Histo Lec - M8 Nervous Tissue Flashcards
It consists of neurons and supporting cells called neuroglia or glial cells
Nervous tissue
are the cells considered to be the basis of nervous tissue
neurons
The main part of a neuron is the?
Cell body/soma
The other processes of the neuron are dendrites, which receive information from other neurons at specialized areas of contact called?
synapses
usually highly branched processes providing locations for other neurons to communicate with the cell body.
dendrites
is a type of neuron in which only one process called a neurite extends from the cell body.
Unipolar neuron
two major processes (axon and dendrite), but may be branched at ends, sensory neurons in retina, cochlea, and olfactory epithelium are of this type.
Bipolar
more than two processes (one axon plus multiple dendrites), most of neurons in brain and spinal cord are of this type.
Multipolar
two major processes that are fused along portions closest to perikaryon - found in spinal ganglia and some cranial ganglia.
Pseudounipolar
efferent, action potential moves from CNS to effector organ
Motor neurons
afferent, action potential moves from sensory organ to CNS
Sensory neurons
form connections between neurons
Interneurons
These cells are situated among the neurons and are generally smaller.
Glial Cells (Neuroglia)
- granular cytoplasm, many branches on short processes
- some of processes are closely applied to neurons, while others form intimate contacts with blood vessels.
- thought to form a conduit for nutrients from blood vessels to neurons.
- found in gray matter.
protoplasmic astrocytes
- long slender processes
- function not well understood
- found chiefly in white matter.
fibrous astrocytes
Smaller than astrocytes, fewer processes
b. Found in both gray and white matter
c. In white matter, these cells form the myelin sheaths that are around many axons, in gray mater they may lightly myelinate some dendrites.
d. Analogous to Schwann cells of peripheral nervous system
e. These cells must be cultured with neurons in order to get neurons to grow in tissue culture. Suggests intimate interactive association.
Oligodendroglia
a. small cell body that is elongated
b. Elongate nucleus with mostly heterochromatin
c. Can be differentiated from other glia by elongate nucleus. Other glia have a spherical nucleus
Microglia
a. ciliated cells forming single layer of cuboidal epithelium that lines the entire neurocoel
b. ciliary action acts to circulate cerebral spinal fluid.
Ependymal cells
They are oval or spindle-shaped cells with scanty cytoplasm and round nucleus at the expanded part of the cell.
Amphicytes or satellite cells
They are found in the PNS. They are cells enclosing both the unmyelinated and myelinated axons in the peripheral nervous system
Neurolemmocytes or Schwann cells
are often referred to as the body’s chemical messengers
Neurotransmitters
are known to play a supporting role for nervous tissue
Glial Cells
Where the axon emerges from the cell body, there is a special region
axon hillock
Within the axon hillock, the cytoplasm changes to a solution of limited components called
axoplasm
there are gaps in the myelin covering of an axon. Each gap is called a
node of Ranvier
It is the first neurotransmitter to be discovered was a small molecule. It plays a major role in the peripheral nervous system, where it is released by motor neurons and neurons of the autonomic nervous system.
acetylcholine.
is the primary excitatory transmitter in the central nervous system
glutamate
is the primary neurotransmitter in the sympathetic nervous system where it works on the activity of various organs in the body to control blood pressure, heart rate, liver function and many other functions.
Noradrenaline (or norepinephrine
the last of the major monoamines, plays a role in metabolism, temperature control, regulating various hormones, and controlling the sleep-wake cycle, amongst other function.
histamine
