’t divide, the cellular components are also never regenerated.
False
Synapse
Pre-Synaptic terminal + Synaptic Cleft + Post-synaptic terminal
End Bulb
another name for terminal end of axon
Synaptic Vesicles
located at the axon terminal
-contain neurotransmitters
Dendrites
part of neuron that is involved in receptor processes
-receives stimuli from other neurons or extracellular environment
T or F: Dendrites are tapered because their diameter decreases as you leave the cell body and branch
True
T or F: Dendrites are almost Never myelinated
True
Dendrites branch off at __ angles.
acute
T or F: Golgi cannot extend into the dendrites
False
T or F: Dendrites contain ribosomes
True
T or F: MT in the dendrites have no particular arrangement
False
How are MT in the dendrites arranged?
evenly spaced
In what way do dendrites function (input)?
dimmer switch
What is an example of a location in the body where neurons do not contain axons?
retina
T or F: Axons maintain a constant diameter
true
Which have a larger diameter, dendrites or axons?
dendrites
Which tends to branch more frequently, dendrites or axons?
dendrites
T or F: Axons can be myelinated.
true
Axons branch off at __ angles.
obtuse
How does the diameter of axon branches compare to the rest of the axon? (larger, smaller or same)
same
T or F: Axons never contain ribosomes
True
T or F: Axon neurofilaments and MT have an evenly spaced arrangement
False
The action potential of axons is ___
all or none
Can axons contain Nissl bodies or golgi?
no
How frequently do axons contain ribosomes?
never
Dendritic spines
mushroom-shaped structures connected to dendritic shaft
- involved in “Plastic” changes o the brain
- adaptation, learning, memory
What is the function of dendritic spines?
increase receptive area
on what order are dendritic spines present in the human cerebral cortex?
10^14
Hw many ribosomes are present in dendritic spines?
None
T or F: Dendritic spines are where most synapses impinging on neurons are made.
true
T or F: Dendritic spines are static structures.
false
T or F: SER and filamentous proteins extend into the dendritic spines.
true
Bipolar neuron
neuron type most often associated with receptors for special senses
T or F: Bipolar neurons are commonly found in the body.
false
Bipolar neurons contain _ axon and _ dendrite
1, 1
Which type of neurons are most common?
multipolar
Multipolar neurons
neurons containing more than 2 processes
Pseudounipolar neuron
Neuron type in which a T shape is formed
- neurons in which stimuli travel from dendrites directly to axon terminal w/out passing through cell body
- neuron type found in sensory neurons and ganglia (DRG)
- centrally located nucleus, single process, and round perikarya
Synapse
Sites of functional contact between neurons and other neurons or effector cells
-convert electrical impulse into a chemical sign via neurotransmitter
T orF: Neurotransmitter’s can be excitatory or inhibitory
True
What holds the pre and post synaptic terminals approximate in the synaptic cleft?
filamentous proteins
Neurotransmitters
Released into synaptic cleft and bind receptors on post-synaptic membrane
-responsible for unidirectional transmission of nerve impulses
dendrodendritic
classification of synapse between dendrites and other dendrites
axosomatic
classification of synapse located at the soma/cell body
axodendritic
classification of synapse on dendrite shaft or spine
Axoaxonic
Classification of synapse on axons
What percent of chemical synapses involve no reuptake of neurotransmitters?
20
T or F: 99.9% of synapses are chemical
true
What percent of chemical synapses involve the reuptake of neurotransmitter?
80%
T or F: Electrical synapses require neurotransmitters.
False
Acetylcholine (Ach) is an example of chemical ____ of neurotransmitter.
without reuptake
Epinephrine, serotonin and dopamine are examples of chemical synapses that ___ neurotransmitters.
reuptake
Cocaine inhibits the reuptake of what in the pleasure centers of the brain?
Dopamine and serotonin
What does electrical synapses use instead of neurotransmitters?
ions
Acetylcholine
very small synaptic vesicle that is clear on micrograph
norepinephrine
synaptic vesicle with small dot in center
inhibitory
synaptic vesicle with a tendency to fallen out
-contains GABA
Serotonin (5HT)
large synaptic vesicle with a very dense core
GABA
most abundant neurotransmitter in CNS
Glutamate
most abundant excitatory neurotransmitter in CNS
Neurotransmitters associated with pleasure centers of the brain?
dopamine and serotonin
Neurotransmitter involved in pain transmission?
substance P
non-directed synapses
synapses without distinct postsynaptic targets
What is the ratio of glia too neurons?
