Muscle contraction (sliding filament), bone remodeling, skin barrier, thermoregulation.
Musculoskeletal And Integumentary
Sliding-filament model
Huxley-Hanson-Huxley-Niedergerke 1954: muscle contraction is sliding of thin (actin) over thick (myosin) filaments; sarcomere shortens…
Excitation-contraction coupling
Depolarisation → DHPR (L-type Ca²+ channel in T-tubule) → ryanodine receptor → SR Ca²+ release → troponin C → tropomyosin shift →…
Motor unit
One α-motor neuron + all muscle fibres it innervates. Size varies (eye: ~10 fibres; leg: ~1000). Size principle: smaller units recruited…
Bone remodeling
Continuous cycle of osteoclast resorption + osteoblast deposition. Regulated by mechanical load (Wolff's law), PTH, calcitriol, calcitonin,…
Skin barrier (stratum corneum)
Outermost epidermal layer: dead enucleated corneocytes embedded in lipid lamellae (ceramides, cholesterol, free fatty acids). Prevents…
Thermoregulation
Homeostatic control of core body temperature (~37°C) by hypothalamic thermostat. Heat loss: cutaneous vasodilation, sweating. Heat…
Myosin cross-bridge cycle
Myosin-II cross-bridge: ATP-binding detaches, hydrolysis cocks head, actin-binding releases Pi → power stroke. Troponin-tropomyosin…
Muscle fibre types
Type I (slow oxidative, red, fatigue-resistant), Type IIa (fast oxidative-glycolytic), Type IIx (fast glycolytic, white, fatigue-prone).…
Osteoblast-osteoclast coupling
Bone formation (osteoblast, collagen-I + hydroxyapatite) balanced with resorption (osteoclast, H⁺ + cathepsin K). RANKL/OPG regulates…
Connective tissue collagen
Type-I collagen triple helix (Gly-X-Y repeat) crosslinked by lysyl oxidase in bone/tendon. Defects: osteogenesis imperfecta (COL1A1),…
Hill muscle force-velocity equation
Hill 1938 hyperbola (P+a)(v+b) = (P_0+a)b describes shortening velocity vs load in tetanised muscle; constants a,b reflect cross-bridge…
Wolff law bone mechanotransduction
Wolff 1892: bone trabecular architecture aligns with principal stress trajectories under load. Cowin-Hegedus 1976 strain-energy-density…
Sliding filament (Huxley 1954)
Huxley-Hanson 1954 + Huxley-Niedergerke 1954 sliding-filament theory; modern myosin-V-cycle Lymn-Taylor 1971.
Hill equation (Hill 1938)
A V Hill 1938 (Nobel 1922) force-velocity hyperbola; modern muscle-mechanics + sport-physiology applications.
Bone remodeling (Frost 1987)
H M Frost 1987 mechanostat-theory; bone responds to mechanical-loading; modern osteoporosis + space-bone-loss research.
Langer lines (1861)
K Langer 1861 cleavage-lines; modern surgical-incision + scar-prevention; collagen-fiber-orientation foundation.
HFSC (Cotsarelis 1990)
Cotsarelis 1990 hair-follicle stem-cells; modern Bulge-niche + alopecia-areata + cosmeceutical-targets.
Satellite cells (Mauro 1961)
A Mauro 1961 muscle satellite-cells; modern Pax7+ self-renewal + regeneration after injury; basis of MSC-therapy.
Wolff's law (1892)
J Wolff 1892 + Frost mechanostat 1987 bone-mechanical-adaptation; modern modern foundational text + Wnt-Sost + 2024 anti-sclerostin…
Hueter-Volkmann (1862)
C Hueter 1862 + R Volkmann 1882 endochondral-ossification compression-stress; modern modern foundational + scoliosis +…
Collagen fibril (Orgel 2006)
J Orgel 2006 in-situ collagen-fibril 2-staggered; modern modern foundational text + AFM-fibril-mechanics + 2024…
Epidermal stem cell (Fuchs 2007)
E Fuchs 2007 + Cotsarelis 1989 epidermal-stem-cell; modern modern foundational + bulge-stem-cell + 2024 ML-driven hair-follicle map.
Nail keratin (Schweizer 1989)
J Schweizer 1989 hair-nail-keratin gene-cluster; modern modern foundational + ectodermal-dysplasia + 2024 reconstructive-nail engineered…
Fiber types (Burke 1971)
R Burke 1971 + Brooke-Kaiser 1970 fiber-types I/IIa/IIx; modern modern foundational + age-related sarcopenia + 2024 mTORC1 + AMPK…