For those of us who need to know 'why'...a physiology and chemistry lesson from my daughter explaining why we should avoid pesticides...
So in my Gross Anatomy 1 class we have talked about Organophosphates (which are chemicals in insecticides, such as parathion and malathion). I just thought you would like to learn a little bit about them. So here it is:
First a brief overview of how your muscles work:
In your body, you have motor unit parts which originate in your spinal chord or brain stem. These motor units consist of a motor neuron, spinal nerve and peripheral nerves, and a neuromuscular junction. This nueromuscular juntion is important when relating to Organophosphates. The neuromuscular junction consists of two parts: a presynaptic portion- which is the nerve fiber end, and a postsynaptic portion-which is connected to the sarcolemma (cell membrane) of your muscle fibers in your muscles. Between the presynaptic and postsynaptic portions there is a space, called the synaptic cleft which signals and chemicals pass through between the two portions.
In order for you muscles to be able to contract, a nerve impulse is sent down from the motor neuron to the presynaptic end. At this end, ACH (acetylcholine-a neurotransmitter chemical) is then released which passes though the synaptic cleft and then binds with specific receptor sites on the sarcolemma of you muscle fiber. This binding sets off an action potential down your transverse tubules of your muscle fiber. This action potential signals Calcium to be released from the sarcoplasmic reticulum of your muscle fibers, The calcium then binds with troponin (a regulatory protein) and actin (a contractile protein (in the "I-band" of your muscle fiber)), which then causes the nearby tropomyosin (regulatory protein) to move aside. This shape change allows myosin (contractile protein (in the "A-band" of your muscle fiber)) to then bind with actin. This binding of actin and myosin causes a contraction of your muscle fiber in your muscle. *****There are thousands of these muscle fibers (or myofibrils) in your muscles, which are grouped into units called Fasciculi***
Now that ACH (acetylcholine) has completed its task of signaling that action potential so Calcium ions could be released, ACH needs to be removed from the muscle so it does not stay contracted. Acetylcholinesterase (ACHe- an enzyme) will degrade that original ACH into acetate and choline. This completes one muscle contraction. Of course, other things are happening but this is the simplified view and their are all sorts of components of the individual muscle fiber. Also, ATP is utilized as an energy source required by the muscles to allow myosin to bind with actin. ATP is obtained from the breakdown of adenosine tri-phosphate to adenosine di-phosphate + a free phosphate ion.
-----BACK TO THE ORGANOPHOSPHATES:
Organophosphates actually INACTIVATE ACHe (the enzyme which degrades the original ACH causing contraction). Therefore, ACH can no longer be hydrolyzed (or broken down), which means you get a huge accumulation of ACH at the postsynaptic portion of the neuromuscular junction.
So this is obviously not a good thing. Hope you find this interesting and helpful. Just one more reason why you should buy organic food without chemicals sprayed all over them.