FUNCTIONAL ANATOMY 2025.TT Flashcards
What are the primary homeostatic functions of the musculoskeletal system?
Venous return from lower limbs, maintaining body temperature, storage of minerals (calcium, phosphate), hematopoiesis, and glycogen storage in muscles
What are the three types of muscle tissue, and how do they differ?
Skeletal muscle (voluntary, striated, attached to bones), Cardiac muscle (involuntary, striated, forms myocardium), Smooth muscle (involuntary, non-striated, found in blood vessels and internal organs)
What is the role of the sarcoplasmic reticulum in muscle contraction?
Stores and releases calcium ions (Ca²⁺) required for muscle contraction by triggering the interaction between actin and myosin
How does the sliding filament theory explain muscle contraction?
Calcium binds to troponin, shifting tropomyosin and exposing actin binding sites; myosin heads form cross-bridges and perform power strokes using ATP, shortening the sarcomere
What is the difference between Type I and Type II muscle fibers?
Type I (slow-twitch, endurance, more mitochondria, aerobic metabolism), Type II (fast-twitch, powerful, fewer mitochondria, anaerobic metabolism)
What are the structural components of a tendon?
Collagen fibers (mainly Type I), elastin, proteoglycans, and non-collagenous proteins; organized into fascicles encased by endotenon, epitenon, and synovial sheath
How do tendons and ligaments differ in their function and composition?
Tendons connect muscles to bones, transmit force, have more collagen; Ligaments connect bones, provide joint stability, contain more elastin for flexibility
What are the different types of synovial joints, and how do they function?
Hinge (elbow, knee, one plane movement), Ball-and-socket (hip, shoulder, all movements), Pivot (rotation, atlas-axis joint), Saddle (thumb, biaxial movement), Condyloid (wrist, movement in two planes), Plane (gliding, intercarpal joints)
What is the function of synovial fluid, and what are its components?
Lubricates joints, reduces friction, absorbs shock; contains hyaluronic acid, lubricin, proteins, and electrolytes
How does fibrocartilage differ from hyaline and elastic cartilage?
Fibrocartilage has dense collagen fibers for shock absorption (e.g., intervertebral discs), hyaline cartilage provides smooth joint surfaces, elastic cartilage contains elastin for flexibility (e.g., ear)
What are the key differences between cortical (compact) and cancellous (spongy) bone?
Cortical bone is dense, found in shafts of long bones, provides strength; Cancellous bone is porous, found in epiphyses, contains red marrow for hematopoiesis
Describe the process of bone remodeling and its importance.
Osteoclasts resorb old bone, osteoblasts deposit new bone, ensuring mineral homeostasis, bone strength adaptation, and fracture repair
What are the hormonal regulators of bone metabolism?
Parathyroid hormone (PTH) increases calcium release from bone, Calcitonin inhibits osteoclasts, Vitamin D enhances calcium absorption, Estrogen inhibits bone resorption
What are the consequences of an imbalance in bone remodeling?
Osteoporosis (excessive resorption, weak bones), Osteopetrosis (reduced resorption, dense but brittle bones), Paget’s disease (disorganized bone remodeling)
How does mechanical stress influence bone remodeling?
Mechanical loading stimulates osteoblast activity and increases bone mass, while reduced stress (e.g., bed rest, microgravity) leads to bone loss
What are the structural components of an osteon?
Central (Haversian) canal with blood vessels and nerves, concentric lamellae, osteocytes in lacunae connected by canaliculi, and Volkmann’s canals linking adjacent osteons
What is the role of osteocytes in bone homeostasis?
Act as mechanosensors, regulate mineral balance, communicate with osteoblasts and osteoclasts via canaliculi
How does endochondral ossification differ from intramembranous ossification?
Endochondral ossification replaces cartilage with bone (long bone formation), Intramembranous ossification forms bone directly from mesenchymal tissue (skull, clavicle)
What is the periosteum, and what are its two layers?
Outer fibrous layer (dense connective tissue for attachment), Inner cambial layer (osteogenic cells for growth and repair)
What is Wolff’s Law in relation to bone adaptation?
Bone remodels in response to mechanical stress, increasing strength in high-load areas and resorbing in low-load areas
How does osteoporosis develop, and what are its risk factors?
Imbalance between resorption and formation; risk factors include aging, hormonal changes, inactivity, low calcium/vitamin D intake, genetics
What is the function of cartilage in fetal development and adult joints?
Serves as a template for bone formation in the fetus (endochondral ossification) and provides cushioning and flexibility in adult joints
How does synovial membrane inflammation contribute to arthritis?
Inflamed synovium produces excess fluid and inflammatory cytokines, leading to joint pain, swelling, and cartilage degradation (e.g., rheumatoid arthritis)
Describe the role of lubricin in joint function.
Lubricin is a glycoprotein secreted by synovial cells that reduces friction in joints and protects cartilage from wear
What are the differences between hypertrophy and atrophy in muscle adaptation?
Hypertrophy is increased muscle mass due to resistance training, Atrophy is muscle loss due to disuse or disease
How does calcium phosphate contribute to bone strength?
Calcium phosphate forms hydroxyapatite crystals, providing rigidity and resistance to compression
What are the key differences between intramembranous and endochondral bone formation?
Intramembranous: direct bone formation (flat bones), Endochondral: cartilage precursor replaced by bone (long bones)
How does weight-bearing exercise impact bone health?
Stimulates osteoblast activity, increases bone density, reduces risk of osteoporosis
What are the major components of the extracellular matrix in cartilage?
Collagen (mainly Type II), proteoglycans (aggrecan, hyaluronan), glycoproteins (lubricin), water
Why is cartilage avascular, and how does it receive nutrients?
Lacks blood vessels; nutrients diffuse from synovial fluid or surrounding tissues via compression and relaxation
How does vitamin D deficiency affect bone health?
Leads to poor calcium absorption, causing rickets in children and osteomalacia in adults
What is the function of the endosteum?
Lines internal bone surfaces, contains osteogenic cells for bone remodeling
Why do long bone fractures sometimes lead to avascular necrosis?
Disruption of the nutrient artery supply can cause localized bone death, especially in the femoral head
How do osteoclasts resorb bone?
Release H⁺ ions and lysosomal enzymes to dissolve mineral matrix and degrade collagen
Why is collagen important in bones and connective tissues?
Provides tensile strength, flexibility, and a framework for mineral deposition
What are the consequences of prolonged immobilization on the musculoskeletal system?
Muscle atrophy, bone resorption, joint stiffness, reduced synovial fluid production
How does aging affect the musculoskeletal system?
Loss of muscle mass (sarcopenia), decreased bone density, reduced joint cartilage thickness, increased stiffness
