General Organisation of the Nervous System Flashcards
What is the role of the nervous system?
To control and adjust the activities of the systems of the body
What is the NS split into
CNS- the brain and spinal chord
PNS- axons, ganglia and supporting cells
ie. anything coming from central area
Describe what is meant by neural tissue
Combination of the nerve cells and support cells
Describe what nerve cells are
High differentiated cell- limited/no capacity for cell division
Limited capacity to repair itself after injury
Transmit electrical impulses along the cell membrane
Can transmit materials from the cell body along the axon
via microtubules
Describe the various functions of support cells
Important for:
physical support
Regulating the interstitial fluid
Bringing nutrients
Describe what a multipolar neurone is like
A multipolar neurone has a cell body containing numerous dendrites- which is highly branched
The synapses on the dendrites are the way in which nerve cells communicate with each other.
Cell body contains RER making material which is going to be transported along the nerve cells
The axon terminated into one or more synaptic terminals- nerve cells comes into contact with either another nerve cell receptor or effector organ
The fact that there are lots of synaptic knobs coming into contact with the cell body means that lots of information is transferred.
Behaviour and response can be variable- adjusting to circumstances
List the different support cells coming out from the CNS
Astrocytes
Microglia
Oligodendrocytes
Ependymal cells
Describe the astrocytes
Looks star shaped and is the largest glial cell
Connects to the capillary wall,axon and the cell bodies
- it maintains the blood-brain barrier
- Like a net- contain microfilaments which give structural strength to the CNS
- Stabalise structure after injury and thereby produce scar tissue (xxx- scar tissue prevents axon from returning)
- Direct neural growth during development
- Control the interstitial environment including recycling NTs
Describe Microglia
(macrophage of the CNS)
Numerous cytoplasmic processes which have fine branches
From the same stem cells as macrophage and monocytes
Numbers increase when there is an infection
Describe ependymal cells
Cells line the chambers and passageways of the CNS, filled with cerebrospinal fluid
Have branching process making contact with glial cells
Function: Monitoring the CSF and ensure there is an integrated system
Describe the Oligodendrocytes
Its processes come into contact with axons either by:
- wrapping them together
- forming the myelin to improve the conducting velocity of the axons
List the support cells coming out of the PNS
Schwann cells
Satellite cells
Describe the schwann cells
Schwann cell wrapping itself around the myelinated axon
Participate in the repair process after injury
Describe the role of Satellite cells
Surround the neuron cell bodies in ganglia
Regulate O2 CO2 and nutrients and Its levels around neurone in ganglia
What are ganglia?
nerve cell bodies of neurone which lie outside the CNS are collected in groups called ganglia
Sensory ganglia
Motor ganglia
Describe the Sensory ganglia
Sitting in vertebral columns
No synapses
Pseudo-unipolar
Describe the Motor ganglia
MULTI-polar
does have synapses
Pre ganglionic comes in- myelinated
post ganglionic comes out-unmyelinated usually
Major Divisions of the brain
Cerebrum Cerebellum medulla oblongata thalamus hypothalamus
How is the brain and spinal chord supported and protected and why is important?
Neural tissue is delicate even with support of glial cells
Protection comes in two forms:
Bony cranium- vertebral column ( this ensures that there is a rigid barrier between the internal and external environment)
BUT this is not enough as it can be damaged by gravity!
therefore..
Meninges
Describe what are meninges
Composed of 3 layers:
Dura Mater - Periosteal and Meningeal
Arachnoid Mater
Pia Mater
Describe the Dura Mater
2 layered structure
Outer layer fuses with periosteum and lining the canal cavity
Inner layer has several specialised fold which further supports the brain
The venous sinuses run between the two layers- it drains the blood from the brain
Describe the Arachnoid Mater
Covers the surface of the brain and deep to it lies the
SARCHNOID SPACE- contains a meshwork of collagen nd elastic fibres- linking it to the Pia Mater
CSF also fills this space
Describe the Pia Mater
tightly attached to the brain by ostrocytes and follows its contours
Describe the flow of CSF
Made in the ventricles constantly- to prevent the build up of pressure it constantly requires to be reabsorbed so goes back into venous sinuses via arachnoid villi
