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2005 lecture 2
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- 1describe neurons- the basic functional unit of the nervous system
- communicate via synapses
- impulses can be excitatory or inhibitory - 2what are neuritesDendrites + axons
- 3descrive nerve cells- hard working cells
- have a large nucleus and prominent nucleolus
- contain a large amount of rough ER - 4describe synapses- cell to cell communication
- neurotransmitters are released into the synaptic cleft - 54 different types of neurons and where they are found1. Anaxonic neuron: in the brain and special sense organs
2. Bipolar neurons: in special sense organs (e.g. eye, ear, nose)
3. pseudo uni polar: sensory neurons (e.g. dorsal root ganglia)
4. Multipolar neurons: motor neurons and interneurons - 6describe glial cells- neuroglia
- supporting cells
- more numerous then neurons
- supporting cells that insulate and protect neurons
- non excitable and non conductive cells
- remove waste and debris
- have roles in repairing injury
- 10 times more glial cells than neurons - 7what are gliomas- glial cells can give rise to gliomas
- they are tumours of glial origin:
astrocytoma, oligodendoglioma, emendymoma, schwannoma
- located throughout the brain - 8list the glial cells of the CNS- oligodendrocytes
- microglia
- astrocytes
- epedymal cells - 9oligodendrocytes- build myelin sheath around axons in the CNS (normally one oligodendrocyte for several axons)
- increase speed of nerve conduction
- prevent escape of electrical energy
- impulses jump from 1 NOR to the next
- do not envelop unmyelinated CNS axons - 10Microglia- the main phagocytic and antigen-presenting cells in the CNS
- immune cells in the brain
- different lineage to other glial cells
- microglia stimulators: viruses/bacteria, dead cells/debris, CNS toxins, damaged neurons, activated astrocytes - 11Astrocytes- provide physical and nutritional support for neurons, regulate the extracellular fluid around the neurons, and regulate ion concentration
- remove excess neurotransmitters in the synapse
- implicated in forming the BBB
- each astrocyte has its own territory and each interact with several neurons and hundresds to thousands of synapses
- can release glio-transmitters to send signals to neighbouring neurons
through connections called "end feet", signals from astrocytes expand or narrow blood vessels controlling the flow of oxygen and nutrients - 12Astrocytes and the blood brain barrierAstrocytes are implicated in forming the BBB.
- they are responsible for homeostasis of the microenvironment in the CNS. Capillary endothelial cells in the brain are joined by tight junctions providing an effective barrier
- Brain capillaries are contacted by astrocytic processes that separate the capillaries from the neurons - 13ependymal cellsline the ventricular system, assist in circulating, producing, and monitoring CSF and cover the choroid plexus
- 14glial cells of the PNS- schwann cells
- satellite cells
- macrophages - 15schwann cells- myelinate axons
- can only myelinate 1 axon
- increase speed of nerve condiction
- prevent escape of electrical energy
- impulses from one NOR to the next - 16satellite cellsprovide physical support for neurons in the PNS
- 17macrophagesprovide physical support for neurons in the PNS
- 18signal transmissionA stimulus goes to first, second, then third order neurons.
First order neurons can have connections with:
- other neurons (second order)
- muscles (neuromuscular synapses)
- glands (neuroglandular synapses) - 19describe upper and lower motor neuronsUMN: have cell bodies in the primary motor cortex and their axons descend through the CNS (entirely within the CNS). Recovery for UMN (brain) is more difficult
LMN: have cell bodies in the brainstem (for cranial nerves) or spinal cord (for spinal nerves) and axons enter the PNS
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- 2005 Fichas sobre 2005 lecture 2, creado por Soph B el 15/09/2019.
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- Soph B
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