Comprehensive Human Anatomy & Physiology I: Chemistry, Water, Organic Molecules, pH, and Enzymes

Matter

anything that takes up space and has mass

Element

simplest form of matter with unique chemical properties

Atom

the smallest possible piece of an element

Atomic number

number of protons in its nucleus

Atomic mass

approximate total number of protons and neutrons

Nucleus

center of atom contains protons and neutrons

Protons

positive charge, mass of 1 amu (atomic mass unit)

Neutrons

neutral charge, mass of 1 amu

Electrons

negative charge, surround the nucleus

Valence electrons

electrons in the outermost shell that interact with other atoms

Octet rule

atoms react to obtain a stable number of 8 valence electrons

Isotopes

elements that differ in the number of neutrons

Atomic weight

Average atomic mass of the mixture of isotopes of an element found in a sample

Molecules

two or more atoms of same element covalently bonded

Compounds

two or more atoms of different elements covalently bonded

Molecular weight

the sum of the atomic weights of its atoms

Ions

charged particles with unequal numbers of protons and electrons

Ionization

transfer of electrons from one atom to another ( stability of valence shell)

Electrolytes

Salts, acids, or bases that ionize (gain or lose e⁻) in water and form solutions capable of conducting electricity

Acid

molecule or compound that donates a H+ ion, a proton donor

Base

molecule or compound that accepts a H+ ion, a proton acceptor

Anion

atom gained electron, net negative charge

Cation

atom lost an electron, net positive charge

Free Radicals

An unstable and very reactive particle with an odd number of electrons

Antioxidants

neutralize free radicals

Ionic Bonds

Attraction of oppositely charged ions (cation & anion) to each other forms an ionic bond - no sharing of electrons.

Covalent Bonds

Formed by sharing valence electrons.

Single Covalent Bond

Share one electron pair.

Double Covalent Bond

Share two electron pairs.

Nonpolar Covalent Bond

Electrons are equally attracted to both nuclei.

Polar Covalent Bond

Electrons are more attracted to one nucleus more than the other.

Diatomic Molecule

When two of the same atoms are participating.

Hydrogen Bonds

Weakest of the bonds; attraction between polar molecules - no sharing of electrons.

pH

Measures the concentration of H+ ions in solution.

Hydrochloric Acid (HCl)

Stomach acid; the reason why it burns when you vomit.

Sodium Hydroxide (NaOH)

Strong Base.

Normal pH Range

Humans' normal pH range is 7.35-7.45.

pH Scale

Ranges from 0-14; levels below 7 are considered acidic, and above 7 are considered basic (alkaline).

Acidosis

Arterial pH drops below 7.35 (physiological acidosis).

Alkalosis

Arterial blood pH rises above 7.45.

Sources of Hydrogen Ions

Most hydrogen ions originate from cellular metabolism.

Strong Acids

All their H+ is dissociated completely in water.

Weak Acids

Dissociate partially in water and are efficient at preventing pH changes.

Buffer System

Any mechanism that resists pH changes by converting a strong acid or base into a weaker acid or base.

Chemical Buffering System

A substance that binds to H⁺ and removes it from solution as its concentration begins to rise, or releases H⁺ into a solution if the concentration drops.

Physiological Buffering System

A system that stabilizes pH by controlling the body's output of acids, bases, or CO₂.

Respiratory system

Acts within a few minutes.

Urinary system

Acts within several hours or days.

Bicarbonate Buffer System

A solution of carbonic acid (H2CO3) and bicarbonate ions (HCO3).

Bicarbonate Buffer System (strong acid)

If strong acid is added, hydrogen ions released combine with the bicarbonate ions and form carbonic acid (a weak acid). The pH of the solution decreases only slightly.

Bicarbonate Buffer System (strong base)

If strong base is added, it reacts with the carbonic acid to form sodium bicarbonate (a weak base). The pH of the solution rises only slightly.

Bicarbonate Buffer System (importance)

This system is the only important ECF buffer.

Phosphate Buffer System

Nearly identical to the bicarbonate system; its components are sodium salts of dihydrogen phosphate (H2PO4¯), a weak acid, and monohydrogen phosphate (HPO42¯), a weak base.

Phosphate Buffer System (effectiveness)

This system is an effective buffer in urine and intracellular fluid.

Protein Buffer System

Proteins are more concentrated than either bicarbonate or phosphate buffers, especially in the intracellular fluid (ICF).

Protein Buffer System (function)

It is able to buffer a solution because of the protein's side groups of their amino acids.

Carboxyl side groups

Will release H⁊ when pH rises.

Amino side groups

Will bind H⁊ when pH falls.

