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Skeletal System
Skeletal System, Membrane Potentials, Muscular System
| Term | Definition |
|---|---|
| Support | Provides framework for soft tissues and body shape |
| Protection | Shields organs (e.g., skull protects brain, ribs protect heart/lungs) |
| Movement | Bones act as levers; muscles attach via tendons |
| Mineral Storage | Stores calcium and phosphate for release into blood |
| Blood Cell Formation (Hematopoiesis) | Occurs in red bone marrow |
| Triglyceride Storage | Fat stored in yellow bone marrow |
| Hormone Production | Osteocalcin regulates insulin and bone growth |
| Interstitial Growth | Growth from within cartilage; chondrocytes divide and secrete matrix → increases length |
| Appositional Growth | Growth at the surface of cartilage/bone; new layers added by chondroblasts or osteoblasts → increases width |
| Diaphysis | Shaft of a long bone; composed of compact bone with medullary cavity |
| Epiphysis | Ends of a long bone; spongy bone interior, covered by articular cartilage |
| Epiphyseal Plate | Growth plate made of hyaline cartilage; site of longitudinal bone growth in children |
| Epiphyseal Line | Remnant of growth plate after ossification (adulthood); bone stops growing in length |
| Organic Portion (35%) | Collagen fibers provide flexibility & tensile strength |
| Inorganic Portion (65%) | Hydroxyapatite crystals (Ca₁₀(PO₄)₆(OH)₂) provide hardness and compression resistance |
| Osteoprogenitor cells | Bone stem cells; become osteoblasts. |
| Osteoblasts | Build new bone matrix (“bone builders”) |
| Osteocytes | Mature bone cells maintaining matrix |
| Osteoclasts | Break down bone (“bone crushers”) |
| Woven Bone | Immature, irregular collagen; forms during development or fracture repair |
| Lamellar Bone | Mature bone; organized into parallel lamellae or osteons |
| Compact Bone Structure | Osteons (Haversian systems) |
| Compact Bone Location | Diaphysis & outer layers |
| Compact Bone Canaliculi | Connect osteocytes for nutrient/waste exchange |
| Cancellous (Spongy) Bone Structure | Trabeculae (lattice-like) |
| Cancellous (Spongy) Bone Location | Epiphyses, flat bones, marrow areas |
| Cancellous (Spongy) Bone Canaliculi | Present but arranged around trabeculae |
| Intramembranous | Bone develops directly from mesenchymal membrane (e.g., skull, clavicle) |
| Endochondral | Bone replaces hyaline cartilage model (e.g., femur, humerus) |
| Resting Zone | Inactive cartilage |
| Proliferation Zone | Chondrocytes divide |
| Hypertrophic Zone | Cells enlarge |
| Calcification Zone | Matrix calcifies, cells die |
| Ossification Zone | New bone forms |
| Medullary Cavity & Bone Growth | Expands as bone lengthens and widens |
| Rickets Cause | Vitamin D deficiency |
| Scurvy | Vitamin C deficiency |
| PTH (Parathyroid Hormone) | Increases blood Ca²⁺, Stimulates osteoclasts |
| Calcitonin (from thyroid) | Decreases blood Ca²⁺, Inhibits osteoclasts |
| Na⁺ (Sodium) Location | Extracellular |
| K⁺ (Potassium) Location | Intracellular |
| Na⁺ (Sodium) Role | Depolarization during action potential |
| K⁺ (Potassium) Role | Sets resting membrane potential (RMP) |
| Adding K⁺ | Depolarizes (less negative RMP) |
| Removing K⁺ | Hyperpolarizes (more negative RMP) |
| Na⁺/K⁺ Pump | Pumps 3 Na⁺ out, 2 K⁺ in → maintains RMP (-70 mV) |
| Polarized Cell | Inside negative, outside positive |
| Depolarization | Inside becomes less negative (+) |
| Repolarization | Return to resting (-) state |
| Voltage-Gated | Open/close with changes in membrane potential |
| Ligand-Gated | Open when neurotransmitter binds |
| Light Receptor | Photoreceptor (Light) |
| Mechanical Receptor | Mechanoreceptor (Touch) |
| Temperature Receptor | Thermoreceptor (Change in temperature) |
| Tactile Receptor | Touch receptor |
| Strength | (Local) Varies, (Action) All-or-none |
| Summation | (Local) Possible, (Action) None |
| Threshold | (Local) May or may not reach, (Action) Must reach (-55 mV) |
| Propagation | (Local) Decreases with distance (Action) Self-propagating |
