From Cells to Cortex Flashcards
What is the function of a dendrite?
direct stimulus towards the cell
Dendritic spine = principle axon target
What is the function of an axon?
Axons direct digital output away from the cell
What are the combined functions of neurons?
- networking
- vectorial impulse transmission/propagation
- dissociative secretion/synpase formation
- chemical transmission
- inihbitory or excitatory
How are neurons classified?
according to the number of processes
Describe a pseudo unipolar cell
Dorsal root ganglion
What is the function of the myelin sheath?
salutory condution (enhances conduction)
Describe myelinated cells in the peripheral nervous system
Schwann cells ‘envelope’ unmyelinated axons contacting 1 or more axons
Descrobe myelinated axons in the central nervous system
One Oligodendrocyte cell builds a number of internodes
Give some examples of unmyelinated axons
sensory fibres carrying pain, temperature, itch
Summarise Multiple Sclerosis (in relation to myelin)
- Phasic disease
- Demyelination
- Inflammation (T cell/macrophage mediated)
- Conduction block (slowing of propagation)
- Crosstalk (paraesthesia)
- Some re-myelination
- Permanent loss (due cell death/axonal loss)
What are the glial cells of the CNS?
- Oligodendrocytes (myelination)
- Astrocytes
- Microglia
- Ependyma (lining cells of the CNS cavities)
What are the glial cells of the PNS?
- Schwann cells (myelination)
- Satellite cells (support cells in ganglia)
What are the functions of astrocytes?
- Metabolic and mechanical support (in CNS scar tissue also)
- Control water distribution
- Potassium buffering
- ROS scavenging (ROS stands for reactive oxygen species)
- Define architecture
- Regulate migration/pruning/synaptogenesis
- Help maintain but do not make up the BBB
Describe astrocyte function in the blood brain barrier
- A barrier composed of endothelial cells AND their tight junctions
- Integrity highly dependent on astrocyte ‘end feet
- So the barrier consists of endothelial cells and their tight junctions and the astrocytes help to maintain it
What are the resident macrophages of the CNS?
Microglial cells
- Phagocytosis and antigen presentation (immune response)
- Synaptic pruning
What are ependymal cells?
- Ciliated cuboidal epithelial cells, line ventricle as part of plexus and secrete (also reabsorb) CSF
- CSF (cerebrospinal fluid) – clear, cell-free fluid produced in specialised ependyma on choroid plexus
What are the main lobes of the cerebral cortex?
How many layers are in the cerebral cortex?
most has 6 layered neocrotex
Limited areas have 3 and 4 layers
What are the two main neuron classes that define the main layers
- stellate interneuron (granular layers) = input and processing
- Pyramidal neurons (pyramidal layers) = output
Draw a diagram showing the layers and communication of the cerebral cortex
Where are interneurons more numerous?
sensory cortex
Where is the presence of pyramidal output more marked
motor cortex
Where is the visual cortex?
occipital lobe = vision only and other areas do the higher order of visual processing
What is the function of the primary motor cortex?
execution of movement
More direct control of motor activity than other areas –> force, direction and speech of muscle contraction
What are the motor association cortex regions?
Organisation of complex movements
Supplementary motor area
What is the function of the premotor cortex?
preparation for action
posture and agit - integration of spatial information and planned movement, grasping
What region is this?
primary somatosensory cortex
