Structures and Cells Flashcards
Describe the organisation of the NS.
The NS can be divided into and afferent and efferent branch. The afferent division conducts sensory and visceral stimuli to the CNS. The efferent division is further divided into an autonomic and somatic division. The autonomic division is further subdivided into the sympathetic, parasympathetic and enteric divisions.
Distribution of neurons and glial cells.
The CNS contains more than 100 billion neurons
2-10 times more glia than neurons
What is the difference between neurons and glial cells?
Neurons generate electrical potentials
Glial cells are not electrically excitable and do not take part in electrical signalling
What are the four compartments of a neuron?
Dendrite
Cell Body
Axon
Synapse
What are the characteristics of a neuron?
Have a high metabolic rate
Require continuous and abundant supply of glucose and oxygen – aerobic respiration
Have extreme longevity
Most neurons that are formed during foetal development remain functional even in old age
They are typically non-mitotic
Mitotic activity is lost during foetal development
Unipolar neuron
Single primary process; pseudounipolar neurons carry somatosensory information
Bipolar neuron
Two distinct processes, e.g. in the retina and in the olfactory system
Multipolar neurons
Single axon but multiple dendrites; most predominant type in vertebrates
Astrocytes
Star like cells that is in contact with neurons and capillaries Help form blood brain barrier (BBB) Regulate tissue fluid composition Provide structural support Replace damaged neurons Regulate neural development
Microglia
Small cells, least common Mediate immune functions Clear cellular debris Clear dead neurons Influence synaptic transmission and synaptogenesis
Ependymal Cells
Simple cuboidal epithelial cells, these line the cavities in the brain and spinal cord, have cilia on their apical surfaces
Line ventricles of brain and central canal of spinal cord
Assist in conduction and circulation of cerebrospinal fluid (CSF)
Oligodendrocytes
Rounded cells with slender cytoplasmic extensions which wrap around CNS axons
Serve to myelinate and insulate CNS axons which allow faster nerve impulse conduction
Satellite Cells
Flattened cells clustered around neuronal cell bodies in a ganglion
Protect and regulate nutrients for cell bodies in ganglia
Schwann Cells (Neurolemmocytes)
Myelinate axons in the peripheral nervous system
One Schwann cell = one segment of myelin sheath on an axon
Gaps between myelin sheaths = nodes of Ranvier
What is the advantage of having gyri and sulci?
Surface area
Explain hemispheric lateralisation.
Lateralisation is the idea that the two halves of the brain are functionally different and that each hemisphere has functional specialisations, e.g. the left is dominant for language, and the right excels at visual motor tasks
What are association areas?
Association areas integrate incoming information and coordinate motor response
Associative areas of the cortex integrate current states with past states to predict proper responses based on sets of stimuli
White matter vs Grey matter
Grey matter is distinguished from white matter in that it contains numerous cell bodies and relatively few myelinated axons, while white matter contains relatively few cell bodies and is composed chiefly of long-range myelinated axons
Cells in the grey matter are composed of chromatophilic substances
What comprises the diencephalon?
The caudal (posterior) part of the forebrain, containing the epithalamus, thalamus, hypothalamus, and ventral thalamus and the third ventricle
What are the functions of CSF
Protection
Buoyancy
Excretion of waste products
