Nervous Tissue and Neurodegenerative Disorders Flashcards
Properties of neurones
- irritability
- receptors
- conductivity
- impulses
- 3 parts (dendrites, cell body, axon)
Cell body (of neurone)
- Nissl bodies (clusters of free ribosomes and rER)
- cytoskeleton (neurofibrils: microtubules and neurofilaments)
- no centrioles
Dendrites
- branched
- location of synapses
Axon
- cylindrical projection
- one per neurone
- specialised to conduct action potentials
- contains mitochondria and cytoskeletal proteins
Neuroglia
-smaller than neurones but more numerous
CNS
- astrocytes
- microglia
- ependymal cells
- oligodendrocytes
PNS
- satellite cells
- schwann cells
Astrocytes (CNS)
- star shaped
- maintain chemical environment
- blood-brain barrier
- provide nutrients to neurones
Microglia (CNS)
- small
- protects the CNS by phagocytosis of invading microbes
- clear away debris of dead cells
Ependymal (CNS)
Line cerebrospinal fluid-filled cavities
- Epithelial cells which line the ventricles of the brain and central canal of the spinal cord
- form cerebrospinal fluid (CSF)
- cilia encourage movement of CSF
- monitor composition of CSF
Oligodendroytes (CNS)
dendrite-like processes
- Structural support, scaffolding
- forms myelin sheath for some CNS cells
Schwann Cells (peripheral nervous system)
- wrap spiral around axons of motor nerves
- collectively called the myelin sheath
- makes up WHITE matter
- acts like insulation on a wire
- nodes of ranvier (spaces between)
Satellite Cells (PNS)
- flattened cells arranged around the cell bodies of neurones
- regulate chemical environment
- involved in repair
Tumours
-most brain tumours are gliomas
Demyelination
- Loss or destruction of myelin sheaths
- can lead to paralysis (eg MS)
- can affect vision, speech, balance and motor co-ordination
Guillain Barre Syndrome
- Immune response where macrophages strip myelin from axons in PNS
- recoverable
Head Injuries -Trauma
- Mild -concussion
- severe -coma
Trauma - Diffuse Axonal Injury
- grey and white matter have different compositions
- axons damaged when they move relative to one another
- often caused by rapid acceleration/deceleration
Stroke
-3rd most common cause of death in developed world
-Can be caused by:
haemorrhage, emboli, atherosclerosis
-Transient ischaemic attack (TIA) lasts up to 24hrs -most common type
Risk factors for a stroke:
- high BP
- high blood cholesterol
- heart disease
treatments include:
- clot dissolving drugs
- cold therapy
Dimentia
- chronic disorder of behaviour and higher intellectual function
- e.g. Alzheimer’s disease
- Brain atrophy
