15 Skeletal System and Muscular System - Vocabulary Flashcards

Vocabulary flashcards covering bone tissue, bone structure, joints, muscles, and energy systems from the lecture notes.

Osseous tissue

Another name for bone tissue; a living, rigid connective tissue that forms bones and remodels with stress.

Bone tissue

Specialized connective tissue that makes up the bones of the skeletal system; dynamic and living.

Organic components of bone

Approximately 30% of bone; includes collagen fibers, proteins, and bone cells that provide flexibility and strength.

Inorganic components of bone

Approximately 70% of bone; mainly calcium and phosphate (hydroxyapatite) that give hardness and durability.

Hydroxyapatite

Calcium phosphate crystals that provide bone hardness and rigidity.

Collagen fibers

Organic component contributing to bone flexibility and tensile strength.

Osteoblasts

Bone-forming cells that synthesize collagen and minerals to build new bone.

Osteocytes

Mature bone cells that maintain bone tissue and communicate with other bone cells.

Osteoclasts

Bone-resorbing cells that break down bone to release minerals like calcium.

Bone remodeling

Continuous renewal of bone through a balance of bone formation (osteoblasts) and resorption (osteoclasts).

Ossification

Bone formation process; converting connective tissue or cartilage into bone.

Intramembranous ossification

Direct bone formation forming flat bones (skull, mandible, clavicles) from mesenchyme. 

Endochondral ossification

Bone formation from a cartilage model; forms most bones, including long bones.

Epiphyseal plate

Growth plate; cartilage layer at the ends of long bones where lengthwise growth occurs.

Periosteum

Tough outer membrane covering bone; contains osteoblasts and blood vessels. Acts as attachment for tendons/ligaments.

Endosteum

Thin membrane lining the inner surface of bone, including the medullary cavity.

Compact bone

Dense, hard outer layer of bone containing osteons and providing strength.

Spongy bone

Lightweight inner bone tissue containing trabeculae and red bone marrow.

Osteon (Haversian system)

Structural unit of compact bone containing a central canal and concentric lamellae.

Haversian canal

Central channel within an osteon that contains blood vessels and nerves.

Lamellae

Concentric rings of bone tissue around the Haversian canal.

Lacunae

Small cavities that house osteocytes within bone tissue.

Canaliculi

Tiny channels connecting lacunae to allow nutrient and waste exchange between osteocytes.

Trabeculae

Thin, crisscrossing plates in spongy bone that help absorb load and house red marrow.

Red bone marrow

Marrow in spongy bone that produces red blood cells, white blood cells, and platelets.

Yellow bone marrow

Marrow in the medullary cavity that stores fat (lipids) for energy.

Hematopoiesis

Production of blood cells, primarily in red bone marrow.

Calcium homeostasis

Maintenance of stable calcium levels in the blood, involving bone storage/release and kidney/intestine handling.

Parathyroid hormone

Hormone that increases blood calcium by stimulating bone resorption and calcium reabsorption in the kidneys.

Activation of vitamin D (calcitriol)

Process that increases intestinal calcium absorption, supporting calcium balance.

Macroscopic structure of bone

Visible bone structure including periosteum, compact bone, and marrow spaces.

Periosteum functions

Protects/nourishes bone, houses osteoblasts, attaches tendons/ligaments, and contains vessels and nerves.

Articular cartilage

Hyaline cartilage covering joint surfaces to reduce friction and absorb shock.

Epiphysis

End of a long bone where growth occurs and spongy bone typically resides.

Diaphysis

Central shaft of a long bone; primarily compact bone.

Medullary (marrow) cavity

Central cavity within diaphysis that contains yellow bone marrow in adults.

Nutrient foramen

Small opening in bone allowing blood vessels to enter and nourish the bone.

Joint (articulation)

Location where two or more bones meet; allows movement and provides stability.

Fibrous joints

Joints connected by fibrous tissue with little or no movement; include sutures, syndesmoses, gomphoses.

Sutures

Fibrous joints between skull bones with minimal movement.

Syndesmoses

Fibrous joints with longer connective tissue allowing limited movement (e.g., tibia-fibula).

Gomphoses

Fibrous joints where a peg-like fit occurs, such as teeth in the jaw.

Cartilaginous joints

Joints linked by cartilage with limited movement; include synchondroses and symphyses.

Synchondroses

Cartilaginous joints united by hyaline cartilage (growth plates).

Symphyses

Cartilaginous joints joined by fibrocartilage (e.g., intervertebral discs).

Synovial joints

Freely movable joints with a synovial cavity, articular cartilage, and a capsule reinforced by ligaments.

Synovial cavity

Fluid-filled space in a synovial joint allowing movement.

Planar (gliding) joint

Flat surfaces slide past one another; example: carpal joints.

