Physiology & Anatomy of Systems Quiz

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Questions and Answers

What is the primary effect of opening sodium (Na+) channels in a cell?

Hyperpolarization

No change in membrane potential

Depolarization (correct)

Repolarization

Which force primarily causes the efflux of potassium (K+) out of the cell when potassium channels open?

Attraction due to opposing charges

Concentration gradient leading to diffusion (correct)

Electrical gradient favoring potassium entry

Mechanical pressure aiding ion movement

What is the resting membrane potential typically assumed to be in most cells?

-70 mV (correct)

-90 mV

-40 mV

-60 mV

What key factor contributes to establishing the resting membrane potential?

Ionic distribution across the membrane Signup and view all the answers

In which scenario would potassium (K+) ions be more likely to flow into the cell?

When there is a high electrostatic attraction for K+ ions from the inside Signup and view all the answers

What two forces influence the movement of ions across the cell membrane?

Electrostatic force and force of diffusion Signup and view all the answers

How does the Nernst equation apply to the membrane potential of cells?

It predicts the equilibrium potentials for specific ions Signup and view all the answers

Which ion typically has the largest influence on the resting membrane potential due to its permeability?

Potassium (K+) Signup and view all the answers

Which ion is predominantly higher in concentration outside of a typical excitable cell at rest?

Na+ Signup and view all the answers

What is primarily responsible for establishing the membrane potential in excitable cells?

Sodium pump activity Signup and view all the answers

During an action potential, what occurs first?

Threshold potential is reached Signup and view all the answers

Which term describes the period during which a neuron cannot fire another action potential?

Refractory period Signup and view all the answers

What is primarily measured in an intracellular recording?

Membrane potential changes Signup and view all the answers

What role does myelin play in the conduction of action potentials?

It increases the speed of propagation. Signup and view all the answers

What is the primary function of the sodium-potassium pump in excitable cells?

To maintain electrochemical gradients Signup and view all the answers

Which of the following most accurately describes an action potential?

A rapid, all-or-nothing electrical signal Signup and view all the answers

What causes the resting membrane potential to be around -70 mV?

The movement of Na+ and K+ ions Signup and view all the answers

Which ion is actively pumped into the cell by the Na+/K+-ATPase pump?

Potassium (K+) Signup and view all the answers

What effect does depolarization of the membrane have on ion movement?

It prevents Na+ from entering the cell Signup and view all the answers

Which type of recording involves placing an electrode outside the cell?

Extracellular Recording Signup and view all the answers

How many sodium (Na+) ions are actively transported out of the cell by the Na+/K+-ATPase pump?

3 Na+ ions Signup and view all the answers

What is the role of ion channels in the membrane?

To provide routes for specific ions to enter and exit Signup and view all the answers

What happens to K+ ions when the inside of the cell is very negative?

K+ is prevented from leaving the cell Signup and view all the answers

What is the primary method through which the resting membrane potential is maintained?

The activity of Na+/K+-ATPase pump Signup and view all the answers

What is the main factor affecting the resting membrane potential calculated using the Goldman Hodgkin Katz equation?

The permeability of the membrane to various ions Signup and view all the answers

What is the resulting value of Vm when considering permeability for K+ and Na+?

-76 mV Signup and view all the answers

Which statement about action potentials is accurate?

They are all or nothing events. Signup and view all the answers

What condition must be met for an action potential to be triggered?

The membrane must reach a specific threshold of depolarization. Signup and view all the answers

At the peak of an action potential, what does the membrane potential approach?

ENa Signup and view all the answers

Which type of axons conduct action potentials faster?

Larger myelinated axons Signup and view all the answers

What happens to the membrane during the refractory period after an action potential?

It is inexcitable. Signup and view all the answers

How does increasing the permeability of K+ ions affect the resting membrane potential?

It makes the resting membrane potential more negative. Signup and view all the answers

What is the equilibrium potential for potassium ions (K+) in the given context?

