Elements in the Body, Free Radicals, and Metabolic Pathways

Vocabulary flashcards covering body elemental composition, isotopes, free radicals, oxidative stress, antioxidants, pH levels, and metabolic chemical pathways.

Oxygen (in the human body)

An element comprising approximately $65\%$ of total body mass; it is a major component of water and other essential compounds, and its gaseous form is essential for respiration.

Carbon (in the human body)

An element comprising approximately $18.5\%$ of body mass that is found in all organic molecules.

Hydrogen (in the human body)

An element comprising approximately $9.9\%$ of total body mass; it is a component of water and most other compounds in the body.

Nitrogen (in the human body)

An element accounting for $3.2\%$ of total body mass that is found in proteins, nucleic acids, and other organic molecules.

Calcium (in the human body)

An element making up approximately $1.9\%$ of total body mass found in bones and teeth; it functions in membrane function (ion channels), nerve impulses (translating to chemical triggers), muscle contraction triggers, and blood clotting (accelerating fibrin grouping).

Phosphorus (in the human body)

An element making up approximately $1\%$ of total body mass; it is found in bones and teeth, nucleic acids, and high-energy compounds such as ATP.

Potassium (in the human body)

An essential element accounting for approximately $0.4\%$ of total body mass.

Sulfur (in the human body)

An element accounting for approximately $0.3\%$ of total body mass that is found in proteins.

Sodium (in the human body)

An element comprising approximately $0.2\%$ of total body mass; it is critical for blood volume (holding water in vessels), membrane function, nerve impulses, and muscle contraction.

Chlorine (in the human body)

An element comprising approximately $0.2\%$ of total body mass; it is important for blood volume, membrane function, and water absorption (working with sodium to create a gradient).

Magnesium (in the human body)

An element making up approximately $0.1\%$ of total body mass that serves as a cofactor for many enzymes.

Isotopes

Atoms of the same element that have different numbers of neutrons, sharing basically the same chemical properties but differing in mass.

Radioisotopes

Isotopes with unstable nuclei that spontaneously break down and emit subatomic particles or radiation; they can break molecules, destroy cells (break DNA and prevent division), and damage tissues.

Free Radical

An ion or molecule with one or more unpaired electrons in its outermost energy level; formed when chemical bonds break and each molecule keeps one electron, or produced via redox reactions.

Redox Reaction

A chemical reaction in which electrons are transferred between chemical species.

Endogenous Free Radicals

Free radicals produced inside the body via enzymatic reactions (such as phagocytosis) or nonenzymatic reactions (such as aerobic respiration).

Exogenous Free Radicals

Free radicals introduced from outside environmental sources, such as pollution and cigarette smoke.

Reactive Oxygen Species (ROS)

Free radicals that originate from molecular oxygen; they aid homeostasis when properly maintained but cause oxidative stress and cellular damage when present in excess.

Reactive Nitrogen Species (RNS)

Free radicals often derived from nitric oxide ($NO$) that lead to nitrosative stress when unmanaged.

Nitric Oxide ($NO$)

A molecule involved in chemical communication with the nervous system, control of blood pressure, and blood clotting.

Anti-oxidants

Substances that inhibit oxidation by donating extra electrons to neutralize free radicals, terminating chain reactions before damage occurs and protecting cells from toxic effects.

Endogenous Anti-oxidants

Antioxidants synthesized naturally within the body, such as antioxidant enzymes.

Exogenous Anti-oxidants

Antioxidants that are obtained externally through the diet.

Omega-3

Anti-inflammatory polyunsaturated fatty acids that support brain and heart health, prevent blood clots, build cell membranes, and aid neural, visual, and immune growth and development.

Omega-6

Pro-inflammatory polyunsaturated fatty acids that support brain function and heart health, aid blood clotting, and promote neural, visual, and integumentary growth and development.

Acid (pH)

A solution with a pH value of $< 6.9$, characterized by an abundance of $H^+$ ions.

Base (pH)

A solution with a pH value of $> 7.1$, characterized by an abundance of $OH^-$ ions.

Neutral pH

A solution with a pH of $7.0$, representing equal balance of $H^+$ and $OH^-$ ions.

Blood pH

Physiological pH maintained at $7.4$; a level that is too low results in acidosis, while a level that is too high results in alkalosis.

Saliva pH

A physiological fluid with a resting pH level of approximately $6.8$.

Bile pH

A digestive fluid that is generally basic, unless it comes directly from the gallbladder after fasting.

Catabolic Pathway

A metabolic pathway where large molecules are broken down into smaller components, releasing energy in the process.

Anabolic Pathway

A metabolic pathway where small molecules are assembled into larger structures, consuming or using energy.

Dehydration Synthesis

A chemical reaction that joins molecules together through the removal of a water molecule.

Hydrolysis

A chemical reaction that breaks apart molecular bonds through the addition of a water molecule.