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BMF > neurotransmission > Flashcards

neurotransmission Flashcards

1
Q
  • ways to classify neurons
    1- —- as bipolar or multipolar aka the number of — from cell body
    2- Neurons that transmit information towards the CNS are —– and Neurons that transmit information from the CNS are —-
    3- type of — they release
    4- —- send information to the central nervous system about the internal and external environment
    5- —– control the activity of the body by controlling muscle and gland functions (contraction, relaxation, secretion).
A
  • morphology ( shape)
  • projections
  • afferent ( arriving )
  • efferent ( existing , effector organ ) aka afferent and efferent are classified by their direction
  • neurotranskitter ( substacne or chemicals they release as dopamine, acetylcholine)
  • sensory nerves
  • motor nerves
    ( sensory and motor and the functional ways of classifying )
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2
Q

signal conduction :
—- receive in-put signals, leading to a
—– propagate out-put signals and are for action potential

A
  • dendrites or cell body ( soma)
    leads to:
    1-depolarisation or
    2-hyperpolarisation of the plasma membrane
  • axons
    ( check slide 7 for structure pls)
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3
Q

1-is the junction between one neuron & the next cell —
2-Specialised structure at which —– impulse is converted to a —- signal for communication between cells (electro-chemical coupling)
types of communication includes:
3-Synapses between nerve and muscle cells are also called —-

A
  • synapse
  • electrical to chemical
  • communication include:
    Nerve-Nerve
    Nerve-Organ / Organ-Nerve
    Nerve-Muscle
    Nerve-Gland
  • neuromuscular junctions or motor end plates
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4
Q

-Typically small, rapid-acting molecules
-e.g. Acetylcholine, Dopamin, glutamate, noradrenaline, GABA
-Generally, neurons release —- type of —

A
  • neurptranmsitter
  • one type of NT
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5
Q

—–releases a chemical, a neurotransmitter
The neurotransmitter diffuses across —-
The neurotransmitter binds to specific receptor proteins on the plasma membrane of the —- to alter its membrane potential

A
  • presynaptic neuron
  • synaptic cleft
  • postsynaptic cell
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6
Q
  • synpses can be —-
  • The neurotransmitter at excitatory synapses —- the postsynaptic membrane.
    example: —
    by which the binding of — to its receptor on postysunaptic cell; open up —-
    which allows — of na
    + ions — membrane potential
  • If depolarisation of the postsynaptic membrane reaches a —- , an action potential is generated in the postsynaptic cell.
A
  • excitatory or inhibitory
  • depolarise
  • acteylcholine (ACh)
    -ACh
  • ligand gated sodium channel
  • influx
  • reduces
  • threshold
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7
Q

-Two basic forms of electrical signals:
1- —- local changes in membrane potential not reaching threshold and these die out over – distances , they can be generated by —- which serves as — signals

A
  • graded and action potential
  • graded potential
  • short
  • action potenial
  • long distance signal
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8
Q

graded potential occur in — , — region of excitable membrane
- Magnitude of graded potential varies directly with the magnitude of the —-

A
  • small
  • specialised
  • triggering event
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9
Q

If depolarisation at a certain spot on the neuron reaches a threshold voltage of approx. —-
the — voltage opens up several —- in portion of plasma membrane

A
  • -50mV
  • reduced voltage
  • voltage gated na+ channels
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10
Q

-Brief, —— (≅100mV) changes in membrane potential during which potential actually —-
- Involves only a —-portion of the total excitable cell membrane at a certain time
- Do not decrease in —- as they travel from their site of initiation throughout remainder of cell membrane

A
  • rapid and large
  • reverses
  • small portion
  • strength
    ( so basically the size is the same but diff frequency )
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11
Q

During an AP voltage-gated Na+ channels open in the PM that allows Na+ movement into the cell this causes —-

A

PM depolarises

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12
Q

if the threshold is not reached there’s no —-

A

action potential

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13
Q

Voltage-gated K+ channels subsequently open which allows K+ to leave the cell down its electrochemical gradient bringing the MP back toward —-

A

resting ( -70mV)
( pls check the graphs especially 27 )

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14
Q

When membrane reaches threshold potential:
1-Voltage-gated Na+-channels in the membrane undergo —-
2- Flow of sodium ions into the ICF —- the membrane potential from — mV to —-mV
3- Flow of potassium ions into the ECF restores the membrane potential to the —-

A
  • conformational changes
  • reverses
  • -70
  • +30
  • resting state
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15
Q

—– period is the period when a further stimulus applied to the neuron (or muscle fiber) will not trigger another action potential.
-In some neurons, the refractory period lasts only —— seconds. In other words, some neurons can transmit up to —– impulses per second
- Due to —– of sodium channels (absolute refractory period) and —– brought about by opening of potassium channels and potassium ions (K+) movement out of cell (relative refractory period).

