Neurons Flashcards
What is a neuron
A neuron is a cell which is specialised for electrical cell signalling
How does an impulse get passed between each neuron
By the connections made between t adjacent dendrites
Where do the axon potentials travel along
They travel alone the axon from the axon hillock
What are the 2 types of neuron communication
Chemical and electrical
How does chemical communication between neurons occur
Via neurotransmitters
Examples of neuro transmitters for chemical commuincation
Serotonin
Glutamate
How does electrical communication occur between neurons
Via direct flow of ions
Explain chemical synaptic transmission
The axon potential arrives to the axon terminal on the pre-synaptic neuron, where it becomes depolarised in the terminal membrane. This causes the voltage gated calcium channels to open and a calcium influx. This calcium influx triggers the neurotransmitters to be released into the synaptic cleft towards the post synaptic neuron
How do neurons differ from each other
Size
Morphology
Neurotransmitter content
Electrical properties
What is neural plasticity
Changes in the neuronal structure and function due to neural activity built off the basis of learning and memory
What is spine remodelling linked to
Neural activity
What are oligodendrocytes
They are myelinated cells of the CNS
They are unique to vertebrates
Rapid nerve conduction due to the myelination of segments of axons
What is the myelin sheath composed of
70% lipids
30% proteins
How is the myelin sheath formed
The myelin sheath is formed by wrapping the axons by the oligodendrocye processes
What are microglia
Resident immune cells of the CNS
Where do microglia originate
They originate in the yolk sac progenitors that migrate into the CNS
How do microglia work
In a resting state the microglia are highly ramified motile processes but upon activation they retract and become ameboid and motile
What is the role of microglia
They proliferate at the sites of injury
Phagocytosis
Immune surveillance
Synaptic plasticity
What are astrocytes
They are start like cells which are the most numerous glial cell in the CNS, they are highly heterogenous
What do astrocytes contribute to
The blood brain barrier
Where are oliodendrocytes most numerous
In white matter
What is the structural function of astrocytes
They define brain micro-architecture
What other functions do astrocytes have
They envelop synapses
Metabolic support
Neurovascular coupling
Proliferate diseases
What are the 3 types of specialised astrocytes
Radial glia
Bergmann Glia
Muller cells
What are radial glia important for
Important for brain development
Where are bergmann glia found
In the cerebellum
Where are muller cells found
Retina
What is an abundance of neuronal cell bodies called
Nuclei
What do axons gather together into
Tracts
Tracts that cross in the midline are called
Commissures
Where are cell bodies and supporting cells located in the PNS
Ganglia
In the PNS what do axons bundle into
Nerves
In the PNS what are axons enveloped in
Schwann cells
What is the blood brain barrier formed of
Endothelial cell tight junctions, basement membrane, astrocyte end feet, pericytes
What is the blood brain barrier sensitive too and what problems does this cause
The blood brain barrier is sensitive to inflammation, hypertension, trauma and ischemia which can cause problems for drug delivery
What are ependymal cells
These are epithelial-like cells which line the ventricles in the brain and the central canal in the spinal cord
What are the function of the ependymal cells
Cerebrospinal fluid production
Cerebrospinal fluid flow
Cerebrospinal fluid absorption
What facilities the flow on ependymal cells
They are ciliated which facilities the flow
What do the ependymal cells allow to happen
Allow for solute exchange between the nervous tissue and cerebrospinal fluid
What is the choroid plexus
They are frond like projections in the ventricles
How are the choroid plexus formed
They are formed from modified ependymal cells which are highly vascularised with a large surface area
What is the main function of the choroid plexus
Production of cerebrospinal fluid by plasma filtration driven by solute secretion
