Nervous Tissue Flashcards
1
Q
What is the most complex system in the body?
A
Nervous Tissue
Formed by a network of many billion nerve cells (neurons) assisted by glial/neuroglial cells.
2
Q
What are the two main components of the Nervous System?
A
Central Nervous System and Peripheral Nervous System
The organization of nervous tissue into these two systems allows for efficient processing and response to information.
3
Q
What does the Central Nervous System consist of?
A
Brain and Spinal Cord
It serves as the processing center of the body.
4
Q
What is the role of the Central Nervous System?
A
Receive and respond to sensory information
It acts as the primary processing center for information in the body.
5
Q
What does the Peripheral Nervous System include?
A
All nervous tissues in the body including nerve endings and ganglia
This system connects the CNS to the rest of the body.
6
Q
What type of information does the Peripheral Nervous System carry?
A
Sensory information from receptors in different organs and motor commands from the CNS
This includes signals from the skin, muscle, etc.
7
Q
Fill in the blank: The nervous tissue is assisted by _______.
A
glial/neuroglial cells
These supporting cells play a crucial role in the function of neurons.
8
Q
True or False: The Peripheral Nervous System only carries sensory information.
A
False
It also carries motor commands from the CNS to muscles and glands.
9
Q
What is the primary purpose of nervous tissue?
A
To carry sensory information from sensory organs to the brain, process that information, and carry motor information from the brain to skeletal muscles.
10
Q
What are the three main functions of nervous tissue?
A
- Carry sensory information from sensory organs to the brain
- Process sensory information to produce perceptions, memories, decisions, and plans
- Carry motor information from the brain to skeletal muscles
11
Q
What is the functional unit of nervous tissues called?
A
Neuron
12
Q
What is the building block of the nervous system?
A
Neurons
13
Q
What key ability do neurons exhibit that allows them to react to stimuli?
A
Irritability
14
Q
What is the term for the ability of neurons to transmit stimuli?
A
Conductivity
15
Q
Are neurons capable of cell division?
A
No, they are incapable of cell division.
16
Q
What happens to neurons once they die?
A
They are irreplaceable.
17
Q
Approximately how many neurons does the human body contain?
A
Around 100 billion neurons.
18
Q
What are the main parts of neurons?
A
Cell Body, Axon, Dendrites
Each part has unique functions and structures.
19
Q
What does the cell body of a neuron contain?
A
Nucleus, organelles, neuroplasm, neurolemma
The cell body serves as the synthetic or trophic center for the neuron.
20
Q
What is the nucleus of the neuron surrounded by?
A
Neuroplasm
The neuroplasm is basophilic and highly pigmented.
21
Q
What organelles are present in the cytoplasm of the neuron cell body?
A
Endoplasmic Reticulum, Golgi Bodies, Mitochondria, Lysosome, Perisosome, Centrosomes, inclusions
These organelles play crucial roles in cellular functions.
22
Q
What are Nissl Bodies?
A
Intensely granular, basophilic bodies found in the RER
They are indicative of the cell’s synthetic activity.
23
Q
What is the function of Golgi bodies in neurons?
A
Synthesize protein components of neurotransmitters
They work alongside the endoplasmic reticulum.
24
Q
What pigments can be found in the neuron cell body?
A
Melanin, iron
These pigments may play roles in cellular processes.
25
What are fat droplets in neurons referred to as?
Lipo fuchsin
## Footnote
These droplets are indicative of metabolic processes.
26
What is an axon?
A single long process ending at synapses that conducts nerve impulses away from the cell body
## Footnote
It is specialized for impulse generation and conduction.
27
What is the plasma membrane of the axon called?
Axolemma
## Footnote
The axolemma contains specialized receptors for neurotransmitters.
28
What is the longest axon in the human body?
Sciatic nerve
## Footnote
It measures more than 1 meter long.
29
Where do axons originate from?
Axon hillock
## Footnote
The axon hillock is a pyramid-shaped region of the perikaryon.
30
What are dendrites specialized for?
Receiving stimuli from other neurons at synapses
## Footnote
Dendrites can vary in number and presence.
