Histology Flashcards
1
Q
What are the two main types of matter in the nervous tissue?
A
Gray matter and white matter
Gray matter consists of neuron and neuroglia cells, while white matter contains nerve processes and neuroglia cells without neuronal cell bodies.
2
Q
What is the primary function of dendrites?
A
Receive and integrate stimuli from other nerve cells
Dendrites are short, tapering, and highly branched processes of a neuron.
3
Q
What is the function of the axon?
A
Transmit impulses to other neurons or effectors, such as muscles and glands
4
Q
What are the supporting cells in the nervous system called?
A
Neuroglia cells
Schwann cells are a type of neuroglia that support and protect neurons.
5
Q
What structures compose a neuron?
A
Cell body and cell processes
The cell body includes the nucleus, cytoplasm, Nissl substance, and neuronal cytoskeletal components.
6
Q
What is the role of the myelin sheath?
A
Insulate axons to increase the speed of impulse transmission
7
Q
Fill in the blank: The axon hillock is devoid of _______.
A
Nissl substance
8
Q
What does the Nissl substance consist of?
A
Rough endoplasmic reticulum (RER) and ribosomes
9
Q
True or False: A single neuron can have multiple axons.
A
False
A single neuron typically has only one axon.
10
Q
What is the appearance of the cell body of a neuron?
A
Oval, round, or polygonal shape with a prominent nucleolus
11
Q
What are the components of the neuronal cytoskeleton?
A
Neurofilaments and neurotubules
12
Q
What is the significance of the Node of Ranvier?
A
Facilitates rapid conduction of impulses along myelinated axons
13
Q
Fill in the blank: Dendrites are typically _______ and highly branched.
A
Short
14
Q
What type of cell processes does the axon consist of?
A
Single process extending long distances from the cell body
15
Q
What is the function of Schwann’s cells?
A
Support and protect neurons; form myelin sheath in peripheral nervous system
16
Q
What is the cytoplasm of a neuron referred to as?
A
Neuroplasm
17
Q
What are the three types of neuroglial cells in the CNS?
A
- Astrocyte
- Oligodendrocyte
- Microglia
These cells provide support and protection for neurons.
18
Q
What is the primary function of astrocytes?
A
Provide structural and metabolic support to neurons
Astrocytes maintain the Blood-Brain Barrier and release glucose from stored glycogen.
19
Q
What distinguishes a pseudounipolar neuron?
A
A single process arises from the cell body and branches off forming central and peripheral branches (T-shape)
Commonly found in dorsal root ganglion and trigeminal ganglion.
20
Q
What is the role of oligodendrocytes in the CNS?
A
Manufacturing and maintaining myelin of the axons
Each oligodendrocyte can provide a myelin sheath to several axons.
21
Q
What are the two types of neurons based on their function?
A
- Sensory / afferent neurons
- Motor / efferent neurons
- Interneurons
Sensory neurons receive input from receptors, motor neurons conduct impulses to effectors, and interneurons establish networks in the CNS.
22
Q
Fill in the blank: The Blood-Brain Barrier (BBB) is a ______ barrier.
A
highly selective
It consists of continuous endothelial cells forming tight junctions.
23
Q
What is the function of microglia?
A
- Clearing debris and damaged structures in CNS
- Protecting CNS from viruses and microorganisms
Microglia are small dark staining cells with elongated nuclei.
24
Q
What are the main components that can easily penetrate the BBB?
A
- O2
- CO2
- Water
- Small lipid soluble materials
Macromolecules cannot enter the intercellular spaces of the CNS.
25
True or False: Blood-Brain Barrier allows antibiotics and therapeutic drugs to pass freely.
False
## Footnote
Macromolecules such as antibiotics and therapeutic drugs cannot enter the CNS.
26
What type of neuron has multiple dendrites and one axon?
Multipolar neuron
## Footnote
This type of neuron is commonly found as motor neurons of the brain and spinal cord.
27
What is the role of Schwann cells in the PNS?
Forming myelin sheaths around axons
## Footnote
Schwann cells are essential for the regeneration of peripheral nerves.
28
What are the two main components of the Central Nervous System (CNS)?
• Brain
• Spinal cord
29
What is the outer and inner structure of the brain?
Outer: Gray matter
Inner: White matter
30
What is the outer and inner structure of the spinal cord?
Outer: White matter
Inner: Gray matter
31
What does gray matter consist of?
• Neuronal cell bodies
• Neuronal glial cells
32
What does white matter consist of?
• Myelinated axons
• Oligodendroglia
33
What is the gray matter of the cerebrum known as?
Cerebral cortex
34
How many layers compose the cerebral cortex?
6 layers
35
What types of cells are found in the molecular layer of the cerebral cortex?
• Horizontal cells
• Neuroglia
• Mostly nerve terminals
36
What types of cells are found in the external granular layer of the cerebral cortex?
• Granule (stellate) cells
• Neuroglia cells
• Small pyramidal cells
37
What types of cells are found in the external pyramidal layer of the cerebral cortex?
