Study Guide: Chemistry and Tissues in Anatomy & Physiology

Chapter 2: Chemistry

States of Matter and Their Properties

The three primary states of matter—solid, liquid, and gas—are distinguished by their shape, volume, and particle arrangement.

• Solids: Definite shape and volume; particles are tightly packed.

• Liquids: Definite volume but no definite shape; particles are less tightly packed than in solids.

• Gases: No definite shape or volume; particles are far apart and move freely.

Energy

Energy is the capacity to do work or cause change. It exists in various forms and is essential for all biological processes.

• Kinetic Energy (KE): Energy of motion.

• Potential Energy (PE): Stored energy due to position or structure.

• Forms of Energy: Chemical, electrical, mechanical, and radiant energy.

Elements and Subatomic Particles

Elements are pure substances consisting of only one type of atom. The human body is primarily composed of oxygen, carbon, hydrogen, and nitrogen.

• Subatomic Particles: Protons (positive charge), neutrons (neutral), and electrons (negative charge).

• Atomic Number: Number of protons in an atom.

• Mass Number: Sum of protons and neutrons.

• Isotopes: Atoms of the same element with different numbers of neutrons.

Atomic Symbol, Atomic Mass, Atomic Number, and Isotopes

• Atomic Symbol: One- or two-letter abbreviation for an element (e.g., H for hydrogen).

• Atomic Mass: Weighted average mass of an atom's isotopes.

• Isotopes: Used in medical imaging and research.

Mixtures: Solutions, Colloids, and Suspensions

Mixtures are combinations of two or more substances that are not chemically bonded.

• Solutions: Homogeneous mixtures; solute particles are very small (e.g., salt water).

• Colloids: Heterogeneous mixtures; solute particles are larger and scatter light (e.g., milk).

• Suspensions: Heterogeneous mixtures; particles settle out over time (e.g., blood).

• Determining Concentration: Molarity ($M = \frac{\text{moles of solute}}{\text{liters of solution}}$), percent solutions, and equivalents.

Electrons in Bonding

Electrons in the outermost shell (valence electrons) determine chemical bonding behavior.

• Energy Shells: Levels where electrons reside; the octet rule states that atoms are most stable with eight electrons in their outer shell.

• Chemically Inert: Atoms with full valence shells (e.g., noble gases).

Chemical Bonds

Chemical bonds are forces that hold atoms together in molecules and compounds.

• Ionic Bonds: Transfer of electrons from one atom to another, forming ions.

• Covalent Bonds: Sharing of electron pairs between atoms.

• Hydrogen Bonds: Weak attractions between polar molecules.

Chemical Equations and Molecular Formulas

Chemical equations represent the reactants and products in a chemical reaction. Molecular formulas show the types and numbers of atoms in a molecule (e.g., $H_2O$).

Synthesis, Decomposition, and Exchange Reactions

• Synthesis (Anabolic) Reactions: Two or more substances combine to form a more complex substance ($A + B \rightarrow AB$).

• Decomposition (Catabolic) Reactions: A complex substance breaks down into simpler substances ($AB \rightarrow A + B$).

• Exchange Reactions: Parts of molecules are exchanged ($AB + CD \rightarrow AD + CB$).

Redox Reactions, Exergonic, and Endergonic

• Redox (Oxidation-Reduction) Reactions: Involve the transfer of electrons between atoms or molecules.

• Exergonic Reactions: Release energy.

• Endergonic Reactions: Absorb energy.

Factors Affecting the Rate of Chemical Reactions

• Temperature: Higher temperature increases reaction rate.

• Concentration: Higher concentration increases reaction rate.

• Particle Size: Smaller particles react faster.

• Catalysts: Speed up reactions without being consumed (e.g., enzymes).

Inorganic vs. Organic Compounds

Organic compounds contain carbon and are typically found in living organisms, while inorganic compounds do not.

• Properties of Carbon: Carbon can form four covalent bonds, allowing for complex molecules.

Acids and Bases

Acids release hydrogen ions ($H^+$) in solution, while bases accept $H^+$ or release hydroxide ions ($OH^-$).

pH Scale

The pH scale measures the concentration of hydrogen ions in a solution.

• pH Formula: $pH = -\log[H^+]$

• Acidic: pH < 7

• Neutral: pH = 7

• Basic (Alkaline): pH > 7

Neutralization Reaction

When an acid and a base react, they form water and a salt.

• Example: $HCl + NaOH \rightarrow NaCl + H_2O$

Buffers

Buffers resist changes in pH by absorbing or releasing $H^+$ ions. The carbonic acid-bicarbonate system is a key buffer in blood.

• Equation: $CO_2 + H_2O \leftrightarrow H_2CO_3 \leftrightarrow H^+ + HCO_3^-$

Macromolecules

Macromolecules are large, complex molecules essential for life, including carbohydrates, lipids, proteins, and nucleic acids.

• Elements Contained: C, H, O, N, (sometimes P and S).

• Monomers: Building blocks (e.g., amino acids for proteins, monosaccharides for carbohydrates).

• Examples: Starch (carbohydrate), triglyceride (lipid), hemoglobin (protein), DNA (nucleic acid).

Tissues

Basics of Tissue Preparation

Tissue preparation involves fixation, embedding, sectioning, and staining to observe tissues under a microscope.

Epithelial Tissue

Epithelial tissue covers body surfaces and lines cavities. It has five distinguishing characteristics:

• Polarity

• Specialized contacts

• Supported by connective tissue

• Avascular but innervated

• Regeneration

• Classification: Based on cell layers (simple, stratified) and cell shape (squamous, cuboidal, columnar).

• Glandular Epithelia: Forms glands that secrete substances.

• Functions and Locations: Protection, absorption, filtration, excretion, secretion, and sensory reception.

Connective Tissue

Connective tissue supports, protects, and binds other tissues. It has four main classes: connective tissue proper, cartilage, bone, and blood.

• ECM (Extracellular Matrix): Composed of ground substance and fibers (collagen, elastic, reticular).

• Cells: Fibroblasts, chondrocytes, osteocytes, and others.

• Functions and Locations: Vary by type; e.g., tendons (dense regular connective tissue), adipose (fat storage).

Muscle Tissue

Muscle tissue is responsible for movement. There are three types:

• Skeletal Muscle: Voluntary, striated, attached to bones.

• Cardiac Muscle: Involuntary, striated, found in the heart.

• Smooth Muscle: Involuntary, non-striated, found in walls of hollow organs.

Nervous Tissue

Nervous tissue transmits electrical impulses throughout the body.

• Location: Brain, spinal cord, nerves.

• Components: Neurons (conduct impulses) and neuroglia (supporting cells).

Membrane Types and Tissue Repair

There are three main types of membranes: cutaneous (skin), mucous (lines cavities open to exterior), and serous (lines closed cavities). Tissue repair involves inflammation, organization, and regeneration or fibrosis.

• Attributes: Each membrane has unique structure and function.

• Tissue Repair: Restores tissue integrity after injury.