31
What do dendrites carry toward the cell?
Impulses
## Footnote
They transmit electrochemical signals known as action potentials.
32
What is the plasma membrane of a dendrite specialized to transmit?
Electrochemical signals (action potentials)
## Footnote
This function is crucial for neuronal communication.
33
What is a multipolar neuron?
Each cell body has one axon with two or more dendrites.
## Footnote
Most common type of neuron.
34
What characterizes a bipolar neuron?
One dendrite and one axon.
## Footnote
The most common bipolar neurons are sensory neurons of the retina and olfactory epithelium of the inner ear.
35
Define pseudounipolar/unipolar neuron.
Includes all other sensory neurons that have a single process that bifurcates close to the perikaryon.
## Footnote
The longer branch extends to a peripheral ending and the other towards the CNS.
36
What is an anaxonic neuron?
Many dendrites but no true axon.
## Footnote
They do not produce action potentials but regulate electrical changes of adjacent CNS.
37
What are sensory neurons also known as?
Afferent neurons.
## Footnote
They receive stimuli and transmit them to the CNS.
38
What is the function of motor neurons?
Transmit impulses from the CNS to the effector cells.
## Footnote
They are also known as efferent neurons.
39
What do interneurons do?
Convey impulse from one neuron to another.
## Footnote
They are also referred to as association neurons.
40
What are Purkinje Cells?
Mostly found in the cerebellar cortex
## Footnote
Purkinje cells are large neurons that play a critical role in motor control.
41
What type of cells are most numerous in the cerebral cortex?
Pyramidal Cells
## Footnote
Pyramidal cells are involved in cognitive functions and are characterized by their pyramid-shaped cell body.
42
Where are Stellate Cells located?
In the cerebral cortex
## Footnote
Stellate cells are star-shaped neurons that contribute to the processing of sensory information.
43
What is a synapse?
Point of contact and site of transmission of nerve impulse between a neuron and another cell
## Footnote
Synapses are crucial for communication within the nervous system.
44
How is information carried along axons?
In the form of action potentials
## Footnote
Action potentials are rapid electrical signals that travel along the length of the axon.
45
What happens at the axon terminals?
Release of molecules called neurotransmitters
## Footnote
Neurotransmitters are essential for transmitting signals between neurons.
46
What are neurotransmitters?
Molecules that act upon receptor complexes in the dendrites and somas of the next neuron
## Footnote
Neurotransmitters play a key role in modulating neuronal communication.
47
What type of influence do excitatory neurotransmitters have?
They cause the postsynaptic sodium channels to open
## Footnote
This leads to depolarization waves in the postsynaptic neuron.
48
What is an inhibitory synapse?
Neurotransmitters open chloride or other anion channels, causing hyperpolarization
## Footnote
This makes the postsynaptic cell's membrane potential more negative.
49
What is the most common neurotransmitter at neuromuscular junctions?
Acetylcholine
## Footnote
Acetylcholine is vital for muscle activation and various brain functions.
50
What happens when excitatory influences exceed inhibitory influences?
The neuron generates an action potential
## Footnote
This action potential can then be transmitted to another neuron.
51
What are the major components of a typical synapse?
Terminal bouton, presynaptic membrane, and the postsynaptic membrane
## Footnote
These components work together to facilitate synaptic transmission.
52
What is the synaptic cleft?
Space between the presynaptic membrane and the postsynaptic membrane
## Footnote
The synaptic cleft is where neurotransmitters diffuse to reach the postsynaptic receptors.
53
What do axon terminals contain?
Lots of vesicles containing neurotransmitter molecules
## Footnote
These vesicles are essential for the storage and release of neurotransmitters.
54
Why do axon terminals usually contain lots of mitochondria?
For the energy needed for the release of neurotransmitters
## Footnote
Mitochondria are crucial for ATP production, which powers neurotransmitter release.
55
What are glial cells?
Nonneural cells that provide a variety of support functions for the neurons
## Footnote
Also known as neuroglial cells.
56
What are the major types of CNS glial cells?
