Lecture 2

Question 1

What is action potential ?

Answer 1

• Electrical charge that runs down the axon from the axon hillock to the terminal buttons
• A brief electrical signal that provides the basis for conduction of information along an axon

Question 2

What is the Sodium Potassium Pump ?

Answer 2

• protein complex
• continually pumps out 3 sodium ions and draws in 2 potassium ions

Question 3

What is resting potential ?

Answer 3

The difference in electrical charge between the inside and the outside of a neuron when the cell is in a non-excited state

Question 4

What is a electrical gradient ?

Answer 4

Difference in electrical charge between the inside and outside of the cell

Question 5

What is a concentration gradient ?

Answer 5

The difference in distribution of ions across the membrane

Question 6

What is the All-or-none Law ?

Answer 6

Once an action potential is triggered in an axon, it is propagated without growing or diminishing to the axon terminal buttons

Question 7

What is the Rate Law ?

Answer 7

Variations in the intensity of a stimulus or other information being transmitted along an axon are represented by variations in the rate at which that axon fires

Question 8

What is a Saltatory Conduction ?

Answer 8

Jumping of action potential from node to node

Question 9

What is the synapse ?

Answer 9

The place where information is transmitted from one neuron to another

Question 10

What is a presynaptic neuron?

Answer 10

Neuron transmitting signal

Question 11

What is a postsynaptic neuron ?

Answer 11

Neuron receiving signal

Question 12

What is a reflex arc ?

Answer 12

Circuit from sensory neuron to a muscle response

Question 13

What were Sherringtons observations ?

Answer 13

1. Reflexes are slower than conduction along an axon
2. Several weak stimuli presented at slightly different times or locations produce a stronger reflex than a single stimulus
3. As one set of muscles becomes excited, another set relaxes

Question 14

What is temporal summation ?

Answer 14

A cumulative effect of a repeated stimuli within a brief time

several impulses from one neuron over time

Question 15

What is spatial summation ?

Answer 15

Combination of effects of activity from 2 or more synapses onto a single neuron

impulses from several neurons at the same time

Question 16

What occurs in inhibitory synapses ?

Answer 16

input from an axon hyperpolarizes the postsynaptic cell, moving the cell’s charge farther from the threshold and decreasing the probability of an action potential

Reduce neuron activity

Question 17

What occurs in excitatory synapses ?

Answer 17

Increase the activity of receiving a neuron

Question 18

What is EPSP ?

Answer 18

• Excitatory postsynaptic potential
• Caused by positively charged sodium entering the neuron
• a graded depolarization

Question 19

What is IPSP ?

Answer 19

• Inhibitory postsynaptic potential
• Caused by negatively charged chloride ions entering the neuron
• A graded hyperpolarization

Question 20

At what 3 places can synapses occur at ?

Answer 20

• On dendrites: axodendritic synapse
• On the soma: axosomatic synapse
• On other axons: axoaxonic synapse

Question 21

What is the presynaptic membrane ?

Answer 21

The membrane of axon terminal

where neurotransmitter is released

Question 22

What is the postsynaptic membrane ?

Answer 22

The membrane opposite of the axon terminal button in a synapse

receives the message

Question 23

What is the synaptic cleft ?

Answer 23

space between presynaptic and postsynaptic membrane

Question 24

What is the synaptic vesicle ?

Answer 24

A small, spherical hollow organelle; contains molecules of a neurotransmitter

Question 25

What is a neurotransmitter ?

Answer 25

Chemical messengers that carry chemical signals

Question 26

What is a ligand ?

Answer 26

A neurotransmitter that binds

Question 27

What are Ligand-Gated Ion Channels ?

Answer 27

Transmembrane ion-channel proteins which open to allow (e.g. Na, K, Cl) to pass through membrane in response to the binding of a chemical messenger

Question 28

What is a ionotropic receptor ?

Answer 28

A receptor that contains a binding site for a neurotransmitter and an ion channel that opens when a molecule of the neurotransmitter attatches to the binding site

Fast acting

Question 29

What is a metabotropic receptor ?

Answer 29

A receptor that contains a binding site for a neurotransmitter which then activates an enzyme that begins a series of events that opens an ion channel elsewhere in the membrane of the cell

Slow but amplified

Question 29

What is neural integration ?

Answer 29

The process by which inhibitory and excitatory postsynaptic potentials summate and control the rate of firing of a neuron

Question 30

What are 8 neurotransmitters ?

Answer 30

• Adrenaline (fight or flight )
• GABA (calming)
• Noradrenaline (concentration)
• Acetylcholine (learning)
• Dopamine (pleasure)
• Glutamate (memory)
• Serotonin (mood)
• Endorphins (euphoria)

Question 31

What are agonists ?

Answer 31

Bind to receptor, producing a similar response to the intended chemical

Question 32

What are antagonists ?

Answer 32

Bind to receptor either on the primary site, or another site, which stops the receptor from producing a response

Question 33

What occurs at the synapse?

Answer 33

1. Action potential arrives at axon terminal
2. Voltage-gated Ca channels open and Ca enters the axon terminal
3. Ca entry causes neurotransmitter-containing synaptic vesicles to release contents by exocytosis
4. Neurotransmitter diffuses across the synaptic cleft and binds to ligand-gated ion channels on the postsynaptic membrane
5. Binding of neurotransmitter opens ligand-gated ion channels, resulting in graded potentials
6. Reuptake by the presynaptic neuron, enzymatic degradation and diffusion reduce neurotransmitter levels, terminating the signal