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Cell membrane potential and homeostasis questions

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Physiology I

Physiology I

Question 1 of 33

1

All of the following are true except

Select one of the following:

  • 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

Explanation

Question 2 of 33

1

All of the following are true about diffusion is dependent

Select one of the following:

  • 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

Explanation

Question 3 of 33

1

All of the following are true about diffusion except?

Select one of the following:

  • 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

Explanation

Question 4 of 33

1

In osmosis there is net movement (passive) of Water across a semi permeable membrane

Select one of the following:

  • True
  • False

Explanation

Question 5 of 33

1

When thinking about Tonicity, think ONLY about NaCL

Select one of the following:

  • True
  • False

Explanation

Question 6 of 33

1

The following are the sequence of events if you add water to ECF - all are true except?

Select one of the following:

  • 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

Explanation

Question 7 of 33

1

Protein Mediated Transport rate will be faster with increase in substrate concentration

Select one of the following:

  • True
  • False

Explanation

Question 8 of 33

1

All of the following about Cardiac glycosides (digitalis) are true except?

Select one of the following:

  • 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

Explanation

Question 9 of 33

1

All of the following are true about RMP except

Select one of the following:

  • 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

Explanation

Question 10 of 33

1

Generation of resting membrane potential - all the following true except?

Select one of the following:

  • 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

  • none of the above

Explanation

Question 11 of 33

1

Increasing the ECF concentration of NA makes the RMP more positive

Select one of the following:

  • True
  • False

Explanation

Question 12 of 33

1

If you make the membrane even more permeable to K - then the membrane will be hyperpolarized

Select one of the following:

  • True
  • False

Explanation

Question 13 of 33

1

All of the following are true about Electronic Potentials except?

Select one of the following:

  • Subthreshold depolarizing events

  • Chemical, mechanical stimuli

  • Polarity inside positive

  • Does not propagate

  • No refractory period

Explanation

Question 14 of 33

1

All are true about Action potential except?

Select one of the following:

  • All or nothing event

  • Chemical or mechanical stimuli

  • Polarity with inside positive

  • Propogates

  • Refractory period (including Absolute refractory period)

Explanation

Question 15 of 33

1

All of the following are true except?

Select one of the following:

  • 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

Explanation

Question 16 of 33

1

TEA (tetra ethyl ammonium)

Select one of the following:

  • Block K current

  • Repolarization is affected

  • You can still get an AP (action potential) with this

  • all of the above are correct

Explanation

Question 17 of 33

1

TTX (Tetrotoxin) and Saxitoxin (STX)

Select one of the following:

  • Block Na voltage gated channels

  • Affects repolarization

  • cannot trigger an AP

Explanation

Question 18 of 33

1

All of the following about AP are true except?

Select one of the following:

  • 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

  • none of the above

Explanation

Question 19 of 33

1

the slower the Time Constant the greater the Propagation Velocity

Select one of the following:

  • True
  • False

Explanation

Question 20 of 33

1

The greater the Length(space) Constant the shorter the membrane will stay depolarized

Select one of the following:

  • True
  • False

Explanation

Question 21 of 33

1

Electrical Synapse has Bidirectional flow whereas a Chemical synapse has Unidirectional flow

Select one of the following:

  • True
  • False

Explanation

Question 22 of 33

1

The Following is the sequence of events at the synapse

Select one of the following:

  • 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

Explanation

Question 23 of 33

1

All of the following about the toxins are true except?

Select one of the following:

  • 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

  • none of the above

Explanation

Question 24 of 33

1

Metabotropic receptor acts through a secondary messenger

Select one of the following:

  • True
  • False

Explanation

Question 25 of 33

1

Inhibitory Postsynaptic Potentials (IPSP) act either by Opening of Cl- or K+ channels

Select one of the following:

  • True
  • False

Explanation

Question 26 of 33

1

NE is the primary excitatory transmitter for postganglionic neurons of the sympathetic nervous system

Select one of the following:

  • True
  • False

Explanation

Question 27 of 33

1

Degeneration of Dopaminergic neurons in substantia Nigra leads to Parkinson's disease

Select one of the following:

  • True
  • False

Explanation

Question 28 of 33

1

Dopamine can be used as treatment for Parkinson's disease

Select one of the following:

  • True
  • False

Explanation

Question 29 of 33

1

All of the following are inhibitory NTMs except

Select one of the following:

  • Glutamate

  • GABA

  • Glycine

  • All of the above

Explanation

Question 30 of 33

1

Nicotinic receptors are Metabotropic whereas Muscarinic receptors are Ionotrophic

Select one of the following:

  • True
  • False

Explanation

Question 31 of 33

1

NMDA receptor is specifically excitatory glutamate receptor for which Glycine must also be bound for the ion channel to open

Select one of the following:

  • True
  • False

Explanation

Question 32 of 33

1

Temporal summation occurs when consecutive synaptic potentials arrive at the postsynaptic cell and add together

Select one of the following:

  • True
  • False

Explanation

Question 33 of 33

1

PCP(phencyclidine) is the antagonist for NMDA receptor

Select one of the following:

  • True
  • False

Explanation

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