In most cases in the sympathetic nervous system, Acetylcholine is the pre-ganglionic neurotransmitter and Noradrenaline is the post-ganglionic neurotransmitter.
Pre-ganglionic neurones are longer in the sympathetic nervous system when compared to the parasympathetic nervous system.
What unique features does the sympathetic nervous system contain that is absent in the parasympathetic nervous system?
Sympathetic chain
Unmyelinated neurones
Plexuses
The motor components of the somatic nervous system contain pre and post ganglionic components after exit from the spinal cord.
Acetylcholine causes the adrenal medulla to secrete what substance? What is this type of interaction known as?
Adrenaline
VIP
Nitric Oxide
Neuro-endocrine interface
Endocrine interface
Autonomic interface
What is the main neurotransmitter at post-ganglionic sympathetic fibres?
Glutamate
Noradrenaline
Acetylcholine
Anticholinesterases are useful in treating myasthenia gravis. Why?
They prolong the time that acetylcholine is present in the synaptic cleft and increases its number, thereby allowing acetylcholine to outcompete with antibodies for the binding site and allow normal contractions to occur, relieving the symptoms of M.G.
They prolong the time that noradrenaline is present in the synaptic cleft and increases its number, thereby allowing noradrenaline to outcompete with antibodies for the binding site and allow normal contractions to occur, relieving the symptoms of M.G.
They decrease the time that acetylcholine is present in the synaptic cleft and increases its number, thereby allowing acetylcholine to outcompete with antibodies for the binding site and allow normal contractions to occur, relieving the symptoms of M.G.
Which are examples of non-depolarising blockers?
Tubocurarine
Pancuronium
Suxamethonium
Hexamethonium
What is an example of a depolarising neuromuscular blocker?
What is an example of a non-competitive antagonist of nicotinic receptors?
What is an example of a muscarinic receptor antagonist?
Atropine
Tropicamide
Pilocarpine
The myenteric plexus is located between which two layers of the GI tract?
Circular muscle
Longitudinal muscle
Submucosa
Mucosa
The submucosal plexus is located between which two layers?
The myenteric plexus is present throughout the GI tract
In general, the submucosal plexus controls muscular activity.
What is the mechanism of action of botulinum toxin?
Proteases cleave the SNARE complex that mediates exocytosis of neurotransmitter
Competitive antagonist at the nicotinic acetylcholine receptors
Non-competitive antagonist at the nicotonic acetylcholine receptor
Depolarising blocker of the neuromuscular junction
Anticholinesterases exhibit suxamethonium-like properties when used in excess.
Why does calcium aid in synaptic transmission?
Calcium causes a conformational change in synaptotagmin which causes acetylcholine to fuse with the presynaptic membrane.
Calcium causes a conformational change in ryanodine which causes acetylcholine to fuse with the presynaptic membrane.
If the end plate potential in a muscle cell exceeds threshold, what happens?
Muscle contraction
Action potential produced
Release of acetylcholine by exocytosis
When an action potential travels along a T-tubule to a muscle triad, what series of events occur?
Action potential causes conformational shape change of the DHP receptor. This receptor then causes unplugging of ryanodine from the sarcoplasmic reticulum. This causes mass efflux of calcium ions from the sarcoplasmic reticulum and subsequent triggering of contraction.
Action potential causes conformational shape change of the DHP receptor. This receptor then causes mass efflux of calcium ions from the sarcoplasmic reticulum and subsequent triggering of contraction.
Action potential causes conformational shape change of the DNP receptor. This receptor then causes unplugging of synaptotagmin from the sarcoplasmic reticulum. This causes mass efflux of calcium ions from the sarcoplasmic reticulum and subsequent triggering of contraction.
Action potential causes conformational shape change of the DHP receptor. This receptor then causes unplugging of ryanodine from the sarcoplasmic reticulum. This causes mass efflux of sodium ions from the sarcoplasmic reticulum and subsequent triggering of contraction.
What regulatory proteins does actin have associated with it?
Tropomyosin
Troponin
Tropocollagen
Tropoelastin
What is the role of calcium in muscle fibres?
To bind to troponin, causing a conformational change which exposes myosin head binding sites.
To bind to tropomyosin, causing a conformational change which exposes myosin head binding sites.
To bind to tropomyosin, causing a conformational change which exposes actin head binding sites.
To bind to troponin, causing a conformational change which exposes actin head binding sites.
Which is longer, the action potential or muscle contraction?
Action potential
What are the 3 energy systems of muscle contraction?
Phosphocreatine
Lactic acid
Oxidative phosphorylation
Substrate level phosphorylation
Hyaluronic acid
Glucuronic acid
Muscle contraction occurs in which order?
Cross-bridge attachment -> Power stroke, hydrolysing ATP via the ATPase capacity of the myosin head -> binding of ATP which breaks cross-bridge attachment -> hydrolysis of ATP which recocks the myosin head to its original position -> repeat
Cross-bridge attachment -> Power stroke, hydrolysing GTP via the GTPase capacity of the myosin head -> binding of GTP which breaks cross-bridge attachment -> hydrolysis of GTP which recocks the myosin head to its original position -> repeat
Cross-bridge detachment-> Power stroke, hydrolysing ATP via the ATPase capacity of the myosin head -> binding of ATP which causes cross-bridge attachment -> hydrolysis of ATP which recocks the myosin head to its original position -> repeat
Do slow twitch fibres or fast twitch fibres produce greater force?
