Lecture Exam 2 (Set 3)

Front 1

Driving forces:

Back 1

concentration gradient and electrical gradient acting on ions

Front 2

equilibrium potential:

Back 2

membrane potential where the two driving forces acting on the ion (gradients) are equal in size but opposite in direction

Front 3

What causes resting membrane potential?

Back 3

1. unequal distribution of ions (concentration gradient)
2. relative membrane permeability to those ions.

Front 4

Define primary active transport common name:

Back 4

Na+-K+ pump

Front 5

Polarized membrane:

Back 5

one side positive, other side negative

Front 6

Hyperpolarization:

Back 6

more negative than rest

Front 7

Depolarization:

Back 7

Membrane potential more positive, less negative

Front 8

Define graded potentials:

Back 8

-use in nervous system
-gathering information
-analyze input
-communicate between cells

Front 9

Characteristics of graded potentials:

Back 9

1. size is graded (bigger=bigger potential charge
2. decremental conductance--as potential travels across membrane of cell, it gets smaller
3. exhibit summation--they can add together

Front 10

Decremental conductance:

Back 10

As potential travels across membrane of cell, it gets smaller

Front 11

Summation:

Back 11

They can add together

Front 12

Types of graded potentials:

Back 12

1. Receptor potentials-change in resting membrane potential due to sensory stimulation of sensory cell terminals--triggered by stimulation-signals
2. (Post) synaptic potentials--change in resting membrane potential due to communication received by another neuron

Front 13

Stimulus gated channels:

Back 13

gate is closed unless gets appropriate stimulus, open if correct signal is received

Front 14

Driving forces:

Back 14

membrane potential-equilibrium potential
-channels close with stimulus gone

Front 15

Kinds of summation:

Back 15

1. Spatial summation--graded potentials that occur in different places on neuron, add together
2. Temporal summation--coming in at same place, occurring at same place and occur one right after the other
--occurring at same time, or both can be active
--allows neurons to analyze information, adding up input

Front 16

Action potentials:

Back 16

Used by neurons for rapid long distance signal

Front 17

Characteristics of action potentials:

Back 17

1. constant amplitude--size always same
2. not related to size of stimulus
3. all-or-none
4. propagation--does not get smaller as it travels--always same size

Front 18

What part of cell gets action potential?

Back 18

Axon hillock and axon

Front 19

Threshold:

Back 19

minimum depolarization necessary to produce action potential

Front 20

Three phases of action potential:

Back 20

Phase 1: depolarization
Phase 2: repolarization
Phase 3: after-hyperpolarization

Front 21

Action potential caused by?

Back 21

gated channels and voltage-gated channels (voltage needed to open at threshold)

Front 22

Sodium channels:

Back 22

1. Will open when membrane potential reaches threshold
2. Na+ voltage-gated channels cause more depolarization
3. "sodium channel activation" "depolarization"
4. Na+ channels automatically close
5. closing time is dependent

Front 23

Potassium channels:

Back 23

1. Potassium voltage-gated channels respond to threshold
2. will open in response to threshold
3. they open slower
4. as sodium channels are beginning to close
5. will help repolarize the cell
6. close voltage dependently--returning below threshold

Front 24

After-hyperpolarization:

Back 24

after action potential

Front 25

Steps for producing action potential:

Back 25

1. Membrane potential is depolarized to threshold
2. Some Na+ voltage-gated channels open
3. Na+ ions flow into cell
4. Cell gets more polarized which causes more Na+ channels to open
5. K+ voltage-gated channels open slowly in response to threshold depolarization
6. Na+ channels close because time is up
7. K+ ions flow out of cell which causes membrane potential to repolarize
8. K+ voltage-gated channels start to close when membrane potential drops below threshold
9. K+ channels close slowly so the membrane potential gets more negative than rest (after-hyperpolarization)
10. K+ channels closed and membrane potential returns to rest

Front 26

Two types of refractory period:

Back 26

1. Absolute refractory period: that time immediately after action potential when you cannot make another--being caused by Na+ voltage-gated channels
2. Relative refractory period--time after absolute refractory period when you can get action potential, but threshold is higher

Front 27

Inactivation gate:

Back 27

closes, but channel remains open--won't respond to voltage

Front 28

What is speed of action potential?

What affects that speed?

Back 28

very fast

1. diameter of axon--bigger=faster
2. if they have myelin-insulating wire

Front 29

Saltatory conductance:

Back 29

movement-jumping in myelinated axon--only place is advantages: 1. speed, 2. metabolic savings, 3. size

Disadvantages: diseases can destroy myelin so can't make action potential