Physiology Flashcards
What is the principal functional unit of the nervous system?
Neurons
How many neurone does the human system have?
10 to the (11-12) neurons
Which non-neuronal cell forms the blood brain barrier and also produces neutrophins?
Astroglia cells
What is the purpose of oligodendrogliocytes?
To produce myelin sheaths
Which cells in the non - neuronal cell is phagocytic in nature?
Microglial cells
What is the purpose of ependymal cells?
- They line the fluid- filled ventricles of the brain in the choriod plexus where the help to produce cerebral spinal fluid.
- They help to direct cell migration during development of the brain.
Which cells contains a glial fibrillary acidic protein (GFAP) that is used as a marker in brain cancers such as astrocytoma or glioblastoma?
Astrocytes
Functions of Astrocytes? ( most abundant)
- Help in recycling neurotransmitters(glutamate, GABA and serotonin)
- They buffer the extracellular potassium concentration .
- Respond to injury (gliosis)
- Help to make up the BBB
Damage to which cells causes multiple sclerosis(MS) or leukodystrophies?
Oligodendrogliocytes
Which glial cell is responsible for myelination in the PNS ?
Schwann cells ( One Schwann cell myelinate one neuron)
Abbreviation COPS
Cns- Oligodendrogliocytes Pns- Schwann cells
What is anterograde transport?
Movement of proteins from soma to terminal ends ( A=ST)
What is retrograde transport?
Movement of proteins from terminal ends to soma (R= TS)
Describe a grade 1 nerve injury
Applied pressure ( resting head on hand)
can result in hypoxia
LEAST HARMFUL ( regeneration starts quickly)
What grade is the most severe type of nerve injury?
Grade 5 ( Completer severance of the nerve)
What are the changes that occur in the nerve cell body at a grade 5 nerve injury?
1.Chromatolysis occurs within 24 hrs ( last about 15-20 days)
2.Neurofibrils and Golgi apparatus starts to disappear/disintegrate
3.Cell body swells assumes a spherical shape
4. Nucleus is the pushed to one side of neurone.
What is Wallerian degeneration?
Wallerian degeneration is an active process of retrograde degeneration of the distal end of an axon that is a result of a nerve lesion.
What are the changes that occur within the nerve fibre when it is damaged?
1.Myelin sheath breaks down
2. Macrophages appear
3.Schwann cells divide mitotically forming cords of cells lying within the endoneurial tubes
4.Macrophages from the endoneurium invade the degenerating myelin sheath and axis cylinder and remove debris. As debris is removed, Schwann cell cytoplasm fills the endoneurial tubes. The process takes - 3 months.
What are the processes that occur at the site of injury?
a. Schwann cells elongate and send processes outward to the injured site. This is known as Regenerative Sprouting.
b. Neurofibrils from the proximal end begin to grow and are guided by the Schwann cells into the old cylinder, in which they grow and eventually form the new axon.
c. Schwann cells then spin new myelin sheaths around the cylinder and gradually the entire neurone is regenerated.
What are functions of the sodium- potassium ATPases pumps?
- Pump 3 Na outside the cell and 2 K inside the cell.
- They generate a small negative charge inside the cell at rest.
- They generate concentration gradients for ions to move.
Which is the cell more permeable towards?
Potassium
Which direction does the chemical gradient of sodium moves?
Inwards
What is the value for a resting membrane potential for a nerve?
-70 mV
What is equilibrium potential?
Membrane potential at which the tendency to move against the electrical or concentration gradient is exactly balanced
What is the equilibrium potential for Chloride?
-70 mV ( equilibrium potential = resting membrane potential)
What is the equilibrium potential for sodium?
+61 mV
What is the equilibrium for potassium?
-94.1 mV
What are the assumptions of Nernst Potential?
1.Membrane is selectively and totally permeable to each ion.
2.Each ion is in electrochemical equilibrium across the membrane.
3.Diffusing ion is isolated from all other ions.
What is Hyperkalemia?