10:1
Glia (neuroglia)
cells that offer protection and support for neurons
T or F: there is a slow, constant turnover of glia
true
T or F: there is true connective tissue in the CNS
false
Astrocytes
- glia with a large morphological to function diversity
- have perivascular end feet covering blood vessels
- help create blood brain barrier (BBB)
- Most numerous glia cells
- cofine Neurotransmitters to the synaptic cleft
Fibrous
astrocyte subtype found in white matter
-contains few, long cellular processes
protoplasmic
astrocyte subtype found in gray matter
-contains many, short-branched processes
Bergmann glia
astrocyte unique to the cerebellum
T or F: GFAP and glutamate synthetase are common markers of astrocytes
True
astrocytomas
tumors of astrocyte cells
T or F: Astrocyte processes can extend up to 100 micrometers
True
Which type of glia are involved in the reaction to injury?
astrocytes
Oligodendrocytes
myelin producing cells of the CNS
oligodendrocytomas
tumors of oligodendrocytes
T or F: Oligodendrocytes produce myelin for only one axon
False
Schwann cells
myelin producing cells of the PNS
T or F: All axons in PNS have myelin about them.
true
microglia
glia with phagocytic properties
-associated with immune response/part of the immune system
what is the embryonic origin of microglia?
mesoderm
T or F: All glia originate from ectodermal tissue
false
What creates microglia?
blood monocytes
Microglia are normally found near ___.
blood vessels
Microglia can act as ___.
antigen presenting cells
T or F: Microglia are normally active so they can respond to injury or pathogen invasion quickly.
false
What do microglia release in order to attract T cells to nearby injury?
cytokines
What do microglia release in order to activate nearby microglia?
interferon gamma
ependymal
cuboidal/columnar epithelia glia cells that line the ventricles and central canal of the Brian and spinal cord
Which glia cell type is often ciliated to facilitate CSF movement?
ependymal
What is commonly used marker for ependymal glia?
vimentin
Which type of glia uses microvilli to sample/monitor CSF?
ependymal
The CSN contains which two structures?
brain and spinal cord
What makes white matter white?
myelin
T or F: white matter contains few to no neuron cell bodies
true
__ matter contains many myelinated axons and lots of glia.
white matter
T or F: The brain contains white matter outside and gray matter inside.
False
The inner structure of the spinal are composed of __ matter.
gray
Nucleus
collection of the neurons in CNS
ganglia
collection of neurons in PNS
Which contains more blood vessels? (white or gray matter)
gray
PNS
cell bodies and nerve process outside the brain and spinal cord
Gray matter
Network of cell bodies, unmyelinated axons and dendrites (AKA neuropil) and glia
Autonomic nervous system
Consists of the CNS and PNS
-related to control of smooth muscle, secretion and modulation of cardiac muscle
Sympathetic nervous system
fight or flight response of the autonomic nervous system
Parasympathetic nervous system
Mate and relate response of the autonomic system
Spinal nerve
location where Doral and ventral roots meet temporarily
T or F: sympathetic ganglia are usually located in the organ of innervation
False
T or F: Sympathetic ganglia are generally located near the spinal column.
true
Afferent
another name for the input units of the reflex arc
efferent
another name for the output units of the reflex arc
Sensory ganglia is found near the __.
Spinal column
Satellite cells
similar to Schwann cell but produce no myelin
T or F: Satellite cells form a distinct layer and uniformly surround neurons
True
T or F: Autonomic motor ganglia is an example of a primary motor neuron.
False
Do sympathetic ganglia live in the head?
no
Which typically has fewer neurons? (sympathetic or parasympathetic)
parasympathetic
Which contains multipolar neurons? (sympathetic or parasympathetic)
sympathetic
T or F: The brain and spinal cord are solid structures
false
T or F: Only the spinal cord is lined with ependymal cells, the Brian is not.
False
T or F: CSF is not produced by the ventricles itself
true
What structure within the ventricles produces CSF?
choroid plexus
choroid
made up of dilated, fenestrated (leaky) capillaries enveloped in invaginated folds of Pia mater
CSF
produced continually by choroid plexus
-circulated through ventricles, central canan, and subarachnoid space
Dura Mater
tough, relative thick sheet of dense connective tissue
-very rich in nerve endings
Arachnoid
delicate sheet of connective tissue coated beneath dura mater
Pia mater
very delicate and thin layer of connective tissue
-only layer directly adhered to brain or spinal cord
What is the subarachnoid space filled with?
CSF
Meningitis
Inflammation of the meninges (mostly arachnoid and pis)
Epineurium
fibrous coat of dense CT found in the PNS
Perineurium
flattened epithelial-like cells in PNS
- joined at edges via tight junctions
- analogous to arachnoid
endoneurium
thin layer of reticular fibers
-produced by Schwann cells in PNS
Nerve fascilicus
Bundle of axons in the PNS
Which CT covering in the PNS directly surround individual axons?
endoneurium
Which CT covering in the PNS surrounds and binds together many fascicles?
epineurium
T or F: Unmyelinated axons still have Schwann cells attached to them
true
Perineural epithelium
1-2 layers of CT in PNS consisting of squamous-like cells
Ependymal
cell type that lines hollow space in ventricles and central canal filled with CSF
T or F: Ependyma cells are not ciliated
False
Choroid cell
cuboidal epithelium cell that secretes CSF
-has cilia and microvilli
T or F: increasing the axon diameter increases the conduction time.
