Histology lecture

Question 1

What are the three functions of the nervous system?

Answer 1

Sensory inputIntegrationMotor output

Question 2

Describe the two types of cells found in nervous tissue.

Answer 2

Nerve cells/neurons: main functional cells of the nervous system that generate and transmit action potentialsNeuroglia, glia, or supporting cells:these are much smaller than nerve cell and they have a supportive role

Question 3

The three special characteristics of neurons are?

Answer 3

Extreme longevity- can function for 100 yearsMost are amiotic- lose their ability to divide as they become communication links in the nervous systemHigh metabolic rate: they will die within a few minutes without oxygen

Question 4

What goes on in the neuron cell body?

Answer 4

It is the biosynthetic center of the neuron. It makes necessary molecules and sends them down the line

Question 5

True or false, action potentials are associated with the cell body?

Answer 5

False. They are not

Question 6

What are Nissl bodies?

Answer 6

clumps of ribosomes

Question 7

What do the dendrites do?

Answer 7

They are the main receptive/main input regions of the neuron

Question 8

Are dendrites myelinated? Why or why not?

Answer 8

No- no action potentials here.

Question 9

What is the purpose of the axon/nerve fiber?

Answer 9

Generation and conduction of action potentials

Question 10

How many axons can a neuron have?

Answer 10

Just one

Question 11

A collection of cell bodies in the CNS is called….

Answer 11

a nucleus

Question 12

A collection of cell bodies in the PNS is called…

Answer 12

a ganglion

Question 13

What is the axon hillock?

Answer 13

It is kind of the base of the cell body where the axon begins to start- no organelles found here and it’s not myelinated

Question 14

Where are interneurons found?

Answer 14

Between motor and sensory neurons

Question 15

How are neurons classified?

Answer 15

By the number of dendritic processes

Question 16

Which types of neurons are the most abundant?

Answer 16

multipolar

Question 17

Where are unipolar neurons mainly found?

Answer 17

In the PNS

Question 18

True or false, multipolar neurons are usually for special sensory?

Answer 18

False- most are for motor function or are interneurons

Question 19

Which neurons are responsible for special sense?

Answer 19

bipolar neurons

Question 20

Which neurons are responsible for general sensory?

Answer 20

Unipolar neurons

Question 21

There are 5 types of synapses, which are the two most common?

Answer 21

Axodendritic synapseAxosomatic synapse

Question 22

What are pre and postsynaptic neurons?

Answer 22

Presynaptic neurons carry the signal towards the synapse Postsynaptic neurons carry the signal away from the synapse

Question 23

What are the two types of synapses? Explain them.

Answer 23

Electrical synapses: found in the heartChemical synapses: the electrical signal is turned into a chemical signal and the neurotransmitter that is released by the axon terminals diffuses across the synaptic cleft where it is received, processed and then turned back into an electrical signal

Question 24

How does chemical transmission occur at the neuronal synapse?

Answer 24

-Voltage is propagated to the end of the axon-Ca2+ channels open which facilitate the fusion of vesicles carrying NT’s to cross the synaptic cleft-NT’s bind to receptors on the post synaptic membrane, each receptor being a ligand-gated channel-the channel opens, ions flow in creating the new charge that is then propagated

Question 25

What are the three ways neurotransmitters are removed from the postsynaptic receptor?

Answer 25

Degradation by enzymesRe-uptake by astrocytes or the presynaptic terminalDiffusion away from the synapse

Question 26

True or false, neuroglia are supportive cells?

Answer 26

True

Question 27

What is the job of the oligodendrocytes?

Answer 27

They produce the myelin sheath in the CNS

Question 28

What is the role of an astrocyte?

Answer 28

It can get rid of excess neurotransmitterit is associated with capillaries and contributes to the blood-brain barrier

Question 29

Where are astrocytes found?

Answer 29

They are found in both the white and gray matter of the brain and spinal cord, BUT MOSTLY IN THE GRAY MATTER 

Question 30

True or false, ependymal cells are epithelial cells?

Answer 30

False. They are not

Question 31

Where are ependymal cells found?

Answer 31

They are low columnar or cuboidal cells that line spaces in the CNS

Question 32

Ependymal cells have extensions that help to move CSF around, true or false?

Answer 32

Truth

Question 33

What is the key defining factor for microglial cells?

Answer 33

The nuclei are elongated. On astrocytes and oligodendrocytes the nuclei are rounded

Question 34

Where do microglia originate from?

Answer 34

Monocytes

Question 35

How many internodal sheaths can a single schwann cell form?

Answer 35

One

Question 36

What are satellite cells?

Answer 36

They surround the neuronal cell bodies in a supportive capacity

Question 37

What makes white matter white?

Answer 37

All the myelin (the oligodendrocytes are plentiful because they are the ones that make myelin)

Question 38

What is gray matter composed of?

Answer 38

neuronal cell bodies and dendrites, unmyelinated axons and their terminals, as well as astrocytes are found here. Gray matter is gray due to Nissl bodies and lack of myelin

Question 39

What are clusters of neuronal cell bodies called in the CNS and the PNS?

Answer 39

CNS- nucleus (think the center)PNS- ganglion (think out in your gangly arms and stuff)

Question 40

What is a bundle of neuronal axons called in the CNS and the PNS?

Answer 40

CNS: tractPNS: nerve

Question 41

Connective tissue coverings associated with nerves

Answer 41

1. endoneurium (cover axon)2. perineurium (cover fascicle or bundle)3. epineurium (cover entire nerve)

Question 42

Nerves can be classified by what direction they're transmitting as well as where they originate from. What are these?

Answer 42

Sensory (afferent)Motor (efferent)Mixed (both motor and sensory)Cranial nerves- originate at the brainSpinal nerves- originate at the spinal cord

Question 43

What are the functions of a myelin sheath?

Answer 43

Protect and electrically insulate axons from other axonsIncrease the speed of tranmission

Question 44

How are nerve fibers myelinated in the PNS?

Answer 44

A schwann cell associates with an axon and wraps it, forming an internodal segment. Each successive layer fuses together

Question 45

Do schwann cells that wrap the axon have a nucleus?

Answer 45

Yep. and it's often fairly big and noticeable

Question 46

The rate of impulse propagation depends on what?

Answer 46

Axon diameter: the large the diameter the faster it goesMyelination- continuous versus saltatory conduction