Neurons And Glia Flashcards
What are dendrites?
→ Long thin extensions making a dendritic tree
→ they are the receptive surface of the nerve cell (synaptic inputs)
What is the dimensions of a slice for a light microscope?
→ 50micron
What does a microtome slice use?
→ slice embedded in wax
What is the disadvantage of a microtome slice?
→ The wax interferes with staining chemicals
What is a cryostat?
→ A frozen version of a microtome
How can you make the brain transparent?
→ Treating the tissue with solvents renders it transparent because it removes the myelin
What does the Nissl stain stain?
→ stains RNA
→ but only in nerve cell bodies
What does the Golgi method use?
→ Silver chromate creates a dense black stain
What is the disadvantage of the Golgi method?
→ It only labels 1-2% of cells
What is a multipolar nerve cell?
→ Many dendrites coming off from the cell body
What is a pyramidal nerve cell?
→ dendrites form a triangular shape
What is a spiny nerve cell?
→ Some dendrites have spines
What is a pseudounipolar dendrite?
→ Sensory cell
What is a bipolar dendrite?
→ two dendritic ends
Describe how you visualise the axon
→ Intracellular injection of biocytin with a very small pipette
→ Set of antibodies against the tracer
→ Antibodies against the tracer antibodies
What is an advantage of the antibody method?
→ Can see multiple features within the cell
→ Can record the electrical activity using the same electrode pipette
What is a disadvantage of the antibody method?
→ Intracellular injections will not give long-range connections
How can long range connections be seen?
→ Small extracellular injections of tracer are taken up and transported by the axons
What is retrograde transport?
→ Transporting back to where the axons came from
Where are excitatory synapses found?
→ On the end of dendritic spines
What do microtubules carry away from the cell body?
→ Structural proteins
→ Neurotransmitter associated proteins
→ Organelles
→ they are the motorways that kinesin travels down
What do microtubules carry towards the cell body?
→ Signaling proteins
→ Debris and used materials
What is the function of actin microfilaments?
→ Provide support
→ help to maintain the shape of cell body and neurites
→ play a vital role in neural embryonic growth and help shape axons and dendrites
How are actin microfilaments involved in memory formation?
→ change the shape of the dendritic spines hence the growth of synapses during memory formation
What does the actin skeleton do?
→ Actin skeletons within the filopodia grow or shrink in response to chemical signals
What is the function of tau protein?
→ proteins that bind together cytoskeletal elements
What disease is tau protein found in?
Alzheimers
What are the 6 functions of astrocytes?
→ They control the movement of materials into and out of tissue
→ Flush waste products from the brain
→ Remove used neurotransmitter from fast synapses
→ control synaptic development and function
→ control electrolyte level in the extracellular space
→ Manufacture/break down substances on behalf of neurons
How is the blood brain barrier formed?
→ Astrocytes make contact with capillaries which induces them to form the blood brain barrier
What do astrocytes look like?
→ A blanket around nerve cells
How do astrocytes link together?
→ In chain gangs that transport material to and from neurons
What are the two types of myelinating glia?
→ Neurolemmocytes (Schwann cells)
→ Oligodendrocytes
What is the difference between Schwann cells and oligodendrocytes?
→ Schwann cells myelinate a single axon in a peripheral nerve
→ Oligodendrocytes myelinate multiple axons in the CNS
What disease arises when myelinating glia are damaged?
→ Parkinsons
What are microglia?
→ Immune cells that migrate into the CNS very early in development
Why are microglia not considered glia?
→ they do not arise from the neural tube like other glial cells
What are the 4 functions of microglia?
→ help the direct development of neurons and constantly monitor their health
→ become ameboid and travel to areas of injury/infection- microglia contract their processes going from a ramified shape into an ameboid structure
→ engulf and eliminate microbes, damaged cells and other particulate matter
→ Secrete factors essential for recovery and repair
What are the four types of glial cells?
→astrocytes
→microglia
→ependymal
→oligodendrocytes/Schwann
What are ependymal cells?
provide the lining of the ventricular system of both the brain and spinal cord.
What are the functions of the ependymal cells?
→Osmotic regulation of cerebrospinal fluid
→Flow of cerebrospinal fluid
→Directing cell migration during brain development
→act as a physical barrier separating brain tissue from cerebrospinal fluid (CSF)
What do deficits in ependymal cell function link with?
→severe neurological condition hydrocephalus
What is brainbow mice?
→Fluorescence microscopy and genetic manipulation techniques (e.g. Cre-Lox) allow us to see brain regions and individual neurons/glial cells in breath-taking detail
What does a prototypical neuron look like?
→cell body
→axon
→dendrites
What are neurofilaments?
→A type of intermediate filament – particularly abundant in axons and important in regulating axonal shape
What are axons composed of?
→Axon hillock
→axon proper
→axon terminal
What is the axon hillock?
→tapers away from the soma to form the initial segment of the axon
What is the axon proper?
axon can branch to form axon collaterals (and recurrent collaterals)
What is the axon terminal?
→site at which the axon comes into contact with other neurons at a synapse
How do the cytoplasm of the axon proper and terminal differ?
→microtubules in proper do not extend to terminal
→terminal contains a pool of synaptic vesicles for neuron to neuron contact.
→ higher levels of mitochondria in terminal
What are the two types of dendritic spines?
→pyramidal
→stellate
What are the three types of neurones according to the connections they make?
→sensory
→interneuron
→motor neuron
What are the two types of axon length?
→Golgi type I- extend to other regions
→Golgi type II- localised
What are the 6 types of neurotransmitters in neurons?
→acetylcholine →GABA →glutamate →dopamine →serotonin →noradrenaline
