Comparison between tract and nerve

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  Comparison between tract and nerve Nerve Nerve contain bundle of axons (nerve fibers) in the peripheral nervous system (PNS) that transmits signals between the central nervous system (CNS) and other parts of the body. It is the most important part of peripheral nervous system Location: Peripheral nervous system. Structure: Made of axons, connective tissue layers (endoneurium: axon is surrounded by it , perineurium: bundle of axons are surrounded by it, epineurium: whole nerve trunk is surrounded by it), and blood vessels. It gets myelination by Schwann cell   Function: Carries sensory signals to the CNS (afferent) from peripheral part of body or motor signals carry from from the CNS (efferent) to target organs like skeletal muscle, cardiac muscle, smooth muscle or glands Example: Sciatic nerve, median nerve, except optic nerve (though optic nerve is technically part of CNS in develop...
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Difference between gray and white matter

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Difference between gray matter and white matter
Topics
Gray matter
White matter
Composition
Nerve cell body ,
Neuroglia,
Processes ,
Blood vessels
Neuroglia,
Processes ,
Blood vessels
Colour
Light grey
White
Percentage
Occupy 40% of brain
Occupy 60% of brain
Maturity
Girl  11 years
Boy 12 years 
Girl 25 years
Boy 20 years
Sex difference
Male 6.5 more gray matter
Female   contain 10 times more  white matter
Proportion of
Men have higher proportion of white matter
women have higher proportion of grey  matter
Function
It is the information processing region  of brain
It makes connection between different information processing region of brain
Oxygen use
It uses almost 95% of oxygen
It uses remaining  5%
Loss of volume
It volume losses constantly throughout the life
its volume losses start after mid age
Other name of
Gray matter also known as substantia grisea
White matter also known as substantia alba

Grey (British)  gray (American) matter and white matter are  found within the  central nervous system.
Composition of gray matter :
1.      Neuron cell body,
2.      Initial portion of dendrites and axon
3.      Neuroglia
4.      Blood vessels
Composition of white matter:
1.      White matter contain
2.      numerous dendrites and myelinated axons, 
3.      neuroglia, and
4.      blood vessels.
Colour:
Gray matter:  actually has a very light gray colour with yellowish or pinkish hues, which come
from blood vessels and neuronal cell bodies.
White matter:  the colour of white matter arises mainly from the whiteness of myelin.
Location
location of gray matter ::
In cerebrum and cerebrum gray matter situated in outer layer of these organs.
In spinal cord it is situated in inner layer of this organ . 
A small collection of gray matter known as nuclei present within the white matter. Example :  basal nuclei/ nuclei: caudate nucleus, putamen, globus pallidus , substantia nigra, subthalamic nucleus , nucleus accumbens and  brain stem nuclei (red nuclei, cranial nerve nuclei) are spread within the cerebral white matter.
Cerebellar nuclei dentate nuclei, fastigi, emboliform etc are the small collection of gray matter present within the white matter of cerebellum .
Ganglia are small collection of gray matter (neuron cell body ) situated outside the central nervous system .
Location of white matter:

White matter forms the bulk of the deep parts of the cerebrum and cerebellum and the superficial parts of the spinal cord  

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