3 Cells of the Nervous System Flashcards
Q: What is the basic structural and functional unit of the nervous system? role? (2)
A: neuron- information processing and responsible for generation and conduction of electrical signals
Q: How many inputs can a neuron take and how many outputs can they have?
A: can have many inputs but only one output
Q: How is neuronal structure diversity achieved?
A: differences in number and shape of processes
Q: What are the features of a neuron? (6) Summarise.
A: -Large nucleus
- Prominent nucleolus
- Abundant rER (since it’s a secretory cell)
- Well developed Golgi (because of need to transport proteins over long distances)
- Abundant mitochondria
- Highly organised cytoskeleton
HIGHLY ORGANISED METABOLICALLY ACTIVE SECRETORY CELL
Q: What is the role of a dendrite? Structure? (3) How many __ can a large pyramidal neuron have?
A: major area of reception of incoming information
- spread from cell body
- branch frequently
- often covered in protrusions called spines (dendritic spines receive the majority of synapses)
may have 30,000/40,000 spines
Q: Draw diagrams for purkinje cells and pyramidal neurons. Where are there a large number of Purkinje Cells? what are they?
A: REFER
cerebellum- inhibitory
Q: Describe the structure of pyramidal neurons. (4)
A: You get primary dendrites coming off the vertices of the pyramid
There are secondary dendrites branching off the primary
Tertiary dendrites branch off the secondary
Single axon coming from a straight side
Q: What’s the role of an axon? Where are they? How many per cell? Branching? (2)
A: -conduct impulses away from cell body
- emerge at axon hillock
- usually 1
- may branch after leaving cell body in 2 places forming axon collaterals: just after leaves cell body or when closer to target cell so it can innovate multiple targets
Q: Diameter of axon changes? result? Can be? (2)
A: -After leaving the axon hillock it maintains the same diameter the whole way down (thereby maintaining the same speed)
-myelinated or not where axonal membrane of a myelinated fibre is only exposed at the Nodes of Ranvier
Q: Benefit of myelination?
A: can get faster conduction without needing larger axon diameter
Q: What do axons contain? (2) Include 2 roles.
A: -abundant microtubules and neurofilaments (play critical role in determining axon caliber/quality)
-intermediate filaments = needed for tensile strength as the cells can be very long
Q: How is the molecular composition of the axon organised? (3)
A: into domains: juxta-paranode -> paranode -> node (where are Na+ channels concentrate)
PARANODE - the area where the ends of the myelin is bound to the axon to form tight junctions - this prevents leakage of current under the myelin sheath
JUXTAPARANODE - an area with dense myelin where you find potassium channels
Q: What are the forms of axon terminals that exist? (2) Describe them.
A: -boutons= basic synapse with a bulb
-varicosties= multiple swellings containing neurotransmitter when axons synapse with many smooth muscle cells as it passes
axon variscosity (synaptic bouton)
Q: What do synapses contain? (3) Length?
A: -abundant mitochondria - 45% of total energy consumption is required for ion pumping and synaptic transmission - this is why neurons are sensitive to oxygen deprivation
- synaptic vesicles
- specialised mechanisms for association of synaptic vessels with membrane
length can vary between mm and m
Q: How are competing inputs from axons organised?
A: integrated in the postsynaptic neuron - NEURONAL INTEGRATION -> produce sigle AP (on/ off signal)