This is an INCREASE in the potassium levels in ones plasma concentration It can result in tachycardia ( Heart beats faster ie. >100 bpm)
What is Hypokalaemia?
This is a DECREASE in the potassium levels in ones plasma concentration.
What happens if there is an increase of the equilibrium potential of Potassium?
The membrane potential (Vm) decreases ( remember the homework!!)
What is Goldman’s Equation ?
The Goldman Equation relates the membrane potential, V, to the concentration gradient of, and membrane permeability to K+, Na+, and Cl- ions. It is derived by working out the membrane potential at which the fluxes of positive and negative ions balance perfectly, so that the net current flow will be zero, and the system will be in equilibrium.
V = RT Ln PK+ [K+]0 + P Na+ [Na+]0 + PCl-[Cl-]i
zF PK+ [K+]i + P Na+ [Na+ ]i + PCl-[Cl-]o
Which cells can undergo action potentials?
Neurons and Muscle cells
Values for depolarisation?
-70 mV to -55mV and to +35mv
Values for hyperpolarisation?
-70mV to -90mV
What is the threshold potential value?
-55mV
Does decreasing the external Na+ concentration have an effect on the resting membrane potential?
NO!
It has an effect on the ACTION POTENTIAL. Resting membrane potential uses leaky channels and the membrane is more permeable to K+ than NA+
Which sodium voltage gate is opened on the inside at rest?
The inactivated gate!!
At depolarisation, which sodium voltage gate is opened?
The activated gate!! ( on the outside)
True or False?
If there is an increase in K+ extracellular concentration , the resting membrane potential will reach closer to threshold potential which may elicit an action potential?
True!!
Remember hw( Using Goldman’s law when calculating an increase in K+ there was a decrease in the equilibrium potential ans = -56mV and Threshold potential is (-55mV)
What is the normal body potassium level?
3.5 - 5.0 mEq/L
What is the All or none law?
A minimum current of threshold intensity generates the full-fledged Action Potential.
Once initiated, the Action Potential does not change in size or form if the current strength is increased above the threshold intensity.
When does NA+ channel activation start?
After 7- 15 mV of depolarisation
What results in after hyper-polarisation?
Na+/ K+ ATPase pump returns the Resting Membrane Potential ( –70mV)
How can one treat Hyperkalemia?
- Enforce a low potassium diet
- IV administration of Calcium to protect the heart and muscles
- Administration of sodium bicarbonate to promote excretion of K+.
At what value are the activation gates for Calcium opened?
+35mV
Where is acetyl choline produced?
In the Synaptic bulb/ Terminal Ends
NOT in the cell body/soma.
What are the two types of Astrocytes?
Fibrous Astrocytes and Protoplasmic Astrocytes
True or False?
Protoplasmic Astrocytes are found in Gray matter?
TRUE!
Where are Fibrous Astrocytes found?
In White matter. FAW ( Fibrous Astrocytes - White Matter)
At what value is the firing level?
-55mV
What is the point at which re-stimulation can occur?
The after- depolarisation
How long does after hyper-polarisation lasts for?
40 ms
What is the Absolute Refractory Period?
This period starts from the Firing level until about 1/3 of repolarization is completed. During the Absolute refractory period NO stimulus , no matter how strong, will excite the nerve/ elicit an action potential.
What is the relative refractory period?
This period starts from the 1/3 depolarisation state , reached from the absolute refractory period, to after-depolarisation ( resting level). A stronger stimulus WILL cause excitation within the nerve.
What is Orthodromic conduction?
This is the normal conduction , in which action potential moves toward the distal ends
What is Antidromic conduction?
This is the conductions towards the soma , the action potential is dissipated in the soma.
Where are voltage gated Na+ channels highly concentrated at?
Nodes of Ranvier - 2,000 - 12,000
Initial segment - 350-500
What is the saltatory conduction?
It is a rapid process that allows myelinated axons to conduct up to 50 times faster than the fastest unmyelinated fibers by “jumping” from one node to the next.
True or False?
