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Anatomy & Physiology 2006 Sem1 ch2

Terms

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Major Elements
Oxygen (O) – 65%, Carbon © - 18.5%, Hydrogen (H) – 9.5%, Nitrogen (N) – 3.2%.
Structure of an Atom
An atom is made up of several subatomic particles: A dense core called the nucleus, within which are positively charged protons (p+) and uncharged neutrons (n0). Negatively charged electrons (e-) move about in a reletively large space surrounding the nucleus.
Atomic Number
A number assigned to each element that identifies the number of protons in the nucleus of an atom.
Atomic Numbers and Mass of the Four Major Elements
Oxygen – 8 & 16.00, Carbon – 6 & 12.01, Hydrogen – 1 & 1.01, Nitrogen – 7 & 14.01
Mass Number
The number of particles within the nucleus of an atom (the sum of the protons and neutrons). This varies depending on both the element and the isotope.
Isotope
An isotope of an element is one which has the atomic number, but a different mass number due to differing numbers of neutrons in the nucleus.
Ion
An atom or group of atoms that has either gained or lost electrons and as such, has an electrical change.
Molecule
The result of two or more atoms sharing electrons.
Compound
Substance that contains two or more different elements.
Valence Shell
The valence shell is the outermost shell of an atom, which contains the electrons most likely to account for the nature of any reactions involving the atom and of the bonding interactions it has with other atoms.
Chemical Bonds (Types)
Ionic bond, Covalent bond, Hydrogen bond.
Octet Rule
All atoms want to be like the nearest noble gas. (Well, they all want to have the same number of valence electrons, anyway). To do this, they either gain or lose electrons (to form ionic compounds) or share electrons (to form covalent compounds).
Cation
Aan atom or molecule which has a positive electrical charge.
Anion
An atom or molecule which has a negative electrical charge.
Ionic Bond
A chemical bond formed by electrostatic attraction between oppositely charged ions.
Covalent Bond
A chemical bond between two atoms or radicals formed by the sharing of a pair (single bond), two pairs (double bond), or three pairs of electrons (triple bond).
Hydrogen Bond
A weak bond between two atoms (one of which is hydrogen) with partial but opposite electrical charges.
Nonpolar Covalent Bond
A covalent bond where the electrons are shared equally between the two atoms.
Polar Covalent Bond
A covalent bond in which more than half of the bond's negative charge is concentrated around one of the two atoms.
Chemical Reaction
Change that takes place when two or more substances (reactants) interact to form new substances (products).
Law of Conservation of Energy
States that energy can neither be created nor destroyed, any energy lost by one object must be gained by another object.
Potential Energy
Energy stored by matter due to its position.
Kinetic Energy
Energy associated with matter in motion.
Exergonic Reaction
More energy released than absorbed.
Endergonic Reaction
More energy absorbed than released.
Activation Energy
The minimum amount of energy needed for a chemical reaction to take place.
Matter
Anything that occupies space and has mass.
Energy
The capacity for doing work. Forms of energy include thermal, mechanical, electrical, and chemical. Energy may be transformed from one form into another.
Chemical Reactions Influences
1) Concentration – The more particles of matter present in a confined space, the greater the chance they will collide. 2) Temperature – The higher the temperature of matter, the more rapidly particles will move about, increasing the chance of a collision with a greater force, thus increasing the chance of starting a reaction.
Catalyst
A chemical substance that increases the rate of a reaction without being consumed. The catalyst lowers the activation energy required, allowing the reaction to proceed more quickly or at a lower temperature.
Mole
A unit of mass equal to the molecular weight of the substance.
Molarity
The moles of a solute per litre of solution (mol/L).
Colloid
Mixture containing particles suspended in a liquid, which are larger than molecular size but small enough to be moved about by molecular collisions. These particles do not settle under gravity.
Suspension
Mixture in which material may mix with the liquid or suspending medium for some time, but will settle eventually.
Solution
A mixture of one or more solutes dissolved in a solvent.
Dissociate
To undergo a reversible or temporary breakdown of a molecule into simpler molecules or atoms.
Acid
A substance that releases H+ ions when dissolved in water. In general scientific usage an acid is a molecule or ion that is able to give up a proton (H+ ion) to a base. A Proton donor.
Base
A substance that, when added to water, reduces the concentration of hydrogen ions (raises the pH). A proton acceptor.
pH Scale
A scale from 0 to 14 reflecting the concentration of hydrogen ions in solution
pH Values of Some Common Bodily Fluids
Gastric juice – 1.2-3.0, Blood – 7.35-7.45, Bile – 7.6-8.6, Cerebrospinal fluid – 7.4, Semen – 7.20-7.60, Saliva – 6.35-6.85, Urine – 4.6-8.0, Vaginal fluid – 3.5-4.5.
Types of Chemical Reactions
