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Irina Kan
Human Physiology Week1-6
| Term | Definition |
|---|---|
| Definition of Homeostasis | Ability of living systems to maintain a relatively stable internal environment despite external changes |
| Dynamic equilibrium | Continuous adjustments that keep internal conditions within ranges |
| Steady state | Stable internal conditions despite external changes |
| Milieu interieur | Claude Bernard's term for the body's internal environment |
| Negative feedback | Control loops that counteract deviations from a set point |
| Set point | Target value for a regulated variable (e.g. 37 C for body temp) |
| Autoregulation | Local, self-adjustments within tissue/organ |
| Allostasis | Achieving stability through change (anticipatory regulation) |
| Thermoregulation | Control of body temperature |
| Osmoregulation | Control of water and electrolyte balance |
| Definition of DNA | The hereditary molecule storing genetic information in nearly all living organisms |
| Nucleotide | The building block of DNA, consisting of sugar, a phosphate group, and a nitrogenous base |
| Nitrogenous bases | The four DNA bases- adenine (A), thymine (T), guanine (G), cytosine (C) |
| Base pairing | Specific pairing of bases via hydrogen bonds (A with T, G with C) |
| Double helix | The twisted ladder structure of DNA formed by two strands |
| Sugar-phosphate backbone | The repeating chain of sugars and phosphates that forms the sides of sugars and phosphates that forms the sides of the DNA ladder |
| Antiparrallel | The two DNA strands run in opposite directions |
| Gene | A sequence of DNA that encodes a functional product (usually a portein or functional RNA) |
| Genome | The complete set of DNA (all genes and noncoding sequences) in an organism |
| DNA replication | The semiconservative process of copying DNA before cell division, primarily carried out by DNA polymerases |
| Phospholipid bilayer | Two layers of phospholipids forming the fundamental membrane structure |
| Hydrophilic heads | Polar phosphate heads that face aqueous environments inside and outside the cell |
| Hydrophobic tails | Nonpolar fatty acid tails that face inward, avoiding water |
| Fluid mosaic model | Concept that membranes are dynamic, with lipids and proteins moving laterally in a "mosaic" arrangement |
| Cholesterol | Lipid that modulates membrane fluidity and stability ( prevents it from becoming too rigid or too liquid) |
| Integral (transmembrane) proteins | Proteins embedded in the bilayer, often spanning it; function in transport, sidnaling, and adhesion |
| Peripheral membrane proteins | Proteins loosely attached to the membrane surface or to integral proteins; roles in signaling and cytoskeletal support |
| Glycoproteins | Membrane proteins with carbohydrate chains on the extracellular side; important for cell recognition and adhesion |
| Lateral diffusion | Side-to-side movement of lipids and many proteins within a leaflet; key to membrane fluidity |
| Selective permeability | Property allowing some molecules to cross the membrane more easily than others |
| Epidermis | The outermost layer of skin that provides a barrier to the environment |
| Hypodermis | (Subcutaneous tissue) the deepest layer made mainly of fat that insulatesand cushions |
| Stratum Corneum | The top sublayer of the epidermis made mainly of fat that insulates and cushions |
| Stratum Basale | The bottom epidermal layer where new skin cells are produced |
| Keratinocyte | The primary cell of the epidermis that makes keratin for strength and protection |
| Melanocyte | A pigment-producing cell that creates melanin to help protect against UV rays |
| Sebaceous gland | An oil gland that secretes sebum to lubricate skin and hair |
| Eccrine sweat gland | A sweat gland involved in cooling the body through perspiration |
| Collagen | The main structural protein in the dermis that gives skin strengh and firmness |
| Osteon (Haversian system) | Cylindrical unit of compact bone; resist load and houses blood supply |
| Central (Haversian) canal | Channel at osteon center for blood vessels and nerves |
| Concentric lamellae | Rings of calcified matrix around the central canal that resist twisting |
| Lacunae | Small cavities between lamellae that contain osteocytes (mature bone cells) |
| Canaliculi | Tiny channels linking lacunae; allow nutrient and waste exchange between osteocytes |
| Trabeculae | Lattice-like struts of spongy bone aligned with stress; surround red marrow |
| Periosteum | Outer fibrous covering of bone; site for tendon/ligament attachment and bone growth/repair |
| Endosteum | Thin membrane lining medullary cavity and trabeculae; contains |
| Diaphysis | Shaft of long bone; mainly compact bone with a medullary (marrow) cavity |
| Epiphysis | Expanded ends of a long bone; mostly spongy bone with articular cartilage forming joints |
| Synovial joint (diarthrosis) | Freely movable joint with a capsule, synovial membrane, and cavity; e.g. knee, shoulder |
| Fibrous joint | Bones joined by dense connective tissue; little/no movement; e.g., sutures, syndesmosis |
| Cartilaginous joint | Bones joined by cartilage (Hyaline or fibrocartilage); limited movements; e.g. synchondrosis, symphysis |
| Articular cartilage | Smooth hyaline cartilage on bone ends in synovial joints; reduces friction and absorbs shock |
| Synovial fluid | Viscous, hyaluronic acid-rich fluid joint cavity that lubricate and nourishes articular cartilage |
| Sarcomere | Basic contractile unit of striated muscle between Z-lines; contains actin (thin) and myosin (thick) filaments |
| Actin | Protein that forms the contractile filaments of muscle cells together with myosin, and is also involved in motion in other types of cell |
| Myosin | Thick filament motor protein with ATPase activity; forms cross-bridges withactin to produce movement |
| Troponin | Regulatory complex (T, I, C) on thin filament; Ca2+ binding to troponin C shifts tropomyosin, exposing actin sites |
| Excitation-contraction coupling | Process linking a muscle fiber action potential to Ca2+ release from the sarcoplasmic reticulum and subsequent contraction. |
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IrinaKan888