Physiological Buffer Systems: Respiratory

Respiratory buffer system adjusts pH by raising or lowering the rate and depth of breathing.

Carbon dioxide (CO₂) effect

Too much carbon dioxide (CO₂) will raise H⁺ concentrations, and the removal of CO₂ will lower H⁺ concentrations.

H+ and pH relationship

A drop in H+ raises pH, the body will decrease breathing rate to accumulate more CO₂, thus lowering the pH to normal.

Renal (Urinary) Mechanisms of Acid-Base Balance

Chemical buffers can tie up excess acids or bases, but they cannot eliminate them from the body.

Lungs and carbonic acid

The lungs can eliminate carbonic acid by eliminating carbon dioxide.

Kidneys and metabolic acids

Only the kidneys can rid the body of metabolic acids (phosphoric, uric, lactic acids, and ketones) and prevent metabolic acidosis.

Renal Mechanisms of Acid-Base Balance

The most important renal mechanisms for regulating acid-base balance are conserving (reabsorbing) or generating new bicarbonate ions and excreting bicarbonate ions.

Kidneys Regulate pH (low pH)

If pH too low, excrete excess hydrogen ions, retain bicarbonate.

Kidneys Regulate pH (high pH)

If pH too high, retain hydrogen ions, excrete bicarbonate.

Water properties

Evaluate the properties of water & their importance to the body, including these terms: polarity, capillary action, high heat of vaporization, adhesion, surface tension, solvency, cohesion, high specific heat, chemical reactivity.

Water

Most mixtures in the body consist of chemicals dissolved or suspended in water.

Universal Solvent

Water is called the universal solvent because it dissolves a broader range of substances than any other liquid.

Hydrophilic

Charged substances that dissolve easily in water.

Hydrophobic

Neutral substances that do not easily dissolve in water.

Polarity (solubility)

To be soluble in water, a molecule usually must be polarized or charged.

Adhesion

Attraction between one substance and another substance.

Cohesion

Molecules of the same substance cling to each other.

Capillary Action

Capillary action is the movement of a liquid through a narrow space, such as a tube, against gravity or without external forces. It occurs when the adhesive forces between the liquid and the surrounding solid surfaces are stronger than the cohesive forces between the liquid particles.

Surface Tension

Because of the cohesion between water molecules, the surface of water forms an elastic film.

Chemical Reactivity of Water

Facilitates and participates in chemical reactions, very chemically reactive, ionization of acids, salts and itself, important in the transport of molecules for reactions (universal solvent), involved in hydrolysis and dehydration synthesis.

Thermal Stability of Water

Water stabilizes internal temperature of the body.

High Specific Heat

Amount of heat required to raise the temperature of 1g of a substance by 1°C.

Hydrogen Bonds in Water

Water's hydrogen bonds inhibit increased temperature (molecular motion) caused by increased heat.

Heat Absorption of Water

Water can absorb a given amount of heat without changing temperature as much.

High Heat of Vaporization

1 ml of perspiration evaporating from the skin removes 500 cal of heat from the body.

Dehydration Synthesis

A process by which two molecules are joined together with the removal of water.

Hydrolysis

A chemical process that splits a molecule by adding water.

Organic Compounds

Includes carbohydrates, monosaccharides, nucleotides, lipids, fatty acids, adenosine triphosphate (ATP), proteins, glycerol, nucleic acids, and amino acids.

Monosaccharides

The simplest form of carbohydrates, consisting of single sugar molecules.

Nucleotides

The basic building blocks of nucleic acids, consisting of a sugar, a phosphate group, and a nitrogenous base.

Lipids

A group of organic compounds that are insoluble in water, including fats and oils.

Fatty Acids

Carboxylic acids with long aliphatic chains, which can be saturated or unsaturated.

Adenosine Triphosphate (ATP)

A high-energy molecule that stores and provides energy for cellular processes.

Proteins

Large biomolecules made up of amino acids that perform a variety of functions in the body.

Glycerol

A simple polyol compound that forms the backbone of triglycerides and phospholipids.

Nucleic Acids

Biomolecules essential for all known forms of life, including DNA and RNA.

Amino Acids

Organic compounds that combine to form proteins, consisting of an amino group, a carboxyl group, and a side chain.

Organic Molecules

Carbon compounds that include carbohydrates, lipids, proteins, nucleotides, and nucleic acids.

Carbon

Bonds readily with other carbon atoms because it has 4 valence electrons and wants 4 more.

Monomers

Subunits of macromolecules (gigantic organic molecules).

Polymers

Series of identical or similar monomers bonded together.

Polymerization

The bonding of monomers together to form a polymer, caused by a reaction called dehydration synthesis.