Unit 2: Homeostasis / Water

Acid

A solution that measures less than 7 on the pH scale

Base

A solution that measures more than 7 on the pH scale

External

the outer surface of something (in this case, the body)

Feedback regulation

A control mechanism that uses the end result to regulate the rate of a process

Homeostasis

internal stability or "steady state" maintained by the body

Internal

the inner surface of something (in this case, the body)

Negative feedback

A type of regulation that responds to a change in conditions by initiating responses that counteract or reverse the change

pH scale

The range of numbers used to describe how acidic a solution is

Positive feedback

A response to change when the stimulus increases the original stimulus

Response

A reaction (to a stimulus)

Stimulus

An environmental change that triggers a response

Adhesion

attraction between unlike molecules

Atom

smallest particle of an element

Cohesion

tendency of molecules of the same kind to stick to one another

Compound

substance containing two or more elements chemically combined in a fixed ratio

Covalent bond

chemical bond that forms when two atoms share electrons

Electron

subatomic particle with a single unit of negative charge

Hydrogen bond

bond created by the weak attraction of a slightly positive hydrogen atom to a slightly negative portion of another molecule

Ion

Atom that has become electrically charged as a result of gaining or losing electrons

Ionic bond

Chemical bond that occurs when an atom transfers an electron to another atom

Molecule

two or more atoms held together by covalent bonds

Neutron

subatomic particle that has no charge (electrically neutral)

Nucleus (of an atom)

The central core that contains protons and neutrons

Polar molecule

molecule in which opposite ends have opposite charges

Proton

subatomic particle with a single unit of positive electric charges

Solute

substance in a solution that is dissolved and is present in a lesser amount

Solution

uniform mixture of two or more substances

Solvent

substance in a solution that dissolves the other substance and is present in greater amount

surface tension

A measure of how difficult it is to stretch or break the surface of a liquid

nonpolar

equal sharing of electrons