Question 1

Given the Nernst equation $$E_{ion} = 61 \frac{1}{z} \log \frac{[ion]_{out}}{[ion]_{in}}$$, what would happen to the equilibrium potential for potassium ($$K^+) if $$the extracellular concentration increases from 3 mM to 7 mM while the intracellular concentration remains at 150 mM?

Accepted Answer

The equilibrium potential for $$K^+$$ becomes less negative.

Question 2

Using the Goldman equation $$V_m = 61 \log \frac{P_{K^+}[K^+]_{out} + P_{Na^+}[Na^+]_{out} + P_{Cl^-}[Cl^-]_{in}}{P_{K^+}[K^+]_{in} + P_{Na^+}[Na^+]_{in} + P_{Cl^-}[Cl^-]_{out}}$$, which ion has the greatest influence on the resting membrane potential in the alpha motoneuron described?

Accepted Answer

Potassium ($$K^+)$$

Question 3

If the permeability of sodium ($$P_{Na^+}) $$increases significantly while other permeabilities remain constant, what is the expected effect on the membrane potential ($$V_m$$)?

Accepted Answer

$$V_m$$ will shift toward the equilibrium potential of sodium ($$E_{Na^+}).$$

Question 4

In Petri dish #3 ([K+] = 5 mM, [Na+] = 100 mM, [Cl-] = 110 mM), what is the primary electrochemical force acting on sodium ions?

Accepted Answer

Sodium ions will tend to move into the cell due to both concentration and electrical gradients.

Question 5

A motoneuron is placed in Petri dish #6 ([NaCl] = 250 mM, [Urea]= 0 mM, [Glucose] = 0 mM). If the ICF osmolarity is 300 mOsM, what will happen to the cell?

Accepted Answer

The cell will shrink because the solution is hyperosmotic and hypertonic.

Question 6

Which of the following best describes the effect of urea in Petri dish #7 ([NaCl] = 100 mM, [Urea]= 100 mM, [Glucose] = 0 mM) on cell tonicity?

Accepted Answer

Urea is penetrating, so the solution is hypotonic despite being isoosmotic.

Question 7

A cell is placed in Petri dish #8 ([NaCl] = 100 mM, [Urea]= 0 mM, [Glucose] = 100 mM). If glucose is non-penetrating, what is the osmolarity and tonicity of the solution?

Accepted Answer

The solution is isoosmotic and isotonic.

Question 8

Which statement about the synaptic arrangement shown in the image is correct regarding summation?

Accepted Answer

Neuron Z can experience spatial summation if it receives simultaneous inputs from neurons W, X, and Y.

Question 9

If neurons W, X, and Y release excitatory neurotransmitters onto neuron Z, what is the likely effect on neuron Z?

Accepted Answer

Neuron Z is more likely to reach threshold and fire an action potential.

Question 10

Which of the following is true regarding the channels involved in action potentials?

Accepted Answer

Voltage-gated sodium channels open rapidly during the depolarization phase.

Question 11

If inhibitory synapses are genetically modified to express adrenergic receptors that block IPSPs, what is the expected effect on the patellar reflex in anesthetized mice?

Accepted Answer

The patellar reflex will be exaggerated due to loss of inhibition.

Question 12

Which statement best describes the role of the peripheral nervous system in the patellar reflex?

Accepted Answer

The peripheral nervous system transmits sensory and motor signals involved in the reflex arc.

Question 13

True or False: The equilibrium potential for chloride ($$Cl^-) $$will be positive if the extracellular concentration is lower than the intracellular concentration.

Accepted Answer

False

Question 14

True or False: Urea contributes to tonicity in a solution because it is a non-penetrating solute.

Accepted Answer

False

Question 15

Which of the following scenarios would result in a cell swelling?

Accepted Answer

Placing the cell in a hypotonic solution.

Question 16

Which statement is correct regarding the effect of anesthetics on neural communication during the patellar reflex?

Accepted Answer

Anesthetics reduce neural communication by inhibiting synaptic transmission.

Question 17

Which of the following is a multi-step process that integrates both osmolarity and tonicity concepts?

Accepted Answer

Calculating the osmolarity and then determining the tonicity based on the presence of penetrating and non-penetrating solutes.

Question 18

Which of the following is true regarding graded potentials in the synaptic arrangement shown in the image?

Accepted Answer

Graded potentials can summate to trigger an action potential in neuron Z.

Study Guide: Membrane Potentials, Osmolarity, Tonicity, and Neuronal Communication

Study Guide - Practice Questions

Study Guide - Flashcards