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The pH Chart Note that each decrease in pH by one pH unit means a 10-fold increase in concentration of hydrogen ions. read more …  

The pH Scale Since hydrogen ions are positively charged, they alter the charge environment of the molecules they are bonded to. These molecules change their shape as a result. This is particularly important for proteins, because their shape is related to their function. The concentration of hydrogen ions is commonly expressed in terms of the…

Hydrogen Bonds? The fact that the oxygen atom of a water molecule is negatively charged and the hydrogen atom is positively charged, means that the hydrogen atoms of one water molecule attract the oxygen atoms of its neighbor, etc. Opposites attract This electrostatic attraction is called a hydrogen bond. This bond is important in determining…

Covalent Bonds Covalent bonds involve a complete sharing of electrons. It occurs most often between atoms that have partially filled outer shells. Thus, if the atoms share similar needs, then electrons will be shared. An atom like carbon forms covalent bonds with other atoms. The electrons travel in orbits around the nuclei of the atoms…

Ionic Bonds? Ionic bonds arise from elements with an almost empty outer shell acting with elements with an almost full outer shell. In this case there is a complete transfer of electrons. A well known example is table salt, sodium chloride. In order to become stable, sodium gives its one outer shell electron to chlorine…

Important Atoms & Electrons ? Electrons are important for several reasons: Chemical bonds form when electrons are transferred or shared between atoms. When the outermost energy level of an atom is almost empty, the atom tends to give up electrons. When the outermost energy level of an atom is almost full, the atom tends to…

Elect your Electrons Nitrogen’s atomic mass = (number of protons: 7) + (number of neutrons: 7) = 14. Therefore, a neutral nitrogen atom must also have 7 electrons to balance its 7 protons. Electrons are very tiny particles which surround the nucleus of an atom. They all have a negative electrical charge. A neutral atom…

BIS = Freeze? The situation is quite different for the third circuit, the Behavioral Inhibition System (BIS). It is associated with the hippocampus, the amygdala, and the basal nuclei. It receives inputs from the prefrontal cortex. The BIS is activated when both fight and flight seem impossible and the only remaining behavioral option is to…

MFB + PVS Aversive stimuli that provoke action responses activate the brain’s punishment (pain) circuit which enables us to cope with unpleasant situations. It includes brain structures, such as the hypothalamus, thalamus, amygdala, hippocampus, and insular cortex. The Peri-Ventricular System (PVS) or punishment circuit, functions by means of acetylcholine, which stimulates the secretion of adrenal…

Drug Dependency? In addition to exerting their effects through molecular mechanisms, these drugs intervene at various points in the brain’s central reward circuit (see above diagram). It is through this combination of effects on the reward circuit and on other brain structures that a drug induces the behaviors and specific subjective sensations. Because neural communication…

THE PLEASURE & PAIN SYSTEMS All these regions are connected by the ‘pleasure or reward bundle’. Their activation causes repetitions of a gratifying action. This then strengthens their associated neural pathways. That’s why reward (pleasure) & punishment (pain) circuits supply the needed motivation for our behaviors. These circuits, acting as programs, can flip on or…

VTA Neurons The axons of the VTA neurons project out synthesized dopamine to modulate the activity of the prefrontal cortex, septum, nucleus accumbens, and amygdala. All of them play an important role in what is called the reward circuit. The punishment and the reward circuits were one of the first to evolve. Parts of it…