Neural Tissues Flashcards
How many neurons?
10 to the power of 11
How many synapses?
10 to the power of 14
How much does the brain weigh?
1.5kg
How many neurons in the enteric nervous system?
10 to the power of 8
What is a ganglion?
Group of cell bodies outside CNS
What is the difference between motor and sensory ganglion?
Motor- smaller neurons- eccentric nuclei
Sensory- big neurons, central nuclei
Which is primary motor cortex?
Brodmann area 4
Which is primary visual cortex?
Brodmann area 17
What is myelin purpose?
Increase conduction velocity and so increases diameter
Where can purkinje cells be found?
Cerebellum
Where can pyramidal cells be found?
Neocortex
Where can you find bipolar cells?
Retina
Which are true unipolar cells?
Rosa and cochlear hair cells
Pseudounipolar example?
One axon, one dendrite e.g dorsal root ganglion
Chemical synapse gap is?
30nm
Divergence example?
Skin
Convergent example?
Retina
What percentage of brain is interneurons?
80
Inhibitory interneurons example?
Renshaw cells in grey matter either inhibit first alpha neuron and or an alpha motor neuron of the same motor pool
Glia cells differ from neurons because?
Do not form synapses No action potentials Able to divide Form myelin sheaths Are most common source of tumour in nervous system
Ratio of neurons to glia cells?
1:10-50
Role of oligodendrocytes?
Production/maintenance of myself sheath in CNS
Role of astrocytes?
Supports neurons through neuronal development and growth,, protection from harmful substances, control vasodilation of local blood vessels
What is origin of microglia?
Mesodermal, develop from monocytes
Role of ependymal cells?
Line brain ventricle and central canal of spinal cord. Form CSF
Role of schwann cells?
Production/maintenance of myelin sheath, PNS regeneration
Role of satellite cells?
Found in PNS, Support neurons, regulate exchange of materials between neurons and interstitial fluid
Glioma?
Largest group of primary tumours derived from glia cells. Highly malignant
Grows fast, inside cranium, difficult to remove
Neuroblastoma?
Most common in children
Outside cranium
Derived from neural crest cells from sympathetic NS
What is often common in neuroblasomas?
Catecholamine levels are raised
