EX1; Cell Communication Flashcards
Neurons make up what percentage of CNS cells
10%
What are the 3 main parts of a neuron
soma; containing the nucleus; protein synthesis
dendrites; major input processes (respond with graded potentials)
axon; output processes for signaling (action potentials)
This is the initial segment of a neuron; the trigger zone for action potentials
axon hillock
This part of the axon is used for vesicle storage
axon terminals
This type of neuron is a sensory/input neuron; transmit information to CNS; the bodies lie outside the CND in ganglia
afferent neuron
This type of neuron is motor/output; transmits commands to effector cells; bodies lie within CNS but axons project outside
efferent neurons
This type of neuron is located within the CNS; functions as integrators and switches
interneurons
What percentage of the CNS do glial cells make up
90%
Which undergoes cell division, neurons or glial cells
glial cells
What are the two types of myelinating glia
PNS; Schwann cells (one axon)
CNS; oligodendrocytes (many axons)
These are macrophage-like glial cells and can be in either unreactive or reactive
microglia
These glial cells regulate ECF, provide neurons metabolically, and surround brain capillaries forming the blood brain barrier
astrocytes
This provides movement of proteins and other material from one part of neuron to another
microtubules
What are the two types of microtubule transport
anterograde
retrograde
This type of transport is from cell body toward terminal
anterograde
What type of motor protein is required for anterograde transport, and what are the speeds of it
kinesins
fast transport for organelles such as neurotransmitter vesicles
slow transpire for structural proteins
This type of transport is from axon terminal towards cell body
retrograde
What type of motor protein is required for retrograde transport and it moves what
dyneins
fast transport of things like growth factors and also viruses
This virus is easily transmitted through oral contact and is transmitted retrogradely where it remains latent in the trigeminal ganglion
herpes simplex virus type 1
True or False
Damaged CNS neurons regenerate
False; they do not
CNS axons do this, but do not reach targets
sprout
This prevents surviving CNS axons from reaching targets
scar formation
Astrocytes make this that inhibits neuron growth
chondroitin sulfate proteoglycans
This is clinically signifiant; dental procedures (extractions) can cause nerve damage
PNS
True or False
functional recovery of the PNC can take place depending on the severity
True
This is associate with protein synthesis; cell body swells, eccentric nucleus
chromatolysis
What becomes of a neuron in response to a severe nerve injury
terminal degeneration
transganglionic degeneration
transynaptic degeneration
What becomes of a neuron in response to a less severe injury
anterograde degeneration
injured cell nucleus (chromatolysis)
These cells produce laminin for substrate for regenerating axons and nerve growth factor (NGF)
Schwann cells
This regulates gene expression and promotes sprouting
NGF
What are the specific components NGF is involved with
microtubules and microfilaments
neurotransmitter production
ion channels
neurotransmitter receptors
Collateral sprouting explains what when there is ipsilateral removal of trigeminal nerve leaving once side anesthetic
crossed-midline sensitivity
This is an anatomically specialized junction between a neuron and another cell at which the electrical activity of the presynaptic neuron influences the electrical activity in the post synaptic cell
synapse
What are the four types of synapses
chemical vs electrical
excitatory vs inhibitory
What are the three types of chemical synpases
axo-somatic
axo-dendritic
axo-axonis
Where are the three location of receptors
postsynaptic
presynaptic
autoreceptors
What are the 6 steps of synaptic transmission
- action potential reaches terminal
- voltage-gated Ca channels open
- calcium enters axon terminal
- neurotransmitter is released and diffused into the cleft
- neurotransmitter binds to post synaptic receptors
- neurotransmitter removed from synaptic cleft
A post-synaptic potential is only how many mVs
0.5mV
What determines if a threshold is reached of a PSP
the combined effect to excitatory or inhibitory synaptic input
This is the adding together of PSPs from one synaptic contract (over time)
temporal summation
This is adding together of PSPs produced by different synapses
spatial summation
At which type of sites can drugs interact with the synaptic junction
a whole bunch of different places
This functions in rapid communication and acts on postsynaptic cell to produce EPSP or IPSP (excitatory or inhibitory)
classical neurotransmitter
This may act postsynaptically to amplify or dampen on-going synaptic activity or may act on pre-synaptic cell to alter synthesis, release, uptake, or metabolism of neurotransmitters
neuromodulators
Actions of neuromodulators includes what
changes in DNA/protein synthesis or enzyme activity; can thus be much slower in action (min-days)
This is synthesized from choline and acetyl in the synaptic terminal; action stopped by diffusion and degration
acetylcholine
