16 Brain Cells Flashcards
Neurons make up __ per cent of the brain cells? What cells make up the other __ per cent?
10%, Glial cells make up 90%. Their role is mainly supportive though.
What is cognition and what does it depend on?
Communication between neurons in the brain enables our behaviour and thoughts.
Cognition depends on the activity of neurons as well as the transmission of information between neurons.
Disruption of neuronal communication by damage, disease, or drugs can affect perception, movement, and cognition.
What are Neurons
Basic signalling unit
distinguished by their function, location, and interconnectivity.
They receive information process it, and then transmit the outcome.
Structure of a neuron
- Dendrites
- Soma (cell body)
- Axon
- Axon terminal
What are dendrites?
They extend from the cell body
Treelike processes that receive inputs from other neurons
What is the soma (cell body)
central part of the neuron
contains metabolic machinery that maintains the neuron, this machinery is suspended in fluid and surrounded by the cell membrane
What is the axon
extend from cell body
function is like a telegraph wire, sending electrical impulses to distance places in the nervous system.
Some axons are covered in myelin and often branch.
What is myelin?
Myelin is formed by oligodendrocytes
fatty substance that surrounds and insulates axons
facilities the conduction of nerve impulse (speeds up the signal)
Appears white
pathology associated with multiple sclerosis causes the destruction of myelin.
What is a axon terminal
Axons end at axon terminals
the axon terminal is where the axon comes into contact with another neuron and transmits information
This point of contact is called the synapes
What is a synapsea and what does it do
where the axon terminal of one neuron contacts another neuron in order to transmit information
it has two sides, pre and post synaptic
at most synapses information in the form of an electrical impulse travelling down the axon is converted in the axon terminal into a chemical signal that crosses the synaptic cleft
the chemical signal is called a neurotransmitter
on the postsynaptic membrane, this chemical signal is converted back into an electrical signal.
what are the pre-and post-synaptic and what do they do?
Presynaptic = before the synapse with respect to the flow of information (axon terminals are presynaptic)
Postsynaptic = after the synapse with respect to the flow of information
What are neurotransmitters?
Stored in and released from synaptic vesicles within the axon terminal
Different neurotransmitters are used by different types of neurons
What are glial cells and what are the main types of glial cells in the CNS?
Glial cells account for more than half of the brain volume
Glial cells support neurons
Main types
- Astrocyte
- Oligodendrocytes
- Microglia
What are astrocytes?
Astrocytes form a barrier between neuronal tissue and blood, called the blood-brain barrier (BBB)
The BBB protects the CNS from some molecules in the bloodstream
What are oligodendrocytes?
Oligodendrocytes myelinate axons
Oligodendrocytes form myelin by wrapping their cell membranes around the axon during development
Myelin is white, hence, axons are referred to as white matter
The myelination of one axon required many olidendrocytes
