nervous tissue Flashcards
what are the 2 categories called that nervous system cells can fall into
neuron
neuroglia (neural glue) cells
describe neuron cells
nerve cell
specialised for signal conduction & information processing, and the relaying of the signal to a particular effector in tissue/organ
describe Neuroglia (neural glue) cells
support, nourish & protect neurons
neuroglia are critical for maintaining homeostasis of interstitial fluid around neurons
explain the structure of a typical motor neuron
Cell body
- nucleus, cytoplasm with typical organelles
Dendrites
- highly branched structures emerging from cell body – essential for receiving input, to carry out effect in body
Axon
- conducts impulse away from cell body toward another neuron or effector
- Emerges at cone-shaped axon hillock
Axon terminals
-at end of axon with synaptic bulbs, which are areas where connections formed with other cells within that system
what do motor neurones do
conducting signal away from CNS and to peripheral of body
Cells that exists within nervous system may be covered with what
myelin substance
what is myelination
Axons covered with a myelin sheath
describe what a myelin sheath is
Made up of Many layered lipid & protein creating insulations
They protect and support the axon
Increases speed of nerve conduction.
what are Nodes of Ranvier
gaps in the myelin that aren’t myelinated
what are nodes or ranvier important for
signal conduction
what do some diseases do to axons covered in myelin sheath
destroy myelin,e.g. multiple sclerosis
what is white matter made up of
primarily myelinated axons
what is grey matter made up of
cell bodies,
dendrites,
unmyelinated axons,
axon terminals
& neuroglia (everything apart form myelinated axons)
explain what the brain cortex is made out of
brain cortex = outer layer
made up of grey matter and white matter located internally. So myelinated axons that carry the info are internally
explain the location of gray and white matter in the spinal chord
grey matter is centrally located and white matter is located externally
nervous system tissues can be what types of matter
grey or white matter. This is du to actual colour of the cells
Half the volume of cns is made up of what
neuroglia
Unlike neurons the neuroglia do not have what function function
conducting impulses
explain neuroglia cell size compared to neuron size
Neuroglia cells are smaller than neurons and can readily divide and multiply, so have capacity to fill brain areas from damage or disease to brain or nervous system. Neurons cannot do this. So is why we see long term affect of brain and spinal cord damage
is the activity of neuroglia heterogeneous or homogeneous
heterogenous
and they have defined locations in nervous system
explain how Neuroglia are migratory in nature
so act as phagocytes so have ability to consume waste products found in nervous system, defending the neural cells from debry waste and pathogens
name the types of neuroglia
Astrocytes (star shape)
Oligodendrocytes
Microglia
Ependymal cells
Schwann cells
Satellite cells
first 4 are neuroglia only found in cns
Last 2 types of neuroglia are located in peripheral nervous system
explain neuroglia Astrocytes (star shape)
blood brain barrier By wrapping around brain capillary’s, to protect nervous system from substance that are in blood
Form of connective tissue cell found in nervous system. And have important link between nerve cells and blood vessels.
explain neuroglia
oligodendrocytes
create myelin in CNS
explain microglia neuroglia
for defence
explain neuroglia Ependymal cells
produce cerebrospinal fluid, that bathes the tissues of the nervous system
They form the membranes that line the areas of the brain known as cerebral ventricles, and they connect with the central canal of spine which also lines with ependymal cells
explain neuroglia Schwann cells
PNS cell support/myelin. As form protective myelin sheath around myelinated nerve fibres
Also provide support for non myelinated cells as well
explain neuroglia satellite cells
in PNS ganglia. Providing some support
