Chapter 3 - Neuronal Membrane at Rest

Question 1

What is an action potential?
A
What are their characteristics?

Answer 1

Nerve impulse
Don’t diminish over distance
Signals of fixed size and duration
Info encoded in frequency, distribution and number of neurons firing

Question 2

What is excitable membrane?

Answer 2

Cells capable of generating and conducting ap

Question 3

What is a resting membrane doing?

Answer 3

Cytosol along inside surface of membrane has neg electrical charge compared to outside
Called resting membrane potential

Question 4

Where is water?

What is responsible for action potential in water?

Answer 4

Inside neuron, cytosol, extracellular fluid

Ions

Question 5

What insulates ions from each other?

Answer 5

Spheres of hydration

Clouds of water with opposite poles

Question 6

What are cations and anions?

Answer 6

Net positive charge

Net negative charge

Question 7

What is the neuronal membrane made of?

Answer 7

Phospholipid bilayer

Isolates cytosol from extracellular fluid

Question 8

What are the three types of proteins?

Answer 8

Enzymes
Cytoskeleton
Receptors

Question 9

How is a protein composed?

Answer 9

Central alpha carbon covalently bonded to hydrogen atom, amino group (NH3+), carboxyl group (COO-), R group

R group varies and is responsible for size and chemical relationships in which participates

Question 10

What are the four levels of structure of proteins?

Answer 10

Primary chain joined by peptide bonds
Secondary Alpha helix coil
Tertiary shaped by R groups
Quaternary structure forms larger molecule from bonding polypeptide chains

Each polypeptide contributing to quaternary is called subunit

Question 11

Which parts of r groups are hydrophobic and philic?

Answer 11

Regions with exposed polar R groups are hydrophilic
Nonpolar R groups are phobic
Proteins suspended in membrane with phobic inside membrane and philic ends in water on either side

Question 12

What are ion channels?

Answer 12

Membrane-spanning proteins
Four to six similar proteins to form pore
Ion selectivity K for K etc.
Gating

Question 13

What is ion pump?

Answer 13

ATP

Question 14

How do ions get across membrane?

Answer 14

Diffusion and electricity

Question 15

What is the resting potential of a neuron’s membrane potential?

Answer 15

Vm = -65 millivolts

Question 16

Four points about charged membranes

Answer 16

1. Large charges in membrane potential are caused by minuscule changes in ionic concentrations.
2. The net difference in electrical charge occurs at the inside and outside surfaces of the membrane.
3. Ions are driven across the membrane at a rate proportional to the difference between the membrane potential and the equilibrium potential.
4. If the concentration difference across the membrane is known for an ion, the equilibrium potential can be calculated for that ion.

Question 17

What is the Nernst equation?

Answer 17

To calculate the equilibrium potential for an ion

Question 18

What is the blood-brain barrier?

Answer 18

A specialization of walls of brain capillaries limiting movement of potassium into extracellular fluid of brain