Week 2 - Neurons Flashcards
How many neurons and glia cells?
~100 billion
How many more glia cells than neurons?
around 10x more glia
What do neurons do?
Communicate!
How many interconnections do neurons have with other neurons?
Up to 10,000.
How fast can this communication occur between neurons?
500hz but 100hz is typical.
What parts of a neuron are the most changeable over time?
The Dendrites (spines extending from the soma).
Typically, each DENDRITIC SPINE has what connecting with it?
One or more AXON TERMINALS from other neurons.
What does each DENDRITIC SPINE represent?
One or more inputs.
What does an APICAL dendrite imply?
Towards the APEX.
What does a BASAL dendrite imply?
Towards the BASE.
What is the difference between APIC and BASAL dendrites?
APICAL is the dendrite pointing upwards from the soma, the BASAL dendrites are those heading East/West.
How do APICAL and BASAL dendrites connect regarding layers?
Since layers are a horizontal strata, APICAL dendrites connect ACROSS/BETWEEN layers, BASAL dendrites connect WITHIN layers.
Axons carry what?
An electro-chemical impulse.
What defines the difference between a Multipolar, Bipolar and Monopolar neuron?
How many projections from the cell body there are.
- Multipolar may have multiple dendrites and a single axon
- Monopolar will have a single projection from cell body but that projection may split into 2 axons.
What type of neuron is AFFERENT?
Sensory.
What type of neuron is EFFERENT?
Motor.
What does AFFERENT mean?
It gets INPUT from sensors (sensory, peripheral neuron - outside the nervous system).
What does EFFERENT mean?
It OUTPUTS signal to CONTROL muscle fibres, glands etc. (motor, also peripheral neuron)
What is an Interneuron neuron?
They are NOT peripheral, they are within nervous system. Only interact with other neurons.
What are ASTROCYTES?
- maintenance (scaffolding)
- waste/dead cells
What do Micro glia do?
- waste
- viruses
- serve to supplement immune system in brain
What type of glial cell is most important regarding communication?
Myelinating types:
- Oligodendrocytes - Central nervous system
- Schwann cells - Peripheral nervous system
If nerve damage occurs, what type of cells can assist with recovery?
Schwann cells. They are in the periphery.
What is the surface of a cell called?
A membrane (or plasma membrane).
What can and cannot pass through a cell membrane?
Most chemicals cannot pass through the membrane.
Protein channels permit a controlled flow of water, oxygen, sodium, potassium, calcium, chloride and other important chemicals.
Which structure contains the chromasomes?
The nucleus.
What structure performs metabolic activities, providing the energy that the cell uses for all activities?
Mitochondrion.
What are the sites within a cell that synthesise new protein molecules?
Ribosomes.
What is the most distinctive feature of a neuron?
Its shape! This varies from one neuron to another.
Some neurons lack…
…axons and well-defined dendrites.
What type of neuron is specialised at one end to be highly sensitive to a particular type of stimulation, such as light or touch?
A sensory neuron.
What is a dendrite’s surface lined with?
Synaptic Receptors. This is where dendrites receive information from other neurons.
What do dendritic spines do?
Increase the surface area available for synapses.
What does the cell body (soma) contain?
The Nucleus, ribosomes, and mitochondria. This is where most of a neuron’s metabolic work takes place.
What is the thin fibre of constant diameter which conveys an impulse toward other neurons, an organ or a muscle?
the Axon.
The axon’s length is comparable to the width of a…
dendrite.
The insulating material coating some axons are called the…
myelin sheath.
What are the interruptions in the myelin sheath known as?
Nodes of Ranvier.
A neuron can have only one…
Axon, but an axon can have many branches.
The end of each branch of an axon has a swelling called…
a presynaptic terminal, also known as an “end bulb” or “bouton (french for Button)”.
An afferent axon…
brings information into a structure.
An efferent axon…
carries information away from a structure.
Every sensory neuron is…
an afferent to the rest of the nervous system.
Every motor neuron is..
an efferent from the nervous system.
If a cell’s dendrites and axon are entirely contained within a single structure, the cell is an ….. or ….. of that structure.
interneuron or intrinsic neuron of that structure.
The shape of a neuron determines its…
connections with other cells and thereby determines its function.
What is the full title of a Glia?
neuroglia.
Where do glia outnumber neurons?
The cerebral cortex.
Where do neurons outnumber glia?
The cerebellum.
What is an astrocyte (glial cell) and what does it do?
It is wrapped around the synapses of functionally related axons. It shields it from chemicals circulating in the surround.
Other than shielding, what else do astrocytes do?
Takes up ions and transmitters released by axons and releases them back, helping to synchronise closely related neurons, enabling their axons to send messages in WAVES.
Astrocytes are important for generating…
Rhythms, such as for breathing.
What do astrocytes do with blood vessels?
They dilate them to bring more nutrients into brain areas that have heightened activity.
What system do microglia act as part of?
The immune system, removing fungi and viruses from the brain.
When do microgrlia proliferate?
After brain damage, to remove dead or damages neurons.
How do microglia contribute to learning?
They remove the weakest synapses.
Where are Oligodendrocytes?
The brain and spinal cord.
Where are Schwann cells?
In the periphery of the body.
What do Oligodendrocytes and Schwann cells do?
Build the myelin sheaths that surround and insulate certain vertebrate axons, and supply axons with nutrients necessary for proper functioning.
They support axons.
What do Radial glia do during embryonic development?
Guide the migration of neurons and their axons and dendrites.
What happens to radial glia when embryonic development finishes?
Most differentiate into neurons, and a smaller number differentiate into ASTROCYTES and OLIGODENDROCYTES.
