nervous system pt.1 Flashcards
junction between two neurons or an effector (muscle or gland)
synapse
presynaptic knobs/axon terminal
releases neurotransmitters
what is the function of neurotransmitters
diffuses across gap and bind to receptor molecules on ion channels in post synaptic membrne (dendrite). cause a slight positive gradient, which triggers action potential
resting membrane potential
neuron is more negatively charged than the fluid surrounding it
during resting membrane potential the outside of a neuron has
high amount of sodium (+), and chloride (-), low potassium (+) and impermeable anions
during resting membrane potential the inside of a neuron has
high amount of potassium (+) and impermeable anions, low amount of sodium (+) and chloride (-)
what are the components on a membrane of an axon?
-sodium-potassium pump
-sodium and potassium voltage gated channels
action potential
rapid and brief depolarization of membrane moves down an axon
-inside becomes +
what occurs during rising phase?
-changes in membrane potential cause voltage gates sodium channels to open. Na > inside
-interior becomes positve
what occurs during repolarization?
-sodium channels close
-potassium channels open; K > outside
-returns inside back to - charge
refractory period
-voltage gate channels are inactivated
-Na-K pump return sodium and potassium to resting state
nervous system of hydra
-nerve net: simplest extensive network in and under epidermis
-signal starts in one area and transmits through the entire body
Planaria: flatworms- bilateral nervous system
-simple bilateral nervous system
-has a PNS and CNS
-two anterior ganglia
annelids: earthworms bilateral
-advanced to segmented ganglia
-distinct afferent and efferent nerves
arthropod: grasshopper
-ganglia are larger
-sense organs
-social behavior