In a Hyperkalemic state , the resting membrane potential of skeletal muscle moves from a normal value of -90mV to a value of -60mV which inactivates Na+ channels and prevents action potential generation
TRUE!!
What are large axons normally associated with?
Proprioceptive sensation, somatic motor function, conscious touch and pressure.
What are small axons normally associated with?
Pain, temperature regulations and autonomic functions
Which nerve fibres are described as slow and gives off pain, temperature and other receptors?
C fibres
Which type of nerve fibres are ONLY found in the Autonomic nervous system?
B fibres (preganglionic)
True of false? A alpha fibres are the fastest and the most responsive nerve fibres.
TRUE!!
True of False? C fibres are all myelinated
FALSE!! All C fibres are UNMYELINATED. A & B fibres are all myelinated.
Which nerve fibres give off a sharp, prickly pain
A delta fibres
Which nerve fibres originate from the Golgi tendon organ?
A alpha Ib
Where does A alpha Ia originate from?
Muscle spindle, annulo-spiral ending
Which never fibres are the most susceptible to local anaesthetics?
C fibres ( Nociceptive fibres)
True or false? B fibres are the most susceptible to Hypoxia
TRUE!!
Which of the following is most susceptible to Pressure?
1.A fibres
2.B fibres
3.C fibres
A fibres
How does axonal Transport occur?
Along microtubules by dynein and kinesin
How does local anesthesia works ( lidocaine,bupivacine)?
They block the conduction of action potentials by blocking voltage -gated Na+ channels on the nerve cell. This causes a gradual increase in the threshold for electrical excitability of the nerve, a reduction in the rate of rise of the action potential, and a slowing of axonal conduction velocity.
What is the only naturally occurring local anesthetic?
Cocaine ( Erythroxylan coca)
What is the purpose of Neutrophins?
They are necessary for the growth and survival of neurons
Describe the nature of Nerve Growth Factor(NGF)?
It has 2 alpha subunits (trypsin like activity)
2 beta subunits
2 gamma subunits (serine protease activity)
How is NGF transported?
Retrograde Transport ( terminal ends to soma)
What is the function of Neurotrophin 3 (NT-3)?
NT-3 is important for proprioceptor neurons that innervate the muscle spindle and mechanoreceptors in the skin.
What is the function of Neurotrophin 4/5(NT -4/5)?
NT-4/5 is important for neurons that innervate the hair follicle
What is the function of brain -derived neurotrophic factor(BDNF)?
They can depolarise neurons.
What is Multiple Sclerosis (MS)?
In MS, antibodies and white blood cells in the immune system attack myelin, causing inflammation and injury to the sheath and eventually the nerves that it surrounds. Loss of myelin leads to leakage of K+ through voltage-gated channels, hyperpolarization, and failure to conduct action potentials.
What are the receptors for NGF?
Tyrosin Kinase A and p75
How wide is the synaptic cleft?
20-40 nm
What is the motor end plate?
Specialized portion of the sarcolemma of the muscle fibre innervated by a single motor nerve ending
What happens as the motor neuronal axon approaches the sarcolemma of the muscle fibre?
It loses its myelin sheath and divides into a number of terminal buttons.
The terminal ending fits into a depression of the muscle membrane which is thrown into folds called?
Palisades
Describe the nature of cholinergic transmission?
It is Ca2+ dependent
What is the name of the protein that Ca2+ binds to in the ANS ?
Calmodulin
What is the name of the enzyme that phosphorylates the Synapsin 1 molecule?
Ca 2+ calmodulin kinase
What are the functions of Synaptotagmin?
- Calcium sensor of release of the neurotransmitter.
- Allows for vesicle fusion proteins to bind during exocytosis.
- Involved in docking, binding and endocytosis f the synaptic vesicles.
What protein is inactivated by Tetanus toxin& Botulinum toxins?
Synaptobrevin
What is the time for the synaptic delay?
0.5 ms
True or False? Acetylcholine seeks out receptors that have high affinity for it, namely nicotinic receptors ONLY found in skeletal muscles.
TRUE!!
Which sub unit of the nicotinic receptor does Acetylcholine bind to?