False
Which axons conduct signals faster? (myelinated or unmyelinated)
myelinated
Myelin
electrical insulator on some axons
T or F: Voltage reversal is inhibited by myelin at the Nodes of Ranvier
False
In myelinated axons, what is the term of how the voltage reversal jumps from node to node?
saltatory conduction
T or F: Voltage sensitive Na+ and K+ channels are located at the Nodes of Ranvier.
True
T or F: All axons have Nodes of Ranvier
False
The conduction velocity vs diameter graph for unmyelinated axons can be best described as ___
linear
T or F: In the PNS, all axons are surround by Schwann cells
True
PNS nerves that are surround by the body of Schwann cut have no myelin wrapping or Nodes of Ranvier are called what?
Unmyelinated
T or F: In myelinated PNS nerves, the Schwann cells cover multiple axons
False
How many axons does on Schwann cell cover in myelinated PNS nerves?
One (technically 1 segment of 1 axon)
Which type of PNS nerves have abutted together Schwann cells in order to form a continuous sheath?
unmyelinated
In the CNS, myelinated axons re surrounded by ____.
Oligodendrocytes
How many axons can on oligodendrocyte myelinated?
5-10
T or F: Unmyelinated axons in the CNS are still surrounded by oligodendrocytes.
false
What glia cell type can surround unmyelinated axons in the CNS?
astrocytes
Which glia type helps control the ionic and chemical environment in the CNS?
astrocytes
T or F: Astrocytes have a role in synaptic activity.
True
Astrocytes form the ___ barrier.
pia-glia barrier
Which endocytotic method does astrocytes use to remove excess neurotransmitters?
pinocytosis
What part of astrocytes regulate transport?
end feet
Which cell junction type links endothelial cells to form the anatomical BBB?
zonula occludens
T or F: The blood brain barrier does not contain a basement membrane
false
What surrounds the BBB?
astrocyte end feet
T or F: Lipid soluble molecules like O2, CO2, and EtOH cross the BBB easily.
True
Which endocytotic method transports macromolecules across the BBB?
Receptor mediated
Axoplasmic transport
movement of material in the neuron
Which pathway of axoplasmic transport is followed by toxins and viruses entering the CNS?
retrograde
Which axoplasmic transport method moves material away from the cell body?
anterograde
In which direction (anatomically speaking) does retrograde axoplasmic transport occur?
toward cell body
T or F: In retrograde axoplasmic transport, there is only a fast type, there is no slow movement.
True
What is the velocity of “fast” anterograde transport?
20-400 mm/day
What is the velocity of “slow” anterograde transport?
0.6-4mm/day
What does fast anterograde transport move?
organelles and molecules
What does slow anterograde transport move?
cytoskeletal and axolemma components
T or F: Anterograde axoplasmic transport involves kinesin.
true
T or F: Retrograde axoplasmic transport utilizes tubulin and actin
false
What MT associated protein does retrograde axoplasmic transport involve?
dynein
Which two cytoskeletal does slow anterograde transport involve?
tubulin and actin
Which pathway does Herpies and Rabies use to invade the CNS?
Retrograde
Can mammalian neurons divid?
no
How often do mammalian neurons divid?
never
T or F: In the case of injury, neurons can divide to regenerated nervosa system functions.
false
T or F: Nervous tissue regeneration represents a permanent loss.
true
T or F: Neuronal process are replaceable through growth and synthetic activity of the soma in a very narrow window of time.
true
What limits possible regrowth of nervous tissue in the CNS?
glial scarring
T or F: PNS fibers can regenerate if the soma isn’t destroyed and severed fibers are well approximated.
true
Chromatolysis
cellular adema and loss of Nissl substance
Secondary degeneration (wallerian)
anterograde degeneration (axon to myelin sheath) -degenerate and invaded by macrophages
What what rate does axonal sprouting (neurites) occur?
.5-3 mm/day
beta-amyloid plaques
aggregated misfolded proteins implicated in Alzheimer disease
Depression
a multifaceted disease with one component thought to involve the reuptake of serotonin and not epinephrine
T or F: SSRI’s and SNRI’s slow down the reuptake of serotonin in depressed individuals.
true
MAOI’s
an “Old school” treatment for depression containing monoamine oxidase that rapidly degrades norepinephrine
Huntington Chorea
Fatal hereditary disease though to be the loss of GABA producing neurons
When (in patients lifetime) does Huntington Chorea typically become evident?
30-40s
Parkinson’s Disease
disease characterized by the loss of dopamine producing neurons in the substantial nigra and basal ganglia
T or F: Dopamine is used in pathways coordinating smooth, focused movements.
true
What is the name of the Parkinson’s disease hallmark resting tremor?
pill rolling tremor
What hallmark of Parkinsons disease describes the loss of smooth movements?
cogwheel rigidity
What is a common Parkinsons disease treatment, a dopamine precursor that can cross the BBB?
L-Dopa
Fibrous astrocytomas
tumors arising from fibrous astrocytes
T or F: 80% of adult primary brain tumors can be classified as fibrous astroctyomas
true
