Chapter 12 Part 2 Action Potential

Question 1

ions concentrated outside neuron (extracellular)

Answer 1

High Na+, Ca+, Cl-

Question 2

ions concentrated inside neuron (intracellular)

Answer 2

High K+, proteins(-)

Question 3

Three important Transmembrane Potential concepts:

Answer 3

The extracellular fluid (ECF) and intracellular fluid (cytosol) differ greatly in
ionic composition (creates concentration gradient)
* Extracellular: High Na+, Ca+, Cl-
* Intracellular: High K+, proteins(-)
2. Cells have selectively permeable membranes
* Ions utilize channels to cross the membrane
* Leak channels, gated channels
* Active transport mechanisms
3. Membrane permeability varies by ion / molecule
* Inside cell has negative charge -70mv in neuron

Question 4

The resting membrane potential of the neuron is

Answer 4

-70mv

Question 5

a ____gradient occurs when there is a Different concentration of specific ions (Na+, K+, Ca+, Cl-) inside and outside
the cell
-tries to equalize concentrations via diffusion

Answer 5

Chemical gradient

Question 6

a ___gradient occurs when there is a Difference in overall charge (positive and negative charges) inside and outside the cell
* Result in potential difference / resting potential
* Neurons: - 70 mV

Answer 6

electrical gradient

Question 7

___gated channels that Open upon the binding of specific chemicals (e.g., ACh)
* Found on neuron cell body and dendrites

Answer 7

Chemically Gated Channels (Ligand gated)

Question 8

___gated Channels that open
due to a changes in transmembrane potential / voltage
* Found in neural axons, sarcoplasmic reticulum, cardiac muscle

Answer 8

Voltage-gated Channels

Question 9

__gated channels open upon physical distortion of the plasma membrane. found in touch receptors.

Answer 9

Mechanically gated channels

Question 10

-is powered by ATP
- 3 Na+ out
2 K+ in
-maintains concentration gradient -70mv

Answer 10

sodium-potassium ATpase (exchange pump)

Question 11

Key features of a graded potential or 4 basic characteristics

Answer 11

1. the transmembrane potential is most changed at the site of stimulation,
   and the effect decreases with distance (Decremental)
2. The local potential is reversible
   
   1. If stimulation ceases, ions leave the cell
   2. Voltage returns to resting potential
3. The change in transmembrane potential may involve depolarization or
   hyperpolarization
   * The ion channels involved determine which
   - Opening sodium channels causes depolarization (+ charges enter cell making it
   less negative)
   -Opening potassium or chloride channels causes hyperpolarization (+ charges
   leave or negative charges enter cell making it more negative)
4. The stronger the stimulus, the greater the change in the transmembrane
   potential and the larger the area affected

Question 12

PROPAGATED changes in transmembrane potential
that Affects an entire excitable membrane

Answer 12

Action Potentials

Question 13

Action potential is _____ changes in transmembrane potential
that Affects an entire excitable membrane

Answer 13

PROPAGATED

Question 14

____propagation occurs in unmyelinated axons
-affects 1 segment at a time, goes in 1 direction (dominous falling)

Answer 14

Continuous propagation

Question 15

Continuous propagation occurs in

Answer 15

UNMYELINATED axons

Question 16

___propagation occurs in myelinated axons
-faster than continuous depolarization

Answer 16

Saltatory propagation

Question 17

Saltatory propagation occurs in______

Answer 17

myelinated axons

Question 18

Voltage gated ion channels open in response to voltage (i.e. when the cell gets depolarized) where as ligand gated channels open in response to a ligand (some chemical signal) binding to them.