Exam 1 Focused Review: Human Body Orientation, Chemistry, Cells, and Tissues

Principle of Complementarity

Structure and Function

The principle of complementarity states that the function of a structure is directly related to its form. This foundational concept in anatomy and physiology explains why anatomical features are shaped the way they are.

• Bones: Hard mineral deposits allow bones to support and protect organs.

• Heart Valves: Ensure unidirectional blood flow, preventing backflow and maintaining efficient circulation.

Example: The structure of alveoli in the lungs maximizes surface area for gas exchange, directly supporting their function.

Homeostasis

Maintaining Internal Stability

Homeostasis refers to physiological processes that maintain a stable internal environment despite external changes. This is crucial for the survival of organisms, allowing them to function under varying conditions.

• Components: Receptor, control center, effector

• Importance: Maintains optimal conditions for cellular processes

Feedback Mechanisms

• Negative Feedback: Most common; counteracts changes to maintain stability (e.g., thermoregulation, blood pressure, glucose homeostasis).

• Positive Feedback: Amplifies the original stimulus, pushing the variable further from the set point (e.g., childbirth, blood clotting).

Example: A thermostat maintaining room temperature is analogous to negative feedback in the body.

Anatomical Terms

Body Orientation and Terminology

Understanding anatomical position, body region terms, directional terms, body cavities, and planes is essential for clear communication in anatomy. These terms are used throughout the semester and should be reviewed regularly.

• Anatomical Position: Standard reference position for the body

• Directional Terms: Superior, inferior, anterior, posterior, medial, lateral, proximal, distal

• Body Cavities: Dorsal, ventral, thoracic, abdominopelvic

• Body Planes: Sagittal, frontal (coronal), transverse

Chemistry of Life

Ions and Chemical Bonds

• Ions: Atoms or molecules with a net electric charge due to the loss or gain of electrons.

• Cations: Positively charged ions (e.g., Na+).

• Anions: Negatively charged ions (e.g., Cl-).

• Ionic Bonds: Attraction between oppositely charged ions (e.g., NaCl formation).

• Covalent Bonds: Sharing of electron pairs between atoms; can be polar or nonpolar.

• Hydrogen Bonds: Weak attractions between a hydrogen atom and an electronegative atom (e.g., water molecules).

pH Scale

The pH scale measures the concentration of hydrogen ions in a solution. Each unit change represents a tenfold change in [H+].

• Formula: $pH = -\log_{10}[H^+]$

• Range: 0 (acidic) to 14 (basic); 7 is neutral.

• Examples: Blood pH ≈ 7.4, gastric acid ≈ 1-2, sodium hydroxide ≈ 14.

Biomolecules

Carbohydrates

• Definition: Molecules including sugars and starches; contain C, H, O in a 1:2:1 ratio.

• Monomers: Monosaccharides (e.g., glucose)

• Polymers: Polysaccharides (e.g., glycogen)

• Function: Main source of cellular fuel; excess stored as glycogen or fat.

Proteins

• Definition: Comprise 10-30% of cell mass; basic structural and functional material of the body.

• Monomers: Amino acids (20 types)

• Polymers: Polypeptides/proteins

• Levels of Structure:

  • Primary: Linear sequence of amino acids

  • Secondary: Alpha helices and beta sheets

  • Tertiary: 3D folding of polypeptide

  • Quaternary: Multiple polypeptides combine

• Functions: Structural (collagen), enzymes, transport (hemoglobin), contractile (actin, myosin), communication (hormones), defense (antibodies)

Nucleic Acids

• Definition: Largest molecules in the body; DNA and RNA

• Monomers: Nucleotides (base, sugar, phosphate)

• Polymers: DNA (double helix), RNA (single strand)

• Functions: Genetic material, directs protein synthesis, self-replication

Lipids

• Definition: Hydrophobic molecules; include fats, oils, phospholipids, steroids

• Saturated Fats: Single bonds, solid at room temperature (e.g., butter)

• Unsaturated Fats: One or more double bonds, liquid at room temperature (e.g., olive oil)

• Triglycerides: Three fatty acids + glycerol; energy storage

• Phospholipids: Main component of cell membranes; have polar and nonpolar regions

• Steroids: Cholesterol, basis for hormones and vitamin D

Cell Structure and Function

Plasma Membrane

The plasma membrane is a selectively permeable barrier composed of a phospholipid bilayer with embedded proteins. It regulates the entry and exit of substances, maintaining the internal environment of the cell.

• Lipid Solubility: More lipid-soluble substances diffuse more readily.

• Size: Smaller molecules diffuse more easily.

• Transport Proteins: Assist movement of ions and large molecules.

