Nervous system Flashcards
Brain
main origin of the central nervous system that sends commands to all other parts of the nervous system
Plasmodesmata
Channels between plant cell walls that allow them to communicate
Gap junctions
Channels connecting animal cells
Hormones
Chemical communicators that act locally and are centrally secreted
Second messengers
signal transduction within cells
Electrical signals
Fast way of sending signals in the body through nerve cells
Neurons
Cells that are optimized for electrical signalling and make up the nervous system
Neurons Signal Directionality
Dendrites to axons
Central cell body
part of the neuron that contains the nucleus
Synapse
Space between neighbouring neurons where signals are passed. The signals passed here are chemical
Resting membrane potential
Neuron cell at rest. The neuron has a negative membrane.
Hyperpolarization
After an action potential the neuron repolarizes beyond resting potential levels preventing backwards action potential
Action potential speed
The speed of an action potential is determined by the diameter of the axon. Mylein sheath also speeds action potential
Invertebrate axons
Axons have a large diameter
Vertebrate axons
Contain myelin sheath
Myelin sheath
Protective layer of the axon that is made of schwan cells and insulated the action potential
Nodes of ranvier
Gaps in the myelin sheath where ion channels are located
Neurotransmitters
Chemicals released from the axons that send signals
Neurotoxins
Chemicals that block action potentials
Tetrodotoxin
Pufferfish neurotoxin that blocks sodium channels
Sensory neurons
neurons that sense external stimuli and generate action potentials in response
Interneurons
neurons that connect the different neurons
Motor neurons
neurons that cause a reaction in muscle cells
Mechanoreceptors
respond to distortion or pressure
