nervous tissue Flashcards
what is the cell body in a nerve cell?
contains nucleus and is where all materials needed by the cell are made
what is the axon in a nerve cell?
adapted to conduct an electrical impulse called an action potential
what is the myelin sheath in a nerve cell?
insulates the axon and has nodes of ranvier
what is at the end of the nerve cell?
axon terminals
what are the nodes of ranvier?
gaps in the myelin sheath that allow impulses to pick up speed and jump across the axon
what is a schwann cell?
produces the myelin sheath
what is the dendrities in the nerve cell?
receives chemical signals from the axon terminal of other neurones
what is a myelinated nerve cell?
has a myelin sheath, white, transmits impulses quickly and has nodes of ranvier
non myelinated is the opposite and is grey
what is depolarisation?
Na+ gate opens and these ions diffuse INTO the cell at -70mv . Gate closes at +40mv (membrane potential)
what is repolarisation?
K+ gate opens and these ions diffuse OUT of the cell. Membrane potential changes from +40mv to -80mv (hyperpolarised)
what is recovery?
K+ ions diffuse back INTO the cell through a non-voltage gated K+ channel. Membrane potential goes back to its resting potential of -70mv ( equilibrium restored)
what is saltatory conduction?
the only part of a myelinated nerve fibre that can depolarise is at the nodes of ranvier where there is no myelin. The nerve impulses jump from one node to another, speeding up reactions.
