| Question |
Answer |
| What is a graded potential? |
A subthreshold electrical stimuli that does not produce a true action potential, but does generate electrical signals |
| What types of stimuli are there? |
Electrical, Chemical, and Mechanical |
| How many types of physiochemical disturbances does stimuli produce and what are they? |
2 Types: 1. local, graded, nonpropagated potentials called Receptor or Generator potential AKA Synaptic potentials or Electrotonic Potentials 2. Action potentials (complete depolarization or nerve impulse) |
| True or False, Graded potentials are conducted with decrement? |
True, Decrement think DECREASE. They decrease in magnitude the further they get from the origin. |
| Why does decrement occur in graded potentials? |
Because charges are lost due to leaky channels as the potential is conducted |
| How far can a graded potential travel? |
1-2 mm |
| True or false, Graded potentials serve as the only communication in some neurons? |
True |
| Name the 4 types of Graded Potentials? |
1. Receptor or Generator Potentials 2. Pacemaker Potential 3. Post synaptic Membrane Potential 4. End Plate Potential |
| Sensory Receptors respond to stimuli from: |
1. Mechanoreceptors (movement) 2. Thermoreceptors (temp) 3. Nocioreceptors (pain) 4. Chemoreceptors (Chemical) 5. Electromagnetic Receptors (Vision) |
| Graded potentials from stimuli are called? |
Receptor Potentials |
| True or False, Graded potentials are responsible for cardiac automaticity? |
True, due to the Pacemaker Potential |
| What type of graded potential develops at the neuromuscular junction? |
End Plate Potential |
| True or False, the size and shape of action potentials are not influenced by the size of the stimulus? |
True |
| True or False, Action Potentials require specific voltage gated ion channels? |
True |
| Can action potentials occur in all regions of the cell membrane? |
No, just the portions that are electically exciteable |
| What is the duration of an action potential? |
1 - 5 msec |
| What senses are dependant upon action potentials? |
Sight, Hearing, and Touch |
| What are the 3 Stages of Action Potentials? |
1. Resting or Polarized Stage 2. Depolarization Stage 3. Repolarization Stage |
| What is the resting membrane potential for Nerves? Heart Pacemaker? Skeletal Muscle? |
Nerves = -90mv Heart Pacemaker = -60mv Skeletal Muscle = -83 mv |
| In what stage of the action potential do Na+ ions flow into the cell? |
Depolarization Stage |
| In what stage of the action potential do K+ ions flow out of the cell? |
Repolarization |
| What is overshoot described as in the action potential generation? |
The point at which the membrane potential becomes positive. |
| What is happening during repolarization? |
Na+ channels are inactivated and K+ are opened |
| True or false, the K+ voltage gate has both fast and slow gates? |
False, K+ has a single slow gate whereas Na+ has both. |
| What is the refractory period? |
The time when it is either impossible or more difficult to generate a second action potential |
| What is absolute refractory? |
The period in which the voltage gated channels have not reset and therefore do not respond to stimulation |
| What is relative refractory? |
This is during the period positive after potential in which the cell is hyperpolarized and is more diffficult to generate a second potential |
| What is voltage Inactivation? |
A cell membrane is maintained at a voltage potential above threshold and the voltage gated channels are not reset then action potentials can not be generated |
| What is accomodation to slow depoalarization? |
This is what happens when a slow depolarizaion occurs which does not cause the voltage gated channels to respond and in turn does not produce an action potential. |
Buen Viaje lv.2 ch 8
