Lecture 1 Flashcards by Tedman McMahon

What type of transport does the Na/K pump use? be specific. (3 words)

Primary active transport

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General makeup of the PM:

lipid and protein, 50/50

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In what tissues are PM’s electrically excitable?

nerve and muscle cells

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What types of signals can a PM transduce into specific cellular responses and activities?

electrical, chemical, and mechanical

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Molecules that can freely diffuse across PM?

O2, CO2, N2, benzene

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Name 3 small uncharged polar molecules that can diffuse across the PM.

H2O, urea, glycerol

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Rate of diffusion equation:

(SA X conc. gradient X PM permeability) / PM thickness

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PM permeability is proportional to:

lipid solubility / molecular size

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about how many AA is the transmembrane alpha-helical polypeptide segment made of?

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Do peripheral proteins create a pathway for the movement of molecules from one side of the membrane to the other?

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This is the “revolving door” type of transport protein:

Carrier protein

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T or F? Carrier proteins are open simultaneously to both the inside and outside of the cell.

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Do carrier proteins use energy directly, indirectly, or both?

both

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Can carrier proteins move molecules against their concentration gradient?

Yes

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T or F? Channel proteins selectively allows for specific molecules to be transported across the membrane.

F. It has no control over what diffuses or the rate of difusion

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From where is energy derived in secondary transport?

the potential energy of the concentration gradient of a molecule (used to move another molecule against gradient)

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What molecule is frequently used in secondary transport to create the concentration gradient from which the energy is derived to transport the other molecule in secondary active transport?

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Is there typically a higher concentration of Na inside or outside the cell?

Outside

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T or F? 2 Na are pumped out for every 3 K that are pumped in.

F. 3 Na out/ 2 K in

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Does the Na/K pump make the inside of the cell more or less positive with every pump?

less positive

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How many transmembrane segments does the large alhpa subunit the Na-K pump have?

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Which subunit positions the Na-K pump in the membrane?

extracellular beta subunit

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How many times does the gamma subunit of the Na-K pump cross the membrane?

1 time

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How many subunits does the Na-K pump have and name them.

3, alpha, beta, gamma

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What is required for the transitional changed bw open and closed states of the Na-K pump?

ATPase activity, P binds to the protein carrier

What charge does P have?

What should you add to a protein if you want to change its shape?

How is the conformation of the Na-K pump changed once the Na has been released to the ECF and K has bound?

P is removed, causing the change in shape

How many ATP are required for each cycle of opening and closing of the Na-K pump?

1 ATP

What percentage of the energy of the body is consumed by the Na-K pump?

about 25%

What percentage of the energy of the brain is consumed by the Na-K pump?

about 70%

T or F? The more Na outside the cell, the lower the stored PE

F. greater PE

Creates a charge gradient:

electrogenic

Does the Na-K contribute a large amount to the resting negative MP of neurons?

Does the Na-K contribute a large amount to the resting negative MP of smooth muscles?

Yes

T or F? The Na-K contributes more to the resting negative MP of the neuron than of smooth muscle.

F. contributes more to the smooth muscle

The transport of Na into the cell is often coupled with the transport of this into the cell:

glucose

What is the name of the protein carrier involved in the coupled transport of Na and glucose into the cell?

SGLT protein

The binding of what molecule causes the change in conformation of the SGLT protein?

glucose

Which molecule is both the first to bind on the EC side and release on the IC side of the SGLT protein?

Na+

What other pump/exchanger depends on the Na-K pump?

Na-Ca exchanger

How would the Ca concentration be effected, if at all, if the Na-K pump was non-functional while the Na-Ca exchanger was functional?

Ca++ will build up in the cell

What effect will digitalis have on a cell?

it will raise the Ca++ levels in the cell

What effect will digitalis have on the heart?

enhance muscle contraction, improving muscle function

What type of transport does the Na-Ca use?

Secondary Active Transport

What effect does ouabain have on a cell?

blocks the Na-K pump

What 2 drugs can block the Na-K pump?

ouabain and digitalis

What effect will low doses of digitalis have on the heart muscle?

raise Na inside heart muscle

How will the Ca levels in the heart muscle be effect with low doses of digitalis?

