Cells and Tissues of the Nervous System Flashcards
what is the CNS and PNS made up of?
central nervous system-brain and spinal cord
peripheral nervous system-cranial and spinal nerves
what does the PNS divide into?
sensory(afferent) division
motor(efferent) divison
what are the two divisions of motor nerves?
somatic
autonomic
what are the two divisions of autonomic system?
sympathetic
parasympathetic
what are neurons?
Structural and functional unit
Excitable cells
Impulses carried as action potentials
what are glial cells?
Non-excitable supporting cells
Much smaller than neurons
Impulse transmission is by action potential which can travel in what direction?
in only one direction from cell body to synaptic terminal
which part of the neuron cant grow back when damaged?
Axon can grow back but if cell body is damaged – loss is irreversible!
what is the myelin sheath?
Increase conduction speed in axons by ‘saltatory conduction’
what forms the myelin sheath?
Schwann cells in PNS
Oligodendrocytes in CNS
what is the cause of multiple sclerosis?
Patchy loss/scarring of myelin sheath (demyelination)- nerve conduction across affected axons abnormal
describe the type of neurone for interneurones & motor neurons
multipolar
describe the type of neurone for olfactory neurons & retinal nerve fibres
bipolar
describe the type of neurone for sensory neurons
pseudounipolar
what does the collection of cell bodies & non-myelinated axons form if diffuse/localised?
grey matter (if diffuse) or nucleii (if localised)
what does the collection of myelinated axons form?
white matter (diffuse) or tracts (bundles of axons carrying specific information within the white matter)
in the periphery what do myelinated axons and cell bodies form?
Myelinated axons form nerves
Cell bodies form ganglia
what type of glial cells in the CNS are important to know?
astrocytes-have efferent surround synapses&capillaries
help in K+ buffering
what early embryology forms the nervous system?
ectoderm- neural tube
which primary vesicle of the neural tube forms the forebrain?
telencephalon
which vesicle of the neural tube forms the eyes?
diencephalon
what are 4 ventricles of the brain
lateral ventricle
III ventricle
cerebral aqueduct
IV ventricle
where do the lateral ventricles lie?
cerebral hemispheres
where does the 3rd ventricle lie?
cavity within the diencephalon
where does the cerebral aqueduct lie?
midbrain
where does the 4th ventricle lie?
hindbrain
what are the 3 coverings of the CNS?
Dura mater
Arachnoid mater
Pia mater
where is the Cerebrospinal fluid (CSF) present?
Inside ventricles
Between pia & arachnoid
what does the CSF do?
maintenance of the “intracranial pressure”
where is the CSF formed?
By choroid plexus in each ventricle
where s the CSF absorbed?
By Arachnoid villi into saggital sinus (venous channel in brain)
what is the blood brain barrier?
protective mechanism
-maintains stable environment for the brain and prevents harmful amino acids & ions entering
where is the BBB absent within the brain?
parts of hypothalamus, posterior pituitary