Alpha subunit
What coats the vesicle facilitating the endocytosis?
Clathrin
What are the roles of the poisonous toxins( Clostridium tetani and Clostridium botulinum ?
These neurotoxins act by preventing the release of neurotransmitters in the CNS and at the neuromuscular junction. The tetanus toxins block the release of GABA and Glycine in which the activity of motor neurons is markedly increased. It causes a spastic paralysis.
Botox A, B and E are toxic to humans. They cleave SNAP-25 blocking the realise of Ach resulting in flaccid paralysis.
Benefits of Botox?
Can be used in Achlasia- it causes relaxation of the sphincter muscle.
Facial muscles to remove wrinkles
Injection into leg muscles to reduce speciosity in individuals with cerebral palsy.
What do Excited postsynaptic potentials EPSP do?
They open Na+ or Ca2+ channels in the postsynaptic membrane, producing an inward current.
Are EPSP’s produced by transient partial depolarisation or transient partial hyperpolarisation?
Depolarisation
Are IPSP’s produced by transient partial depolarisation or transient partial hyperpolarisation?
Hyperpolarisation ( They are produced by an increase in Cl- transport.
At what time do EPSP/IPSP’s peak?
1-1.5 ms after stimulus
True or false? There is an INCREASE in membrane potential towards the resting value ( +35 to -70)
TRUE!! ( more negative - Increasing membrane potential)
look at the numbers 35 to 70 is an increase lol
True or False? There is a DECREASE in membrane potential towards the resting value (-70 to +35)
TRUE ( more positive- decreasing membrane potential )
look at the numbers 70 to 35 is a decrease lol
Which one gives a quicker signal transmissions? Electrical or Chemical synapse?
Electrical synapses has a much quicker response. This is because they contain gap junctions formed between the cells resulting in a low resistance bridge in which ions can pass through easily.
What is the Latent Period?
This is the time taken for the impulse to reach the recording electrodes.
What happens during a local response?
During the slow rise to firing, Na+ channels begin to open .
Where are the cell bodies of the preganglionic sympathetic neurons located?
1.In the intermediolateral (IML) column of the spinal cord
2.In motor nuclei of some cranial nerves.
Describe pre-ganglionic axons?
They are small - diameter, myelinated , relatively slow conducting B fibres.
Describe post ganglionic neurons?
They are unmyelinated C fibres
Where do postganglionic neurons terminate?
They terminate on the visceral effectors.
What type of muscles are not under the control of the ANS?
Skeletal muscles
True or False? Not all neurons that leave the central nervous system release Acetylcholine
FALSE!! All neurons leaving the CNS release acetylcholine
What neurotransmitter do Postganglionic sympathetic neurons release?
Norepinephrine or Acetylcholine
Where is the sympathetic region located ?
T1- L2 ( the thoraco lumbar region )
Where is the parasympathetic region located?
Cranial nerves, 3( Occulomotor nerve), 7(Facial nerve),9 ( Glossopharangeal nerve) and 10 (Vagus nerve) and Sacral Nerves S2-S4 ( Cranio sacral region )
True or false? In the sympathetic nervous system Post- ganglionic fibres are Cholinergic.
FALSE!!! Post ganglionic fibres are ADRENERGIC because they release NE.
Pre ganglionic fibres are CHOLINERGIC because they release Acetylcholine.
True or False? In the parasympathetic nervous system, Post ganglionic fibres are Cholinergic.
TRUE!! In the PARASYMPATHETIC system both pre-ganglionic AND post-ganglionic fibres are CHOLINERGIC because they both release acetylcholine.
True or false? There are some exceptions to Sympathetic postganglionic neurons?
TRUE!! Some postgangionic sympathetic neurons are CHOLINERGIC and not adrenergic. These are: the sympathetic post ganglionic neurons that innervate the 1) Eccrine sweat glands 2) the blood vessels in some skeletal muscles
What is the name of the enzyme that breaks down acetylcholine?
Acetylcholinesterase
What is supplied by the greater splanchnic nerve?
