An electrophysiologists stimulation an optic nerve fiber ele

An electrophysiologists stimulation an optic nerve fiber electrically and records a frequency of action potentials of 60 spikes per minute. She also notes the production of acetylcholine as the synapse. What will happen if the increases the strength of the stimulus? What would happen if she bathed the nerve fiber in TEA (blocks voltage gated Na^+ ion channels)? What would happen if she bathed the nerve fiber in TTX (blocks voltage gated K^+ ion channels)? Explain how acetylcholine can cause the production of an inhibitory postsynaptic potential (IPSP) A student from human physiology class decides to skip class and go sailing in the Atlantic Ocean but during his trip he falls into the ocean and drinks some water. Explain in details how negative feedback mechanisms maintain his blood osmolality.

Solution

5.

when student drink ocean water ,after sometime the ocean water salt solute will have dispersed and increase plasma osmolality.the body detects this change in salt concentration by neat mechanism.

The nucleus of hypothalamus ,that is responsble for detecting any kind of change in presser osmolality.As the salt con.rises the OVLT(organum Vasculosum of the lamina terminal) stumulates the MnPO(median preoptic nucleus) for thirst stimulation,creates to intake more water. when MnPO stimulated, the student drink more water to dilute concentration of salt in his body.this mechanism is supposed to negative feedback system(drinking water lower POSM by diluting the salt content),however the sea water that student drink was still hypertonic to plasma salt concentration,exacerbating the problem inseated of alleviating it.