A
  • refractory period
  • inactivation
  • reploarisation
  • 0.001-0.002
  • ## 500-1000
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16
Q
  • action potential is an —
  • The — of the action potential is an intrinsic property of the cell.
    -So long as they can reach the —- of the cell, strong stimuli produce no stronger action potentials than weak one
  • , the strength of the stimulus is encoded in the —- of the action potentials that it generates.
A
  • all-or-none
  • threshold
  • frequency
17
Q

The neurotransmitter at inhibitory synapses —- the postsynaptic membrane as:
1- binding of – to its receptor on the postsynaptic neuron opens up —–
2-The entry of negatively charged chloride ions —-the membrane potential (e.g. from — to — ), meaning even more negative charge —- the cell
-This increased membrane potential (or more negative charges inside the cell) counteracts any excitatory signals that may arrive at that neuron.

A
  • hyperpolarises
  • GABA ( : gamma aminobutyric acid )
  • up ligand-gated chloride (Cl−) channel.
  • increases
  • -70 to -90
  • inside
18
Q

-axons of most neurones are encased in a fatty sheath called the —-
-Myelin functions as an —-which — current flow
-It is the expanded plasma membrane of a neighboring cell called the —–
- Where the sheath of one Schwann cell meets the next, the axon is —-
-The voltage-gated sodium channels of myelinated neurones are confined to these spots —-
- The influx of —- ions at one node creates enough —–o reach the threshold of the next. Thereby the action potential jumps from one node to the next. This results in a faster propagation of action potentials.

A
  • myelin sheath
  • electrical insulator
  • restrict flow
  • Schwann cell or oligiodendtryte
  • unprotected
  • nodes of ranvier
  • sodium
  • depolarisation
19
Q

-straited muscle as:
- unstraited as:

A
  • skeletal and cardiac
    -smooth
    info:
    -the cytoplasm: mostly actin and myosin filaments
  • nuclei and organelles are pushed to the edge
  • the endoplasmic (sarcoplasmic) reticulum is arranged as a system of tubes around groups of myofibrils. Tubes of the sarcoplasmic reticulum drain into large tubes called T-tubes.
20
Q

The “output” of PNS consists of motor neurones running from the CNS to the muscles and glands called —-
1- — :skeletal muscle
neuromuscular junction (NMJ)
2- —-:cardiac or smooth muscle

A
  • effector
  • nerve somatic motor nerve
  • nerve autonomic NS
21
Q

motor neurons in innervate skeletal muscle fibres:
-Cell bodies of motor neurons located in —
- Thick, myelinated axons —
- Several fine branches with many varicosities (swellings), called —-
- —-
- Boutons lie over —- folds on muscle
- Each muscle cell is innervated by —motor neuron; each motor neuron can innervate —–

A
  • ventral horn
  • somatic efferent fiber
  • synaptic bouton
  • synaptic cleft
  • postsynaptic junctional folds
  • one
  • many muscle fibres
22
Q

-Motor neurons and skeletal muscle fibres are chemically linked at the —-
-Action potentials traveling down (large, myelinated) motor neurons of the sensory-somatic efferent branch of the nervous system cause the —– at which they terminate :

A
  • Neuromuscular Junction (NMJ)
    -contraction of skeletal muscle fibers and they terminate :
    -always excitatory
    -create miniature end plate potentials (mEPP) from single vesicle release
23
Q

The junction between the terminal of a motor neuron and a muscle fiber is called the —- which is a specific type of —

A

neuromuscular junction (“motor end plate”). It is a specific type of synapse.