* Astrocyte
* Ependymal Cell
* Microglial Cell
* Oligodendrocyte
57
What are the two types of astrocytes?
* Protoplasmic Astrocyte
* Fibrous Astrocyte
58
Where are protoplasmic astrocytes most commonly found?
In the grey matter and spinal cord
59
Where are fibrous astrocytes located?
In the white matter
60
What is one function of astrocytes?
Helps form the blood-brain barrier
61
What is another function of astrocytes?
Regulates interstitial fluid composition
62
What do astrocytes provide to the CNS?
Structural support and organization
63
How do astrocytes assist with neuronal development?
By providing support during the process
64
What do astrocytes do when neurons die?
Replicate to occupy space of dying neurons
65
What is the most common immunostain in neuropathology?
Anti-GFAP (Glial Fibrillary Acidic Protein)
66
What do ependymal cells line?
Ventricles of brain and central canal of spinal cord
67
What is one function of ependymal cells?
Assist in production and circulation of CSF
68
What is the role of microglial cells?
Phagocytic cells that move through the CNS
69
How do microglial cells protect the CNS?
By engulfing infectious agents and other potential harmful substances
70
What do microglial cells contain in their cytoplasm?
Many lysosomes for digestion
71
What immunohistochemistry method is used for microglial cells?
Using a monoclonal antibody against HLA (Human Leukocytic Antigen)
72
What is the primary function of oligodendrocytes?
Myelinates and insulates CNS axons
73
What is the benefit of oligodendrocytes myelinating axons?
Allows faster action potential propagation along axons in the CNS
74
What are the two types of glial cells in the PNS?
Satellite Cell and Neurolemmocyte
## Footnote
Neurolemmocyte is also known as Schwann Cells, named after Theodore Schwann.
75
What is the primary function of satellite cells?
Electrically insulates PNS cell body and regulates nutrient and waste exchange for cell bodies in ganglia.
76
What do neurolemmocytes (Schwann Cells) do?
Surround and insulate PNS axons and myelinate those having large diameters.
77
How do neurolemmocytes affect action potential?
Allows for faster action potential along an axon in the PNS.
78
What are the two divisions of the nervous system?
Anatomic Division and Functional Division.
79
What does the Central Nervous System (CNS) consist of?
Brain and Spinal Cord.
80
What does the Peripheral Nervous System (PNS) include?
All nervous tissue in the body.
81
What is the Somatic Nervous System responsible for?
All neurons in CNS and PNS associated with muscle, skin, and sense organs.
82
Fill in the blank: The _______ Nervous System is responsible for involuntary control.
Autonomic
83
What are the major structures of the Central Nervous System?
Cerebrum, Cerebellum, Spinal Cord
84
What connective tissue is absent in the Central Nervous System?
Collagen
85
What protects the Central Nervous System?
Meninges and bones (skull) and vertebrae
86
What is the thickness of the cerebral cortex?
About 2 mm
87
What is the primary function of the neurons in the cerebral cortex?
Integration of sensory information and initiation of voluntary motor responses
88
What are the types of neurons found in Layer I of the cerebral cortex?
Predominantly horizontally running dendrites and axons
89
What type of neurons are found in Layers II, IV, and VI of the cerebral cortex?
Small tightly packed neurons (mainly granule cells)
90
What type of neurons are found in Layers III and V of the cerebral cortex?
Larger neurons (mostly pyramidal cells)
91
What is the cerebellum often referred to as?
Little brain
92
What are the layers of the cerebellar cortex?
* Granule cell layer
* Purkinje cell layer
* Molecular layer
93
What is contained in the anterior horn of the spinal cord?
Motor neurons that innervate muscle fibers
94
What does the posterior horn of the spinal cord contain?
Interneurons in both sensory and motor pathways
95
What constitutes the white matter of the spinal cord?
Nerve fibers
96
What are the functions of the meninges?
* Protect the nervous system
* Provide mechanical stability
* Provide a support framework for arteries and veins
* Enclose a space filled with CSF
97
What are the three layers of the meninges?
* Dura mater
* Arachnoid
* Pia mater
98
What is the dura mater?
