December Exam Review Notes 5

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Western University
Anatomy and Cell Biology
Anatomy and Cell Biology 3309
Kem Rogers

Usually, NT is reuptaken by neurons or glia, or degraded by enzymes o Many drugs affect NT uptake or effects SSRIs are antidepressants that prevent the reuptake of serotonin MAOs prolong dopamine signalling and are therefore useful in parkinsons Recall that there are 10x more glial cells than neurons o Astrocytes These nurture neurons They support the BBB, but do NOT form it They are partly responsible for non-regeneration in the CNS o Oligodendrocytes These myelinate CNS axons o Microglia These are activated by injury/inflammation They phagocytose injured cells and remove debris o Ependymal cells These line fluid cavities such as the central canals and ventricles in the brain They produce and secrete CSF They have cilia that help circulate the CSF The cerebrum (cortex) is the largest part of the brain The meninges are 3 CT layers that wrap around the brain o Dura mater This is the outer layer It is attached to the skull It is a hard, tough structure o Arachnoid This is a mesh-like structure It forms trabeculars, which are column-like structures that form the subarachnoid space, which contains CSF and blood vessels It buffers head impact o Pia mater Soft and delicate membrane It wraps the brain It also sheaths blood vessels entering the cortex Meningitis is an inflammation of the meninges o It can lead to the breakdown of the BBB, which is dangerous because then pathogens can enter BBB o The endothelial cells in the brain are NOT fenestrated (therefore, continuous endothelium) This forms the BBB o Some substances can easily cross the endothelial cells (eg. O2, CO2) o Other substances must be transported transcellularly Therefore, there are many transporter molecules on these endothelial cells MS o This is an autoimmune disease where the body attacks myelin sheaths of neurons This leads to neuronal damage o It eventually affects the BBB and causes it to breakdown As a result, T-lymphocytes can enter the brain The brain develops from the embryonic neural tube o This consists of the ectodermal cells that form the tube during development The cerebrum has hills (gyri) and folds (sulci) o There is a lot of folding of the cortex in order to increase SA o It has gray matter on the outside (predominantly neuronal soma) and white matter on the inside (axons of myelinated cells and glial cells) Gray matter includes soma, unmyelinated axons, dendrites, synapses, glia, neuropil, and blood vessels White matter includes myelinated axons, glia, and blood vessels There are different nuclei in the brain, where cell bodies accumulate o These are part of the gray matter The cerebellum has leaf-like foldings to increase its SA as well o These folds are known as folia The cerebral cortex is organized into 6 layers o The outer layer is the molecular layer It has very few cell bodies Instead, there are dendrites and synapses o The next layer is the external granular layer It has small neurons o External pyramidal layer This contains small pyramidal neurons and satellite cells This layer and the one above it contain a lot of cell bodies o Inner granular layer There are a lot of interneurons here It is a major input layer o Inner pyramidal layer There are very large pyramidal neurons here; they have huge apical dendrites This is a major output layer o Multiform (polymorphic) cell layer This layer contains different cell types It has some output The cerebellum is also arranged into specific layers o The outer layer is the molecular layer It contains few cell bodies There are dendrites and axons present o Purkinje cell layer This is a single layer of purkinje cells, which have huge cell bodies (50 m) and very elaborate dendritic trees that project into the molecular layer o Granule cell layer This is the innermost layer It has many cell bodies that are very densely packed Climbing fibers wrap around purkinje cell dendrites There is only one output out of the cerebellum o This is the axons of the purkinje cells o They bundle up in the white matter and leave the cerebellum Ganglia are a collection of cell bodies in the periphery (i.e. not in the CNS) o In the CNS, a collection of cell bodies is known as a nuclei The spinal cord only extends until the conus medullaris, which is near the end of the thoracic area o Below this, there is the cauda
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