BIOG 1440 Prelim 4 Poll Ev

What does the Nernst equation describe?

A. the membrane potential where electrical force = chemical force for an ion

B. equilibrium potential for an ion

C. reversal potential for an ion

A, B, C

A resting potential is recorded as -60 mV. If you add a drug that blocks all Na channels, what will happen to resting potential?

A. it will not change

B. it will depolarize towards ENa

C. It will hyperpolarize slightly

D. It will hyperpolarize to EK

D

Resting potential is recorded as -60 mV. You artificially depolarize the cell to -50 mV. What happens to the Na and K currents flowing through the leak channels?

A. INa will decrease while IK will increase

B. INa will increase while IK will decrease

C. Both INa and IK will increase

D. Both INa and IK will decrease

A

Because of the electrochemical gradient, when voltage-gated sodium channels first open,

A. sodium ions diffuse in, and the inside of the membrane will become more negative.

B. sodium ions diffuse in, and the inside of the membrane will become more positive.

C. sodium ions diffuse out, and the inside of the membrane will become more positive.

D. sodium ions diffuse out, and the inside of the membrane will become more negative.

B

Why are electrical synapses faster than chemical synapses?

A. direct current flow from pre to post synaptic cell

B. no need to open pre-synaptic calcium channels

C. no need to fuse vesicles with membrane

D. all of the above

D

In a chemical synapse,

A. APs in the pre synaptic terminal cause voltage gated calcium channels to open

B. neurotransmitters can cause ligand gated Na channels to open

C. neurotransmitters can be broken down by enzymes

D. neurotransmitters can be taken up by the presynaptic terminal

E. all of the above

E

Why are modulatory G protein coupled receptor responses slower than ionotropic responses?

A. need to activate G protein

B. need to synthesize second messengers

C. there is second messenger mediated protein modification

D. channels open only after the protein modification

E. all of the above

E

Why are excitatory post synaptic potentials excitatory?

A. they are depolarizing from the resting potential

B. they open channels to cations

C. they aim to depolarize the cell above the AP threshold

D. they close channels to ions

C

If a neuron has 3 excitatory inputs and one inhibitory input, and they all fire at the same time, the response will be

A. three times as large as single EPSP

B. two times as large as single EPSP

C. larger, but unsure of how much

D. cannot determine

D (depends on spatial position of inputs)

Sensory stimuli active sensory receptors by...

A. directly triggering ion channels to open

B. directly generating an action potential

C. directly polarizing a neuron

D. triggering ion channels to open via a second messenger

A,D

If receptor potential is sufficient, it can trigger an AP carried to CNS. Which of the following are true?

A. receptor response is all or nothing

B. receptor response is relative to stimulus strength

C. action potential is all or nothing

D. action potential magnitude is relative to stimulus strength

E. action potential frequency is relative to stimulus strength

B, C, E

What occurs after involuntary skeletal muscle stretch?

A. gamma motor neurons in the muscle spindle are activated, signal is sent to spinal cord, alpha motor neurons activated, signal sent to same muscle, muscle contracts

B. sensory neurons in muscle spindle activated, signal sent to spinal cord, alpha motor neurons activated, signal sent to same muscle, muscle contracts

C. sensory neurons in muscle spindle activated, signal sent to spinal cord, gamma motor neurons activated, signal sent to antagonistic, muscle contracts

D. sensory neurons in muscle spindle activated, signal sent to spinal cord, alpha motor neurons activated, signal sent to same muscle, muscle relaxes

B

Which of the following happens during voluntary behavior?

A. sensory stimulus initiates behavior

B. gamma motor neurons are activated to inhibit spindle

C. alpha motor neurons contract spindle

D. alpha and gamma motor neurons get excited together

D

Which protein shortens when muscles contract?

A. myosin

B. actin

C. troponin

C. tropomyosin

D. none of the above

D

What events occur prior to the actin-myosin interactions that lead to sarcomere contraction?

A. Na released by sarcoplasmic reticulum

B. Ach released by a motor neuron

C. Ach binds receptors on a muscle cell plasma membrane

D. voltage gated Ca channels open

E. Ca released by motor neuron

F. protein complex binds Ca

G. protein complex undergoes a conformational shift to expose myosin heads

H. the flow of ions down a concentration gradient provides the energy for repeated actin-myosin interactions

B, C, D, F

What features do the movement of striated muscle and eukaryotic cilia have in common?

A. use of ATP hydrolysis

B. constrained by nexin

C. use of intracellular motor proteins

D. depend on calcium ion concentration

E. depend on sliding microtubules

A, C

Which are true about prokaryotic flagella?

A. powered by ATP hydrolysis

B. the basal body acts as a motor

C. driven by ions flowing down a concentration gradient

D. stimulated by neurotransmitter release

E. stimulated by molecules binding to chemoreceptors

B, C, E