| Resting Membrane Potential Ion Involved | K⁺ primarily |
| Resting Membrane Potential Why Negative? | More K⁺ leaves than Na⁺ enters; negative proteins inside |
| RMP reported negative | because the inside is negatively charged relative to outside |
| All-or-None Principle | Once threshold is reached, an action potential fires completely—no partial signals |
| Refractory Periods (Absolute) | No new AP possible (Na⁺ channels inactive) |
| Refractory Periods (Relative) | Stronger stimulus can trigger AP (K⁺ channels open) |
| Presynaptic Neuron | Sends signal via neurotransmitters |
| Synaptic Cleft | Gap between neurons |
| Postsynaptic Membrane | Has receptors → triggers response |
| Muscle System Functions | Movement, posture, joint stability, heat generation |
| Muscle System Characteristics | Excitability, contractility, extensibility, elasticity |
| Skeletal | Striated, voluntary |
| Cardiac | Striated, Involuntary, Intercalated discs |
| Smooth | Non-striated, Involuntary, Gap junctions |
| Endomysium | Around each fiber |
| Perimysium | Around fascicles |
| Epimysium | Around whole muscle |
| Myofiber | Muscle cell |
| Myofibril | Long contractile unit inside myofiber |
| Myofilament | Actin (thin) and Myosin (thick) proteins within myofibrils |
| Sarcomere, | Z-disc to Z-disc, Functional contractile unit |
| A Band | Thick (myosin) + thin overlap |
| I Band | Thin (actin) only |
| H Zone | Thick only |
| M Line | Middle of sarcomere |
| Actin | Thin; contains tropomyosin & troponin (binds Ca²⁺) |
| Myosin | Thick; heads form cross-bridges |
| Ca²⁺ Role | Binds troponin → exposes binding site |
| Power Stroke | Myosin pulls actin |
| Recovery Stroke | Myosin resets with ATP |
| Transverse Tubules | Carry electrical impulses deep into muscle for synchronized contraction |
| Sliding Filament Model | Actin slides over myosin → sarcomere shortens → muscle contracts |
| Attach | Breaks cross-bridge |
| Hydrolysis | Cocks myosin head |
| Release of Pi | Power stroke |
| Motor Unit | One neuron + all fibers it controls |
| Recruitment | Increasing # of active motor units to produce greater force |
| Muscle Tone | Slight, constant contraction at rest; maintains posture and readiness |
| Length-Tension Curve | Max tension at optimal length (actin/myosin overlap ideal), Too stretched → few cross-bridges; too short → filaments overlap excessively |
| ATP depletion / ion imbalance Muscle Fatigue | most common |
| Lactic acid accumulation / low pH Muscle Fatigue | second |
| CNS fatigue / psychological Muscle Fatigue | least common |
| Rigor Mortis | After death, ATP stops → cross-bridges stay locked → stiff muscles |
| Creatine Phosphate | Rapidly regenerates ATP from ADP in muscle cells (short-term energy source) |
| Fast-Twitch (Type II) Fibers | Strength/power; fatigues quickly |
| Slow-Twitch (Type I) Fibers | Endurance; resists fatigue |
| Myoglobin | Oxygen-binding protein; stores O₂ for aerobic respiration |
| Smooth Muscle | Appears smooth (no striations; filaments not in sarcomeres), Maintains same force over varying lengths (better than skeletal muscle) |
| Cardiac Muscle | Intercalated Discs: Contain gap junctions & desmosomes → synchronize contractions |
| BQ: Why was the British sailors something | limes, They needed Vitamin C |
| Stem cells | Undifferentiated; can become various cell types. |
| BQ: What makes a motor unit depolarize | Recruitment |
| BQ: How long does Rigor Mortis last | 36 hours |
| calcium stored in muscle cell? | sarcoplasmic reticulum? |
| Excitability | the ability of a cell or tissue to respond to a stimulus and generate an electrical signal |
| contractility | the ability of a muscle or tissue to shorten or contract, especially the heart's ability to pump blood |
| extensibility | the ability of muscle tissue and other body tissues to be stretched or lengthened without damage |
| elasticity | ability of a deformed material body to return to its original shape and size when the forces causing the deformation are removed |
Created by:
mdonovan8742
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