The foundation beneath every body-system chapter: how the body is organized, how cells exchange materials, how energy is used and how tissues respond to injury.
Chemical → cellular → tissue → organ → organ system → organism. A tissue is a group of related cells and extracellular material performing related functions. An organ contains multiple tissue types working together.
Homeostasis is dynamic regulation of the internal environment within ranges compatible with function. Most regulatory systems use negative feedback, where a change triggers responses that oppose the original disturbance. Positive feedback amplifies a process until a terminating event, such as parts of childbirth or blood clotting.
Metabolism includes all chemical reactions in the body. Catabolism breaks larger molecules into smaller components and can release usable energy. Anabolism builds larger molecules and requires energy. ATP is the cell's major immediately usable energy currency.
| Plasma membrane | Selective boundary controlling exchange and communication. |
| Nucleus | Contains most cellular DNA and regulates gene expression. |
| Mitochondria | Major site of aerobic ATP production. |
| Ribosomes | Protein synthesis. |
| Endoplasmic reticulum | Rough ER participates in protein processing; smooth ER in lipid-related functions and other cellular processes. |
| Golgi apparatus | Modifies, sorts and packages cellular products. |
| Lysosomes | Contain digestive enzymes involved in breakdown/recycling. |
Diffusion: particles move down a concentration gradient. Osmosis: movement of water across a selectively permeable membrane in response to solute differences. Facilitated diffusion: passive movement using membrane proteins. Active transport: requires energy to move substances against gradients. Endocytosis/exocytosis: vesicular transport into/out of cells.
| Tissue | Core function | Massage connection |
|---|---|---|
| Epithelial | Covers surfaces, lines cavities, forms glands. | Skin integrity matters for contact, infection control and local contraindications. |
| Connective | Supports, binds, protects, stores and transports; includes bone, cartilage, adipose, blood and connective tissue proper. | Fascia, tendons, ligaments, bone and blood are all connective tissues but have very different properties. |
| Muscle | Contracts to produce movement/force. | Skeletal muscle is voluntary; cardiac and smooth muscle are involuntary. |
| Nervous | Communication through electrical/chemical signaling. | Nerve irritation produces different warning sensations than ordinary muscular pressure. |
Cutaneous membrane: skin. Mucous membranes: line passages opening to exterior, such as digestive/respiratory tracts. Serous membranes: line closed ventral cavities and cover organs. Synovial membranes: line inner surfaces of synovial joint capsules and produce synovial fluid.
Inflammatory phase: hemostatic and inflammatory responses begin cleanup/protection. Proliferative/repair phase: fibroblasts, new extracellular matrix and new vessels contribute to repair. Remodeling/maturation: collagen organization and tissue properties continue changing over time. These phases overlap rather than switching on exact dates.
Massage decisions depend on tissue status. Aggressive mechanical loading appropriate for healthy tissue may be inappropriate during acute injury or fragile healing.
The classic signs are rubor (redness), calor (heat), tumor (swelling), dolor (pain), and functio laesa (loss/diminishment of function). Inflammation itself is a protective biological response and is not synonymous with infection.
Osmosis moves what? Water. Protein synthesis? Ribosomes. ATP powerhouse? Mitochondria. Most common homeostatic mechanism? Negative feedback. Tendon tissue category? Connective tissue. Skin surface tissue? Epithelial tissue within a complex organ.