All of the following are true except
The role of negative feedback system is to bring it back to Set point
The role of a positive feedback is all about destabilizing the system and amplifying the signal
Blood clotting, uterine contractions in response to oxytocin are examples of positive feedback
None of the above
All of the following are true about diffusion is dependent
It is dependent on the cross sectional area thru which the flow of solute is measured
The difference in solute concentration between regions
The distance (or thickness) between regions A and B
The lipid solubility of the solute
The difference in solvent concentration between regions
All of the following are true about diffusion except?
IF you increase the molecular size the Net flux increases
The more the solubility in lipid the faster that molecule diffuses (like CO2 vs O2)
The thinner the membrane the faster the net flux
larger the concentration difference the faster the net flux
In osmosis there is net movement (passive) of Water across a semi permeable membrane
When thinking about Tonicity, think ONLY about NaCL
The following are the sequence of events if you add water to ECF - all are true except?
ECF will be diluted compared to ICF
Water will move from ECF to ICF
Increase in ECF volume and decrease in ICF volume
Once it reaches equilibrium both ECF and ICF will have the same osmolarity
Protein Mediated Transport rate will be faster with increase in substrate concentration
All of the following about Cardiac glycosides (digitalis) are true except?
Blocks NaK ATPase
Increase the ICF concentration of Na and decrease the ICF concentration of K
This will increase the chemical gradient for Na to come into the cell
Ca antitransporter slows down which increases the ICF conc of Ca thereby increasing contractility
All of the following are true about RMP except
When RMP = -110 mv inside is more negative --> draws K into the cell and it is hyperpolarized enough to have more K coming in than leaving, despite that being against it's conc gradient
When RMP = +30 inside is more positive than the outside -->both the electrical and chemical gradient is pushing K out of the cell
none of the above
Generation of resting membrane potential - all the following true except?
if only K is permeable, Equilibrium potential for K will determine the RMP and it will be -94mV
If only Na is permeable then the RMP would be +60mV (which is the equilibrium potential for Na)
When there are 2 ions moving (back of forth thru the membrane) the RMP will be determined by the ion with the greater number of leaky (non-gated) channels
Increasing the ECF concentration of NA makes the RMP more positive
If you make the membrane even more permeable to K - then the membrane will be hyperpolarized
All of the following are true about Electronic Potentials except?
Subthreshold depolarizing events
Chemical, mechanical stimuli
Polarity inside positive
Does not propagate
No refractory period
All are true about Action potential except?
All or nothing event
Chemical or mechanical stimuli
Polarity with inside positive
Propogates
Refractory period (including Absolute refractory period)
All of the following are true except?
At rest - membrane is most permeable to Na
At Threshold - voltage-gated Na channels open
Rising phase and overshoot - membrane becomes so depolarized that it overshoots and is reversed in polarity
At or near the peak the Na permeability begins to decrease and K permeability through voltage-gated K channels increase (Both channels open in response to hitting Threshold, just Na open much faster)
Repolarization - Na voltage gated channels have started closing and voltage gated channels are opening
After hyperpolarization - voltage gated K channels are still open but they will gradually close at this point
TEA (tetra ethyl ammonium)
Block K current
Repolarization is affected
You can still get an AP (action potential) with this
all of the above are correct
TTX (Tetrotoxin) and Saxitoxin (STX)
Block Na voltage gated channels
Affects repolarization
cannot trigger an AP
All of the following about AP are true except?
AP is initiated at axon hillock - where there are the greatest number of voltage-sensitive gates are located
Nodes of Ranvier will increase the propagation of the AP
Inhibitory Post synaptic mediators like GABA will activate Cl- channels which causes and influx of Cl- which in turn will hyperpolarize the cell
the slower the Time Constant the greater the Propagation Velocity
The greater the Length(space) Constant the shorter the membrane will stay depolarized
Electrical Synapse has Bidirectional flow whereas a Chemical synapse has Unidirectional flow
The Following is the sequence of events at the synapse
An AP arrives at the presynaptic terminal
Voltage-gated Ca channels open and Ca enters the cell
This Ca triggers the fusion of synaptic vesicle with the post synaptic membrane
NTM (neuro transmitter) diffuse across the synaptic cleft and bind to the specific receptors on the post synaptic cell
Bound receptors will activate the post synaptic cell and the NTM breaks down and is taken up by the pre synaptic terminal or other cells or diffuses away from the synapse
All of the following about the toxins are true except?
Conotoxin will inhibit the release of NTM
Tubocurarine and Bungotoxin block the AcH receptors
Tetanus toxin cleaves synaptobrevin - prevents the release of GABA - causing spastic paralysis
Botulin cleaves synaptobrevin - prevents the release of Ach - flaccid paralysis
Metabotropic receptor acts through a secondary messenger
Inhibitory Postsynaptic Potentials (IPSP) act either by Opening of Cl- or K+ channels
NE is the primary excitatory transmitter for postganglionic neurons of the sympathetic nervous system
Degeneration of Dopaminergic neurons in substantia Nigra leads to Parkinson's disease
Dopamine can be used as treatment for Parkinson's disease
All of the following are inhibitory NTMs except
Glutamate
GABA
Glycine
All of the above
Nicotinic receptors are Metabotropic whereas Muscarinic receptors are Ionotrophic
NMDA receptor is specifically excitatory glutamate receptor for which Glycine must also be bound for the ion channel to open
Temporal summation occurs when consecutive synaptic potentials arrive at the postsynaptic cell and add together
PCP(phencyclidine) is the antagonist for NMDA receptor