Coeliac ganglion
True or False ? The superior mesenteric ganglion is supplied by the small (lesser ) splanchnic nerve.
TRUE!!
What does the least splanchnic nerve supply?
The inferior mesenteric ganglion
What is the name of the drug that blocks nicotinic cholinergic receptors for the Auntonomic ganglia of sympathetic and parasympathetic nerves and adrenal medulla (Nn)?
Hexamethonium
What is the name of the drug that block the nicotinic cholinergic receptors that are located in the neuromuscular junction of skeletal muscles?
D- Tubocurarine(Curare)
True or false? Lacrimal glands are sympathetic.
FALSE!! Lacrimal glands are PARASYMPATHETIC . They allow for the secretion of tears.
Which drug blocks the muscarinic cholinergic receptors?
Atropine
True or False? Adrenal medulla is directly innervated by postganglionic sympathetic fibers.
FALSE!! It is directly innervated by PREGANGLIONIC sympathetic system.
Where are cell bodies that release pre-ganglionic fibres found?
Lateral Horn
Where do cervical ganglia ( sympathetic system) provides innervation to?
Structures in the head- eyes and sacral organs.
Where do Sacral ganglia( sympathetic system) provide innervation to?
Pelvic organs
Fill in the blank” The axons of some of the postganglionic neurons leave the chain ganglia and reenter the spinal nerves via the ______”
Grey Rami communicans
Give some examples of pre vertebral ganglia in the Sympathetic system?
Coeliac ganglia
Superior mesenteric ganglia
Inferior mesenteric ganglia
“CSI”
True or False? Adrenal medulla has postganglionic neurons.
FALSE!!
What nerves arises from T5-T9
Greater splanchnic Nerves
What nerves arise from T10 -12?
Smaller splanchnic nerves
Fill I the blanks “ ________ arise from L1-L3.
Least splanchnic nerves
What percent of Epinephrine is released by the Adrenal Medulla during a sympathetic discharge?
80% ( 20% NE)
What receptors are present on arrector pili muscles?
Alpha 1 receptors
True or False? Atropine causes pupillary constriction?
FALSE!! It causes pupillary DILATION.
What happens when Atropine exceeds its therapeutic dose?
It causes the release of Histamine resulting in vasodilation causing a DECREASED blood pressure.
True or False? An overstimulation of the Pukinje system by the sympathetic system may result in an increased risk for Arrythmias?
TRUE!!
Fill in the Blank “ When SA Node is overstimulated it results in _______”
Positive Chonotropic Reaction
Fill in the blank “ When ______ is overstimulated it may result in a Dromotopic reaction .
AV Node
Where are M1 receptors located
CNS
Gastric gland
Salivary gland
Which receptors are placed at the Gastric glands , salivary glands, eye, GIT and blood vessels ?
M3 receptors
Where are M2 receptors
Heart , GIT and CNS
What receptors undergo the Gq pathway?
H1, α 1, V1 M1 and M3
“Queen Clarke said that you may HAVe 1 M&M
Queen - Gq pathway
Clarke - Activation of Protein Kinase C via IP3 and DAG
Where are norepinephrine, epinephrine and dopamine found?
In the plasma
True or False? Acetylcholine spreads farther and has a prolonged reaction than Norepinephrine.
FALSE!! NE spreads farther and has a prolonged reaction than Ach. Ach is the shortest acting neurotransmitter/ drug.
What type of receptors do the Atria and Ventricle contain?
β1 and β 2
Fill in the blank. “Binding of an agonist to β- adrenoceptors activates the __________ to activate adenylyl cyclase and increase cAMP.”
Gs-coupling protein
What receptors stimulate the G inhibitory coupling protein?
M2 α2 D2
“ People who are too(2) MAD inhibit themselves AAAAlot.
A- Andenyl cylase
A-ATP
A- cyclic Amp
A- Protein Kinase A
Which drugs can inhibit acetylcholinesterase at peripheral and central cholinergic synapses, prolonging the actions of acetylcholine at these synapses?
