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Flashcards in Cytology Deck (110):
1

What does the polarity of a cell refer to?

The number of poles (denrites and axons)

2

Which polarity is commonly found in neurons?

- Multipolar

3

Which neuron is commonly found in specialized sensory systems?

- Bipolar

4

Which neuron is commonly found in general senses?

- Pseudounipolar

5

How is a pseudounipolar neuron identified?

It is a specialized bipolar neuron in which the axon can bypass the cell body for faster propagation.

6

How are neurons classified according to axon length?

- Golgi I (long)
- Golgi II (short)

7

What do Golgi I neurons connect?

- One subsystem to another

8

What do Golgi II neurons connect?

- Neurons within the same subsystem

9

What are segmental Golgi II neurons?

- Project to the same segment (1 - 3 segments)

10

What are associative Golgi II neurons?

- Project ipsilaterally

11

What are commissural Golgi II neurons?

- Project contralaterally

12

What propriospinal Golgi II neurons?

- Project to other spinal column segments ( 5 - 10 - 15 segments)

13

What function do propriospinal Golgi II neurons perform?

- Motor reflex functions

14

What are tract cells?

- Golgi I neurons that only reside in the CNS
- Cells contain same information, and respond to the same modalities
- Form tracts

15

Which type of Golgi neuron is an interneuron?

Golgi II

16

What is an afferent neuron?

- Arriving to point of reference

17

What is an efferent neuron?

- Exiting point of reference

18

Which type of neuron is typically sensory?

- Afferent

19

Which type of neuron is typically motor?

- Efferent

20

What is an excitatory neuron?

- Causes an action

21

What is an inhibitory neuron?

- Prevents an action, or makes it more difficult

22

What is a modulatory neuron?

- Nervous system influences a structure or environment that makes the target neuron harder or easier to fire

23

What does it mean if a neuron has tonic/ regular spiking?

- The neuron is constantly firing

24

What does it mean if a neuron is phasic/ busting?

- Neurons fire in bursts

25

What does it mean if a neuron is fast spiking?

- It has fast firing rates

26

What are thin spike neurons?

I don't know ???????????

27

What are cholinergic neurons?

Neurons that release acetylcholine

28

What are cholinergic neurons' function?

- Primary stimulator to muscles
- Inhibitor of parasympathetic nervous system

29

What are GABAergic neurons?

- Primary inhibitors

30

What are glutamatergic neurons?

- Excitatory neurons

31

What are dopaminergic neurons?

- Excitatory neurons that release dopamine

32

What are serotonin releasing neurons?

- Excitatory neurons that release serotonin

33

What are the non-neural cells of the CNS and PNS?

- Neuroglia

34

By how much do glia cells outnumber neurons?

5 - 50: 1

35

What percentage of the total CNS is comprised of glia cells?

- 40 %

36

What are the 4 main functions of the glia cells?

- Development
- Support
- Nurture: (What nutrients the nuerons will and won't receive)
- Maintenance of relatively constant environment (nutrition, and impulse conduction)

37

What are the most abundant neuroglia?

- Astrocytes

38

What type of neuron do astrocytes resemble?

- Multipolar cells

39

Where are fibrous astrocytes found?

In white matter

40

Where are protoplasmic astrocytes found?

In gray matter

41

What astrocytes that are found on the outside of blood vessels called?

- Perivascular glia

42

Where are oligodendroglia found?

Within the white matter of the CNS

43

What do oligodendroglia produce?

Myelin

44

What tissue do microglia originate from?

- Mesoderm

45

What type of cells do microglia replace in the CNS?

- White blood cells

46

How do microglia arrive in the nervous system?

Through the blood

47

What are ependymal cells?

Neural epithelial derivative cells that line the ventricles.

48

What are the origin cells of the neuroglia?

- Spongioblasts

49

How many cell layers are there in the ependymal layer?

- One

50

What is the out-pocketing of the ependymal layer, and what is its function?

- The Choroid Plexus
- Produces CSF

51

What is the origin of cerebrospinal fluid?

- Blood (it is a filtrate of blood)

52

What are the 2 components of the blood brain barrier?

- Tight endothelial layer
- Psedopodia/ astrocytes plug holes

53

What cells produce myelin in the periphery?

- Schwann Cells

54

What cells are analogous to astroglia in the periphery?

- Satellite glia

55

What are the perineural glia?

- Add structure to peripheral nervous system

56

What is a Gliosis?

- Proliferation of astrocytes that form plaques and scars that form barriers in the nervous system

57

Describe an axospinous synapse.

Axon synapses with spine of dendrite

58

Describe an axodendritic synapse.

Axon synapses with dendrite

59

Describe an axosomatic synapse.

Axon synapses with cell body

60

Describe an axoaxonic synapse.

Axon synapses with axon

61

Describe a chain synapse.

Axon synapses with multiple axons

62

Describe an en passant synapse.

Synapse occurs along path of neuron (not at end-plate)

63

What is an electrical junction?

- A gap junction that conducts fast due to no neurotransmitter being required to activate

64

What is an iontotropic receptor?

- Actional potential hits synapses and relases neurotransmitter, which opens gate, sodium flows in, and an action potential occurs

65

What is a metabotropic receptor?