Na levels will be raised and this will slow the removal of Ca via the Na-Ca exchanger

Another name for potential difference:

voltage

T or F? The Na/K pump creates a lare negative charge inside the cell.

F. Only creates a small neg charge in cell

You should always assume he net charge outside the cell is:

zero

When is the resting MP the EP (equilibrium potential)?

electrical gradient exactly opposes the chemical gradient

Around how much K would have to leave the typical cell to reach EP (equilibrium potential)?

very little, less than 1/10th

Functions of electrical signals in neurons:

1. combine info from many inputs 2. transmit info 3. activate mem proteins 4. stimulate transmitter release

Mathematic term for membrane potential difference:

70 mV = 70 ____ th of a volt:

thousandth

in what type of solution is a cell placed when measuring internal voltage with a voltmeter?

saline solution

How can you measure a current?

count the # of ions passing through (ions/sec)

This is the energy to move charge:

voltage

How is conductance calculated?

1/Resistance

This is a measure of the ease of moving a charge across a membrane:

conductance

2 ways to decrease conductance:

make path longer or more narrow

T or F? Excitation is occurring when a cell is made more positive.

T or F? Excitation is occurring when a cell is made more negative.

F. inhibition

T or F? Excitation of the cell leads to polarization of the cell.

F. Depolarization

T or F? The flow of Cl- into a cell will lead to depolarization.

F. hyperpolarization

Will the outflow of K+ from a cell depolarize of hyper polarize the cell?

hyperpolarize

2 ways to hyperpolarize a cell:

Increase flow of Cl- in or increase flow of K+ out

Depolarization initiates what 2 events?

AP production and neurotransmitter release at synapse

Would hyperpolarization make the production of an AP more or less difficult?

T or F? When the cell depolarizes the membrane potential increases.

F. The membrane potential decreases.

T or F? When the cell hyperpolarizes the membrane potential increases.

What do aquaporin channels allow the passage of?

water, glycerol, ammonia, and urea

Can charge molecules pass through aquaporins?

How many times does the aquaporin span the membrane?

6-transmembrane structure

Where are aquaporins most prominent?

kidney

T or F? Facilitated diffusion can move molecules across a membrane that would normally not cross the membrane over any amount of time, no matter how long.

F. Any of the molecules would pass through, some just very slowly

is the carboxylic end of the aquaporin positioned on the L or R side?

T or F? As the solute concentration of a fixed volume of water increases, the concentration of the water increases.

F. the concentration of the water decreases

Will the concentration of water increase of decrease when salt is added to 1L of water?

decrease

symbol for osmotic pressure:

symbol for pi

define osmotic pressure:

hydrostatic pressure (force) required to counterbalance osmosis

Which solution has a higher water concentration, 0.1 M sucrose solution or 0.01 M sucrose solution?

0.01 M sucrose solution

This is the pressure water exerts on a membrane dividing two compartments filled with solution:

osmotic pressure

Equation for osmolarity:

molarity of solute X # of solute particles that dissociate in solution

What is the osmolarity of 0.15 M NaCl?

0.3 osm

What is the osmolarity of 0.1 M MgCl2?

O.3 osm

What is the osmolarity of body fluids, e.g. CSF?

.35 osm

if the cell's volume increases when placed in a solution, the solution is (hyper/hypo)tonic?

hypo

if the cell's volume decreases when placed in a solution, the solution is (hyper/hypo)tonic?

hyper

whether water would go in or out of a cell when placed in solution:

tonicity

Molarity of blood:

0.15 M (check)

What can happen to neurons when they are under stress such as in a stroke?

they can lyse

T or F? All isosmotic solutions are isotonic solutions.

What would happen to a RBC placed in a 0.3M glycerol solution?

it will lyse

How can a cell avoid lysing if it is place in a hypotonic solution?

swell channels, allowing solute to leave the cell

What molecule(s) can leave the cell via swell channels?

Cl- (and K+?)