Chapter 2

Question 1

Charles Scott Sherrington

Answer 1

Neurons communicate
by transmitting chemicals
at junctions, called “synapses”
-Order of reflex of reflex: 1st sensory neuron, 2nd interneuron, 3rd connects to motor neuron or afferent neuron (bring in information)

Question 2

Sherrington’s reflex

Answer 2

• As one set of muscles becomes excited, another set relaxes
• Reflexes are slower than conduction along an axon
• how neurons communicate with each other by studying reflexes (automatic muscular responses to stimuli) in a process known as a reflex arc

Question 3

Temporal Summation

Answer 3

Repeated stimuli can have a cumulative effect and can produce a nerve impulse when a single stimuli is too weak

Question 4

EPSP

Answer 4

Excitatory postsynaptic

• graded potential that decays over time and space
• sodium gates open

Question 5

Presynaptic neuron

Answer 5

neuron that delivers the synaptic transmission

Question 6

Postsynaptic neuron

Answer 6

neuron that receives the message

Question 7

Spatial Summation

Answer 7

 combined effect of several nearly

simultaneous stimulations at several synapses onto one neuron

Question 8

Temporal summation

Answer 8

combined effect of quickly repeated

stimulation at a single synapse

Question 9

IPSP

Answer 9

Inhibitory Postsynaptic Potential

• temporary hyperpolarization of a membrane
• potassium or chloride gates open

Question 10

Sherrington wrong

Answer 10

Sherrington assumed that synapses produce on and off responses
Synapses vary enormously in their duration of effects

Question 11

Spontaneous Firing Rate

Answer 11

The periodic production of action potentials despite synaptic input

Question 12

SFR EPSP

Answer 12

increase the number of action potentials above the spontaneous firing rate

Question 13

SFR IPSP

Answer 13

decrease the number of action potentials below the spontaneous firing rate

Question 14

What does it mean when we say the membrane is polarized?

Answer 14

This means that there is an electrical difference across the cell membrane.

Question 15

How is EPSP like depolarization?

Answer 15

Deporalization is the action it gets more positive, epsp is when it gets to the high level

Question 16

How is IPSP like hyperpolarization?

Answer 16

Hyperporazation becomes begative, IPSP is finally negative

Question 17

Difference between EPSP and an action potential

Answer 17

Action potential is a nerve impulse

EPSP is graded potential

Question 18

Otto Loewi

Answer 18

First to convincingly demonstrate that communication across the synapse occurs via chemical means

Question 19

Neurotransmitters

Answer 19

chemicals that travel across the synapse and allow communication between neurons

Question 20

Otto Loewi’s experiment

Answer 20

Found that stimulating one nerve released something that inhibited heart rate, and stimulating a different nerve released something that increased heart rate
Realized that he was collecting and transferring chemicals, not loose electricity

Question 21

The Sequence of Chemical Events at the Synapse

Answer 21

1. The neuron synthesizes chemicals that serve as neurotransmitters
2. Action potentials travel down the axon
3. Released molecules diffuse across the cleft, attach to receptors, and alter the activity of the postsynaptic neuron