What is choline re-uptakes by
presynaptic neuron
What are four examples of neurons that release ACh
motor neurons
neurons in nuclus basalis and pons
all preganglionic neurons
all postganglionic parasympathetic neurons
Where are two locations of ACh neurons in the CNS
basal forebrain
pontine nuclei
These ACh receptors are mostly found in the CNS but also in parasympathetic postganglionic synapse (salivary glands)
muscarinic receptors
The binding of ACh in muscarinic receptors triggers what
G protein that either open or closes ion channels
depolarizing or hyperpolarizing
Muscarinic receptors are blocked by what
atropine
These ACh receptors are few in the CNS
nicotinic receptor
ACh binding in nicotinic receptors triggers what
opening ion channels with the receptor
depolarizing
Nicotinic receptors are blocked by what
curare (e.g. neuromuscular junction)
This ACh disease is an autoimmune disease in which individuals make autoantibodies to nicotinic receptors; muscle weakness; treated with acetylcholinisterase inhibitors
myasthenia gravis
This ACh is a common form of dementia, loss of neurons in the nucleus basal is leading to decrease in cholinergic activity in cortex
alzheimers disease
This is synthesized from amino acids, specifically tyrosine
catecholamines
What is the life cycle (3 steps) of catecholamines
- synthesis in presynaptic terminal; stored in vesicles
- release is Ca dependent
- termination of action; presynaptic neuron re-uptake and degradation (MAO)
True or False
Neurons that synthesize catecholamines are found through the CNS
False; the neurons are only found in very limited locations
True or False
receptors for catecholamines are found extensively throughout the CNS
True
What are the type of catecholamines receptors
G-protein coupled receptors
True or False
Catecholamine is involved with only a few functions and dysfunctions
False; it is involved with many
This is synthesized in the pre-synaptic terminal and is found in specific areas of the midbrain and brainstem
dopamine
The two main groups of dopamine G-protien receptors are D1 and D2; what are their functions
D1 - activate adenylate cyclase
D2 - inhibit adenylate cyclase (leading to hyperpolarization)
This disorder involves the D2 receptors being impaired, commonly presented with rhythmic oral movements
tardive dyskinesia
This is found in locus ceruleus (attention/sleep) and other brainstem groups with autonomic and homeostatic functions and is often referred to as noradrenaline and adrenaline
norepinephrine and epinephrine
norepinephrine neurons include what
sympathetic postganglionic neurons and some CNS
epinephrine neurons include what
adrenal gland as circulating hormone (not much in CNS)
These are G protein coupled receptors involving NE
noradrenergic receptors
What are the functions of α receptors (α1 and α2) involving NE
α1; intracellular release of Ca; excitatory
α2; inhibitory via opening of K channels or blocking Ca
What is the function of β receptors ( β1, β2, β3) involving NE
open Ca channels
This is synthesized from tryptophan and is found in the rostral raphe nucleus (sleep, mood, homeostatic function) and the caudal raphe nuclei (sensori-motor function) and uses G protein coupled receptors
serotonin
What is the function of serotonin
may different functions ranging from sensrimotor systems to cognitive function (mood)
This is found only in a small population of hypothalamic neurons involved in sleep-wakefulness; G-protein coupled receptors
histamine (derived from histidine)
This is the most common excitatory amino acid (the other is aspartate)
glutamate
The excitatory amino acids bind several classes of what
ionotropic receptors; have channels permeable to Na, K, and Ca
aslo binds to metabotropic receptors (G-protein)
This is involved with functions that last (memory, chronic pain, etc.); excitotoxcitiy; excessive excitation causes neuron death from Ca reading toxic levels
NMDA (n-methyl-D-asparate) receptor
NMDA receptors are involved in the synaptic mechanism of what
long term potentiation
What are two factors promoting long ted potentiation
phosphorylation of NMDA receptor
calcium entry into cell via NMDA; phosphorylation of AMPA and an increased number, synthesis of retrograde nitric oxide
This is a major inhibitory neurotransmitter in the CNS, modified form of glutamate of which can form Huntington chorea, form of motor spasticity
GABA (gamma-amminobutyric acid)
GABA (A) is an ionotropic receptor that opens what
Cl channels
GABA (B) is a metabotropic receptor that opens what
K channels
glycine is an inhibitory neurotransmitter in the spinal cord that does what
receptor opens Cl channels
blocked by strychnine
There are over 80 of these identified and are often co-released with neurotransmitters (synthesized in stroma and must be transported to be released) can function as a neuromodulator, and its action can last a long time terminated by proteolysis and diffusions
peptides
This is a gas transmitter that can modulate neurotransmitter release, plays a role in numerous brain functions and has an excitotoxicity role in injuries
nitric oxide
This is usually an excitatory (taste) transmitter usually co-release with classical neurotransmitters
ATP