Nervous Tissue Flashcards
what does the nervous system include
various organs like the brain and the spinal cord
receptors of sensory organs
the nerves that link the nervous system with all the organs and tissues in the body
what does the nervous system do
receives information from external and internal environments, processes the information and sends out a signal for an appropriate response
what is the nervous system divided into
central and peripheral nervous system
what is the function of the peripheral nervous system
delivers sensory information to the central nervous system where it is processed and the signals are sent back out to the PNS where it will send out the appropriate signals.
what can the peripheral nervous system be subdivided into
the somatic system and autonomic system
what is the somatic system in charge of
voluntary control and movement
what is the autonomic system in charge of
heartbeats and breathing that we do not consciously think of
explain the autonomic nervous system
the system in control of heartbeats and breathing. can be subdivided into the parasympathetic and sympathetic system. the parasympathetic system regulates the less urgent processes like digestion, whereas sympathetic is in charge of fight or flight responses
what are the different cells of the nervous system
neurons and glial cells
what are neurons
nerve cells which are the main functional unit of the nervous system. specifically designed for sending signals and communicating with organ tissues. they communicate between cells and have a high metabolic rate. they are long lived
what are glial cells
support cells with various different roles - protect, provide nutrients and immune function to neurons.
describe the structure of neurons
all contain dendrites, which are highly branched processes that extend away from the cell body and play a key role in intracellular communication. this is where signals are received on neurons.
they all have a large cell body, and a single axon. axons are long single cellular processes that extend away from the cell body. some can be up to a meter in length. this part of the neuron is designed for propagating action potentials.
there are also axon terminals which are branches. the foot of these branches are terminal boutons.
what enables the generation of action potential in neurons
their excitability - the small difference in charge between the inside and the outside of the cell.
what is action potential
brief change in charge
what are nissl bodies
clusters of rough endoplasmic reticulum with free ribosomes surrounding it. gives neurons a granular appearance when viewed histologically
what gives white matter its distinctive colour
myelin
give a brief summary of termical boutons
these form synpases with other neurons - eg neuromuscular junctions between motor neurons and skeletal muscle tissue. the action potential travels down the axon to the terminal boutons, where it goes from electrical transmission to a chemical transmitter known as acetyl choline, which then signals the skeletal muscle fibre to contract.
what is the neuromuscular junction
a synapse between a skeletal muscle and a motor neuron
what is neuroglia
also known as glial cells, they are support cells of the nervous system. some cells exist in the CNS - the CNS tissues consist of many different neurons, and the processes are embedded in a mass of support cells known as neuroglia.
they are highly branched cells that occupy spaces between neurons.
what are the four types of neuroglia
ependymal
astrocytes
microglia
oligodendrocytes
what are ependymal cells
these make up specialised epithelium that lines fluid filled ventricles in the brain and in the spinal cord. they are tightly bound together at their adjacent luminal surfaces. they dont rest on the basement membrane.
what do the various cili and microvilli on the luminal surface of ependymal cells function as
they help to move spinal fluid and regulate the composition of spinal fluid
what are astrocytes
these are star shaped, and are the most numerous glial cells that support cells within the central nervous system. they are highly branched, and act to provide mechanical support and mediate the exchange of metabolites between neurons and the vascular system
the processes wrap around the blood vessels and regulate the metabolites that leave blood vessels. they form part of the blood brain barrier
what are microglia
these are smaller sized cells derived from monocytes and macrophages. in response to tissue damage they will transform into large phagocytic cells