Medium pyramidal cells and neuroglia
38
What is the internal granular layer of the cerebral cortex characterized by?
• Thin layer
• Small granule cells
• Neuroglia (greatest cell density)
39
What types of cells are found in the internal pyramidal layer of the cerebral cortex?
• Large pyramidal cells
• Neuroglia (lowest cell density)
40
What is found in the multiform layer of the cerebral cortex?
Various shapes cells (Martinotti cells) and neuroglia
41
What is the structure of the gray matter in the cerebellar cortex?
• Neurons
• Glial cells
42
What is the structure of the white matter in the cerebellar cortex?
• Nerve processes
• Glial cells
43
What are the three layers of the cerebellar cortex?
• Molecular layer
• Purkinje cell layer
• Granular layer
44
What types of cells are found in the molecular layer of the cerebellar cortex?
• Stellate cells
• Basket cells
• Neuroglia
45
What types of cells are found in the Purkinje cell layer of the cerebellar cortex?
Large Purkinje cells and neuroglia
46
What types of cells are found in the granular layer of the cerebellar cortex?
Small granule cells and neuroglia
47
What are the three layers of the meninges?
• Dura mater
• Arachnoid mater
• Pia mater
48
What is the dura mater?
Outermost layer; dense collagenous tissue
49
What is the arachnoid mater composed of?
Fibroblast, collagen, and elastic tissue
50
What is the pia mater?
Thin layer of connective tissue covering the surface of the brain and spinal cord
51
What is the shape of gray matter in the spinal cord?
H-shaped
52
What types of neurons are found in the anterior horn of the spinal cord?
Motor neurons
53
What types of neurons are found in the posterior horn of the spinal cord?
Sensory neurons
54
What is the function of the choroid plexus?
Responsible for secreting and maintaining the chemical composition of the cerebrospinal fluid (CSF)
## Footnote
The choroid plexus is formed by folds of pia mater housing capillaries and ependymal cells.
55
What type of epithelium lines the ventricles of the brain and central canal of the spinal cord?
Low columnar to cuboidal epithelium
## Footnote
This epithelium is associated with abundant microvilli on its apical surface.
56
What are the two types of ganglia in the peripheral nervous system (PNS)?
* Sensory ganglia: aggregation of sensory neurons (pseudounipolar neurons)
* Autonomic ganglia: aggregation of postganglionic neurons (multipolar neurons)
## Footnote
Sensory ganglia contain neurons that transmit sensory information, while autonomic ganglia are involved in involuntary functions.
57
What is the role of Schwann cells?
Form myelin sheath around segments of axons in the peripheral nervous system
## Footnote
One Schwann cell forms myelin around a segment of one axon.
58
What is the structure surrounding individual axons in the PNS?
Endoneurium
## Footnote
Endoneurium is a thin layer of loose connective tissue surrounding each axon.
59
What are the components of a ganglion?
* Cell bodies
* Axons
* Support cells: satellite cells and Schwann cells
* Loose fibrocollagenous support tissue (stroma)
## Footnote
Ganglia serve as aggregations of neuron cell bodies located outside the central nervous system.
60
What is the appearance of a neuron cell body in a ganglion?
Large nucleus with prominent nucleolus, surrounded by satellite cells
## Footnote
The cytoplasm of the neuron cell body contains Nissl substance.
61
True or False: The external sheath is the innermost covering layer of a nerve bundle.
False
## Footnote
The external sheath is the outermost covering layer of the nerve bundle.
62
Fill in the blank: The _______ is the cytoplasm of Schwann cells.
Neurilemma
## Footnote
Neurilemma surrounds the myelin sheath formed by Schwann cells.
63
What type of supporting cells are found in both sensory and autonomic ganglia?
Satellite cells
## Footnote
Satellite cells supply nutrients to neurons.
64
What are the two sheaths associated with peripheral nerves?
* External sheath
* Internal sheath
## Footnote
These sheaths include connective tissue layers that protect and support the nerve fibers.
65
What is a myelinated axon?
An axon that is covered by a myelin sheath, which is produced by oligodendroglia in the CNS and Schwann cells in the PNS.
## Footnote
Myelination increases the speed of signal propagation.
66
What is the function of the myelin sheath?
To insulate axons and increase the speed of signal transmission through saltatory conduction.
## Footnote
Myelin sheath formation differs between the CNS and PNS.
67
What is the Node of Ranvier?
A small space between each segment of myelin sheath on a myelinated axon.
## Footnote
It is crucial for saltatory conduction.
68
How does signal propagation differ between myelinated and unmyelinated axons?
Myelinated axons propagate signals faster than unmyelinated axons, which conduct signals more slowly through continuous conduction.
## Footnote
Myelination allows for more efficient nerve impulse transmission.
69
What are the components of synaptic morphology?
* Presynaptic membrane: releases neurotransmitters
* Postsynaptic membrane: contains binding-gated ion-channel receptors
* Synaptic cleft: gap for neurotransmitter diffusion
## Footnote
These components are essential for neurotransmission.
