PSYC 2220 Lecture Notes - Lecture 2: Far-Sightedness, Spectral Sensitivity, Ciliary Muscle
13 Aug 2016
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The refractory period is 1 millisecond this allows for signals to travel over long distances as the intensity of a stimulus increases, the ring rate increases. However, there is an upper limit: only 500 to 800 nerve impulses per second can be sent down an axon added stimulus intensity can cause ring to go above or below the spontaneous activity level. During resting potential: uid outside the axon is rich with. Sodium ions (na+) and uid inside axon is rich with potassium ions (k+) during rising phase of action potential: sodium ion channels open to let sodium ions inside the axon (selective permeability). This add positive charges into axon, making it go from -70 mv to +40 mv. +40 mv charge is reached, membrane becomes impermeable to sodium ions (sodium ion channel closes) during falling phase of action: once sodium ion channel closes, potassium ion channel opens (becomes permeable to k+).
