Unit 9 - Neural Tissue

Question 1

What does the central nervous system do?

Answer 1

Integrates information

Question 2

What does the peripheral nervous system do?

Answer 2

Transmits sensory and motor signals between the central nervous system and the rest of the body

Question 3

What are 3 general functions of the nervous system?

Answer 3

Sensory, integrative, motor

Question 4

What does a sensory function of the nervous system mean?

Answer 4

It detects stimuli and transmits information to the nervous system

Question 5

What does an integrative function of the nervous system mean?

Answer 5

Receives signals from many neurons and carries out integrative function

Question 6

What does a motor function of the nervous system mean?

Answer 6

Sends signals out to muscles and gland cells

Question 7

What are neurons?

Answer 7

Highly specialized nerve cells that generate and conduct nerve impulses

Question 8

What are neuroglial cells?

Answer 8

Supporting cells that provide physical sport, remove debris, and provide electrical insulation

Question 9

Describe the primary components of a neuron.

Answer 9

The soma
The axon
Dendrites
Synapses

Question 10

What is the soma?

Answer 10

The cell body of a neuron

Question 11

What is the axon?

Answer 11

A long slender projection that conducts electrical impulses away from the cell body

Question 12

What are dendrites?

Answer 12

Tree-like structures that receive messages from other neurons

Question 13

What are synapses?

Answer 13

Specialized junctions between neurons

Question 14

What are myelin?

Answer 14

A mixture of proteins and phospholipids forming a whitish insulating sheath around many nerve fibers, increasing the speed at which impulses are conducted

Question 15

What is the advantage of an axon being myelinated?

Answer 15

An axon covered with myelin (myelinated) increases the speed of action potentials

Question 16

What is the most common neuron?

Answer 16

Multipolar neuron

Question 17

Function of sensory (afferent) neurons

Answer 17

Detect stimuli
Transmit to the CNS
Conducts signals towards CNS

Question 18

Function of interneurons (association)

Answer 18

Receive signals from many neurons and carry out integrative function

Question 19

90% of all neurons are…?

Answer 19

Interneurons

Question 20

Function of motor (efferent) neurons

Answer 20

Sends signals out to muscles and gland cells

Question 21

Name the 6 types of neuroglial cells

Answer 21

Oligodendrocytes
Ependymal cells
Microglia
Astrocytes
Schwann cells
Satellite cells

Question 22

Describe how an injured nerve fiber may regenerate.

Answer 22

After peripheral nerve injury, axons readily regenerate. The distal portion of the axon, which is disconnected from the cell body, undergoes Wallerian degeneration. This active process results in fragmentation and disintegration of the axon. Debris is removed by glial cells, predominantly macrophages.

Question 23

Explain how a membrane may become polarized.

Answer 23

A cell becomes polarized by moving and storing different types of electrically-charged molecules on different sides of its membrane

Question 24

Define resting potential.

Answer 24

Charge difference across the plasma membrane

Question 25

What is depolarization?

Answer 25

Membrane voltage shifts to a less negative value

Question 26

What is repolarization?

Answer 26

The change in membrane potential that returns it to a negative value just after the depolarization phase of an action potential which has changed the membrane potential to a positive value

Question 27

What is hyperpolarization?

Answer 27

When the membrane potential becomes more negative at a particular spot on the neuron’s membrane

Question 28

List the changes that occur during an action potential.

Answer 28

Resting membrane potential, local potential, threshold, depolarization, spike, repolarization, hyperpolarization

Question 29

Explain the difference between action potentials and nerve impulses.

Answer 29

A nerve impulse is a sudden reversal of the electrical gradient across the plasma membrane of a resting neuron. The reversal of charge is called an action potential.

Question 30

Define refractory period.

Answer 30

Period of resistance to stimulation

Question 31

Define saltatory conduction.

Answer 31

The propagation of action potentials along myelinated axons from one node of Ranvier to the next node, increasing the conduction velocity of action potentials

Question 32

Define synapse.

Answer 32

Nerve signal reaches the end of axon which triggers the release of a neurotransmitter

Question 33

Explain how a nerve impulse is transmitted from one neuron to another.

Answer 33

Nerve impulses begin in a dendrite (there can be many dendrites), then move to the cell body, then down to the axon tip. There is only one axon, but it can have many tips. When a nerve impulse is transferred is called a synapse.

Question 34

Explain the role of calcium in the release of neurotransmitters.

Answer 34

Nerve impulse causes Calcium ions to enter presynaptic neurone. Entry of calcium ions causes fusion of vesicles with presynaptic membrane and the neurotransmitter is released by exocytosis.

Question 35

Define neuropeptide

Answer 35

Chemical messengers made up of small chains of amino acids that are synthesized and released by neurons. Neuropeptides typically bind to G protein-coupled receptors to modulate neural activity and other tissues like the gut, muscles, and heart.

Question 36

What do excitatory postsynaptic potentials (EPSP) do?

Answer 36

Bring the neuron’s potential closer to its firing threshold

Question 37

What do inhibitory postsynaptic potentials (IPSP) do?

Answer 37

Change the charge across the membrane to be further from the firing threshold

Question 38

Describe the “trigger zone” of a neuron.

Answer 38

Where action potential is generated

Question 39

Define facilitation.

Answer 39

A process in which one neuron enhances the effect of another one

Question 40

What does divergence allow?

Answer 40

One neuron to communicate with many other neurons in a network

Question 41

What does convergence allow?

Answer 41

A neuron to receive input from many neurons in a network

Question 42

Explain how nerve impulses are amplified.

Answer 42

Converging nerve fibers amplify nerve impulses. In convergence, two or more incoming fibers contact a single neuron, whereas in divergence, impulses leaving a neuron pass into several output fibers. Several nerve fibers converging onto one nerve fiber amplifies nerve impulses.