Hinge joint

Joint allowing flexion/extension like elbow.

Pivot joint

Joint allowing rotation around a single axis, e.g., neck rotation.

Condyloid joint

Joint with an oval articular surface allowing movement in two planes; example: knuckles.

Saddle joint

Joint with saddle-shaped surfaces allowing movements in two planes; example: thumb base.

Ball-and-socket joint

Multiaxial joint allowing a wide range of motion in all directions (e.g., shoulder).

Synarthrosis

Immovable joint.

Amphiarthrosis

Slightly movable joint.

Diarthrosis

Freely movable synovial joint.

Skeletal muscle

Voluntary muscle attached to bones that contracts to create movement.

Tendon

Connects muscle to bone, transmitting muscle force.

Epimysium

Outer connective tissue sheath surrounding a whole muscle.

Perimysium

Connective tissue around muscle fascicles (bundles of fibers).

Endomysium

Connective tissue surrounding individual muscle fibers.

Sarcolemma

Plasma membrane of a muscle fiber.

Sarcoplasm

Cytoplasm of a muscle fiber.

Myofibril

Long, thread-like structure inside muscle fibers containing contractile proteins.

Sarcomere

Functional unit of a muscle fiber; region between two Z-lines where contraction occurs.

Actin

Thin filament protein involved in contraction.

Myosin

Thick filament motor protein that pulls actin during contraction.

Troponin

Regulatory protein that binds calcium and moves tropomyosin to expose actin sites.

Tropomyosin

Regulatory protein that blocks/ exposes myosin binding sites on actin depending on calcium.

Calcium ions (Ca2+)

Ions released from the sarcoplasmic reticulum to enable contraction by binding to troponin.

ATP

Adenosine triphosphate; main energy currency driving cross-bridge cycling.

Cross-bridge

Myosin head bound to actin forming a connection that enables filament sliding.

Sliding filament theory

Model describing how actin and myosin filaments slide past each other to shorten a sarcomere.

Neuromuscular junction (NMJ)

Synapse where a motor neuron communicates with a muscle fiber to stimulate contraction.

Acetylcholine (ACh)

Neurotransmitter released at NMJ to trigger muscle fiber depolarization.

Acetylcholinesterase (AChE)

Enzyme that breaks down ACh in the synaptic cleft to stop stimulation.

Motor neuron

Nerve cell that transmits signals from the CNS to muscles.

Excitation-contraction coupling

Process linking an electrical signal (action potential) to muscle contraction via Ca2+ release.

Sarcoplasmic reticulum (SR)

Organelle in muscle cells that stores and releases Ca2+ during contraction.

Calcium release from SR

Ca2+ release triggered by the action potential to initiate contraction.

ACh at NMJ

Acetylcholine released into the synaptic cleft to activate the muscle cell.

Energy systems in muscle activity

Three systems supply ATP: ATP-PC (phosphagen), anaerobic glycolysis, and aerobic respiration.

ATP-PC system (phosphagen system)

Immediate energy system using ATP and creatine phosphate for short, high-intensity efforts.

Creatine phosphate (CP)

High-energy phosphate donor that regenerates ATP from ADP in the ATP-PC system.

Creatine kinase

Enzyme that catalyzes the regeneration of ATP from ADP using CP.

Anaerobic glycolysis

Glucose breakdown without oxygen producing ATP and lactate; lasts ~30 seconds to 2 minutes.

Glycogenolysis

Breakdown of glycogen to glucose to fuel glycolysis.

Glycolysis

Glucose conversion to pyruvate in the cytoplasm, yielding ATP; can produce lactate without oxygen.

Lactate (lactic acid)

Byproduct of anaerobic glycolysis; contributes to muscle fatigue.

Aerobic energy system

Most sustainable energy system using oxygen; fuels prolonged, low-to-moderate activity.

Krebs cycle (Citric Acid Cycle)

Oxidation of acetyl-CoA in mitochondria generating NADH/FADH2 for ATP production.

Electron transport chain (ETC)

Series of proteins in mitochondria that produce large amounts of ATP using NADH/FADH2 and oxygen.

Fat as fuel

Fatty acids are a primary fuel during long-duration, low-to-m moderate-intensity activity.

Type I fibers

Slow-twitch muscle fibers; high endurance, fatigue-resistant.

Type II fibers

Fast-twitch muscle fibers; high force output but fatigue more quickly.

Motor unit

A motor neuron and all the muscle fibers it innervates.

Agonist (prime mover)

Muscle that actively contracts to create a movement.

Antagonist

Muscle that relaxes to allow the movement; can slow or stop motion.

Synergist

Muscle that assists the agonist in performing a movement.

Fixator

Muscle that stabilizes a joint to enable efficient movement.