cells and tissues of the nervous system Flashcards
how many pairs of cranial nerves are there?
12
how many pairs of spinal nerves are there?
33
what are the two populations of cells that make up the nervous system?
neurons
glial cells
what are some features of neurons?
structural and functional unit
excitable cells
impulses carried as action potential
what are some functions of glial cells
non excitable supporting cells
much smaller than neurons
what is a typical neuron composed of?
multiple dendrites, one axon
how many directions can action potentials travel in?
1 - from the cell body to the synaptic terminal
what comprises the nucleus of neurons?
loose chromatin
prominent nucleolus
what organelles are contained within neurons?
mitchondria
rER
diffuse golgi aparatus
what part of the neuron can grow back?
the axon
what part of the neuron does not grow back after damage?
cell body
what is the purpose of the myelin sheath?
increases conduction speed in axons by saltatory conduction
what are myelin sheaths formed by?
schwann cells in PNS
oligodendrocytes in CNS
what happens if the myelin sheath becomes dysfunctional?
nerve conduction across the affected axons is abnormal
what is seen on an MRI of a patient with multiple sclerosis?
whitish plaques of demyelination
what are 3 types of neurons?
multipolar
bipolar
pseudounipolar
what type of neuron comprises ALL sensory neurons?
pseudounipolar
where is the head of the neuron located in a pseudounipolar neuron?
dorsal root ganglion
what is the name of a collection of grey matter in the CNS?
nucleus
what is the name for a collection of grey matter outside the CNS?
ganglion
what forms tracts?
collections of myelinated axons
what is a tract?
bundles of axons carrying specific information within the white matter
what forms white matter?
collections of myelinated axons
what are astrocytes?
most common type of glial cell- they surround synapses and capillaries and help in K+ buffering
what is the function of microglia?
phagocytosis and scar formation
what does the cerebellum do?
controls balance and coordination
what are the 3 divisions of the brainstem?
pons
medulla
midbrain
what makes up the diencephalon?
thalamus
hypothalamus
what does the cavity of the neural tube persist as in the adult brain?
ventricles
what is contained within the ventricles?
CSF
what are the names of the different ventricles?
lateral - 2
III ventricle
cerebral aqueduct
IV ventricle
what connects the lateral ventricles with the 3rd ventricle?
interventricular foramen
where do the lateral ventricles lie?
cerebral hemispheres
where does the the III ventricle lie?
cavity within 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
what is contained within the subarachnoid space?
CSF
what is the function of the ventricles?
secrete CSF
what is contained within the subdural space?
blood vessels penetrating into the CNS
where is CSF formed?
choroid plexus in each ventricle
where is CSF absorbed?
by arachnoid villi into saggital sinus (venous channel in the brain)
what do dural folds do?
keep the various parts of the brain in place
what are the names of the dural folds?
falx cerebri
tentorium cerebelli
falx cerebelli
diaphragma sellae
what is the blood brain barrier?
protective mechanism that helps maintain a stable environment for the brain and prevents harmful amino acids and ions present in the bloodstream and blood cells from entering the brain
what composes the blood brain barrier?
- endothelium - tight junction
- thick basal lamina
- foot processes of astrocytes
where is the BBB absent?
parts of the hypothalamus
posterior pituitary
what can pass freely across the blood brain barrier?
lipid soluble molecules
oxygen
water
how do water soluble molecules pass the blood brain barrier?
they are pump mediated
