Too Much of a Good Thing. The vitamin A content in beef liver is very high, with 100 grams of raw liver containing over three times the recommended daily value. As a fat-soluble vitamin, vitamin A accumulates in your own liver and can cause serious health issues at high levels.
Acetylcholine is released when a nerve impulse reaches a myoneural junction. It diffuses across the synaptic cleft and binds to cholinergic receptors on the muscle fibers, causing them to contract. cholinesterase splits acetylcholine into its components, thus stopping stimulation of the muscle fibers.
(B) Ca2+ channels open in response, and Ca2+ ions diffuse into the end bulb. The influx of Ca2+ causes many of the synaptic vesicles to fuse with the neuron membrane. Thousands of acetylcholine (ACh) molecules are released into the synaptic cleft. A few diffuse across the synaptic cleft and bind to the acetylcholine receptors that are embedded in the membrane of the postsynaptic neuron. (C) When both ACh binding sites are occupied, the acetylcholine receptors open.