70
What characterizes an unmyelinated axon?
It lacks a myelin sheath, resulting in slower nerve impulses and continuous conduction.
## Footnote
Several unmyelinated axons can be enveloped by a single Schwann cell.
71
What happens to a neuron after injury?
Neurons have limited regeneration capabilities; a destroyed neuron is lost in the CNS, while the PNS can repair through axonal regeneration.
## Footnote
Chromatolysis and myelin debris phagocytosis are part of the recovery process.
72
What is axonal degeneration?
The process of degeneration of the axon following injury, which includes chromatolysis and loss of Nissl substance.
## Footnote
It is a critical step in the response of neurons to injury.
73
What are the types of synapses?
* Chemical synapse: communication via neurotransmitters
* Electrical synapse: direct electrical coupling between nerve cells
## Footnote
Both types facilitate neuron communication.
74
True or False: The CNS has a high capacity for neuronal repair.
False
## Footnote
The CNS has limited repair capabilities compared to the PNS.
75
What is a myelinated axon?
An axon that is covered by a myelin sheath, which is produced by oligodendroglia in the CNS and Schwann cells in the PNS.
## Footnote
Myelination increases the speed of signal propagation.
76
What is the function of the myelin sheath?
To insulate axons and increase the speed of signal transmission through saltatory conduction.
## Footnote
Myelin sheath formation differs between the CNS and PNS.
77
What is the Node of Ranvier?
A small space between each segment of myelin sheath on a myelinated axon.
## Footnote
It is crucial for saltatory conduction.
78
How does signal propagation differ between myelinated and unmyelinated axons?
Myelinated axons propagate signals faster than unmyelinated axons, which conduct signals more slowly through continuous conduction.
## Footnote
Myelination allows for more efficient nerve impulse transmission.
79
What are the components of synaptic morphology?
* Presynaptic membrane: releases neurotransmitters
* Postsynaptic membrane: contains binding-gated ion-channel receptors
* Synaptic cleft: gap for neurotransmitter diffusion
## Footnote
These components are essential for neurotransmission.
80
What characterizes an unmyelinated axon?
It lacks a myelin sheath, resulting in slower nerve impulses and continuous conduction.
## Footnote
Several unmyelinated axons can be enveloped by a single Schwann cell.
81
What happens to a neuron after injury?
Neurons have limited regeneration capabilities; a destroyed neuron is lost in the CNS, while the PNS can repair through axonal regeneration.
## Footnote
Chromatolysis and myelin debris phagocytosis are part of the recovery process.
82
What is axonal degeneration?
The process of degeneration of the axon following injury, which includes chromatolysis and loss of Nissl substance.
## Footnote
It is a critical step in the response of neurons to injury.
83
What is the role of Schwann cells in PNS regeneration?
Schwann cells dedifferentiate and proliferate, aiding in the repair process and guiding axonal regrowth.
## Footnote
They play a crucial role in the regeneration of peripheral nerves.
84
Fill in the blank: The small gap between the presynaptic and postsynaptic membranes is called the _______.
synaptic cleft
85
What is continuous conduction?
The process by which unmyelinated axons propagate nerve impulses slowly without myelin insulation.
## Footnote
This is in contrast to the faster saltatory conduction in myelinated fibers.
91
92
What is required for the regeneration of PNS axons and dendrites?
The cell body must be intact and functional.
93
What are gliomas?
Primary brain tumors most commonly derived from glial cells.
94
Name the three major types of gliomas.
* Astrocytic tumors: astrocytoma
* Oligodendrocytic tumors: oligodendroma
* Ependymal tumors: ependymoma
95
What is the process of neuronal regeneration in the CNS characterized by?
Inefficient clearance of myelin debris and slow process of myelin removal.
96
What does gliosis refer to?
An increase in the number of glial cells.
97
What is a consequence of astrocytes depositing scar tissue?
Failure of nerve regeneration and permanent damage.
98
What are the characteristics of tumors of the PNS?
* Neurilemmoma
* Schwannoma
* Neurinoma
* Mostly benign and less than 1% become malignant.
99
Where do vestibular schwannomas typically occur?
On the nerve that connects the inner ear and brain.
100
What is Guillain-Barre syndrome (GBS)?
An acute inflammatory demyelinating polyradiculoneuropathy.
101
What is the effect of damage to the myelin sheath?
Loss or decrease in the ability to transmit electrical impulses along nerve fibers.
102
What happens to myelin in multiple sclerosis (MS)?
It becomes detached from the axon and eventually destroyed.
103
What are the symptoms of multiple sclerosis dependent on?
The area of the brain affected.
104
What type of therapy is used for the treatment of demyelinating diseases?
Immunomodulatory therapy.
105
Fill in the blank: Astrocytes deposit _______ which leads to failure of nerve regeneration.
scar tissue
106
True or False: Most tumors of the PNS are malignant.
False
