Neuron Structure & Function + The Nervous System

Question 1

What is the function of sensory neurons?

Answer 1

receive and transmit information about an anima;’s environment or its internal physiological state

Question 2

What is the function of interneurons?

Answer 2

receive and transmit information received by sensory neurons and transmits it to motor neurons

Question 3

What is the function of motor neurons?

Answer 3

signal a muscle or gland to cause a response in the body

Question 4

Where are stimuli received by the neuron?

Answer 4

dendrites

Question 5

Where are synaptic stimuli summed?

Answer 5

axon hillock

Question 6

____ potentials travel through the cell body
____ potentials travel through the axon

Answer 6

graded; action

Question 7

What is membrane potential?

Answer 7

a difference in electrical charge across the cell membrane

Question 8

Resting membrane potential is ____ mV

Answer 8

-70

Question 9

Na+ moves ____ the cell through the ____ Na+ channel

Answer 9

into; voltage-gated

Question 10

K+ moves ____ the cell through the ____ K+ channel

Answer 10

out; voltage-gated

Question 11

The sodium-potasium pump pumps ____ Na+ ions ____ the cell and ____ K+ ions ____ the cell.

Answer 11

3 Na+ ions; out
2 K+ ions; into

Question 12

True or False:
The sodium-potassium pump pumps a net positive charge of ions into the cell.

Answer 12

False

Question 13

At resting potential:
Membrane potential is more negative/positive inside the cell than outside.

Answer 13

negative

Question 14

At resting potential:
There is a greater/lower concentration of Na+ ions outside the cell than inside.

Answer 14

greater

Question 15

At resting potential:
There is a greater/lower concentration of K+ ions inside the cell than outside.

Answer 15

greater

Question 16

Threshold potential is ____ mV.

Answer 16

-55

Question 17

What happens at threshold potential?

Answer 17

Na+ voltage-gated ion channels open and the action potential fires.

Question 18

What is depolarization?

Answer 18

an increase in membrane potential from a negative resting potential

Question 19

List the steps of an action potential.

Answer 19

1. resting
2. depolarization
3. peak action potential
4. repolarization
5. hyperpolarization

Question 20

At peak action potential:
Membrane potential is more negative/positive inside the cell than outside.

Answer 20

positive

Question 21

At peak action potential:
There is a greater/lower concentration of Na+ ions outside the cell than inside.

Answer 21

lower

Question 22

At peak action potential:
There is a greater/lower concentration of K+ ions inside the cell than outside.

Answer 22

higher

Question 23

How are chemical gradients formed?

Answer 23

from concentration differences

Question 24

How are electrical gradients formed?

Answer 24

from charge separation

Question 25

What is the flow of chemical gradients?

Answer 25

high concentration --> low concentration

Question 26

What is the flow of electrical gradients?

Answer 26

positive --> negative

Question 27

What kind of ion channels are primarily present at the neuron's dendrites? Why?

Answer 27

ligand-gated ion channels neurotransmitters bind to these channels in the post-synaptic neuron

Question 28

What are the two types of graded potentials?

Answer 28

excitatory postsynaptic potential (EPSP) inhibitory postynaptic potential (IPSP)

Question 29

What happens when a dendrite receives an EPSP?

Answer 29

cell depolarizes more likely to initiate an action potential

Question 30

What happens when a dendrite receives an IPSP?

Answer 30

cell hyperpolarizes less likely to initiate an action potential

Question 31

What are the conditions of an action potential occurring?

Answer 31

if the sum of EPSPs and IPSPs reach the threshold potential

Question 32

How does no summation occur?

Answer 32

multiple EPSPs widely spaced in time do not set off an action potential

Question 33

How does temporal summation occur?

Answer 33

multiple EPSPs arrive quickly at a single synapse

Question 34

How does spatial summation occur?

Answer 34

single EPSPs arrive at the same time at different synapses

Question 35

How does cancellation occur?

Answer 35

an EPSP and IPSP cancel each other out and no action potential occurs

Question 36

How does action potential propagation occur?

Answer 36

depolarization spreads through the axon and triggers more voltage-gated sodium channels to open and more action potentials to occur

Question 37

What is the role of myelin?

Answer 37

insulates the axon and increases the rate of action potentials

Question 38

True or False: Strong stimuli (more concentration) in the synapse cause neurons to fire more frequent action potentials.

Answer 38

True

Question 39

True or False: Synapses are fixed.

Answer 39

False Synapses are not fixed, which allows for neuroplasticity and learning/memory.

Question 40

Where are voltage-gated channels found in the neuron?

Answer 40

cellular membrane

Question 41

Where are ligand-gated channels found in the neuron?

Answer 41

dendrites

Question 42

What are the steps of synapse communication?

Answer 42

1. stimulated by the action potential 2. voltage-gated Ca2+ channels open 3. vesicles at the axon terminals respond to Ca2+ by fusing with the pre-synaptic membrane 4. vesicles perform exocytosis to release neurotransmitters into the synaptic cleft 5. neurotransmitters bind to ligand-gated ion channels in the post-synaptic membrane 6. neurotransmitters are re-absorbed into the pre-synaptic terminal and stored until the next action potential arrives

Question 43

What are the two divisions of the nervous system?

Answer 43

central nervous system and peripheral nervous system

Question 44

What are the components of the central nervous system?

Answer 44

brain and spinal cord

Question 45

What are the components of the peripheral nervous system?

Answer 45

sensory and motor nerves

Question 46

What are the two divisions of the peripheral nervous system?

Answer 46

somatic and autonomic

Question 47

What is the somatic nervous system responsible for?

Answer 47

controlling voluntary activity

Question 48

What is the autonomic nervous system responsible for?

Answer 48

controlling involuntary activity

Question 49

What are the two divisions of the autonomic nervous system?

Answer 49

parasympathetic and sympathetic

Question 50

What does the parasympathetic nervous system do?

Answer 50

rest and digest

Question 51

What does the sympathetic nervous system do?

Answer 51

fight or flight

Question 52

What are afferent neurons?

Answer 52

send information toward the CNS

Question 53

What are efferent neurons?

Answer 53

send information away from the CNS

Question 54

True or False: Simple reflex circuits go through the CNS.

Answer 54

False Simple reflex circuits bypass the brain.

Question 55

How does the patellar reflex work?

Answer 55

1. patellar tendon is struck 2. stretch receptor in muscle responds by sending a signal along the sensory 3. sensory neuron synapses with motor neuron in the spinal cord 4. motor neuron sends signal to muscle, which contracts 5. inhibitory interneuron inhibits contraction of the muscle

Question 56

What is the purpose of the sodium-potassium pump?

Answer 56

to maintain resting membrane potential by pumping a net negative charge (more cations are pumped out the cell than inside)

Question 57

What happens if a myelinated and unmyelinated neuron arrive at different dendrites and deliver EPSPs?

Answer 57

No spatial summation would occur because the myelinated neuron would arrive at the dendrite before the unmyelinated neuron

Question 58

What is the refractory period of the action potential?

Answer 58

The point at which hyperpolarization is occurring; no action potential could occur at this time while the K+ ions are still closing

Question 59

What would happen if the Na+ and K+ voltage gated channels opened at the same time?

Answer 59

no action potential would occur the movement of ions would "cancel" each other out

Question 60

How does morphine affect the synapse over time?

Answer 60

* increases synaptic activity over time * to maintain homeostasis, the body decreases the number of receptors in the post-synaptic membrane in order to decrease synaptic activity back to normal

Question 61

What is an agonist?

Answer 61

a molecule (usually a drug) that mimics existing neurotransmitters