Organophosphates pesticides and Nerve gases
Give examples of organophosphates?
Parathion - Insecticide
Malathion - Insecticides
Sarin - Nerve gas
Soman - Neve gas
Echothiophate - Therapeutic
Which drugs can be described as irreversible anti cholinesterase?
Organophosphates
How can one treat Organophosphate toxicity?
Atropine and Pralidoxime
True or False? Atropine can reverese the nicotinic effects caused by Organophosphate toxicity?
FALSE!! Atropine can reverse the Muscarinic effects (DUMBBELSS).
True or False? Pralidoxime can be used to reverse the nicotinic effects of Organophosphate toxicity only within a few hours.
TRUE!!
Fill in the Blank. With regards to organophosphate toxicity, ______ can cross the BBB while ______ CANNOT cross the BBB.
Atropine and Pralidoxime
What are some examples of direct cholinomimetic agonists?
Bethany - Bethanechol
Call - Carbachol
Me- Methacholine
Please - Pilocarpine
“Bethany call me please”
What is contraction of the iris / constriction of pupils known as ?
Miosis
What are cholinomimetic drugs?
These are medications that directly act on muscarinic or nicotinic receptors, because they mimic acetylcholine.
Which drug is a potent stimulator of sweat, tears, and saliva and is used to treat Open-angle and closed-angle glaucoma and xerostomia (Sjogren syndrome
Pilocarpine
“You can cry, drool, and sweat on your PILow.”
Which drug can be used as a channel test for the diagnosis in Asthma?
Methacholine - It should stimulates muscarinic receptors in airway when inhaled.
Fill in the blank . “ Bethanechol is used in treatment for _______”
Urinary Retention
“ Bethany call me to activate your bladder”
P.S. I never came up with this one lol
Which drug is known as a carbon copy of acetycholine and is used to constrict pupils relive intraocular pressure in open-angle glaucoma?
Carbachol
What receptors do the drug Pilocarpine act on?
M3 receptors
What do indirect cholinomimetics (anticholinesterase) do?
They function by blocking the breakdown of acetylcholine into acetate and choline by acetylcholinesterase . This prolongs the action of acetylcholine in the synapse.
What are the drugs Donepezil, Rivastigmine, Tacrine, Galantime used to treat?
1st line treatment in Alzheimer’s disease
“ Dona Riva dances at ThAt Gala “
Which drug is used in the diagnosis of Myasthenia gravis?
Edrophonium (Alcohols)
Which drugs is used for the Treatment of Myasthenia Gravis, Paralytic ileus, urinary retention and the reversal of non-depolarizing neuromuscular blockade as with tubocurarine?
Neostigmine
Which direct cholinergic drugs are classified as Alkaloids?
Pilocarpine - Pass
Muscarine - Me
Nicotine - Netters
Lobeline - Lasts
” Pass Me Netters & Lasts”
Which direct cholinergic drugs are classified as Choline Esters?
Acetylcholine
Methacholine
Bethanechol
Carbachol
Why is Acetylcholine not given as a drug?
It has a very short half-life ( 5-30seconds)
It has a diffused activation of cholinergic system ( it’s non specific)
It is a highly polar compound and thus cannot cross BBB
Patients with what conditions should be cautiously watched when given Cholinergic drugs?
Patients with COPD, Asthma , Peptic Ulcers, Hypothyroidism , Ischemic Heart disease with coronary problems,Parkinson’s disease
True or False? Pyridostigmine is an Alkaloid?
FALSE!!! Physostigmine is an Alkaloid
Which group of irreversible cholinergic drugs can be classified as Carbamates?
Physostigmine
Neostigmine
Pyridostigmine
“Mines are carbamates”
What drug is used to treat for overdoses of Atropine, phenothiazines, tricyclic antidepressants?
Physostigmine
” Physostigmine phyxes(fixes) atropine overdose.
Fill in the bank “ __________ is also used for the treatment of Myasthenia Gravis(long acting) and it does not penetrate the CNS.