- Neurotransmitter causes a morphological change, and a channel is activated via a secondary transmitter

66

How is a neuron that originates in the spinal cord, but then has an axon that travels into the periphery myelinated?

- The axon is myelinated by oligodendroglia in the spinal cord, and by schwann cells in the periphery.

67

What is the branch of an axon called?

A collateral

68

Which protective layers of the spinal cord continue on into the peripheral nerve?

The dura and arachnoid mater.

69

Which protective layer lines the spinal cord directly?

Pia mater

70

Name the 3 protective sheaths of the spinal nerves.

Endoneurium
Perineurium
Endoneurium

71

Which protective coating of the peripheral nerves covers a fascile?

Perineurium

72

What is a fascile?

A collection of axons

73

What is the protective coating that lines each individual axon?

Endoneurium

74

What is the protective coating that lines collections of fasciles?

Epineurium

75

What is the epifascicular epineurium?

Epineurium that surrounds the entire nerve.

76

What is the inferfascicular epineurium?

Epineurium that holds all the fasciles together.

77

What are the 3 functions of interfascicular epineurium?

-Loose attachment to epifascicular epineurium allows for the sliding of one fascile over another
- Helps facilitate dispersion of compressive forces
- Gives nerve structure

78

What type of collagen makes up the perineurium?

- Type I and Type II

79

How is the collagen of the perineurium oriented?

- In oblique, longitudinal, and circumferential directions

80

How many cell layers thick is the perineurium?

-Up to 15 cell layers thick

81

What is the primary function of the perineurium?

Antiloading shearing responses/ mechanical strength

82

What function does the perineurium provide in the brain?

Blood brain barrier

83

What is the composition of endoneurium? (What is it made up of? What is it orientation?)

- Loose CT of type I and II; longitudinally oriented between axons
- Basal lamina made up of type IV collagen

84

How are nerves supplied blood?

- Vessels run longitudinally along the perineurium and periodically enter epineurium
- Divide into arterioles that form an anastomatic netowrk in epineurium and perineurium
- Vessels enter endoneurium and travel longitudinally as capillaries

Termed: Epineurial, perineurial, and endoneurial arteries

85

Describe the relationship between unmylelinated nerves and schwann cells.

- One schwann cell's cytoplasm will surround many different axons like sticks and a ballon

86

What is the continues layer formed by multiple schwann cells surrounding a nerve?

- Neurolemma

87

Are myelinated or unmyelinated fibers more common?

Umyelinated

88

Are myelinated or unmyelinated fibers larger?

Myelinated

89

What is a mesaxon?

- Gap in the outer cytoplasm of the schwann cell caused by the axon

90

How do myelinated fibers differ form unmyelinated fibers in the periphery?

1 schwann cell: 1 axon

Schwann cell wraps around axon forming a thick fatty covering

91

What is a node?

The gap between myelin sheaths

92

What is an internode?

The area of myelination

93

How do myelinated axons different in the CNS compared to the PNS?

- There is no neurolemme
- There is not a 1:1 relationship
- One oligodendroglia provides myelin to many axons

94

Why can the CNS not regenerate as well as the PNS?

- There is no neurolemma sheath to guide axon regeneration

95

What is the first classification of nerve fibers?

- General: Distributed throughout the body
- Special: Restricted throughout the body

96

What is the second classification of nerve fibers?

- Visceral: Autonomic/ brachial arches
- Somatic: Somites, body, skin, muscles, joints

97

What is the third classification of nerve fibers?

- Afferent: Sensory (Received by spinal cord)
- Efferent: Motor (Sent from spinal cord)

98

What are the 4 anatomic functional types of cranial and spinal nerves?

- General Somatic Afferent (GSA)
- General Visceral Afferent (GVA)
- General Visceral Efferent (GVE)
- General Somatic Efferent (GSE)

99

What anatomic functional type of nerve provides conscious sensation (pain, temperature, touch, proprioception)?

- General Somatic Afferent

100

What anatomic functional type of nerve provides visceral sensation? (Pain from ischemia, blood pressure, etc.)

- General Visceral Afferent

101

What anatomic functional type of nerve provides autonomic motor drive to smooth and cardiac muscle and glands (parasympathetic, sympathetic - preganglionic and postganglionic fibers)?

- General Visercal Efferent

102

What anatomic functional type of nerve provides voluntary motor drive to skeletal muscle (derived from myotomes)?

- General somatic efferent

103

What is the explanation for referred pain in terms of a functional anatomical perspective?

- Visceral and somatic afferent fibers travel the same pathways, and can activate the same sensory neurons as somatic fibers

104

What are the only spinal/ cranial nerves that do not have all 4 components?

- Cutaneous nerves

105

What are the 3 anatomic functional components unique to cranial nerves?

- Special Visceral Efferent
- Special Visceral Afferent
- Special Somatic Afferent

106

Which anatomic functional component provides visceral sensations of taste and smell?

Special Visceral Afferent

107

Which anatomic functional component provides somatic sensations of vision, hearing, and equilibrium?

Special Somatic Afferent

108

Which anatomic functional component provides voluntary motor drive to skeletal muscle (derived from the branchiomeres)?

Special Visceral Efferent

109

What is the name of the general nerve classification based on size and speed of conduction?

Erlanger - Gasser

110

What is the name of the sensory root nerve classification?

Lloyd - Hunt