24
Q

-Axon terminal of motor neuron forms — with a single —-
- signals are passed between nerve terminal and muscle fiber by mean of —-
- Released ACh binds to receptor sites on —- cell membrane
- Binding triggers opening of —- in motor end plate
- —— movements depolarize motor end plate, producing —–
-Local current flow between depolarized end plate and adjacent muscle cell membrane brings adjacent areas to —-
- —– is initiated and propagated throughout muscle fiber

A
  • neuromuscular junction
  • muscle cell
  • NT ACh
  • motor end plate of muscle cell membrane
  • specific channels
  • ion movement
  • end plate potential ( EPP or end plate spike)
  • threshold
  • action potential
25
Q

-Chemical messenger (neurotransmitter) carries —- from —- to—-
- —- was one of the first neurotransmitters discovered , its produced in — of the motor neuron by the enzyme —- which uses —- and —- as substrate , in the CNS its released within —

A
  • signals
  • nerve
  • muscle
  • acetylcholine
  • pre synaptic terminal
  • choline acteyltransferase
  • acetyl coenzyme A
  • choline
  • cholinergic system (excitatory)
26
Q

The terminals of motor axons contain thousands of — filled w —-

A

vesicles
neurotransmitter acetylcholine ACh

27
Q

When an action potential reaches the —–, hundreds of these vesicles release their —- onto a specialized area of the —– membrane on the muscle fiber. This area contains a cluster of ligand-gated ion channels that are opened by ACh and let —- diffuse in.

A
  • axon terminal
  • ACh
  • postsynaptic membrane
  • sodium ions na+
    ( check graph )
28
Q

-muscle fiber has resting membrane potential of —
- influx of sodium ions — the potential and creates a — by —- and the magnitude depends on the — of ACh

A
  • -80mV
  • reduces
  • end plate potential
  • depolarisation
  • amount/duration
29
Q

the depolarising effect of EPP open —- channels eliciting an — in the fiber
the action potential sweeps down the length of the fiber and leads to —
- muscle contraction following ca+2 release in —

A
  • voltage gated na+ channels
    -action potential
  • contraction of the muscle
  • excitation-contraction coupling
30
Q

-Receptor for ACh at postsynaptic membrane of skeletal NMJ is the
—
- the drug – also activated this receptor
- nicotine receptors are — and the — is intrinsic part of the receptor
- nicotine ACh receptor mediate very – responses

A
  • muscle type nicotine receptor ( Nm or N1)
  • nicotine
    -ionotropic
  • ion channel
  • rapid
31
Q

nicotine receptors are found at the — of —
and they can also be found in —- and —

A
  • neuromuscular junction of skeletal muscle
  • autonomic nervous system ( ganglion )
  • central nervous system
32
Q

—– concentrated on the external surface of the postsynaptic membrane and in the synaptic cleft.
- breaks down the — in the neuromuscular junction ( 25,000 molecules per sec )
- sodium channels – and the field is – for the arrival of another nerve impulse

A
  • ACETYLCHOLINESTERASE ( AChE)
  • neurotransmitter ACh
  • closes
  • cleared
33
Q

Nicotinic cholinergic receptors at the NMJ can be blocked by several drugs which can induce —–

A
  • paralysis and/or cessation of breathing ( respiratory muscles are skeletal muscles too )
34
Q

—- contains substances that inhibit binding of ACh to nAChR causes —-
—-used as neuromuscular blocking agents during surgical anaesthesia to relax skeletal muscle

A
  • curare
  • curare payalyses skeltal muscle
  • D-tubocurarine ( an Acetylcholinesterase inhibitors)
35
Q

—- blocks release of ACh - prevents muscles responding to nerve impulses , works by cleaving —- required for vesicle release
- Ingesting 0.0001 mg can —-
- caused by —-
treats — , disorders including :
- cosmetic use as:
- — contracts muscles

A

-botulinium toxin ( botox)
- synaptic proteins
-kill an adult
- improper canned food
- Treats dystonias – disorders including spasms, involuntary twitches
- reduces wrinkles and frown lines
- permanently

36
Q

—– , disease in which immune system attacks motor end-plate ACh receptor. Commonest primary disorder of neuromuscular transmission.
-Mainly in adulthood: 20 / 100,000
-too little — effect extreme —-
- traded w :

A
  • myasthenia graves
  • ACh
  • extreme muscle contraction weakness
  • Treated with AChE inhibitor (neostigmine) – prolongs effect of ACh, or immunosuppressants
37
Q

choose the correct ans:
How would neuromuscular transmission be affected in the presence of an acetylcholinesterase (AChE) inhibitor?
1. Muscle contraction would be delayed.

  1. Muscle contraction would be prolonged.
A

2222( check last slide plssss)

BMF (17 decks)

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