Acetylcholine? and more.?

Question

What is acetylcholine? Also tell me its effect on the plasma membrance of a muscle cell.

If the water cells inside and outside a cell suddenly become hydrophobic, would the transport of materials into and out of the cells be affected? and how is it affected?

Just help me on these two I don't get. I think I got the second one, but I just wanna double-check.

*On the 2nd one, its not water cells, I meant to say water molecules.

*Also, maybe change the hydrophobic to nonpolar. That may make more sense.

Answer 1

1. Acetylcholine (ACh)- a neurotransmitter- ALWAYS causes an excitatory response on the plasma membranes of skeletal muscle cells. It acts to open ion channels that will cause a major influx of Na+ into the muscle cell.This leads to an end-plate potential which depolarizes the membrane and leads to an action potential in the muscle membrane. The action potential spreads through the entire membrane and down the T-tubules (which are continous w/ the membrane). In the T-tubules, there are voltage DHP receptors that respond to the action potential and physically pull open ryanodine channels. Ryanodine channels opening allows for Ca2+ to flow out of the sarcoplasmic reticulum. This calcium binds to troponin, which shifts tropomysin out of the way to expose the actin binding sites. Myosin heads can now bind (w/ ATP) and the muscle contracts.
2. water cells? - I'm not sure what you're asking- water could never become hydrophobic (water fearing, hating). However, if water channels (aquaporins) mutated into hydrophobic channels, water could neither leave nor enter the cell. This would be a huge problem. Take for instance your kidneys, the first part of your urinary system. IF you couldn't move water from the tubules and back into your blood, you would have to drink 180 (I think) liters of water a day. This is almost impossible! If you didn't your blood would get so thick, it would severely slow down your blood flow, meaning you may not be able to deliver adequate amounts of oxygen to all your vital organs in a timely manner. I hope this helps.

Answer 2

I can't say about transport across the cellular membrane, but acetylcholine is a neurotransmitter. It is vital to the transmission of nerve impulses, unconscious ones as well as deliberate ones.

Materials which inhibit the actions of aceythcholine esterases will cause rapid death due to failure of nerve impulse leading to inability to breathe and irregular and failing heartbeat.

Only a few tenths of a milligram is required to be a fatal dose.

The common name for these substances is 'nerve gas'.

Answer 3

good idea