Final Notes Skeleton Physiology from Course pack

Latent Period Before Contraction

The initial stage before muscle contraction where action potential triggers calcium release.

Ca²⁺

Calcium ion that binds to troponin during muscle contraction.

Cross-bridges

Formed when myosin binds to actin during the contraction phase.

Power stroke

The action where myosin heads flex to pull actin during contraction.

Muscle Relaxation Phase

Occurs when calcium levels fall and ATP is used to detach myosin from actin.

Adenosine Triphosphate (ATP)

Active energy molecule used for muscle contractions.

Creatine Phosphate (CP)

Storage molecule for excess ATP energy in resting muscle.

Aerobic Metabolism

Primary energy source of resting muscles requiring oxygen.

Lactic Acid Fermentation

Process where pyruvate is reduced to lactate during muscle activity.

Muscle Fatigue

Condition resulting from depletion of metabolic reserves and buildup of lactic acid.

Fast-Twitch Muscle Fibers

Muscle fibers that contract quickly and fatigue rapidly.

Slow-Twitch Muscle Fibers

Muscle fibers that contract slowly and are resistant to fatigue.

Muscle Hypertrophy

Increase in muscle size and strength from heavy training.

Muscle Atrophy

Reduction in muscle size and strength due to lack of activity.

Origin of a Muscle

The attachment point of a muscle that remains fixed during contraction.

Insertion of a Muscle

The attachment point of a muscle that moves when it contracts.

Prime Mover (Agonist)

The main muscle responsible for a specific motion.

Synergist

A muscle that assists the prime mover in a specific action.

Fixator

A muscle that stabilizes the origin of the prime mover.

Antagonist

A muscle that opposes the action of another muscle.

Axial Muscles

Muscles that position the head and spinal column, making up 60% of skeletal muscles.

Appendicular Muscles

Muscles that support the limbs and girdles, making up 40% of skeletal muscles.

Effects of Aging on Muscles

Changes include smaller muscle fibers, reduced elasticity, and increased fibrosis.

Diaphysis

The shaft or central part of a long bone.

Epiphysis

The end part of a long bone.

Medullary Cavity

The cavity inside the diaphysis that contains bone marrow.

Periosteum

Outer membrane covering the bone.

Compact Bone

Dense, mineralized bone tissue forming the outer layer of bone.

Spongy Bone

Porous bone tissue found within the interior of bones.

Haversian System

The structural unit of compact bone, also called an osteon.

Osteocytes

Mature bone cells that maintain the bone matrix.

Osteoclasts

Cells that dissolve bone matrix and release minerals.

Osteoblasts

Cells that secrete bone matrix; they become osteocytes when encased by bone.

Parathyroid Hormone (PTH)

Hormone that increases calcium ion levels in the blood.

Calcitonin

Hormone that decreases calcium ion levels by inhibiting osteoclast activity.

Ossification

The process by which other tissues are replaced by bone.

Intramembranous Ossification

Bone formation directly from a fibrous membrane, creating flat bones.

Endochondral Ossification

Bone formation by replacing hyaline cartilage.

Bone Remodeling

The ongoing replacement of old bone tissue with new bone tissue.

Vitamin D3

Essential vitamin for calcium absorption and bone growth.

Joint Anatomy

Study of the structure and function of joints in the body.

Articular Cartilage

Cartilage that covers the ends of bones at joints.

Volkmann's Canals

Channels connecting blood and nerve supply of the periosteum to Haversian canals.

Canaliculi

Hairlike canals that connect lacunae in bone.

Lacunae

Cavities within bone that contain osteocytes.

Bone Cells

Cells responsible for bone formation and maintenance, including osteoblasts, osteoclasts, and osteocytes.

Lactic Acid

Byproduct produced during anaerobic respiration in muscles.

Glucose to ATP Conversion

The process in cellular respiration that converts glucose into ATP.

Creatine Phosphokinase (CPK)

Enzyme that helps recharge ADP to ATP using Creatine Phosphate.

Muscle Injury Recovery

The ability of muscles to recover from injuries decreases with age.

Exercise Tolerance

The capacity to endure physical activity, which declines with age.

Nutritional Factors for Bone Growth

Includes calcium, phosphate, Vitamin D3, and hormones stimulating growth.

Metabolism Types

Aerobic and anaerobic processes that generate ATP in muscles.

Energy Efficiency in Eukaryotic Cells

Approximately 40% of energy in cellular respiration is converted to ATP.

Skeletal Muscle Size with Aging

Tends to decrease in diameter as part of the aging process.

Muscle Injury Types

Includes depletion of reserves, damage to muscle structure, and low pH.

Segmentation of Muscular System

Divided into axial and appendicular muscles.

Skeletal Muscle Function

Supports body structure and facilitates movement.

T-tubules Function

Channels that transmit action potential into muscle fibers.

Troponin Function

Regulates muscle contraction by binding calcium ions.

Muscle Fiber Components

Muscle fibers consist of actin, myosin, and other proteins.

Role of Mitochondria in Muscles

Generate ATP through aerobic metabolism.

Chemical Signaling in Muscle Contraction

Calcium ions facilitate the alteration of tropomyosin.

Blood Flow to Muscles

Increased during exercise to supply oxygen and nutrients.

Myofibrils

Contractile threads found in striated muscle cells.

Muscle Tone

Slight tension in muscles at rest, contributing to posture.

Effector Muscle Activity

Muscles that cause movement in response to signals.

Skeletal Muscle Characteristics

Striated muscle fibers under voluntary control.

Eccentric Contraction

Muscle lengthens under tension.

Concentric Contraction

Muscle shortens while contracting.

Static Contraction

Muscle length remains unchanged while tension is produced.

Muscle Spindle Function

Monitors muscle stretching and aids in reflex actions.

Golgi Tendon Organ Function

Detects tension in muscle tendons and prevents excessive force.

Exercise-Induced Muscle Damage

Microtrauma to muscle fibers that can lead to hypertrophy.

Hormonal Regulation of Muscles

Includes growth hormone and thyroid hormone effects on muscle metabolism.

Muscle Fiber Recruitment

Process of activating more muscle fibers for increased strength.

Motor Unit

A motor neuron and the muscle fibers it innervates.

Nebulin Role in Muscle Fibers

Helps regulate the length of actin filaments.

Tropomyosin Role in Muscle Contraction

Covers binding sites on actin, preventing contraction unless displaced by calcium.

Hematopoiesis

The process of blood cell production in the bone marrow.

Yellow Bone Marrow Function

Stores fat and serves as a reserve for blood cells.

Bone Growth Factors

Nutrients and hormones essential for developing and maintaining strong bones.

Sympathetic Activation and Muscle Activity

Increases energy release and blood flow to muscles during stress.