-90 mV Signup and view all the answers

What will happen to the resting potential (Vm) if a cell becomes permeable to sodium ions (Na+)?

Vm will increase towards +50 mV Signup and view all the answers

What is the driving force on Na+ when Vm is -70 mV?

-120 mV Signup and view all the answers

How does the permeability of the membrane to potassium ions (K+) compare to sodium ions (Na+)?

Membrane is more permeable to K+ than Na+ Signup and view all the answers

At what membrane potential (Vm) does the passive flow of Na+ in match the passive flow of K+ out?

-70 mV Signup and view all the answers

If Vm is set to -90 mV, what effect does this have on K+ ion movement?

K+ will not move at all Signup and view all the answers

In the Nernst equation, what does it mean when it states it deals with one ion at a time?

Each ion's concentration gradient is analyzed separately Signup and view all the answers

What does the term 'driving force on ion' refer to?

The difference between membrane potential and equilibrium potential Signup and view all the answers

What is the consequence of having high conductance for K+ in a membrane?

K+ will passively flow out of the cell Signup and view all the answers

Study Notes

General Learning Outcomes

Understand Na+ and K+ ion concentrations inside and outside of cells.
Learn measurement techniques for electrical events in excitable cells.
Grasp properties of cell membranes relevant to neurophysiology.
Comprehend potential difference, current, and capacitance related to cell membranes.

Electrochemical Equilibria and Membrane Potential

Membranes separate and store charges; crucial for creating potential differences.
Na+ and K+ channels are key to establishing membrane potential (MP).
Differential permeability of the membrane influences MP.
Electrochemical gradients set up by sodium pumps, voltage-dependent channels, and membrane capacitance.

Action Potential, Propagation, and Nerve Conduction

Action potentials (AP) are characterized by specific properties including threshold and refractory periods.
Membrane depolarization and repolarization involve voltage and conductance changes.
Myelination increases conduction speed of APs.

Measurement of Electrical Potentials

Extracellular recording uses an electrode outside the cell.
Intracellular recording employs an electrode inside the cell.
Patch clamping involves sealing an electrode to the cell surface to measure ion flows.

Resting Membrane Potential

The typical resting membrane potential (Vm) is around -70 mV.
Influenced primarily by Na+, K+, and Ca2+ ions.
Equilibrium potential of an ion prevents its movement based on concentration gradient.
High internal negativity prevents K+ from leaving; high internal positivity hinders Na+ from entering.

Membrane Structure and Function

The membrane is a hydrophobic barrier composed of lipids and proteins.
Na+/K+-ATPase actively pumps 3 Na+ out and 2 K+ in, crucial for maintaining depolarized internal environments.
Ion channels (Na+ and K+) provide pathways for rapid ion movement, crucial for action potential dynamics.

Ionic Distribution and Membrane Potential

The ionic distribution establishes resting membrane potential.
Forces acting on ions include electrostatic forces (based on charge) and diffusion forces (based on concentration).
Nernst equation is used to calculate equilibrium potentials for specific ions, guiding the net flow of ions.

Driving Force on Ions

Driving force on K+ is +20 mV during resting potential; facilitates K+ efflux.
Driving force on Na+ is -120 mV; drives Na+ influx during depolarization.

Permeability and Conductance

High conductance areas permit easier movement of K+ ions, critical for maintaining the resting potential.
Differences in conductance shapes resting membrane potential calculations.

Goldman Equation for Resting Membrane Potential

The Goldman equation accommodates permeability differences for calculating overall Vm.
High K+ permeability (50x greater than Na+) significantly influences Vm calculations.

Basic Principles of the Action Potential

Triggered by depolarizing stimuli leading to a specific threshold.
APs are all-or-nothing events; they propagate rapidly and without decrement.
At peak AP, Vm nears ENa; refractory periods follow, during which the membrane remains inexcitable.

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Description

Test your knowledge on the electrochemical potentials and axon potentials in the context of physiology and anatomy. This quiz will cover the concentrations of Na+ and K+ ions in cells and the measurement of electrical events in excitable cells.