Anatomy & Physiology I - Chapter 2: Chemical Level of Organization

Vocabulary flashcards covering atomic structure, elements, chemical bonds, water properties, acids, bases, pH, and organic macromolecules from Chapter 2 notes.

Matter

Anything that occupies space and has mass.

Elements

Pure substances that cannot be broken down into simpler substances by ordinary chemical means.

Major Elements in the Human Body

The four major elements ($CHON$) making up the human body: Carbon ($C$), Hydrogen ($H$), Oxygen ($O$), and Nitrogen ($N$).

Trace Elements

Elements present in very small amounts in the human body but vital for health, including $Ca$, $P$, $K$, $Na$, $Cl$, $Mg$, $Fe$, and $I$.

Atom

The smallest unit of an element that retains the unique properties of that element.

Protons ($p^+$)

Subatomic particles located in the nucleus with a positive ($+$) charge and a mass of approximately $1\,\text{amu}$.

Neutrons ($n^0$)

Subatomic particles located in the nucleus with a neutral ($0$) charge and a mass of approximately $1\,\text{amu}$.

Electrons ($e^-$)

Subatomic particles orbiting the nucleus in electron shells/energy levels, carrying a negative ($-$) charge and a negligible mass of approximately $\frac{1}{1800}\,\text{amu}$.

Atomic Number

The number of protons in the nucleus of an atom, which uniquely identifies an element and equals the number of electrons in a neutral atom.

Mass Number (Atomic Mass)

The total number of protons and neutrons in the nucleus of an atom, representing the approximate total mass of the atom.

Isotopes

Atoms of the same element that have the same number of protons but different numbers of neutrons.

Radioisotopes

Unstable isotopes that emit radiation as they decay, used medically as tracers for diagnostic imaging and in radiation therapy.

Valence Electrons

Electrons located in the outermost electron shell of an atom.

Octet Rule

The principle that atoms tend to gain, lose, or share electrons to achieve a stable outer shell of $8$ electrons (or $2$ for the first shell), driving chemical reactions.

Ionic Bonds

Chemical bonds formed by the transfer of electrons from one atom to another, resulting in charged ions that are strong in a dry state but dissociate in water (e.g., $NaCl$).

Cation

A positively charged ion formed when an atom loses electrons.

Anion

A negatively charged ion formed when an atom gains electrons.

Covalent Bonds

Chemical bonds formed by the sharing of electrons between atoms.

Nonpolar Covalent Bond

A type of covalent bond formed by the equal sharing of electrons between atoms (e.g., $O_2$, $CH_4$).

Polar Covalent Bond

A type of covalent bond formed by unequal sharing of electrons due to differences in electronegativity (e.g., $H_2O$), resulting in partial positive ($\delta+$) and partial negative ($\delta-$) charges.

Hydrogen Bonds

Weak attractions between a partially positive hydrogen atom in one polar molecule and a partially negative atom (like oxygen or nitrogen) in another polar molecule or within the same large molecule.

Reactants

Starting substances in a chemical reaction.

Universal Solvent

A property of water describing its ability to dissolve many polar and ionic substances due to its polarity and hydrogen bonding.

Hydrophilic

Water-loving substances that dissolve in water.

Hydrophobic

Water-fearing substances that do not dissolve in water.

High Heat Capacity

The property of water allowing it to absorb and release large amounts of heat with only a slight change in its own temperature, vital for thermoregulation.

High Heat of Vaporization

The property of water where evaporation of water from the skin cools the body.

Cohesion

The property of water molecules sticking to each other.

Adhesion

The property of water molecules sticking to other surfaces.

Acids

Substances that release hydrogen ions ($H^+$) when dissolved in water (e.g., $HCl$ in the stomach).

Bases

Substances that release hydroxide ions ($OH^-$) or accept hydrogen ions ($H^+$) when dissolved in water (e.g., $NaOH$, $NH_3$).

pH Scale

A scale ranging from $0$ to $14$ that measures the concentration of hydrogen ions ($H^+$) in a solution.

Acidic Solution

A solution with a $\text{pH} < 7$, indicating a higher $H^+$ concentration.

Neutral Solution

A solution with a $\text{pH} = 7$, indicating equal $H^+$ and $OH^-$ concentrations (e.g., pure water).

Alkaline (Basic) Solution

A solution with a $\text{pH} > 7$, indicating a lower $H^+$ concentration.

Normal Blood pH

The physiological pH range of blood, which is approximately $7.35-7.45$.

Buffers

Chemical systems that resist drastic changes in pH by either releasing or binding $H^+$ ions (e.g., bicarbonate buffer system in blood).

Organic Compounds

Molecules that contain carbon, typically bonded to hydrogen, oxygen, and nitrogen.

Macromolecules

Large, complex organic molecules, often polymers.

Polymers

Large molecules made of repeating smaller units called monomers.

Dehydration Synthesis

A chemical reaction in which monomers join to form polymers by removing a water molecule.

Hydrolysis

A chemical reaction in which polymers break down into monomers by adding a water molecule.

Carbohydrates

Organic compounds composed of carbon, hydrogen, and oxygen ($CH_2O$) that serve as a primary source of quick energy for cells and as structural components.

Monosaccharides

Simple sugars, such as glucose, fructose, and galactose.

Disaccharides

Carbohydrates formed by joining two monosaccharides, such as sucrose, lactose, and maltose.

Polysaccharides

Carbohydrates formed by joining many monosaccharides, including glycogen (animal energy storage), starch (plant energy storage), and cellulose (plant structural fiber).

Lipids

Generally hydrophobic organic compounds composed primarily of carbon and hydrogen with little oxygen, functioning in long-term energy storage, insulation, protection, hormones, and cell membrane components.

Triglycerides

Fats and oils composed of glycerol and $3$ fatty acids that function as stored energy.

Phospholipids

Modified triglycerides containing a phosphate group that form the basic lipid bilayer structure of cell membranes.

Steroids

Lipids with a four-ring carbon structure, including cholesterol and steroid hormones like estrogen and testosterone.

Eicosanoids

Signaling molecules classified as lipids, such as prostaglandins.