Nerve signal transmission

How do the pumps and channels differentiate between sodium and potassium ions to selectively move one out of the cell and the other into the cell To answer this question, we must examine the ions more closely. Both ions are cations of group lA metals. All group 1A 

In order for a nerve cell to transmit a signal, sodium and potassium ions must flow in opposite directions through specific ion channels in the cell membrane. 

The relative size of sodium and potassium ions is an example of a periodic property one that is predictable based on an element s position within the periodic table. In this chapter, we examine several periodic properties of elements, including atomic radius, ionization energy, and electron affinity. We will see that these properties, as well as the overall arrangement of the periodic table, are explained by quantum-mechanical theory, which we examined in Chapter 7. The arrangement of elements in the periodic table— originally based on similarities in the properties of the elements— reflects how electrons fill quantum-mechanical orbitals. 

A Dmitri Mendeleev is credited with the arrangement of the periodic table. 

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The influx of Ca(Il) across the presynaptic membrane is essential for nerve signal transmission involving excitation by acetylcholine (26). Calcium is important in transducing regulatory signals across many membranes and is an important secondary messenger hormone. The increase in intracellular Ca(Il) levels can result from either active transport of Ca(Il) across the membrane via an import channel or by release of Ca(Il) from reticulum stores within the cell. More than 30 different proteins have been linked to regulation by the calcium complex with calmoduhn (27,28). 

Other types of insecticides have been developed and used over the past several decades. To discuss them all requires an entire course. There is an ASIDE which illustrates the halogenated hydrocarbons most of which are not in current use because of their effects on the environment (DDT) and toxicity to humans (Dieldrin/Aldrin). Estrogenic acivity of DDT led to fatal fragility in the eggs of certain predatory birds. All of these compounds are lipophilic and interfere with nerve signal transmission. 

The physiological effects of ion channels are based on the regulation of ion fluxes (e.g., K+, Na+, Ca2+, Cl-) across membranes, which affect, for example, osmotic pressure, nerve signal transmission, and muscle contraction. Ion permeation is extremely fast (up to 107 ions s-1) and highly selective [1],... 

Acetyl coenzyme A (acetyl CoA) can serve as a donor of acetate groups in biochemical reactions. One such reaction is the formation of acetylcholine, an important neurotransmitter involved in nerve signal transmission at neuromuscular junctions. The structure of choline is shown below. Draw the structure of acetylcholine. 

Biological systems. Many biological processes involve "active" or carrier-mediated transport. Two examples are oxygen transport and nerve signal transmission. A good reference for biological membrane systems Is Fendler 9). 

CAN YOU ANSWER THIS Other ions, including calcium and magnesium, are also important to nerve signal transmission. Arrange these Jour ions in order of increasing size K, Na, Mg, and Ccr. ... 

Artificial sweeteners taste sweet because they fit into the receptor pocket that normally binds sucrose. In fact, both aspartame and saccharin bind to the active site in the Tlr3 protein more strongly than sugar does For this reason, artificial sweeteners are "sweeter than sugar." It takes 200 times as much sucrose as aspartame to trigger the same amount of nerve signal transmission from taste cells. 

Amphetamine is another powerful drug related to the alkaloid ephedrine. Whereas morphine slows down nerve signal transmissions, amphetamine enhances them. Amphetamine is an example of a stimulant, a drug that increases alertness and wakefulness. Amphetamine is widely used to treat Attention-Deficit H)q3eractivity Disorder (ADHD) and is prescribed under the trade name Adderall. Patients suffering from ADHD find that amphetamine helps them to focus and concentrate more effectively. However, because amphetamine produces alertness and increased stamina, it, too, is often abused. 

As the main structural material for bones and teeth, caldnm is the most abundant mineral in the body. Calcium also plays an important role in nerve signal transmission and in blood clotting. If blood calcium levels get too low, calcium stored in bones will release into the blood causing loss of bone mass. Persistently low blood calcium levels result in osteoporosis, a condition in which bones become weakened by calcium loss. The adult DRI for calcium is 1000 mg/day. Adolescents and older adults need a bit more. One cup of milk contains approximately one-third of the adult DRI. Other calcium-rich foods include cheese, sardines, oysters, and broccoli. 

Which periodic property is particularly important to nerve signal transmission Why ... 

Suppose you were trying to find a substitute for in nerve signal transmission. Where would you begin your search What ions would be most like K For each ion you propose, explain the ways in which it would be similar to and the ways it would be different. Refer to periodic trends in your discussion. 

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