Ch. 2 (Anatomy & Physiology: An Integrative Approach 2nd Edition)

atom

the smallest particle that exhibits the chemical properties of an element

element

substance composed of only one type of atom;

element facts

92 naturally occurring elements; hydrogen is the lightest and smallest; uranium is the largest and heaviest

periodic table of elements

elements are grouped into major, minor, and trace elements based on the percentage each composes by weight in the human body

Most common Elements of the Human Body

12 of them occur in living organisms in greater than trace amounts

Major Elements of Human Body

Compose more than 98% of body weight; oxygen, carbon, hydrogen, nitrogen, calcium, phosphorus

Minor Elements of Human Body

Compose less than 1% of body weight; sulfur, potassium, sodium, chlorine, magnesium, iron

Atoms are composed of

neutrons, protons, and electrons

Subatomic particles

neutrons, protons, and electrons

atomic mass unit (amu)

the mass of a subatomic particle is very small; consider 1 amu is equal to 1.66X10^-27 kilograms

neutron

uncharged; meaning it is neutral

proton

positive charge of one (+1)

atomic nucleus

electron

negative charge of one (-1); very small mass- only 1/1800th of the mass of a proton or neutron

chemical symbol

assigned to each element; identified by first letter or first plus an additional letter of its English name

atomic number

indicates the number of protons in an atom of that element ;located above its symbol in the period table

atomic mass

indicates the mass of both protons and neutrons in the atomic nucleus, reflects the heaviness of an element's atoms

O

Oxygen- 65%

C

Carbon- 18%

H

Hydrogen- 10%

N

Nitrogen- 3%

Ca

Calcium-1.5%

P

Phosphorus-1%

S

Sulfur- 0.25%

K

Potassium- 0.20%

Na

Sodium- 0.15%

Cl

Chlorine- 0.15%

Mg

Magnesium- 0.05%

Fe

Iron- 0.006%

Number of Protons

(p)= atomic number

Number of Neutrons

(n)= atomic mass (p+n) - atomic number (p)

Number of Electrons

(e) = proton number (p)

Isotopes

different atoms of the same element that have the same number of protons and electrons but differ in the number of neutrons

average atomic mass

the weighted average of the atomic mass for all isotopes of an element

radioisotopes

unstable because they contain and excess number of neutrons

physical half-life

the time it takes for 50% of the radioisotope to become stable

biological half-life

the time required for half of the radioactive material to be eliminated from the body

octet rule

atoms obtain an outer shell with eight electrons and gain chemical stability through the loss, gain, or sharing of electrons

chemical compounds

stable associations between two or more elements combined in a fixed ratio

ions

atoms or groups of atoms with either a positive charge or a negative charge; produced from the loss or gain of one or more electrons

electrolyte balance

the state of maintaining homeostatic blood levels of the different ions

electrolyte imbalance

when the blood concentration of an electrolyte becomes either too high or too low

Cations

Ions with a positive charge

Anions

Negatively charged ions

Sodium ion

most common extracellular cation, participant in conducting electrical signals in nerves and muscle, most important in osmotic movement of water, sodium gradient involved in cotransport of other substances across a plasma membrane

Potassium Ion

most common intracellular cation, participant in conducting electrical signals in nerves and muscles, role in glycogen storage in live and muscle, function in pH balance

Calcium Ion

hardness of bone and teeth, muscle contraction, exocytosis, blood clotting, second messenger in hormonal stimulation of cells

Magnesium Ion

required for ATP productio

Hydrogen Ion

concentration determines pH of blood and other fluids of the body

Chloride Ion

alters nerve cell responsiveness to stimulation, component of stomach acid (HCI), chloride shift in erythrocytes

Bicarbonate IonIon

conversion of CO2 gas to HCO3-, whcih is transported in the blood, buffering of pH in blood

Phosphate

as Ca3(PO4)2, it hardens bone and teeth, component of phospholipids (membranes), component of nucleotides, including ATP nucelic acids (DNA and RNA), most common intracellular anion, intracellular buffer

Common Cations

Sodium, Potassiu, Calcium, Magnesium, Hydrogen

Common Anions

Chloride, Bicarbonate, Phosphate

Ionic Bonds

When cations and anions may bind together by electrostatic interactions; they form salts

Ionic Compound

chemical bond formed when a cation is electrostatically attracted to an anion

covalently bonded molecule

Resulting from when electrons are shared between atoms

molecular compounds

most molecules are composed of two or more different elements

molecular formula

the number and types of atoms composing a molecule

isomers

molecules composed of the same number and types of elements but arranged differently in space

covalent bond

When atoms share electrons

single covalent bond

one pair of electrons shared between atoms

double covalent bond

sharing of two pairs of electrons between two atoms

triple covalent bond

three pairs of electrons are shared between atoms in some molecules

nonpolar covalent bond

When two atoms of the same element have equal attraction for electrons, they share the electrons equally

polar covalent bond

When different atoms have varying degrees of electronegativity or attraction for electrons, and thus may share electrons unequally

polar (dipole) molecules

refers to the poles of partial electrical charges, which are analogous to poles of a magnet

nonpolar molecules

molecules containing nonpolar covalent chemical bonds

polar molecules

partial electrical charges on different portions of a molecule

amphipathic molecules

molecule that contains a hydrophobic region and a hydrophilic region

intermolecular attractions

When molecules have weak chemical attractions to other molecules

hydrogen bond

a weak attraction formed when a hydrogen atom of one molecule is attracted to a slightly negative atom within either the same molecule or a different molecule

van der Waals forces

The interactions that occur when electrons orbiting the nucleus of an atom of a nonpolar molecule are for a brief instant, distributed unequally

hydrophobic interactions

When nonpolar molecules are placed in water or another polar substance

Phases of Water

Gas, Liquid, Solid

Water Functions

Transports, Lubricates, Cushions, Excretes Wastes

Cohesion

the attraction between water molecules

Surface Tension

the inward pulling of cohesive forces at the surface of water

Adhesion

the attraction between water molecules and a substance other than water

Temperature

a measure of kinetic energy, or random movement, of atoms or molecules within a substance

Specific Heat

the amount of energy (measured in calories) required to increase the temperature of 1 gram of a substance by 1 degree Celsius

Heat of Vaporization

the energy required for the release of molecules from a liquid phase into the gaseous phase for 1 gram of a substance

Solvent

substance (water) holding a solute in solution

Solute

substance dissolving in a solvent

universal solvent

Water

dissolve

disperse into water

hydrophilic

water-loving

hydration shell

many water molecules surround the substance

dissociate

pull apart of separate

electrolytes

chemical that dissociates when added to water and can conduct an electrical current; includes salts, bases, and acids.

nonelectrolytes

substances that remain intact when introduced into water, such as glucose that do not conduct an electric current

hydrophobic

water-fearing

hydrophobic exclusion

When hydrogen bonds exclude or force out nonpolar molecules

hydrophobic interaction

The interaction between the molecules of the excluded nonpolar substance

proton donor

an acid

proton acceptor

a base

base

substance that accepts a hydrogen ion

buffer

substance that minimizes a change in pH even after an acid or base is added

mixture

formed from the combining or mixing of two or more substances

suspension

mixture of a solvent with large materials that do not dissolve (blood)