T6 Muscles and Nerves Flashcards
Name a B1 blocker.
Metoprolol
What is atropine used for?
Prevent sinus bradycardia after MI, anticholinesterase poisioning treatment, prevent bradycardia in surgery
What is a twitch vs a tetanus?
A twitch is a brief mechanical response to a single AP, tetanus is sustained mechanical response to a series of APs
Name an B1 selective agonist.
Dobutamine
Where are A1 postsynaptic receptors found?
Smooth muscle
What does the lateral horn of grey matter contain?
Preganglionic autonomic neuron cell bodies
Where are B1 postsynaptic receptors found?
Mainly heart
What are M3 antagonists and botox used to treat?
Overactive bladder
Name a A blocker.
Phenoxybenzamine
Where is acetylcholinesterase located?
Post synaptic membrane
How long does suxamethonium last?
5m
What surrounds single myofibres?
Endomysium
What surrounds a whole muscle?
Epimysium
What would be the effect of blocking ganglionic nicotinic receptors at rest?
Constapation
What would be the effect of blocking ganglionic muscarinic receptors at rest?
Decrease sweating
What is the light part of a striation?
The I band
What do denticulate ligaments do?
Join spinal chord to lateral vertebral walls
How is Ca2+ released to smooth muscle?
From the extracellular space via Ca2+ channels. These are opened by binding of phospholipase 3 to receptors, releasing IP3 which acts on SR which acts on ion channels to cause Ca2+ influx
Which zone only contains myosin?
The H zone
How long is a single twitch?
100-300 ms
How are cardiac muscle cells linked mechanically and electronically?
By desosome and adherens junctions mechanically, by gap junctions electrically (intercalated discs)
Is the vasomotor tone controlled by the sympathetic or parasympathetic nervous system?
Sympathetic
How many motor neurons innervate a motor unit in a whole muscle?
One motor unit is innervated by one motor neuron
Where are autonomic cholinergic receptors located?
In paravertebral ganglia
What would be the effect of blocking ganglionic adrenergic receptors at rest?
Loss of vasomotor tone
What is ipatropium used to treat?
Asthma
What is a muscle compartment surrounded by?
Deep fascia
Is the heart innervated by the sympathetic or parasympathetic nervous system?
Both
Which zones get shorter on contraction?
H and I zones
What connects SM cells?
Membrane dense areas and gap junctions
Which system should control HR at rest?
Parasympathetic
What does the posterior, or dorsal, horn of grey matter contain?
Cell bodies of sensory neurons
What does the ventral or anterior root of a spinal nerve contain?
Motor fibres only
What do oligodendrocytes do?
Insulate neurons in CNS
What does the anterior, or ventral, horn of grey matter contain?
Motor neurons
What is the name of the dural fold between cerebral hemispheres?
Falx cerebri
How long is a cardiac fibre?
200um
What are microglia?
Macrophages of CNS
What does monoamineoxidase inhibitors do?
Treat depression
What happens in cross bridge cycling in a single sacromere when Ca2+ is present?
It is asynchronous
Is visual accommodation sympathetic or parasympathetic?
Parasympathetic
What are ependymal cells?
CSF secreting cells
What do astrocytes do?
Contribute to blood brain barrier, give strength to CNS
What does monoamineoxidase do?
Recycles noradrenaline
Where is the ultimate control of the autonomic nervous system?
Hypothalamus
Where is cerebrospinal fluid produced?
In the lateral ventricles and antero-inferior to the cerebellum
What is the end plate potential?
Local depolarisation resulting from Na+ influx causing AP to propagate from NMJ to ends of fibre
How are smooth muscle cells linked mechanically and electronically?
Mechanically by membrane dense areas, electronically by gap junctions
Give an example of an A1 selective blocker.
Prazonin
What are transverse tubules?
Invaginations of sacrolemma
What are intercalated discs formed of?
An adherens junction and a gap junction
What surrounds a muscle fibre?
Endomysium and sacrolemma
What is released from sympathetic nerve terminals?
Noradrenaline and ATP and neuropeptide Y
Describe the contractile mechanism of smooth muscle?
Ca2+ binds to calmodulin, activating myosin light chain kinase, which adds Pi to the myosin light chain so it will bind actin
Name an A2 selective agonist.
Phenylephrine
What is concentric contraction?
Force produced and muscles shorten
What do A-blockers do?
Lower blood pressure but have many side effects
What is hyoscine used to treat?
Motion sickness
What is atropine?
A muscarinc antagonist
Name the neuroglia.
Astrocytes, oligodendrocytes, microglia and ependymal cells
What surrounds a bundle of myofibres?
Perimysium
Name an anticholinesterase which lasts minutes.
Edrophonium
What do Schwann cells do?
Surround all neurons in PNS
What is isometric contraction?
Force produced but no shortening
Name a B blocker.
Propanolol
Is the detrusor innervated by the sympathetic or parasympathetic nervous system?
Both
Are exocrine glands controlled by the sympathetic or parasympathetic nervous system?
Parasympathetic
What is Ohm’s law?
Voltage = current x resistance V=IR
What line marks the centre of a centromere?
The M line
What connects bundles of actin in SM?
Dystrophin
What is pyridostigmine used to treat?
Myasthenia gravis
What does botox do?
Inhibits acetylcholine release causing long lasting muscle paralysis
Where is cerebrospinal fluid found?
In the subarachoid space
How long is a twitch in cardiac muscle?
200 ms
How do cardiac cells get Ca2+ for contraction?
From the SR and through L-type voltage gated channels via Ca2+ induced Ca2+ release
Where are B2 non synaptic receptors found?
Airways, liver, uterus
Name two anticholinesterases which lasts hours.
Pyridostigmine, neostigmine
What is the length of a sacromere?
From Z disc to Z disc
Name an A1 selective agonist.
Cloridine
Is the metabolism controlled by the sympathetic or parasympathetic nervous system?
Sympathetic
What is the dark part of a striation?
The A band
Where does the impulse travel from the beginning of excitation contraction coupling?
From neuromuscular junction to T tubules to sarcoplasmic reticulum
What surrounds a muscle fascicle?
Perimysium
Which band varies in length with muscle contraction?
The I band
What do drugs that block presynaptic A2 receptors do?
Enhance sympathetic neurotransmission as negative feedback receptors here control neurotransmitter release
What does suxamethonium do?
It is a nicotinic agonist that causes a depolarisation block as fibre is unable to repolarise.
Name a A and B blocker.
Labetalol
Name an B2 selective agonist.
Sabutamol
Is renin release controlled by the sympathetic or parasympathetic nervous system?
Sympathetic
What is eccentric contraction?
Braking action, muscles stretched by other muscles
What does parcuronium do?
Blocks neuromuscular tranmission as it is a nicotinic antagonist
Where does arachoid membrane end?
S2
What do indirect sympathomimetics do?
Cause NA to be released from storage vesicles
What does the dorsal or posterior root of a spinal nerve contain?
Sensory fibres only
