Nervous Coordination Flashcards
What is the structure of the mammalian neurone?
Cell body- larger amount of rough endoplasmic reticulum for the production of proteins and neurotransmitters
Dendrons- extensions which divide into dendrites, carry an impulse towards the cell body
Axon- single long extension that carries the impulse away from the cell body
What is the myeline sheath?
Insulates the axon
What is a schwann cells?
Surround the axon with their myelin-rich membrane and they protect the insulation and play a part in never regeneration.
What are the Node of Ranvier?
Long gaps between adjacent Schwanna cells ever 1-3 nm
What is a nerve impulses?
A nerve impulse can be defined as a self propagating wave of electrical activity
What is resting potential?
Resting potential is the electrical charge difference across the neurone membrane Maintaining the resting potential enquires constant energy as the interior of the neurone is more negative charged then the exterior
How is the resting potential acheived?
Sodium-Potassium Pump remain open allowing facilitated diffusion of Na+ and K+ and a small amount of Na+ ions diffuse back however active transport takes over to achieve a greater positive charge on the outside.
What is the action potential?
Achieved when a stimulus triggers a change in the neurone membrane potential.
How does an action potential along a myelinated axon?
Myelinated neurones, the myeline sheath insulates the axon, concentrating ion flow at nodes of Ranveir causing salutary conduction where the action potential jumps from node to node, allowing for faster and more efficiency
All or nothing principle of action potentials
If the value is below a stimulus level, no action potential occurs so has to be over a threshold value.
Organisms determines stimulus intensity through frequency and different threshold values. The brains role is to interpret the impulses from various neurones and process them
What is the refractory period?
A brief period when the voltage gated sodium channels are closed preventing further action potential to ensure one way propagation. This mechanisms maintains integrity and efficiency of neural signalling.
What are the type of synapses?
Excitatory synapses- triggers new action potentials in the postsynaptic neurone
Inhibitory Synapses- prevent or reduce the likelihood of action potential in the postsynaptic neurones
What is an example of a neurotransmitter?
Key one acetylcholine
What are features of the presynaptic neurone?
Synaptic knob- swollen end of the axon contains mitochondria and SER
Synaptic vesicles- store neurotransmitters
How does a signal travel from one synapse to the other?
Action potential causes Ca2+ ions to open causing the synaptic vesicles to migrate and fuse to the presynaptic membrane. Aceytlcholine molecules diffuse across the synaptic cleft When the acetylcholine molecule binds to the receptor siteon the Na+ channels and they diffuse into the postsynaptic neurone. The influx of Na+. ion causes a new action potential as Na+/K+ pumps depolarise. Acetylcholinesterase hydrolyse acytelcholine into ethnic acid and choline and diffuses back into the presynaptic neurone. ATP from mitochondria is used to recombine the choline and ehtanoic acid into acetylcholine once again.
