(also known as spike or impule) a rapid change in membrane voltage ("potential") from negative (-70 mV in nerve cells) to positive and then back to negative.  This causes an electrical current that proceeds down an axon.

to form a thin layer of molecules of a substance on the surface of a solid or liquid.

molecules that contain an amino group (NH2

a condition where your red blood cells do not carry enough oxygen, usually because the number of red cells is too low

a chemical that makes you lose feeling and awareness.  A general anesthetic is one that will cause you to lose consciousness.  A local anesthetic will cause a loss of feeling in a particular area or part of the body.

anything (usually a protein) that elicits an immune response.  Bacteria and viruses are two examples of antigens.

One of a set of alternate forms of a gene. An example is the different alleles of eye color. Each of the different forms of the gene code for eye color, only each codes for a different color i.e. blue, brown, green.

single celled micro-organisms that can be free living or live in/on other organisms.  

a greenish-yellow fluid excreted from the liver into the small intestine, near the attachment to the stomach.  This fluid helps emulsify or dissolve fats so the body can absorb them.  Bile consists of cholesterol, bile salts, and worn out red blood cells. An imbalance in these chemicals leads to gallstones.  

a personality disorder in which the person oscillates between a deep depression and elation or happiness.  Usually the changes are gradual, but can be very sudden.  This disorder used to be called manic depressive disorder