Musculoskeletal system
54 flashcards covering Musculoskeletal system for the MCAT Biology & Biochemistry section.
The musculoskeletal system is the body's framework that supports movement and maintains posture, consisting of bones, muscles, joints, ligaments, and tendons. Bones form a rigid skeleton that protects organs and stores minerals, while muscles attach to bones via tendons to produce motion through contraction and relaxation. Joints allow for flexibility and range of motion, making this system essential for daily activities, physical stability, and overall health.
On the MCAT, the musculoskeletal system frequently appears in Biology and Biochemistry questions, often testing anatomy, physiology, and integration with other systems like the nervous system. Expect multiple-choice questions on topics such as muscle contraction mechanisms, bone structure and remodeling, or disorders like arthritis, with common traps including confusing muscle types or overlooking how hormones affect bone density. Focus on understanding key processes, like the sliding filament theory, and their clinical relevance to score well.
A concrete tip: Practice identifying major bones and muscles on diagrams to solidify your visual recall.
Terms (54)
- 01
Bone
A rigid connective tissue that forms the skeleton, providing support, protection, and a site for mineral storage and blood cell production.
- 02
Muscle
A soft tissue composed of fibers that contract to produce movement, maintain posture, and generate heat in the body.
- 03
Joint
A point where two bones meet, allowing for movement and flexibility while being stabilized by ligaments and cartilage.
- 04
Ligament
A band of tough, fibrous tissue that connects bones to other bones, providing stability to joints and preventing excessive movement.
- 05
Tendon
A strong, fibrous cord that attaches muscles to bones, transmitting the force of muscle contraction to produce motion.
- 06
Sarcomere
The basic unit of striated muscle, consisting of repeating sections of actin and myosin filaments that shorten during contraction.
- 07
Actin
A thin filament protein in muscle cells that interacts with myosin to enable the sliding mechanism of muscle contraction.
- 08
Myosin
A thick filament protein in muscle cells that forms cross-bridges with actin, using ATP to pull and cause muscle shortening.
- 09
Sliding filament theory
The mechanism explaining muscle contraction, where actin filaments slide past myosin filaments, shortening the sarcomere without changing filament length.
- 10
Neuromuscular junction
The synapse between a motor neuron and a muscle fiber, where acetylcholine is released to trigger muscle contraction.
- 11
Acetylcholine
A neurotransmitter released at the neuromuscular junction that binds to receptors on muscle cells, initiating an action potential for contraction.
- 12
Motor unit
A single motor neuron and all the muscle fibers it innervates, allowing coordinated contraction for precise movements.
- 13
Osteoblast
A bone-forming cell that synthesizes and mineralizes the bone matrix, contributing to bone growth and repair.
- 14
Osteoclast
A large cell that breaks down bone tissue by dissolving minerals and matrix, playing a key role in bone remodeling and calcium homeostasis.
- 15
Compact bone
The dense outer layer of bone that provides strength and protection, containing Haversian systems for nutrient delivery.
- 16
Spongy bone
The porous inner layer of bone, made of trabeculae that offer structural support and house red bone marrow for blood cell production.
- 17
Epiphysis
The end portion of a long bone, typically containing spongy bone and articular cartilage, which aids in joint function and growth.
- 18
Diaphysis
The shaft of a long bone, composed mainly of compact bone, that provides leverage for movement and houses the medullary cavity.
- 19
Haversian canal
A central channel in compact bone that contains blood vessels and nerves, supplying nutrients to surrounding bone tissue.
- 20
Synovial joint
A freely movable joint, such as the knee or elbow, enclosed in a synovial capsule that contains fluid for lubrication and shock absorption.
- 21
Cartilage
A flexible connective tissue that covers joint surfaces, providing cushioning and reducing friction during movement.
- 22
Tendinitis
Inflammation of a tendon, often caused by overuse, leading to pain and swelling at the attachment site to bone.
- 23
Osteoporosis
A condition characterized by reduced bone density and increased fragility, resulting from an imbalance in bone resorption and formation.
- 24
Rickets
A disorder in children caused by vitamin D deficiency, leading to soft and deformed bones due to impaired mineralization.
- 25
Slow-twitch muscle fibers
Muscle fibers that contract slowly and are fatigue-resistant, specialized for endurance activities like long-distance running.
