Cell Physio (review test)

Question 1

Shared characteristics of simple and facilitated diffusion of glucose

Answer 1

Both types occur down an electrochemical gradient

Question 2

During upstoke of the nerve action potential

Answer 2

There is net inward current and the cell interior becomes less negative

• Te inward current is carried by sodium
• movement of positive charge into the cell

Question 3

Solution A and B are separated by a semipermeable membrane that is permeable to K but not to Cl. Solution A is 100 mM KCL and solution B is 1 mM KCL. what will happen?

Answer 3

K will diffuse from solution A to solution B until a membrane potential evelops with solution A negative with respect to solution B

Question 4

The correct temporal sequence for events a the neuromuscular junction is

Answer 4

Uptake of ca into the presynaptic terminal; release of ACh; deoplarization of the muscle end plate

Question 5

Characteristic component shared by skeletal and smooth muscle

Answer 5

Elevation of intracellular calcium for excitation-contraction coupling

Question 6

Repeated stimulation of a skeletal muscle fiber fauses a sustained contraction. Accumulation of which solute in intracellular fluid is responsible for tetanus

Answer 6

Calcium

Question 7

Soluions A and B are separated by a membrane that is permeable to calcium and impermeable to Cl. Solution A contains 10 mM CaCl2 ans solution B contains 1 mM CaCl2. Assuming that 2.3 RT/F = 60mV, Ca will be at electrochemical equilibrium when

Answer 7

solution A is -30mV

Question 8

A 42 y/o man with myasthenia gravis notes increased muscle strength when he is treated with AChE inhibitor. The basis for his improvement is increased

Answer 8

levels of ACh at the muscle end plate

Question 9

In a hospital error, a 60 year old woman is infused with large volumes of a solution that causes lysis of her RBC. The solution was most likely

Answer 9

300mM urea

• 150mM NaCL and 300mM mannitol are isotonic
• 350mM mannitol and 150mM CaCl2 are hypertonic
• 300 MM urea is hypotonicc

Question 10

During a nerve action potential, a tmulus is deliered as indicated by the attow shown in the following figure. In response to the stimulus, a second action potential _____

Answer 10

will not occur

• because the stimulus was delivered during the absolute refractory portion

Question 11

Solution A and B are separated by a membrane that is permeable to urea. Solution A is 10MM urea, and soluton B is 5 mM urea. if the concentration of urea in solution A is doubled, the flux of urea across the membrane wall will

Answer 11

Triple

• Flux is proportional to the concentration dfference across the membrane

Question 12

A muscle cell has an intracellular [Na] od 14 mM and extracellular [Na] of 140 mM. Assuming that 2.3 RT/F = 60 mV, what would the membrane potential be if the muscle cell membrane were permeable to Na?

Answer 12

+60

• Nernst equation
• ENa = 2.3RT/zF Log Ce/Ci = 60 mV log 140/14 =60

Question 13

at which labeled poiny on the action potential is K+ closest to electochemical equilibrium?

Answer 13

5

• the hyperpolarizing afterpotential represents the period durimg K permeability is the highest and the membrane potential is clsoest to the K equilibrium potential

Question 14

What process is responsible for the change in membrane potential that occurs between poin1 and point 3

Answer 14

Movement of na into the cell

Question 15

What process is responsible for the change in membrane potential that occurs between point 3 and point 4

Answer 15

Movement of K out of the cell

Question 16

The velocity of conduction of action potential along a nere will be increased by

Answer 16

myelinating the nerve

Question 17

Solutions A and B are separated by a semipermeable membrane. Solution A contains 1 mM sucrose and 1mM urea. Solution B contains 1 mM sucrose. the reflection coefficient for urea is zero. for sucrose is one. What will happen

Answer 17

Solution A is hyperosmotic with respect to solution B, and the solutions are isotonic

*

Question 18

transport of D and L glucose proceeds at the same rate down the elctrochemical gradient by which of the following processes

Answer 18

facilitate diffusion

Question 19

how can we double permeability of a solute in a lipid bilayer

Answer 19

doubling the oil/water partition coefficient of the solute

Question 20

A newly developed local anesthetic blocks sodium channels in nerves. Which of the following effects on the action potential would it be expected to produce?

Answer 20

Decrease the rate of rise of the upstroke of the action potential

Question 21

At the muscle end plate, ACh causes opening of the

Answer 21

Na and K channels and depolarization to a value halfway between sodium and K equilibrium potentials

Question 22

An inhibitory postsynaptic potential

Answer 22

hyperpolarizes the postynaptic membrane by opening Cl channels

Question 23

Which of the followinf would occur as a result of the inhibition of Na, K, ATPase?

Answer 23

increased intracellular calcium concentration

Question 24

Temporal sequence for excitation-contraction coupling in skeletal muscle?

Answer 24

Action potential in the muscle membrane; depolarization of the T tubules; release of calcium from the SR

Question 25

Which of the following transport processes is involved if transport of glucose from the intestinal lumen into a small intestinal cell is inhibited by abolishing the usual Na gradient across the cell membrane?

Answer 25

Cotransport

Question 26

In skeletal muscle, which of the following events occurs before depolarization of the T tubules in the mechanism of excitation contraction coupling?

Answer 26

Depolarization of the sarcolemma membrane

Question 27

Which of the following is an inhibitory neurotransmitter in the CNS

Answer 27

GABA

Question 28

ATP is used indirectly for which of the following processes

Answer 28

Absorption of glucose by intestinal epithelial cells

Question 29

Causes rigor in the skeletal muscle?

Answer 29

A decrease in ATP level

Question 30

Degeneration of dopaminergic neurons has been implicated in ____

Answer 30

Parkinson disease

Question 31

Assuming complete dissociation of all solutes, which of the ff would be hyperosmotic to 1mM NaCl?

• A. 1mM glucose
• B. 1.5 mM glucose
• C. 1 mM CaCl2
• D. 1 mM sucrose
• E. 1mM KCl`

Answer 31

1mM CaCl2

Question 32

A new drug is developed that blocks the transporter for H+ secretion in the gastric parietal cells. Which of the following transport processes is being inhibited?

Answer 32

Primary active transport

Question 33

A 56 y/o woman with severe muscle weakness is hospitalized. The only abdnormality in her labratory values is an elevated serum K concentraion. the elevatedserum K causes muscle weakness because

Answer 33

Na channels are closed by depolarization

Question 34

In contraction of GI smooth muscle, this event occurs after bindinf of calcium to calmodulin

Answer 34

Increased myosin-light-chain kinase

Question 35

In an experimental preparation ofa nerve axon, membrane potential (Em), K equilibrium potential and K conductance can be measured. Which combination of values will create the largest outflow current flow

Answer 35

E