Nervous system

Question 1

What structures are part of the CNS?

Answer 1

Brain and spinal cord.

Question 2

What is the main role of the CNS?

Answer 2

Processing and integrating information, and initiating responses.

Question 3

What does the PNS do?

Answer 3

It connects the CNS to the body’s limbs and organs.

Question 4

What are afferent neurons?

Answer 4

Neurons that carry sensory information to the CNS.

Question 5

What are efferent neurons?

Answer 5

Neurons that carry motor commands from the CNS to effectors.

Question 6

Name two divisions of the PNS.

Answer 6

Somatic and autonomic nervous systems.

Question 7

What does the autonomic nervous system control?

Answer 7

Involuntary activities such as heart rate, digestion, and respiration.

Question 8

What is the sympathetic division responsible for?

Answer 8

Preparing the body for stress or emergencies (“fight or flight”).

Question 9

What does the parasympathetic division promote?

Answer 9

Rest, digestion, and energy storage.

Question 10

Where are sensory neurons located?

Answer 10

In dorsal root ganglia (PNS), entering the spinal cord dorsally.

Question 11

What is the role of astrocytes?

Answer 11

Regulate blood-brain barrier and maintain extracellular environment.

Question 12

Which CNS cells form myelin?

Answer 12

Oligodendrocytes.

Question 13

Which cells act as immune defense in the CNS?

Answer 13

Microglia.

Question 14

What do ependymal cells do?

Answer 14

Produce and circulate cerebrospinal fluid.

Question 15

What do Schwann cells do?

Answer 15

Form myelin in the PNS and help axon regeneration.

Question 16

What is the function of satellite cells?

Answer 16

Support neuron function in ganglia.

Question 17

Which glial cell types are found in both the CNS and PNS?

Answer 17

None; types are unique to each system.

Question 18

Which glial cell repairs the CNS after injury?

Answer 18

Astrocytes (limited capacity).

Question 19

What glial cell phagocytoses pathogens?

Answer 19

Microglia.

Question 20

Why is myelination important?

Answer 20

It increases the speed of nerve impulse conduction.

Question 21

What is the main function of a dendrite?

Answer 21

To receive incoming signals.

Question 22

What part of the neuron sends signals?

Answer 22

The axon.

Question 23

What is the axon terminal’s function?

Answer 23

Releases neurotransmitters.

Question 24

What insulates axons in the CNS?

Answer 24

Oligodendrocytes.

Question 25

What maintains the resting membrane potential?

Answer 25

Na⁺/K⁺ pump and leaky K⁺ channels.

Question 26

What is the RMP value in neurons?

Answer 26

Approximately –70 mV.

Question 27

Why is the inside of a neuron negative?

Answer 27

Due to the higher permeability to K⁺ and presence of negative proteins.

Question 28

What is the role of the Na⁺/K⁺ pump?

Answer 28

Pumps 3 Na⁺ out and 2 K⁺ in, maintaining ion gradients.

Question 29

What are nodes of Ranvier?

Answer 29

Gaps in the myelin sheath where ion channels cluster.

Question 30

What are non-gated channels?

Answer 30

Ion channels that are always open (leak channels).

Question 31

What triggers an action

Answer 31

potential? Reaching the threshold potential (~ –55 mV).

Question 32

What happens during depolarization?

Answer 32

Na⁺ channels open and Na⁺ enters the cell.

Question 33

What restores the RMP?

Answer 33

Na⁺/K⁺ pump and closing of K⁺ channels.

Question 34

What is the refractory period?

Answer 34

A time when the neuron can't fire another AP.

Question 35

Can APs vary in strength?

Answer 35

No, they are all-or-none.

Question 36

Why does AP travel in one direction?

Answer 36

Due to the inactivation of Na⁺ channels behind it.

Question 37

What ion is responsible for repolarization?

Answer 37

K⁺ exiting the cell.

Question 38

What prevents backward propagation?

Answer 38

Refractory period.

Question 39

Where are APs regenerated?

Answer 39

At each successive segment of the axon membrane.

Question 40

What is saltatory conduction?

Answer 40

APs jump from node to node.

Question 41

What cells form myelin in the CNS?

Answer 41

Oligodendrocytes.

Question 42

What cells form myelin in the PNS?

Answer 42

Schwann cells.

Question 43

Where do APs occur in myelinated axons?

Answer 43

At the nodes of Ranvier.

Question 44

Why is saltatory conduction faster?

Answer 44

Less membrane area needs to depolarize.

Question 45

Does saltatory conduction save energy?

Answer 45

Yes, fewer ions cross the membrane = less work for Na⁺/K⁺ pump.

Question 46

Do small axons conduct faster than large ones?

Answer 46

No, larger axons conduct faster.

Question 47

What helps regenerate APs at each node?

Answer 47

Voltage-gated Na⁺ channels.

Question 48

Can unmyelinated axons conduct APs?

Answer 48

Yes, but more slowly via continuous conduction.

Question 49

What is an EPSP?

Answer 49

An excitatory postsynaptic potential.

Question 50

What is an IPSP?

Answer 50

An inhibitory postsynaptic potential.

Question 51

What part of the neuron decides to fire an AP?

Answer 51

The axon hillock.

Question 52

What is spatial summation?

Answer 52

Integration of signals from multiple locations.

Question 53

What is temporal summation?

Answer 53

Integration of signals arriving in rapid succession.

Question 54

Can EPSPs and IPSPs cancel each other out?

Answer 54

Yes.

Question 55

What determines if a neuron fires?

Answer 55

Whether the sum of inputs reaches threshold.

Question 56

What neurotransmitter is used at neuromuscular junctions?

Answer 56

Acetylcholine.

Question 57

Can neurons be both pre- and post-synaptic?

Answer 57

Yes, depending on the synapse. Neurons can be in the middle of a multi-neuron chain of communication, especially in the CNS.

Question 58

What ensures unidirectional signal flow?

Answer 58

Synaptic structure and neurotransmitter release.