Nervous Tissue Flashcards
What are the two main subdivisions of the nervous system?
Central and Peripheral nervous system
What is inside the Central nervous system?
Brain, spinal cord and optic nerve
What is inside the Peripheral nervous system?
All nervous tissue outside the Central nervous system
What are the two divisions within the peripheral nervous system?
Sensory/Afferent and Motor/Efferent divisons
What does the Sensory/Afferent division of the peripheral nervous system do?
Brings information to the Central nervous system
What does the Motor/Efferent division of the peripheral nervous system do?
Brings information from the Central nervous system to organs, muscles and glands
What are the 3 main functions that the nervous system has?
Sensory: Detection of internal and external stimuli to send to the central nervous system
Integrative: Analysis and storing information
Motor: Stimulation of muscles and glands through the peripheral nervous system
What are the two types of cells in nervous tissue?
Neurons and Neuroglia
How long can neurons be?
Up to 1m long
What are the components of a neuron?
Cell body, dendrites and an axon
Is the dendrite the input or output of the neuron?
Input
Is the axon the input or output of the neuron?
Output
Do neurons divide?
No
Do neurons have a low or high metabolic rate?
High metabolic rate, as they die quickly without oxygen
What are the 4 types of neurons?
Multipolar, Bipolar, Unipolar and Anaxonic neurons
What is the most common type of neuron in the body?
Multipolar neurons
How many dendrites do Multipolar neurons have?
2 or more
All motor neurons are what type of neuron?
Multipolar neurons
How many axons do multipolar neurons have?
One
How many dendrites do bipolar neurons have?
One dendrite into the cell body
How many axons do bipolar neurons have?
One
What types of functions are bipolar neurons involved in?
Special senses (Sight, Smell, Hearing, etc.)
What is special about the dendrites and axon in a unipolar neuron?
They are continuous, one line that doesn’t pass through the cell body
In relation to the axon and dendrites of a unipolar neuron, where is the cell body?
Off to one side, not in line with the axon
What is special about the dendrites and axons in an anaxonic neuron?
You can’t anatomically tell the difference between them
Where are anaxonic neurons found?
In the brain and special sense organs
How well understood are anaxonic neurons?
Very poorly understood
In which sections of the nervous system are neuroglia found?
Both the central and peripheral nervous system
Can neuroglia divide?
Yes
How do neuroglia communicate?
Chemicals
What are the functions of neuroglia?
Physical structure, tissue repair, nutrient supply to neurons, regulating interstitial fluid around neurons and phagocytosis
What are the types of central nervous system neuroglia?
Astrocytes, Oligodendrocytes, Microglia and Ependymal Cells
What shape are astrocytes?
Star-shaped
What is the largest neuroglia?
Astrocytes
How are astrocytes organised?
Into a syncytium (network)
What is the key role of the Astrocyte?
To maintain a stable environment around neurons (e.g. by regulating ions) and to maintain the blood-brain barrier
Other than maintaining the blood-brain barrier, what else can Astrocytes do?
They can support and repair nervous tissue and communicate with neurons via gliotransmitters (e.g. glutamate)
What is the role of an oligodendrocyte?
To form a myelin sheath (protein lipid layer) around central nervous system axons
How many neurons can oligodendrocytes myelinate?
More than one
What do microglia do?
They are phagocytic, so clean up dead nervous tissue or invading bacteria
What creates cerebrospinal fluid?
Ependymal cells
What do ependymal cells do?
Create cerebrospinal fluid, move it around our brain and also monitor its quality
Where are ependymal cells found?
Anywhere where cerebrospinal fluid is found (ventricles in brain and central canal of spinal cord)
What does cerebrospinal fluid do?
Provides a mechanical buffer and moves nutrients and waste
What is the peripheral nervous system’s equivalent of the Oligodendrocyte?
The Schwann cell
How many axons can a Schwann cell myelinate?
One
How many axons can a Schwann cell support, without providing a myelin sheath?
Multiple
What is the central nervous system’s equivalent to the Schwann cell?
The Oligodendrocyte
What is the peripheral nervous system’s equivalent to the astrocyte?
The Satellite cell
What do satellite cells do?
They surround cell bodies in the peripheral nervous system to support them and regulate fluid exchange
What is the central nervous system’s equivalent to the Satellite cell?
The Astrocyte