Slow twitch
Fast twitch
Which type of muscle fibre generally fatigues quicker?
The spinal cord exists from?
C1 -> L2
C1 -> L1
C1 -> T10
C1 -> S3
How many spinal nerves are there, and how many are there for each section of the spinal cord?
31 - 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal pair
31 - 6 cervical, 12 thoracic, 6 lumbar, 6 sacral, 1 coccygeal pair
30 - 7 cervical, 14 thoracic, 3 lumbar, 5 sacral, 1 coccygeal pair
27 - 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal pair
Why do the first 7 cervical nerves begin above the cervical vertebrae but the thoracic spinal nerves begin below the thoracic sections of the spinal cord?
There are 8 cervical spinal nerves but only 7 cervical vertebrae therefore the thoracic spinal nerves are 'displaced' and run below each thoracic vertebrae piece.
There are 6 cervical spinal nerves and 7 cervical vertebrae so the thoracic spinal nerves are 'displaced' and run below each thoracic vertebrae piece.
The meninges of the nervous system run in what order from inside to outside?
PAD
DAP
PDA
DPA
What is a dermatome?
An area of skin with single spinal nerve innervation
An area of skin with dual spinal nerve innervation
An area of muscle with single spinal nerve innervation
An area of muscle with dual spinal nerve innervation
What is a myotome?
Conditions such as shingles do not show the usefulness of dermatomes.
Sulci are the depressions in the brain structure.
Gyri are the ridges in the brain.
Upper motor neurones are found where?
Brain
Spinal cord
In the context of motor units, a graded force describes what?
The amount of motor unit recruitment needed. If it is a large force then fast-twitch elements are recruited. If it is a small force then slow-twitch elements are recruited.
The amount of motor unit recruitment needed. If it is a small force then fast-twitch elements are recruited. If it is a large force then slow-twitch elements are recruited.
Recruitment of motor units describes what?
The number of motor units firing, specifically an increase.
The frequency of motor units firing, specifically an increase.
The number of motor units firing, specifically a decrease.
The frequency of motor units firing, specifically a decrease.
Rate coding describes what?
Contractile force is proportional to what?
Cross-bridge number
Force produced by cross-bridges
Velocity produced by cross-bridges
Number of ATP molecules
Force produced by Troponin conformation change
Force produced by Tropomyosin conformation change
Slow-twitch fibres produce less force but over a longer period of time. Fast-twitch fibres produce more force but over a shorter period of time.
Neurogenic and Myopathic motor unit diseases have what common symptoms?
Weakness
Wasting
Muscle mass increase
Absence of fasciculations
ALS affects what part of the motor neuron?
Cell body
Axon
Peripheral neuropathies typically affect which part of the motor neuron?
What is responsible for DMD?
A fault in dystrophin - a vital part of a protein complex that anchors the cytoskeleton of a muscle fibre to the ECM through the cell membrane
A fault in collagen - a vital part of a protein complex that anchors the cytoskeleton of a muscle fibre to the ECM through the cell membrane
A fault in elastin - a vital part of a protein complex that anchors the cytoskeleton of a muscle fibre to the ECM through the cell membrane
What plasma indicator shows signs of DMD muscle damage?
High creatine kinase levels in the serum - should be only intracellular.
Low creatine kinase levels in the serum - should be only intravascular.
High plasma protein binding
Low plasma protein binding
Dermatomyositis is a condition characterised by what?
Inflammation and visible rashes, with atrophy of muscle fibres.
Inflammation and visible rashes, with hypertrophy of muscle fibres.
Efficacy of a drug means?
The ability of a drug to produce a response
The likelihood of a drug binding to a receptor
The mechanism by which the drug acts
The permeability of the drug to the plasma membrane
What is meant by an inverse agonist?
A drug that decreases activity of the agonist and produces the opposite response to the agonist.
A drug that produces the same response as the agonist but with higher efficacy.
What is meant by allosteric inhibition? What is an example and it's subsequent mechanism?
Binding of a drug to a site other than the agonist binding site.
Binding of a drug to the same site as the agonist binding site.
Benzodiazepam - binds to an alternative site on GABA receptors. This causes a conformational change and creates higher affinity for GABA to bind to the receptor. This therefore increases the inhibitory effect that GABA provides, making users feel drowsy.
Benzodiazepam - binds to an alternative site on GABA receptors. This causes a conformational change and creates lower affinity for GABA to bind to the receptor. This therefore decreases the inhibitory effect that GABA provides, making users feel more alert.
The body can become desensitised to drugs. For example intake of tobacco which contains nicotine can cause inactivation of nAchR in very high doses.
RMP is primarily maintained at -65mV to -70mV by?
The permeability of the membrane to potassium ions
Na+/K+ ATPase
The permeability of the membrane to sodium ions
None of the options
An action potential can be initiated in the absolute refractory period.
An action potential can be initiated in the relative refractory period.
Myelinated axons conduct action potentials faster.
The 'feet' of motor proteins possess what property that allows them to 'walk' along the cytoskeleton?
ATPase activity
GTPase activity
ATP supply
