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 does horseradish peroxidase do?
→ Linked to an enzyme that deposits a black insoluble substance around the 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
What is used to find out where axons synapse?
→ electron microscope
What is the magnification and resolution of an electron microscope?
→ > 100,000 magnification
→ <0.5nm resolution
Where are excitatory synapses found?
→ On the end of dendritic spines
What is the function of kinesin?
→ kinesin moves anterogradely and retrogradely within the axon carrying structural proteins that are being made in the cell body
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 three ways mice brains can be genetically engineered to express tracer protein?
→ Cells that use a specific neurotransmitter
→ Cells of a specific type
→ Cells that make a specific type of connection
Why can GFP be expressed in all animals?
→ Genetic code is degenerate
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
→ engulf and eliminate microbes, damaged cells and other particulate matter
→ Secrete factors essential for recovery and repair
