Summary Notes: Musculoskeletal, Circulatory, Respiratory, and Digestive Systems

50 vocabulary flashcards covering bones, joints, muscles, heart, vessels, respiratory, and digestive/metabolic concepts from the notes.

Bone

A living organ of the skeletal system composed of osseous tissue that provides support, protection, movement, mineral storage, and blood cell formation.

Axial skeleton

Bones forming the body's long axis: skull, vertebral column, and rib cage.

Appendicular skeleton

Bones of the limbs and girdles that attach limbs to the axial skeleton.

Osseous tissue

Bone tissue; matrix with collagen and calcium phosphate crystals.

Osteon

The structural unit of compact bone consisting of concentric lamellae around a central canal.

Haversian canal

Central canal in an osteon containing blood vessels and nerves.

Osteocytes

Mature bone cells that maintain the bone matrix in lacunae.

Osteoblasts

Bone-forming cells that secrete collagen and ground substance.

Osteoclasts

Bone-resorbing cells that break down matrix and release minerals.

Osteoprogenitor cells

Stem cells that differentiate into osteoblasts.

Periosteum

Outer fibrous membrane covering bone; contains vessels and nerves.

Endosteum

Inner membrane lining the medullary cavity and trabeculae.

Compact bone

Dense bone tissue organized into osteons; strong and weight-bearing.

Spongy bone

Lattice-like bone with trabeculae; lighter and houses red bone marrow.

Epiphysis

Bone end; site of articulation and growth.

Diaphysis

Shaft of long bone; houses medullary cavity.

Epiphyseal plate

Hylaine cartilage plate for bone length growth in growing individuals.

Epiphyseal line

Ossified remnant of the growth plate after growth ends.

Intervertebral disc

Fibrocartilage pad between vertebrae resisting compression.

Articular cartilage

Hyaline cartilage covering joint ends to reduce friction.

Joints (articulations)

Points where two or more bones meet; classified by structure and function.

Fibrous joints

Joints joined by dense fibrous tissue; immovable or slightly movable.

Cartilaginous joints

Bones united by cartilage; immovable or slightly movable.

Synovial joints

Freely movable joints with a joint cavity and synovial fluid.

Suture

Fibrous joint between skull bones.

Pubic symphysis

Slightly movable cartilaginous joint between the pubic bones.

Articular capsule

Fibrous outer layer and inner synovial membrane enclosing a synovial joint.

Synovial fluid

Lubricates joints, absorbs shock, supplies nutrients to cartilage.

Meniscus

Fibrocartilage discs in a knee joint; stabilises and absorbs shock.

Bursae

Fluid-filled sacs that reduce friction between moving structures.

Tendons

Attach muscle to bone.

Skeletal muscle

Voluntary, striated muscle tissue composed of muscle fibers.

Myofibril

Contractile elements within a muscle fiber.

Sarcomere

Contractile unit of a myofibril; thick and thin filaments.

Actin

Thin filament protein forming part of the thin filament.

Myosin

Thick filament motor protein that binds to actin during contraction.

Tropomyosin

Regulatory protein that blocks actin active sites in relaxed muscle.

Troponin

Calcium-binding regulatory protein that moves tropomyosin to expose actin sites.

Sarcoplasmic reticulum

Calcium storage organelle in muscle fibers; releases Ca2+ during contraction.

T-tubules

Transverse tubules that propagate action potentials into the muscle fiber.

Neuromuscular junction

Synapse between a motor neuron and a skeletal muscle fiber; site of ACh release.

Acetylcholine (ACh)

Neurotransmitter released at the NMJ to stimulate contraction.

Sliding filament theory

Contractile mechanism where actin filaments slide over myosin to shorten the sarcomere.

Sinoatrial (SA) node

The natural pacemaker of the heart; initiates the heartbeat.

Atrioventricular (AV) node

Delays conduction between atria and ventricles; can become pacemaker if SA node fails.

Bundle of His

AV bundle; conducts impulses from AV node to bundle branches.

Purkinje fibers

Subendocardial conducting network that depolarises ventricles.

Cardiac cycle

Sequence of systole and diastole generating a heartbeat.

End-diastolic volume (EDV)

Volume in ventricle at end of diastole.

End-systolic volume (ESV)

Volume remaining in ventricle after systole.

Preload

Degree of myocardial stretch before contraction; relates to EDV.

Afterload

Pressure ventricles must overcome to eject blood.

Stroke volume (SV)

Volume ejected per beat; SV = EDV − ESV.

Cardiac output (CO)

Volume pumped per minute; CO = SV × HR.

Pulmonary circulation

Circulation of blood to the lungs for oxygenation.

Systemic circulation

Circulation delivering oxygenated blood to the body.

Arteries

Blood vessels carrying blood away from the heart; thick-walled and high-pressure.

Veins

Blood vessels carrying blood toward the heart; contain valves and operate under lower pressure.

Capillaries

Microscopic vessels where exchange of gases and nutrients occurs; very thin walls.