Locomotion and Movement

Beginner - Story ModeTopper - Revision

1. Movement vs Locomotion - The Dance and The Journey

Imagine you are at a wedding. Moving your hands dancing is movement but not going anywhere. Walking from stage to buffet is locomotion - whole body changes place. In biology, amoeba stretches pseudopodia, paramecium beats cilia, you lift arm - all movement. Some movement results in locomotion.

Story - The Transport Company: Body has 3 types of trucks. Skeletal muscle trucks are voluntary, striated like zebra crossing, multinucleated, attached to bones via tendons, you control them for dance. Smooth muscle trucks are involuntary, non-striated, spindle-shaped single nucleus, in gut blood vessels pushing food blood without you thinking. Cardiac muscle trucks are in heart, striated but involuntary, branched, intercalated discs like handshake between workers, never gets tired. Amoeboid movement like thief sneaking - macrophages and leucocytes make pseudopodia engulf bacteria. Ciliary movement like rowing boat - trachea cilia push mucus up, fallopian tube cilia push egg. Flagellar like whip - sperm tail lashing. Muscular like crane lifting limbs.

Part 1A - Types of Movement Dance vs Journey

Part 1B - Muscle Fiber Structure Fascicle Zoom

Revision: Movement body part change position, Locomotion whole body change place. Amoeboid pseudopodia WBC macrophage, Ciliary trachea fallopian, Flagellar sperm, Muscular limbs. Muscle types: Skeletal voluntary striated multinucleated, Smooth involuntary non-striated spindle single nucleus gut vessels, Cardiac involuntary striated branched intercalated discs heart never fatigue.

2. Sarcomere - The Tiny Construction Site

Sarcomere is functional unit of muscle like one brick in wall. Between two Z lines is one sarcomere 2-3 micron. A band dark has myosin, I band light has only actin, H zone only myosin, M line middle.

Creative - LEGO Blocks: Actin thin filament is double helix F-actin made of G-actin balls, wrapped by tropomyosin thread like security tape covering binding sites, troponin complex is guard with 3 staff TnT ties to tropomyosin TnI inhibits TnC catches calcium like catcher in cricket. Myosin thick filament is golf club with head heavy meromyosin HMM has ATPase and actin binding, tail light meromyosin LMM. When muscle relaxes, tropomyosin covers actin binding sites, myosin cannot bind. Think of actin as road with roadblocks tropomyosin, troponin as traffic police holding roadblock until calcium signal comes.

Part 2A - Sarcomere Z I A H M LEGO

Part 2B - Sliding Filament Cross Bridge Cycle Zoom

Revision: Sarcomere Z to Z functional unit, I band actin only light, A band myosin+actin dark, H zone myosin only, M line middle. Thin filament F-actin G-actin double helix tropomyosin thread troponin TnT TnI TnC Ca2+ binding. Thick filament myosin head HMM ATPase cross bridge tail LMM. Relaxed tropomyosin blocks binding sites.

3. Sliding Filament - The Tug of War

Muscle contracts when actin slides over myosin, like two teams pulling rope, Z lines come closer, I band H zone shrink, A band stays same. How does it start? Motor neuron releases acetylcholine at NMJ, action potential travels T-tubule to sarcoplasmic reticulum releases Ca2+.

Story - The Cricket Match: Calcium is ball, Troponin C is wicket keeper catches ball, pulls tropomyosin security tape away, exposes binding sites on actin. Myosin head is batsman ready with ATP energy. Cycle: 1. Myosin head binds actin forming cross bridge, 2. Power stroke myosin pulls actin like rowing boat oar, ADP+Pi released, sarcomere shortens, 3. ATP binds myosin head detaches, 4. ATP hydrolyzed myosin cocked back ready. This repeats as long as Ca2+ high. When Ca2+ goes back to SR, tropomyosin covers sites, muscle relaxes. Red fibers slow twitch high myoglobin mitochondria fatigue resistant marathon runners, White fibers fast twitch low myoglobin quick fatigue sprinters. Motor unit one motor neuron + all muscle fibers it innervates, fine movements small motor units like eye few fibers, gross movements large motor units like thigh many fibers.

Part 3A - Axial Skeleton 80 Bones Skull Vertebra

Part 3B - Appendicular 126 Bones Limbs Girdles Zoom

Revision: Sliding filament actin slides over myosin Z closer I H shrink A same. NMJ ACh T-tubule SR Ca2+ release Ca2+ binds TnC tropomyosin moves binding sites exposed cross bridge formation power stroke ATP detachment cocking repeat. Red slow twitch high myoglobin mitochondria fatigue resistant, White fast low myoglobin quick fatigue. Motor unit motor neuron + fibers fine small gross large.

4. Skeleton - The Body's Scaffolding

206 bones total, 80 axial central pole, 126 appendicular side branches. Axial: Skull 22 cranial 8 facial 14 + ear ossicles 6 + hyoid 1, Vertebral column 26 vertebrae cervical 7 thoracic 12 lumbar 5 sacrum 1 coccyx 1, Ribs 12 pairs true 1-7 false 8-10 floating 11-12, Sternum breast bone.