Synthesis reactions – known as anabolism in the body, it is the process of building larger compounds and cellular matter from simpler compounds - such as in the building of muscle fibre from nutrients.(A + B  AB). Decomposition reactions – known as catabolism in the body, Is the destruction of complex components into smaller components - such as the breakdown of muscle tissue or the release of energy from ATP. (AB  A + B). Exchange reactions - reactions in the body that consist of both synthesis and decomposition reactions. (AB + CD  AD + BC). Reversible reactions – Products can revert to original reactants. (AB  A + B).
Inorganic Compound
Compounds which usually lack carbon and are structurally simple.
Organic Compound
Compounds which always contain carbon, usually contain hydrogen and always have covalent bonds. Most are large molecules and many are made up of long chains of carbon atoms.
Hrdrolysis
The decomposition of organic compounds by interaction with water.
Dehydration Synthesis Reaction
A chemical reaction whereby two smaller molecules join to form a larger molecule, and one of the products formed is a water molecule.
A.T.P
Adenosine triphosphate, the molecule which is the source of energy for most metabolic processes in living organisms.
Major Carbohydrate Groups
Monosaccharides – Simple sugars that contain from 3 to 7 carbon atoms, Disaccharides – Simple sugars formed from the combination of two monosaccharides by dehydration synthesis, Polysaccharides – from tens to hundreds of monosaccharides joined by dehydration synthesis.
Cellulose
A polysaccharide found in plants that cannot be digested by humans but provides bulk to help eliminate feces.
Lipid
Organic molecules, generally containing hydrocarbon chain(s), that are insoluble in water but dissolve readily in nonpolar organic solvents. One class the phospholipids, forms the structural basis of biological membranes.
Triglycerides
Simple fat compounds. Triglycerides make up most animal and vegetable fats and are the principal lipids in the blood, where they circulate bound to protein, forming high- and low-density lipoproteins.
Saturated Fats
Triglycerides that contain only single covalent bonds between fatty acid carbon atoms.
Monounsaturated Fats
Tryglycerides containing fatty acids with one double covalent bond between two fatty acid carbon atoms.
Polyunsaturated Fats
Triglycerides containing more that one double covalent bond between fatty acid carbon atoms.
Phospholipids
Lipids (fat molecules) in which phosphoric acid as well as fatty acids are attached to a glycerol backbone. Phospholipids are found in all living cells and in the bilayers of cell membranes.
Steroids
A steroid is a lipid characterised by a carbon skeleton with four fused rings. Different steroids vary in the functional groups attached to these rings. Hundreds of distinct steroids have been identified in plants and animals. Their most important role in most living systems is as hormones.
Proteins
Large molecules containing carbon, hydrogen, oxygen and nitrogen. The major structural component of all body tissue, and necessary for muscular growth and cellular repair. Proteins are also a functional component of enzymes, hormones, etc. Used for energy only when carbohydrates and fats are not available.
Enzymes
Complex proteins, produced by body cells, which are crucial catalysts for biochemical reactions and for building or synthesising most compounds in the body.
Amino Acid
The single molecular units (20 in total), that when chained together form a protein. The number, type, and sequence of amino acids found in the chain determine the shape and function on the protein.
ADP
An important chemical our cells use to produce energy—ADP forms when ATP (the source of cellular energy) breaks down to fuel muscle contractions. To recreate ATP and thus replenish our cells' energy stores, ADP combines with creatine phosphate.
Anaerobic
Literally "without oxygen". A high-intensity energy system where the muscles lack sufficient oxygen to successfully burn fuel, resulting in the production of lactic acid. Anaerobic exercise is very intense and can only be sustained for short periods of time.
Aerobic
Literally "with oxygen". Commonly used to describe exercise intensity where muscles can use oxygen to convert glucose and fat into energy.
Hydrostatic Pressure
The pressure exerted by the weight of fluids. As depth increases in water, the pressure also increases due to an increased column of water above the point in question.
Osmotic Pressure
The pressure exerted by a solution necessary to prevent osmosis into that solution when it is separated from the pure solvent by a semipermeable membrane.
Tonicity
Measure of a solutions ability to change the volume of cells by altering their water content.
Isotonic
Relating to isotonicity or isotonia. Having equal tension - denoting solutions possessing the same osmotic pressure - more specifically, limited to situations in which cells can neither swell nor shrink.
Hypertonic
The solution on one side of a membrane where the solute concentration is greater than on the other side.
Hypotonic
The solution on one side of a membrane where the solute concentration is less than on the other side.
Hemolysis
Water molecules enter a cell faster than they can leave, causing the cell to swell and burst. (Related to hypotonic solutions)
Crenation
Water molecules move out of a cell faster than they can enter, causing the cell to shrink. (Related to Hypertonic solutions)

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