Lecture 6

Question 1

Structure- Function Relationships - Neural Circuits

Answer 1

• Neurons are organized into functional circuits that rapidly conduct info to a target
• a stimulus is concerted into chem/electrical signals that arr carried rapidly through a relay of Neurons called a neural circuit

Question 2

Neurons vs. Neural Circuits

Answer 2

1. Signal reception (input): dendrites
2. Signal integration: axon hillock
3. Signal Conduction: axon
4. Signal Transmission (output): axon terminals

Question 3

Sensory Neurons

Answer 3

Signal reception (input) - dendrites

Question 4

Interneurons (2 of them)

Answer 4

• signal integration: axon hillock
• signal conduction: axon

Question 5

Motor Neurons

Answer 5

Signal Transmission (output): axon terminals

Question 6

Neural Circuits (alternate between)

Answer 6

• graded and all-or-none signals
• electrical and chemical signals

Question 7

How do Ligand-Gated ion Channels Work

Answer 7

Convert chemical signals into electrical signals by changing the membrane potentials

Question 8

What are Graded Potentials

Answer 8

The electrical signals generated by the ligand gated ion channels

Question 9

What are the graded potentials proportional to

Answer 9

Stimulus strength
Ex. The concentration of neurotransmitter

Question 10

With no Neurotransmitter

Answer 10

• Ions can not pass through the channel
• ion channel is in the closed conformation

Question 11

With Low Neurotransmitter

Answer 11

• some ions can cross the membrane
• some are in the open conformation

Question 12

With High Neurotransmitter

Answer 12

• many ions cross the membrane
• most ion channels are in open confirmation

Question 13

What can Graded Potentials do:

Answer 13

• depolarize the cell via Na+ and CA2+ channels)
• hyperpolarize the cell via Na+ and Ca- channels

Question 14

Ions move down

Answer 14

The electrochemical Gradients

Question 15

Signals Decay Due to:

Answer 15

1. Membrane Permeability
2. Cytoplasm Resistance
3. Decremental Spread or Electronic Conduction

Question 16

Signals decay due to: 1. Membrane permeability

Answer 16

Leakage of ions across the membrane

Question 17

Signals decay due to: 2. Cytopasmic resistance

Answer 17

Inherent resistance to current flow

Question 18

Signals decay due to: 3. Decremental Spread or Electronic Conduction

Answer 18

Signal magnitude decreases as it moves away from the source

Question 19

Pathway for signals (4 possible):

Answer 19

1. Neurotransmitter binds to a ligand-gated Na+ channel
2. Na+ enters cell through the open channel
3. Current spreads through the cell
4. The strength of the signal decreases with distance

Question 20

Transition from Graded potential to all-or-None Response

Answer 20

Graded Potentials in the axon hillock need to depolarize the membrane beyond the threshold potential for the axon to fire an action potential

Question 21

Graded Potential are Integraded to Trigger Action Potentials: Spatial Summation

Answer 21

Graded Potentials from different locations can interact to influence the net charge in membrane potential at the axon hillock

Question 22

Graded Potential are Integraded to Trigger Action Potentials: Excitatory

Answer 22

Signals depolarize the membrane

Question 23

Graded Potential are Integraded to Trigger Action Potentials: Inhibitory

Answer 23

Signals hyperpolarize the membrane

Question 24

Graded Potential are Integraded to Trigger Action Potentials: Temporal Summation

Answer 24

Graded potentials occurring at slightly different times can interact to influence the net graded potential

Question 25

AP triggered when:

Answer 25

Membrane potential at axon hillock reaches threshold potential

Question 26

Once AP triggered:

Answer 26

AP is an all-or-none response

Question 27

What Causes rapid changes in Vm;

Answer 27

Caused by ions not electrons

Question 28

Does AP require ATP

Answer 28

No it does not

Question 29

Ion Concentration restored by:

Answer 29

Na+/K+ ATP ase