- 26
Fast-twitch muscle fibers
Muscle fibers that contract quickly and powerfully but fatigue rapidly, suited for short, intense activities like sprinting.
- 27
Isometric contraction
A type of muscle contraction where tension is generated without a change in muscle length, such as holding a weight steady.
- 28
Isotonic contraction
A muscle contraction that produces movement by changing length while maintaining constant tension, as in lifting a weight.
- 29
Concentric contraction
A shortening contraction where the muscle pulls on bones to move a joint, like the biceps contracting to bend the elbow.
- 30
Eccentric contraction
A lengthening contraction where the muscle resists while being stretched, such as lowering a weight slowly to control motion.
- 31
ATP in muscle contraction
The primary energy source for muscle contraction, hydrolyzed by myosin to power the cross-bridge cycle and enable filament sliding.
- 32
Creatine phosphate
A high-energy compound in muscles that rapidly regenerates ATP from ADP during short bursts of intense activity.
- 33
Glycolysis in muscles
The anaerobic breakdown of glucose to produce ATP in muscles, allowing energy production without oxygen for brief periods.
- 34
Oxygen debt
The amount of oxygen needed after exercise to restore muscles to their resting state, repaying the deficit incurred during anaerobic activity.
- 35
Myoglobin
An oxygen-binding protein in muscle cells that stores and releases oxygen for use during contraction, similar to hemoglobin in blood.
- 36
T-tubules
Transverse tubules in muscle fibers that conduct electrical impulses from the cell membrane to the sarcoplasmic reticulum for coordinated contraction.
- 37
Sarcoplasmic reticulum
A specialized endoplasmic reticulum in muscle cells that stores and releases calcium ions to trigger contraction.
- 38
Calcium's role in contraction
Calcium ions bind to troponin, causing a conformational change that exposes actin binding sites for myosin, initiating the cross-bridge cycle.
- 39
Troponin and tropomyosin
Regulatory proteins on actin filaments; troponin binds calcium to move tropomyosin, allowing myosin to interact with actin during contraction.
- 40
Cross-bridge cycle
The repetitive attachment, pivoting, and detachment of myosin heads to actin, powered by ATP, that results in muscle shortening.
- 41
Bone remodeling
The continuous process of bone resorption by osteoclasts and formation by osteoblasts, maintaining bone strength and calcium balance.
- 42
Wolff's law
The principle that bone adapts its density and structure in response to the mechanical stresses placed on it, such as through exercise.
- 43
Parathyroid hormone
A hormone that increases blood calcium levels by stimulating osteoclast activity and bone resorption, as well as kidney reabsorption.
- 44
Calcitonin
A hormone that lowers blood calcium levels by inhibiting osteoclasts and promoting calcium deposition into bone.
- 45
Vitamin D
A fat-soluble vitamin that enhances calcium absorption in the intestines and promotes bone mineralization, preventing conditions like rickets.
- 46
Types of fractures
Breaks in bone that vary by pattern, such as transverse, spiral, or comminuted, often requiring different treatments based on severity.
- 47
Sprain vs. strain
A sprain is an injury to a ligament from joint overstretching, while a strain is an injury to a muscle or tendon from excessive force or tearing.
- 48
Bursitis
Inflammation of a bursa, a fluid-filled sac that reduces friction between tissues, often causing pain and swelling near joints.
- 49
Osteoarthritis
A degenerative joint disease involving wear and tear of cartilage, leading to pain, stiffness, and reduced mobility in affected joints.
- 50
Rheumatoid arthritis
An autoimmune disorder where the immune system attacks joint linings, causing inflammation, swelling, and potential joint deformity.
- 51
Electromyography
A diagnostic technique that measures electrical activity in muscles to assess nerve and muscle function, often used for neuromuscular disorders.
- 52
Biomechanics of leverage
The application of physics principles to the musculoskeletal system, where bones act as levers and muscles provide force to amplify movement efficiency.
- 53
Muscle spindle
A sensory receptor in skeletal muscle that detects changes in muscle length and stretch, helping to regulate muscle tone and reflexes.
- 54
Golgi tendon organ
A sensory receptor at the muscle-tendon junction that monitors tension, inhibiting muscle contraction to prevent injury from excessive force.