Introduction to the brain, neurone and overview of the nervous system and development & structure of the CNS Flashcards
what are the main functions of the nervous system?
- sensory - senses changes through sensory receptors
- motor- respond to stimuli
- integrative - analyses and stores information
What are the 2 main cell types in the NS?
- neurons
- glial cells - supporting cells
Describe the structure of a neuron
- cell body
- dendrities (process/ extension) that carries impulse toward cell body
- axon- carries impulse away from cell body
- some neurons are myelinated - contain myelin sheath around axon which increases velocity of impulse
Compare and contrats** multipolar motor neurons vs pseudounipolar sensory neurons**
- Multipolar motor neurons - have 2 or more dendrites, they have a** single axon** with 1 or more branches, **most common type **of neuron - all neurons controlling skeletal muscle & ANS
- Psuedounipolar sensory neurons - short peripheral process from cell body to receptor, the cell body is in the sensory ganglia which is part of CNS
What are the neuroglia in the CNS?
- oligodendroglia,
- astrocytes,
- ependymal cells,
- microglia
what are the neuroglia in the PNS?
- satellite cells
- schwann cells
What are the 3 classes of neuron?
- sensory (afferent)
- motor (efferent)
- inter
SAME
(sensory afferent motor efferent)
What are the main functions of the CNS?
- integrate and co-ordinate incoming and outgoing neural signals
- higher mental functions eg thinking & learning
What is a ‘nucleus’ in the CNS (hint : different than in a cell)
a collection of nerve cell bodies in the CNS
what is a ‘tract’ in the CNS?
- a bundle of nerve fibers (axons) connecting neighbouring or distant nuclei of the cerebral cortex
What does grey matter contain in comparision to white matter?
- grey matter conatins nerve cell bodies (nuclei)
- white matter contains fibre tract systems
What kind of shape is grey matter in the spinal cord & what are the 2 ends of it called?
- grey matter in the spinal cord is H shaped
- it has horns - a dorsal (posterior) horn and a ventral (anterior )horn
What are** commissural fibres** ( type of white matter fibre)?
- these fibres connect the right and left hemispheres
EGCORPUS CALLOSUM
what are** projection fibres **(type of white matter fibres)?
- they connect higher and lower parts of the CNS eg corona radiata
what are** association fibres** (type of white matter fibre)?
- they connect structures **within the same hemisphere **
- eg arcuate short fibres
what 2 structures is the CNS protected by?
Bone - ie skull and vertebral column
Membranous coverings - the meninges which has 3 layers
what are the** 3 layers of the meninges**?
- pia matter (delicate - innermost layer)
- arachnoid mater (spider web like)
- dura mater (dense, collagenous)
what fluid sits between pia mater and arachnoid matter?
cerebrospinal fluid
what is the leptomeninx?
the arachnoid and pia mater make up the leptomeninx
* they are called this because of their cellular structure
what are the 2 layers of the dura mater?
- inner **meningeal **layer
- outer periosteal layer
what does the inner layer of the dura mater form?
the inner meningeal layer forms many infoldings
1. falx cerebri in the longitudinal cerebral fissure which seperates the 2 hemipsheres of the brain
2. also the tentorium cerebelli - seperates occipital lobes of hemispheres from the cerebellum
3. **falx cerebelli **
4. **diaphragma sellae **- smallest infolding - covers pituitary gland
how are the** venous sinuses ** formed by dura mater?
by separating the 2 layers of dura mater along lines which creates the sinuses
what is the function of the venous sinuses?
- large veins from brain surface empty blood into these sinuses
- the sinuses drain into the internal jugular veins (IJV)
Describe the arachnoid mater
- web like arachnoid trabeculae bridge
- not attached to dura but** pressure of the CSF keeps it in direct contact**
- arachnod granuations project through dura into blood - filled venous sinus
Describe pia mater
- the pia mater gives the brain a** shiny appearance**
- it** adheres to the brain surface **and follows all contours
what is the CSF secreted by?
the choroid plexus in the ventricles
what are the properties of CSF?
- clear liquid
- surrounds brain & spinal cord to provide cushioning and nourishment
- similar contents to plasma - however less protein and different ion conc
Where does CSF go to from choroid plexus?
- leaves ventricles and enters the sub arachnoid space
- it then exits the subarachnoid space via arachnoid granulations to venous blood in dural venous sinuses
what are the ventricles of the brain?
- lateral ventricle
- 3rd ventricle (dincephalon)
- 4th ventricle
what structure connects the 3rd ventricle to the 4th ventricle?
the cerebral aqueduct
what is the** diencephalon**?
a division of the forebrain
what is meningitis?
inflammation of the meninges - either bacterial or viral
how many cervical vertebrae versus cervical nerves are there?
- 7 cervical vertebrae
- 8 cervical nerves
what is a dermatome?
area of skin supplied by a single spinal nerve root eg L4
what is a myotome?
region of skeletal muscle supplied by single spinal nerve root eg L3
Describe sensory ganglia vs automatic ganglia & give examples of each
- sensory ganglia - ganglia without synapse eg dorsal roots ganglion
-automatic ganglia - ganglia w/ synapses eg otic ganglion
describe ipsilateral vs contralateral
ipsilateral - on the same side
contralateral - on the opposite side
what does decussate mean in relation to the nervous system?
to switch from one side to the other
