HUBS1403 - Week 9 P1

Question 1

What are the six major types of transmembrane proteins?

Answer 1

Anchoring proteins, Recognition proteins, Enzymes, Receptor proteins, Carrier proteins, Channel proteins

These proteins play various roles in cell signaling, transport, and maintaining cell structure.

Question 2

Name four types of ion channels in the nervous system.

Answer 2

Leak channels, Ligand-gated channels, Mechanically-gated channels, Voltage-gated channels

Each type of ion channel has a specific role in neuronal signaling and function.

Question 3

Typical intracellular Potassium (K⁺) concentration (mM)?

Answer 3

~150 mM

This high concentration is crucial for maintaining resting membrane potential.

Question 4

Typical extracellular Potassium (K⁺) concentration (mM)?

Answer 4

~5 mM

This low concentration contributes to the concentration gradient essential for neuronal activity.

Question 5

Typical intracellular Sodium (Na⁺) concentration (mM)?

Answer 5

~15 mM

Sodium concentration is significantly lower inside the cell compared to outside.

Question 6

Typical extracellular Sodium (Na⁺) concentration (mM)?

Answer 6

~150 mM

This gradient is critical for action potential generation.

Question 7

Typical intracellular Chloride (Cl⁻) concentration (mM)?

Answer 7

~10 mM

Chloride ions also influence the membrane potential.

Question 8

Typical extracellular Chloride (Cl⁻) concentration (mM)?

Answer 8

~120 mM

This gradient affects inhibitory synaptic transmission.

Question 9

Typical intracellular Calcium (Ca²⁺) concentration (mM)?

Answer 9

~0.0001 mM

Calcium is kept at very low levels intracellularly to facilitate signaling.

Question 10

Typical extracellular Calcium (Ca²⁺) concentration (mM)?

Answer 10

~2 mM

The high extracellular concentration is vital for neurotransmitter release.

Question 11

How does the density of gated ion channels vary across a neuron?

Answer 11

Density varies significantly; for example, voltage-gated sodium channels are concentrated at the axon hillock and along the axon, while ligand-gated channels are often concentrated at synapses.

This distribution is crucial for the proper functioning of neurons.

Question 12

How is resting membrane potential established?

Answer 12

Unequal ion distribution across the membrane, selective permeability of the membrane, and the Na+/K+ pump.

These factors work together to create a stable resting state for the neuron.

Question 13

How is equilibrium potential related to concentration and electrical gradients?

Answer 13

Equilibrium potential is the membrane potential at which the net flow of an ion is zero. It’s determined by both the concentration gradient and the electrical gradient (membrane potential). The Nernst equation calculates this.

This concept is fundamental in understanding how ions move across the membrane.

Question 14

How do changes in membrane ion permeability alter membrane potential?

Answer 14

Increased permeability to an ion causes the membrane potential to move closer to that ion’s equilibrium potential. Increased Na⁺ permeability depolarizes, increased K⁺ permeability hyperpolarizes.

The dynamics of permeability changes are key in action potential generation.

Question 15

To which ion’s equilibrium potential will the membrane potential be closest?

Answer 15

The ion species to which the membrane is most permeable at that moment.

This principle is critical in understanding how different ions affect neuronal excitability.