Neurons Flashcards
Synapse
Junction/gap between the branches of adjacent neurons (axon terminal of one neuron and the dendrites of another)
Neuromuscular junction
Where an axon meets a skeletal muscle (doesn’t meet another neuron)
Nerve fibres
Axons and dendrites of a neuron
Nerves
Bundles of nerve fibres outside the CNS
Nervous system
Made up of neurons
Neurons
Basic structural unit of the nervous system, specialised cells with a specialised structure
Cell body description and function
Contains nucleus and other organelles, controls function of the cell
Dendrites description and function
Fairly short extensions of the cytoplasm of the cell body, carry messages or nerve impulses into the cell
Axon description and function
Single, long extension of the cytoplasm
Schwann cell description and function
Cell surrounding the axon, forms the myelin sheath
Myelin description and function
Fatty layer that covers axons, Speedup movement of nerve impulses along the axon (main function), acts as an insulator, protects axon from damage
Neurilemma description and function
Outermost layer of the Schwann cell, helps in repair of injured fibres
Node of Ranvier description and function
Gaps in the myelin sheath, speed up the nerve impulse
Axon terminals description and function
Where the branches of the axon terminate, converts nerve/electrical impulses into a chemical message
Functional types of neurons
Afferent (sensory), efferent (motor), inter (connector, association)
Afferent (sensory) neuron
Sends impulses towards central nervous system, has receptors
Efferent (motor) neuron
Sends impulses away from the central nervous system
Interneuron (connector, association)
Sends impulses between sensory and motor neurons
Structural types of neurons
Multipolar, Bipolar, Unipolar
Multipolar neuron
one axon and multiple dendrites, most interneurons in the brain and spinal cord and most motor neurons to the skeletal muscles
Bipolar neuron
one axon and one dendrite (left of the cell body), in the eye, ear and nose and take impulses from the receptor cells to other neurons
Unipolar neuron
have just one extension (the axon), cell body is to one side of the axon, most sensory neurons carrying messages to the spinal cord
Nerve impulses
Can only travel in one direction along a neuron, travel from dendrites to the cell body to the axon