Transport Mechanisms

• Passive Transport: Movement down a concentration gradient without energy input (e.g., diffusion, osmosis).

• Active Transport: Movement against a concentration gradient, requiring energy (ATP).

  • Primary: Direct use of ATP (e.g., Na+/K+ pump)

  • Secondary: Uses energy from ion gradients created by primary transport

Red Blood Cell Tonicity

• Isotonic: No net water movement; cells retain normal shape.

• Hypertonic: Cells lose water and shrink.

• Hypotonic: Cells gain water, swell, and may burst (lyse).

Cell Organelles

• Nucleus: Contains genetic material; controls cell activities.

• Nuclear Envelope: Double membrane with pores for molecular transport.

• Nucleoli: Ribosome production sites.

• Chromatin/Chromosomes: DNA-protein complex; condenses during cell division.

• Rough ER: Protein synthesis and modification.

• Smooth ER: Lipid synthesis, detoxification, Ca2+ storage.

• Ribosomes: Sites of protein synthesis.

• Golgi Apparatus: Modifies, sorts, and packages proteins and lipids.

• Lysosomes: Intracellular digestion.

• Mitochondria: ATP production; powerhouse of the cell.

• Cilia/Flagella: Movement of substances or the cell itself.

• Cytoskeleton: Structural support, cell movement.

• Cytoplasm: Site of most cellular activities; includes cytosol, organelles, inclusions.

Tissues

Epithelial Tissue

Epithelial tissue forms boundaries, protects, secretes, absorbs, and filters. It covers body surfaces, lines cavities, and forms glands.

• Simple Epithelium: Single cell layer; absorption, secretion, filtration.

• Stratified Epithelium: Multiple layers; protection in high abrasion areas.

• Cell Shapes: Squamous (flat), cuboidal (cube-like), columnar (tall).

Examples:

• Simple Squamous: Diffusion/filtration (lungs, blood vessels)

• Simple Cuboidal: Secretion/absorption (kidney tubules)

• Simple Columnar: Absorption/secretion (digestive tract)

• Pseudostratified Columnar: Secretion, propulsion (trachea)

• Stratified Squamous: Protection (skin, mouth, esophagus)

• Transitional: Stretching (bladder)

Connective Tissue

Connective tissue is the most abundant and widely distributed tissue type. It supports, protects, and binds other tissues. Major classes include connective tissue proper, cartilage, bone, and blood.

• Components: Ground substance, fibers (collagen, elastic, reticular), cells (fibroblasts, chondroblasts, osteoblasts, etc.)

• Functions: Support, protection, insulation, transportation (blood)

Tissue Class and Example	Subclasses	Cells	Matrix	General Features
Connective Tissue Proper	Loose (areolar, adipose, reticular); Dense (regular, irregular, elastic)	Fibroblasts, fibrocytes, defense cells, adipocytes	Gel-like ground substance; all three fiber types (collagen, reticular, elastic)	Binding, resisting tension, nutrient storage
Cartilage	Hyaline, elastic, fibrocartilage	Chondroblasts (growing), chondrocytes (mature)	Gel-like ground substance; fibers: collagen, elastic (in some)	Resists compression, cushions, supports
Bone Tissue	Compact, spongy	Osteoblasts, osteocytes	Gel-like ground substance calcified with inorganic salts; fibers: collagen	Support, protection, stores calcium
Blood	---	RBCs, WBCs, platelets	Plasma (no fibers)	Transport of gases, nutrients, wastes

Muscle Tissue

Muscle tissue is responsible for movement. It is well vascularized and consists of elongated cells (muscle fibers).

• Skeletal Muscle: Voluntary, striated, multinucleate; attached to bones

• Cardiac Muscle: Involuntary, striated, branching, intercalated discs; heart walls

• Smooth Muscle: Involuntary, non-striated, spindle-shaped; walls of hollow organs

Nervous Tissue

Nervous tissue is the main component of the nervous system (brain, spinal cord, nerves). It regulates and controls body functions.

• Neurons: Transmit electrical signals

• Supporting Cells: Support, insulate, and protect neurons

Epithelial Membranes

• Cutaneous: Skin; keratinized stratified squamous epithelium + connective tissue

• Mucous: Line body cavities open to exterior; secrete mucus

• Serous: Line closed body cavities; secrete serous fluid (pleura, pericardium, peritoneum)

Glands

• Endocrine: Ductless; secrete hormones into blood/lymph

• Exocrine: Secrete products onto body surfaces or into cavities (e.g., sweat, oil, salivary glands)

• Unicellular Exocrine: Mucous and goblet cells

• Multicellular Exocrine: Duct and secretory unit; supported by connective tissue