Creative - Building Construction: Skull is helmet protecting brain, vertebral column is central pillar with 33 vertebrae but fused to 26, cervical neck flexible nod yes no, thoracic attached to ribs cage protects heart lungs, lumbar lower back bears weight strongest, sacrum triangular fused 5 sacral vertebrae, coccyx vestigial tail 4 fused. Ribs are curved bangles, sternum is tie in middle. Appendicular: Pectoral girdle clavicle collar bone + scapula shoulder blade glenoid cavity, Forelimb humerus longest upper arm, radius ulna forearm, carpals 8 wrist, metacarpals 5 palm, phalanges 14 fingers. Pelvic girdle two coxal bones ilium ischium pubis acetabulum socket, Hindlimb femur longest strongest thigh bone, patella kneecap sesamoid, tibia shin fibula calf, tarsals 7 ankle, metatarsals 5 foot, phalanges 14 toes. Longest femur smallest stapes ear.

Part 4A - Joints Classification Fibrous Cartilaginous Synovial

Part 4B - Synovial Joint Structure & Types Zoom

Revision: Total 206 bones Axial 80 Skull 22 (8 cranial 14 facial) + 6 ear ossicles +1 hyoid Vertebral 26 (C7 T12 L5 S1 Co1) Ribs 24 (7 true 3 false 2 floating) Sternum 1 Appendicular 126 Pectoral 4 Upper limbs 60 Pelvic 2 Lower limbs 60. Femur longest Stapes smallest. Pectoral clavicle scapula glenoid, Pelvic ilium ischium pubis acetabulum, Forelimb humerus radius ulna carpals 8 metacarpals 5 phalanges 14, Hindlimb femur patella tibia fibula tarsals 7 metatarsals 5 phalanges 14.

5. Joints - The Doors and Hinges

Joint is place where two bones meet. Fibrous immovable sutures skull, Cartilaginous slightly movable pubic symphysis vertebrae, Synovial freely movable most common with fluid.

Story - Doors of House: Fibrous joint like fixed window sealed with fiber no movement sutures skull, syndesmosis tibia fibula, gomphosis tooth in jaw. Cartilaginous like door with rubber gasket slight movement synchondrosis rib sternum, symphysis pubic symphysis with fibrocartilage. Synovial like well-oiled door with hinges has articular cartilage smooth white cushion, joint cavity synovial fluid lubricant, capsule fibrous, synovial membrane secretes fluid, ligaments ropes hold. Types: Ball and socket shoulder hip maximum movement 360, Hinge elbow knee ankle one plane like door hinge, Pivot atlas axis head rotates radius ulna, Gliding carpals tarsals sliding, Saddle thumb carpometacarpal, Condyloid wrist MCP. Synovial fluid reduces friction like oil.

Part 5A - Motor Unit Red White Fibers NMJ ACh

Part 5B - Disorders Myasthenia Dystrophy Arthritis Zoom

Revision: Fibrous immovable sutures syndesmosis gomphosis, Cartilaginous slightly movable synchondrosis symphysis, Synovial freely movable articular cartilage synovial fluid capsule ligaments. Types: Ball socket shoulder hip, Hinge elbow knee, Pivot atlas axis radioulnar, Gliding carpals tarsals, Saddle thumb, Condyloid wrist MCP.

6. Disorders & Final Summary

Myasthenia gravis autoimmune ACh receptors blocked weak muscles ptosis drooping eyelid. Muscular dystrophy dystrophin deficiency progressive weakness pseudohypertrophy. Tetany low Ca++ wild contractions. Arthritis joint inflammation osteo wear tear rheumatoid autoimmune gout uric acid crystals.

Creative - The Repair Workshop: Myasthenia gravis like phone charger port blocked autoantibodies block ACh receptors, muscles get tired evening. Muscular dystrophy like building with faulty cement dystrophin missing, muscles degenerate genetic X-linked. Tetany like faulty wiring low calcium causes muscle spasm carpopedal. Arthritis like rusted hinges osteo age wear cartilage, rheumatoid immune attacks synovial, gout like salt crystals deposition uric acid in small joints big toe painful. Osteoporosis porous bone low estrogen post menopause fracture prone. Prevention exercise calcium vitamin D no smoking. Final summary: Movement dance, Locomotion journey, 3 muscle types skeletal voluntary striated multinucleated, smooth involuntary spindle, cardiac branched intercalated, Sarcomere Z to Z, Sliding filament Ca2+ troponin tropomyosin cross bridge ATP, Skeleton 206 axial 80 appendicular 126 femur longest stapes smallest, Joints fibrous cartilaginous synovial 6 types, Motor unit red slow white fast.

Part 6A - Final Summary Locomotion vs Movement

Part 6B - Full Revision Table Disorders Zoom

Revision: Myasthenia gravis autoimmune ACh receptors blocked ptosis, Muscular dystrophy dystrophin X-linked pseudohypertrophy, Tetany low Ca++ spasm, Arthritis osteo rheumatoid gout uric acid, Osteoporosis porous low estrogen. Red slow high myoglobin mitochondria fatigue resistant, White fast low myoglobin quick fatigue. NMJ ACh motor end plate. Motor unit neuron + fibers.