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
what are oligodendrocytes
these are cells that contribute to the myelination of axons. the ratio of this is 1 to every 50 axons. any one axon needs to derive its myelin coat from numerous oligodendrocytes - the permitted length of a myelin sheet from one oligodendrocyte is not very long, so many have to surround a single axon.
they encase the axons to provide structural support but also functional support because it increases the movement of action potential across the axon
what are schwann cells
these form myelin sheath around peripheral neurons, and provide structural and metabolic support.
non myelinated are single schwann cell encasing a small diameter axon of neurons to provide protection. for the larger axons, there are many schwann cells
what are satellite cells
these are cells mostly located in the central nervous system within the grey matter. they are found in structures known as ganglions, which are located outwith the central nervous system
what are ganglions
aggregations of neuronal cell bodies located near the spinal cord, where the satellite cells are located
what is the function of satellite cells
there is not much known about the function of these cells, though it is assumed they provide functional and structural protection to neuronal cell bodies
what is the exact function of the nervous system
to provide rapid and precise communication between different parts of the body via the action of neurones
what are neurons specialised for
intercellular communication
what is the difference between neurons
they can display substantial difference in size and shape
what do dendrites respond to
external stimuli
where do dendrites convey the information they receive from external stimuli
the cell body
what are the elements to the cell body of a neuron
- a large nucleus and a prominent nucleolus
- nissl bodies
- numerous mitochondria
what epithelium is associated with ependymal cells
simple ciliated cubiodal epithelium
is there a basement membrane on ependymal cells
no
how are non myelinated axons associated with schwann cells
they are enveloped in cytoplasm of schwann cells
how are myelinated axons related to schwann cells
they are gradually wrapped by the schwann cell membrane to create a myelin sheath
describe the build of satellite cells
they cover the surface of neuronal cell bodies
which two components form the peripheral nervous system
spinal nerves and cranial nerves
which two components form the central nervous system
brain and spinal cord
what is the structure of neurons designed to refelct
their function of intracellular communication
what is the functional of a neuronal axon
to rapidly propagate action potentials through the neuron to the axon terminals
what is the generic name for the chemical signals released from the axon terminal
neurotransmitters
what is the name of the junction where the axon terminals of one neurone interact and communicate with the dendrites of an adjacent neurone in a pathway
synapse
what are the different neuroglial cells located within the central nervous system
- astrocytes
- ependymal cells
- oligodendrocytes
- microglia
which type of neuroglia forms the blood brain barrier
astrocytes
which type of neuroglia lines the spinal canal
ependymal cells
which type of neuroglia cells myelinates neuronal axons in the central nervous system
oligodendrocytes
which type of neuroglial cell myelinates neuronal axons in the peripheral nervous system
schwann cells
which type of neuroglial cell has phagocytic capacity
microglial cells
