Locomotion and Movement Lecture Notes

Vocabulary flashcards covering major terms and definitions from the lecture on locomotion, muscular structure, contraction mechanism, skeletal components, joints and associated disorders.

Movement

Any change in the position or shape of a body part or the whole organism.

Locomotion

Voluntary movement that results in a change of place or location.

Amoeboid Movement

Cell movement produced by pseudopodia and streaming of protoplasm, seen in macrophages and leucocytes.

Ciliary Movement

Coordinated beating of cilia to propel fluids or cells, e.g., in trachea or oviduct.

Muscular Movement

Movement produced by contraction of muscle fibers, enabling limb, jaw, tongue actions, etc.

Muscle

Mesoderm-derived contractile tissue possessing excitability, contractility, extensibility and elasticity.

Skeletal Muscle

Striated, voluntary muscle attached to bones; responsible for posture and locomotion.

Visceral Muscle

Smooth, non-striated, involuntary muscle in walls of hollow organs.

Cardiac Muscle

Striated, branched, involuntary muscle forming the heart wall.

Sarcolemma

Plasma membrane of a muscle fiber.

Sarcoplasm

Cytoplasm of a muscle fiber containing multiple nuclei.

Sarcoplasmic Reticulum

Endoplasmic reticulum of muscle fibers; stores and releases Ca²⁺ ions.

Myofibril

Long, parallel contractile filament bundle inside a muscle fiber.

Myofilament

Protein filament (actin or myosin) within a myofibril.

Actin

Protein forming the thin filaments of a myofibril.

Myosin

Protein forming the thick filaments of a myofibril.

I-Band

Light band of thin actin filaments in a myofibril.

A-Band

Dark band containing thick myosin filaments in a myofibril.

Z Line

Elastic line bisecting the I-band; anchor point for thin filaments.

M Line

Fibrous membrane holding thick filaments together in the center of the A-band.

Sarcomere

Functional contractile unit between two successive Z lines.

H Zone

Central region of A-band not overlapped by thin filaments in resting muscle.

F-Actin

Filamentous polymer of G-actin forming part of thin filament.

G-Actin

Globular actin monomer that polymerizes to form F-actin.

Tropomyosin

Protein filament lying along actin and covering myosin-binding sites.

Troponin

Regulatory protein on tropomyosin that binds Ca²⁺ to expose actin sites.

Meromyosin

Monomeric unit of myosin; consists of a globular head and tail.

Heavy Meromyosin (HMM)

Globular head plus short arm of myosin containing ATPase and actin-binding sites.

Light Meromyosin (LMM)

Long tail portion of myosin molecule.

Cross Bridge

Temporary link formed when myosin head binds to actin during contraction.

Sliding Filament Theory

Concept that muscle contraction occurs by thin filaments sliding over thick filaments.

Motor Neuron

Nerve cell that transmits contraction signals to muscle fibers.

Motor Unit

A motor neuron and all the muscle fibers it innervates.

Neuromuscular Junction

Synapse between a motor neuron and a muscle fiber’s sarcolemma.

Acetylcholine

Neurotransmitter released at neuromuscular junction to trigger action potential.

Myoglobin

Red oxygen-binding pigment in muscle; abundant in red fibers.

Red Fibers

Muscle fibers rich in myoglobin and mitochondria; rely on aerobic respiration.

White Fibers

Muscle fibers low in myoglobin; fewer mitochondria; depend on anaerobic glycolysis.

Skeletal System

Framework of 206 bones and cartilages supporting the human body.

Axial Skeleton

80 bones of skull, vertebral column, sternum and ribs.

Appendicular Skeleton

Bones of limbs and their girdles.

Skull

22-bone structure protecting brain and forming face.

Hyoid Bone

U-shaped bone at base of buccal cavity; supports tongue muscles.

Ear Ossicles

Three tiny middle-ear bones—malleus, incus, stapes.

Vertebral Column

26-vertebra backbone protecting spinal cord.

Atlas

First cervical vertebra that supports skull.

Axis

Second cervical vertebra allowing head rotation.

True Ribs

First seven rib pairs directly attached to sternum.

False Ribs

8th–10th rib pairs joined to sternum via 7th rib cartilage.

Floating Ribs

11th and 12th rib pairs with no ventral attachment.

Pectoral Girdle

Clavicle and scapula; attaches upper limb to axial skeleton.

Scapula

Triangular shoulder blade bone with spine and glenoid cavity.

Clavicle

Collar bone linking scapula to sternum.

Glenoid Cavity

Depression on scapula articulating with humerus head.

Pelvic Girdle

Two fused coxal bones attaching lower limbs to axial skeleton.

Coxal Bone

Hip bone formed by fusion of ilium, ischium and pubis.

Acetabulum

Cup-shaped socket in coxal bone receiving femur head.

Patella

Knee-cap bone covering the knee joint anteriorly.

Joint

Point of contact between two bones or bone and cartilage.

Fibrous Joint

Immovable joint with bones joined by dense connective tissue, e.g., skull sutures.

Cartilaginous Joint

Slightly movable joint with bones united by cartilage, e.g., intervertebral discs.

Synovial Joint

Freely movable joint with fluid-filled cavity between bones.

Ball and Socket Joint

Synovial joint allowing multi-axial movement, e.g., shoulder.

Hinge Joint

Synovial joint permitting movement in one plane, e.g., knee.

Pivot Joint

Synovial joint for rotation, e.g., atlas–axis articulation.

Gliding Joint

Synovial joint with sliding movements, e.g., between carpals.

Saddle Joint

Synovial joint allowing opposable movement, e.g., thumb base.

Myasthenia Gravis

Autoimmune disease causing weakness by impairing neuromuscular transmission.

Muscular Dystrophy

Genetic disorder with progressive skeletal muscle degeneration.

Tetany

Rapid muscle spasms due to low blood calcium levels.

Arthritis

Inflammation of joints leading to pain and reduced mobility.

Osteoporosis

Age-related reduction in bone mass increasing fracture risk.

Gout

Joint inflammation from uric acid crystal deposition.