Leathery outer layer consisting of elongated fibroblast and large amounts of extracellular collagen
99
What is the arachnoid barrier layer composed of?
2-3 layers of cells attached by continuous tight junctions
100
What is the pia mater?
Innermost layer consisting of 1-2 layers of flattened fibroblast adherent to the brain and spinal cord surface
101
What is meningitis?
Inflammation of meninges
102
What can cause meningitis?
* Infection by virus
* Bacterial agents
* Fungal agents
103
What are collections of axons that carry action potentials called in the PNS?
Nerves
## Footnote
In the CNS, they are referred to as tracts.
104
What are clusters of neuron cell bodies called in the PNS?
Ganglia
## Footnote
In the CNS, they are known as nuclei or cortices.
105
What does the posterior root ganglion carry?
Sensory information
## Footnote
It transmits information from the body back to the CNS.
106
What does the anterior root ganglion carry?
Motor signals
## Footnote
It transmits signals from the CNS to the muscles and internal organs.
107
What is the outer covering of peripheral nerves called?
Epineurium
## Footnote
It is a sheet of dense irregular connective tissue.
108
What are axons in a nerve arranged into clusters called?
Fascicle
109
What connective tissue surrounds a fascicle?
Perineurium
110
What is the name of the loose connective tissue that surrounds each axon in a fascicle?
Endoneurium
111
What are posterior root ganglia also known as?
Sensory ganglia
## Footnote
They are enlargements in the posterior peripheral nerve roots of the spinal cord.
112
What type of cells surround neuron cell bodies and regulate the extracellular ionic environment?
Satellite cells
113
What is the myelin sheath composed of?
Lipid-rich cell membrane of Schwann cells or oligodendrocytes
## Footnote
It provides insulation and facilitates faster nerve conduction.
114
What process occurs as a Schwann cell envelops an axon for myelination?
The wrapping process proceeds from the outside going inside.
115
What forms the major dense line in the spiraling myelin?
The closely opposed inner surface of the membrane.
116
What is the gap between each pair of Schwann cells called?
Node of Ranvier
117
Fill in the blank: The cytoplasm of the Schwann cell will be ______ during the myelination process.
Excluded
118
True or False: The node of Ranvier exposes the axon membrane to the extracellular environment.
True
119
What does the autonomic nervous system comprise?
Autonomic motor nerves
## Footnote
It includes pathways involving two neurons: a preganglionic neuron and a postganglionic neuron.
120
How many neurons are involved in the pathways of the autonomic nervous system?
Two neurons
## Footnote
The preganglionic neuron has its cell body in the CNS, while the postganglionic neuron has its cell body in a ganglion.
121
What are the two divisions of the autonomic nervous system?
* Parasympathetic division
* Sympathetic division
* Enteric Autonomic (sometimes considered a division)
## Footnote
Enteric autonomic components are located in the wall of the digestive tract.
122
What is the primary function of the parasympathetic division?
Maintains normal body homeostasis
## Footnote
It is involved in resting and relaxation situations.
123
Where are the ganglia of the parasympathetic division located?
Within or near the effector organs
## Footnote
This proximity facilitates its functions in homeostasis.
124
What physiological changes occur during the sympathetic division's activation?
* Increased heart rate
* Increased blood pressure
* Increased excitement
## Footnote
These changes are part of the body's 'fight or flight' response.
125
What is the role of the sympathetic division?
Controls the body’s responses during emergencies and excitement
## Footnote
It prepares the body for 'fight or flight' situations.
126
Fill in the blank: The _______ division is involved in the constriction of the pupils and slowing of the heart rate.
[Parasympathetic]
## Footnote
This division promotes relaxation and homeostasis.
127
True or False: The enteric autonomic system is located within the central nervous system.
False
## Footnote
The enteric nervous system components are located in the wall of the digestive tract.
128
What are some functions of the parasympathetic division?
* Constriction of pupils
* Slowing of heart rate
* Dilation of blood vessels
## Footnote
These functions support resting and recovery processes.
129
Where are the ganglia of the sympathetic division located?
Close to the CNS
## Footnote
This location allows quick responses to stressors.
