how does lead enter the human body?

how does lead enter on nerve cells in the human body?

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  • 8 years ago
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    Some common sources of lead include: water, paint, electric storage batteries, insecticides, auto body shops, gasoline, etc.

    Most of the dysfunctions produced by the absorption of lead are due to lead's ability to mimic and inhibit the actions of calcium. In humans the lead is directly absorbed, distributed, and excreted. Once in the bloodstream lead is distributed to three main compartments: blood, soft tissue (kidney, bone marrow, liver, and brain), and mineralized tissue (bones and teeth).

    Cells absorb lead through the same channels they absorb calcium from. The drugs that regulate the intake of calcium also increase the amount of lead uptake. High levels of lead decrease transport of calcium and vice versa, therefore these two metals function as competitive inhibitors. Lead can enter through the same ion channels as calcium and regulate the activity of those channels to uptake more lead into the cell.

    Lead, even at low concentrations, has the ability to increase the basal release of the neurotransmitters from the presynaptic nerve endings. This can occur both in the PNS and CNS. Micromolar concentrations of lead can cause the spontaneous release of dopamine, acetylcholine (ACh), and gama-aminobutyric acid (GABA). Control movement and emotional response are some of the brain processes that are affected by dopamine. An acetylcholine receptor has the responsibility for transducting nerve impulses to muscular contraction. GABA is an amino acid classified as a neurotransmitter. GABA is thought to play a role in the secretion of growth hormones according to some studies. Lead can also block the release of neurotransmitters when the action potential is taking place. This double effect of lead can have serious consequences on a developing nervous system. It can result in a decrease of pruning, what shapes the early brain, of an infant. The early brain, which has more synapses than an adult brain, is patterned according to the stimuli received during development. If there is an increase in neural activity, brought about by lead, the development process can be inhibited and have permanent effects on synaptic anatomy and function of the brain. It is believed that this is one of the causes of learning and behavioral problems that occur in children.

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