Pyridostigmine
Where does the Autonomic Nervous system arise from?
Neural Crest Cells
What are some examples of Synergism?
Salivation,
Secretion by exocrine glands of the gut,
Copulation
True or False? A decrease in membrane potential leads to Hyperkalemia.
TRUE!!
True or False? At low doses Atropine can increase the heart rate through central stimulation of a vagus nerve .
FALSE!! At low doses Atropine will DECREASE the heart rate through central stimulation of a vagus nerve.
Will high doses of Atropine result in Tachycardia?
Yes, It will block the M2 receptors of the heart.
What is the name of the enzyme which will convert Tyrosine to Dihydroxyphenylalanine(DOPA)
Tyrosine hydoxylase
What is the name of the enzyme which will convert DOPA to dopamine.
Amino acid decarboxylase
If there is a deficiency of the enzyme phenylethanolamine-N- methyltransferase which substance won’t be formed?
Epinephrine (Nor-epinephrine won’t get converted to Epinephrine)
What is the function of the enzyme Dopamine -B- hydroxyalse ?
To convert Dopamine to Nor-Epinephrine
What are examples of small molecule transmitters?
GABA, glutamate, glycine (Monoamines- NE,E, dopamine and serotonin)
What are large molecule transmitters?
Substance P, enkephalin, and vasopressin.
What is the name of the enzyme that converts acetyl and chloine to acetylcholine?
Choline acetyltransferase (ChAT)
What is the function of an autoreceptor?
They inhibit further release of the neurotransmitter.
True or False? Ionotropic receptors (Ligand-gated channels) are important for fast synaptic transmission?
TRUE!!
What are the two divisions of receptors?
Ligand-Gated Channels( Ionotropic receptors)
Metabotropic receptors (G - protein coupled receptors)
Fill in the blank “ After release of norepinephrine into the synaptic cleft, it is rapidly routed back into the sympathetic nerve terminal by a ________”
Norepinephrine transporter (NET)
What transports norepinephrine to re-enter the neuron to be sequestered into the synaptic vesicles?
Vesicular monoamine transporter (VMAT)
Which drug blocks the Na+-dependent choline transporter (CHT) which transports choline into the presynaptic nerve terminal.
Hemicholinium
What does the drug Vesamicol do?
It blocks the transport of Acetylcholine from the cytoplasm into vesicles by the vesicle- associated transporter (VAT)
True or False? Nn ( nicotinic receptors found in the CNS and Autonomic ganglia) is compromised of α, β, γ, δ, and ε subunits.
FALSE!!! Nn is only compromised of alpha and beta.
What subunits of nicotinic receptors found at the neuromuscular junction compromised of?
Two α, one β, one δ, and either one γ or one ε subunit
Where are M1 receptors located?
In the brain & autonomic ganglia
True or false? M3 receptors are found in the heart ?
FALSE!! M3 receptors are found on smooth muscles/glands
Fill in the blank “_______ are receptors are located on the heart”
M2
What is the rate limiting step in the synthesis of catecholamines?
The conversion of tyrosine to dopa
Which drug blocks dopamine from being transported from the cytoplasm into the vesicle by the vesicular monoamine transporter (VMAT)?
Reserpine
True or False? Epinephrine and norepinephrine are metabolized to biologically inactive products by OXIDATION by the enzyme Monoamine oxidase.
TRUE!!!
Fill in the blank “Epinephrine and norepinephrine are metabolized to biologically inactive products by METHYLATION by the enzyme _______”
Catechol-O-methyltransferase (COMT)
Where is the enzyme Monoamine oxidase found?
On the mitochondrion
Where is the enzyme catechol-O-methyltransferase (COMT) located?
liver, kidneys, and smooth muscles , brain glial cells, and small amounts are found in postsynaptic neurons.
What is the most plentiful catecholamine metabolite in the urine.
Vanillylmandelic acid
Fill in the blanks “Measurement of the concentrations of the O-methylated derivatives of Norepinephrine and Epinephrine ________ and __________ in the urine is a good index of their rate of release?
