Human Anatomy and Physiology: Chemistry, pH, and Homeostasis Review Flashcards

Comprehensive vocabulary flashcards covering atomic structure, chemical bonds, properties of water, pH and buffer systems, and homeostatic regulation mechanisms.

Homeostasis

The continuous process of establishing and maintaining a relatively stable internal environment within the body.

Dynamic Equilibrium

A physiological state in which systems continually adapt and adjust to changing conditions to maintain regulated variables within a normal range of values.

Extracellular Fluid

The fluid that bathes or surrounds the cells of the body, constituting the body's internal environment.

Interstitial Fluid

The extracellular fluid located in the spaces surrounding tissue cells.

Plasma

The liquid portion of blood that carries blood cells, nutrients, and dissolved substances.

Cerebrospinal Fluid

Fluid produced by the brain that circulates over the brain surface and down the spinal cord.

Receptor

A homeostatic sensor composed of cells sensitive to a particular stimulus or environmental change that sends information to a control center.

Control Center

An integration center that receives and processes information from receptors, determines whether a change is significant, and sends out commands via electrical or hormone signals.

Effector

A target cell, muscle, or gland that responds to commands from the control center to carry out instructions and restore homeostasis.

Extrinsic Regulation

Systemic homeostatic regulation controlled by the nervous system (rapid electrical signals) or endocrine system (slower chemical signals) to adjust multiple body systems.

Autoregulation

An automatic, local homeostatic response when a cell, tissue, organ, or organ system adjusts itself directly to respond to an environmental change without system-wide control.

Negative Feedback Loop

A homeostatic mechanism in which the physiological response opposes or negates the original stimulus, keeping a regulated variable within a normal range.

Positive Feedback Loop

A control mechanism in which the physiological response enhances or amplifies the initial deviation from normal, accelerating a process to completion.

Solution

A uniform liquid mixture composed of two or more substances.

Solute

The dissolved substance present in a smaller amount within a solution.

Solvent

The liquid component of a solution in which solutes are dissolved or distributed, present in the greatest amount.

Aqueous Solution

A solution in which water serves as the solvent.

Colloid

A solution containing large molecules that remain uniformly dispersed indefinitely without settling out, such as blood plasma.

Suspension

A mixture containing large particles that remain in liquid while mixed but settle out of solution if left undisturbed, such as whole blood.

Hydrophilic

Refers to polar molecules and ions that readily interact with and dissolve in water.

Hydrophobic

Refers to nonpolar molecules, fats, and oils that do not readily interact with or dissolve in water.

Heat Capacity

The quantity of heat required to raise the temperature of a unit mass of a substance by $1\,^\circ\text{C}$.

Thermal Inertia

The ability of a substance like water to change temperature slowly due to its unusually high heat capacity.

Electrolytes

Soluble, inorganic substances whose dissociated ions conduct electricity in solution.

pH

The negative logarithm of the hydrogen ion ($H^+$) concentration of a solution measured in moles per liter, given by $\text{pH} = -\log([H^+])$.

Mole

A quantity of a substance with a weight in grams equal to its atomic weight, containing the exact same number of atoms as a mole of any other element.

Acid

A proton donor that dissociates in solution to add hydrogen ions ($H^+$) and lower the pH.

Base

A proton acceptor that removes hydrogen ions ($H^+$) from a solution and raises the pH.

Salt

An ionic compound that dissociates in water into cations and anions other than hydrogen ions ($H^+$) or hydroxide ions ($OH^-$).

Buffer

A compound composed of a weak acid and a weak base that stabilizes the pH of a solution by neutralizing added acids or bases.

Atom

The smallest stable unit of matter.

Proton

A positively charged subatomic particle ($p^+$) located in the nucleus of an atom.

Neutron

An electrically neutral subatomic particle ($n^0$) located in the nucleus of an atom.

Electron

A light, negatively charged subatomic particle ($e^-$) that orbits around the nucleus in electron shells.

Valence Shell

The outermost electron shell of an atom, where the number of electrons determines chemical stability and reactivity.

Atomic Number

The number of protons in the nucleus of an atom, unique to each element.

Atomic Mass Number

The total number of protons and neutrons in the nucleus of an atom.

Atomic Weight

The average mass of an element's atom, taking into account the relative abundance of its naturally occurring isotopes.

Element

A pure substance composed of atoms of only one kind, which cannot be broken down into simpler substances by ordinary physical means.

Isotopes

Versions of the same element that have different numbers of neutrons and therefore different atomic masses.

Radioisotopes

Isotopes with unstable nuclei that break down spontaneously through radioactive decay.

Ion

An atom or molecule with an electric charge formed by gaining or losing one or more electrons.

Cation

A positively charged ion formed when an atom loses one or more electrons.

Anion

A negatively charged ion formed when an atom gains one or more electrons.

Free Radical

A reactive atom, ion, or molecule containing an unpaired electron in its valence shell.

Molecule

Two or more atoms joined together by shared electrons or chemical bonds.

Compound

A chemical substance composed of two or more atoms of different elements covalently bonded in fixed proportions.

Ionic Bond

A chemical bond formed by the electrostatic attraction between oppositely charged cations and anions following electron transfer.

Covalent Bond

A strong chemical bond created when two or more atoms share electrons to fill their valence shells.

Nonpolar Covalent Bond

A covalent bond in which electrons are shared equally between atoms with similar electronegativity.

Polar Covalent Bond

A covalent bond in which electrons are shared unequally between atoms with different electronegativity, generating slight partial charges.

Hydrogen Bond

A weak attraction between the partially positive end of a hydrogen atom in a polar covalent bond and the partially negative end of an atom in another polar covalent bond.