Normetanephrine and Metanephrine
True or False? The efferent nervous system involves conduction AWAY from CNS to the periphery.
TRUE!!! They go to the effector organs.
(Efferent - effector organs)
True or False? The afferent system involves conduction towards the nervous system.
TRUE!!
What is the name of the protein that takes the material down to the terminal endings?
Kinesin
What is the name of the protein used to take materials to the soma?
Dyenin
What location of the axon is unmyelinated?
Nodes of Ranvier
True or False? Axons contain Ribosomes.
FALSE!!! Axons do NOT contain ribosomes. The cell body synthesizes proteins.
What is the Release phenomenon?
When higher centres in the CNS are destroyed, activity of lower centres of CNS are often increased causing a unrestricted activity of a lower brain center.
What is the resting membrane potential for cardiac and skeletal muscle?
~ -85 to -90mV
True or False? At rest the membrane of the nerve cell is NOT permeable to Na+ ions but is permeable to K+ ions & Cl- ( partially ) due to the presence of the leaky channels.
TRUE!!!
What is the permeability ratio for each ion at rest ?
pK+ : pNa+ : pCl-
1 : 0.04 : 0.45
At what point can re-stimulation of the nerve occur?
After Depolarisation
What is Accommodation?
If excitation is maintained, Na+ voltage–gated channels will begin to flip from the closed rest state to the inactivated state, by-passing the activated state.
True or False? An increase in the extracellular Ca2+ levels (hypercalcemia) can cause stability of the membrane by reducing excitability.
TRUE!!!
True or False? Hypercalcemia causes an INCREASE in the excitability of nerves.
FALSE!!! HYPOCALCEMIA does that!!
Fill in the blanks. “The minimal intensity of stimulating current needed to produce an action potential is called the ______”
Threshold intensity
True or False? Compound action potentials follow the All or None Law.
FALSE!! They do NOT follow all or none law
What is the Compound Action Potential?
It is the maximal response reached when the maximal stimulus strength is attained.
Fill in the blanks. “ Core resistance ______ with fibre length.”
INCREASES
True or False? Thicker myelin sheaths are better insulators.
TRUE!!
Fill in the blanks. “________ elicits the process of Neurotransmission or low resistance bridges(gap junctions).”
Othrodromic Conduction
What is cholinergic crisis?
This develops as a result of overstimulation of nicotinic and muscarinic receptors at the neuromuscular junctions.
What are the different phases in Valve manoeuvre?
Phase I: Sudden rise in arterial pressure as the intrathoracic pressure adds to the aortic pressure
HR declines
Phase II: Compression of the veins prevents venous return, cardiac filling decreases and MAP falls
reflex tachycardia + TPR
Phase III: Glottis opens, BP falls due to the sudden fall in intrathoracic pressure
HR
Phase IV: BP rebounds due to rapid venous return
reflex bradycardia
What type of the brain heat production and regulates heat loss?
Anterior hypothalamus
How does one Treat Ryanaud’s disease?
*Block the sympathetic reflex response to cold.
*Cut the sympathetic chain at T2 – T3
*Lumbar sympathectomy at level L 2,3 can improve blood flow in the lower limbs
What type of Neurotransmission takes place within skeletal muscles & smooth & cardiac muscles?
Skeletal neurotransmission- stereotypical cholinergic neurotransmission
Cardiac& smooth muscle-diffuse transmission
What type of vesicles stores Glycine,GABA, Amino acids?
Flattened, clear ,vesicles
What neurotransmitter is stored in clear, spheroid vesicles?
Acetylcholine
Fill in the blanks.” Peptides are stored in ______ vesicle”
Large, dense-core
What type of vesicles stores Epinephrine NE,DA and serotonin?
Spherical , dense-core vesicles
Botulinum toxin A &B inactivates which vesicular membrane protein?
SNAP-25
Tetanus toxin & Botulinum toxins B, D,F inactivate which vesicular membrane protein?
Synaptobrevin
Syntaxin is inactivated by which botulinum toxin?
C
“ C - syntaxin”
