Human Skeletal System PDF

HUMAN SKELETAL SYSTEM  OUTLINE IV. Human Skeletal System 1. Functions of the Bone and the Skeletal System 2. Bone Tissue a. Structure of Bone b. Histology c. Blood and Nerve Supply of Bone d. Bone Formation e. Fracture and Repair of Bon...

HUMAN SKELETAL SYSTEM  OUTLINE IV. Human Skeletal System 1. Functions of the Bone and the Skeletal System 2. Bone Tissue a. Structure of Bone b. Histology c. Blood and Nerve Supply of Bone d. Bone Formation e. Fracture and Repair of Bone f. Bones Role in Calcium Homeostasis g. Exercise and Bone Tissue 3. The Axial Skeleton 4. The Appendicular Skeleton 5. Aging  HUMAN SKELETAL SYSTEM ❑Skeletal System ✓ The entire framework of bones and cartilages, along with ligaments and tendons. ✓ Functions: 1. Supports soft tissue and provides attachment for skeletal muscles 2. Protects internal organs 3. Assistance in movement, along with skeletal muscles 4. Stores and releases minerals(Ca and P) 5. Contains red bone marrow w/c produces blood cells 6. Contains yellow bone marrow storing triglycerides  HUMAN SKELETAL SYSTEM ❑ Structure of Bone (Long): 1. Diaphysis 2. Epiphyses 3. Metaphyses 4. Articular cartilage 5. Periosteum 6. Medullary cavity 7. Endosteum  HUMAN SKELETAL SYSTEM ❑ Structure of Bone (Long): 1. Diaphysis ✓ The long, cylindrical, main portion of the bone. 2. Epiphyses ✓ Growing over; are the proximal and distal ends of the bone. 3. Metaphyses ✓ Epiphyseal plate is a layer of hyaline cartilage allowing diaphysis of the bone to grow in length. 4. Articular cartilage ✓ a thin layer of hyaline cartilage reducing friction and absorbs shock at freely movable joints.  HUMAN SKELETAL SYSTEM ❑ Structure of Bone (Long): 5. Periosteum ✓ It protects the bone, assists in fracture repair, helps nourish bone tissue and serve as an attachment point for ligaments. ✓ Attached to Perforating fibers, thick bundles of collagen that extend from periosteum into the bone ECM. ✓ 2 Layers of the periosteum 1. Outer fibrous layer – dense irregular connective tissue 2. Inner osteogenic layer – cells  HUMAN SKELETAL SYSTEM ❑ Structure of Bone (Long): 6. Medullary Cavity ✓ a hollow, cylindrical space within diaphysis that contains fatty YBM and numerous blood vessels. 7. Endosteum ✓ a thin membrane that lines the medullary cavity.  HUMAN SKELETAL SYSTEM ❑ Histology ▪ Calcification is the deposition of mineral salts, primarily hydroxyapatite, in a framework formed by collagen fibers in which the tissue hardens. ✓ Bone tissue contains an abundant extracellular matrix that surrounds widely separated cells. 1. Extracellular matrix (15% water, 30% collagen fibers, and 55% crystallized mineral salts) calcium phosphate + calcium hydroxide + calcium carbonate + ions (magnesium, fluoride, potassium, and sulfate) = Bone tissue hardens 2. Bone cells (osteogenic cells, osteoblasts, osteocytes, and osteoclasts) ✓ The combination of crystallized salts (hardness), collagen fibers (flexibility) and organic salts (tensile strength) are responsible for the characteristics of bone.  HUMAN SKELETAL SYSTEM ❑ Histology ✓ Bone Cells 1. Osteoprogenitor cells - the only bone cells to undergo cell division. 2. Osteoblasts - synthesize and secrete collagen fibers and other organic components needed to build the extracellular matrix of bone tissue, and they initiate calcification. 3. Osteocytes - the main cells in bone tissue and maintain its daily metabolism, such as the exchange of nutrients and wastes with the blood. 4. Osteoclasts - are huge cells derived from the fusion of as many as 50 monocytes and are concentrated in the endosteum. Resorption is part of the normal development, maintenance, and repair of bone. HUMAN SKELETAL SYSTEM HUMAN SKELETAL SYSTEM  HUMAN SKELETAL SYSTEM ❑ Blood and Nerve Supply of Bone: A. Arteries 1. Periosteal arteries 2. Nutrient artery 3. Nutrient foramen 4. Metaphyseal arteries 5. Epiphyseal arteries B. Veins 1. Nutrient veins 2. Epiphyseal veins 3. Metaphyseal veins 4. Periosteal veins  HUMAN SKELETAL SYSTEM ❑ Bone Formation ✓ Ossification or osteogenesis is the process by which bone forms. ✓ Four Principal Situations: 1. The initial formation of bones in an embryo and fetus. 2. The growth of bones during infancy, childhood, and adolescence until their adult sizes are reached. 3. The remodeling of bone (replacement of old bone by new bone tissue throughout life). 4. The repair of fractures (breaks in bones) throughout life.  HUMAN SKELETAL SYSTEM ❑ Bone Formation 1. The initial formation of bones in an embryo and fetus. a. Intramembranous ossification - bone forms directly within mesenchyme, which is arranged in sheetlike layers that resemble membranes. ✓ Flat bones of the skull, most of the facial bones, mandible (lower jawbone), medial part of the clavicle (collar bone), and the soft spots. b. Endochondral ossification - bone forms within hyaline cartilage that develops from mesenchyme. HUMAN SKELETAL SYSTEM HUMAN SKELETAL SYSTEM HUMAN SKELETAL SYSTEM  HUMAN SKELETAL SYSTEM ❑ Bone Formation 2. Bone growth during infancy, childhood, and Adolescence ✓ During infancy, childhood, and adolescence, bones throughout the body grow in thickness by appositional growth, and long bones lengthen by the addition of bone material on the diaphyseal side of the epiphyseal plate by interstitial growth.  HUMAN SKELETAL SYSTEM ❑ Bone Formation ✓ Growth in length 1. Interstitial growth of cartilage on the epiphyseal side of the epiphyseal plate and 2. Replacement of cartilage on the diaphyseal side of the epiphyseal plate with bone by endochondral ossification. ✓ Epiphyseal (growth) plate is a layer of hyaline cartilage in the metaphysis of a growing bone.  HUMAN SKELETAL SYSTEM ❑ Bone Formation ✓ Four Zones of the Epiphyseal Plate: 1. Zone of resting cartilage - nearest to the epiphysis and consists of small, scattered chondrocytes. Cells do not function in bone growth. Rather, they anchor the epiphyseal plate to the epiphysis of the bone. 2. Zone of proliferating cartilage - slightly larger chondrocytes in this zone are arranged like stacks of coins. These chondrocytes undergo interstitial growth as they divide and secrete extracellular matrix. 3. Zone of hypertrophic cartilage - consists of large, maturing chondrocytes arranged in columns. 4. Zone of calcified cartilage - the final zone of the epiphyseal plate is only a few cells thick and consists mostly of chondrocytes that are dead because the extracellular matrix around them has calcified.  HUMAN SKELETAL SYSTEM ❑ Bone Formation ✓ Four Zones of the Epiphyseal Plate: HUMAN SKELETAL SYSTEM HUMAN SKELETAL SYSTEM  HUMAN SKELETAL SYSTEM ❑ Repair of a bone fracture HUMAN SKELETAL SYSTEM HUMAN SKELETAL SYSTEM HUMAN SKELETAL SYSTEM  HUMAN SKELETAL SYSTEM ❑ Bones Role in Calcium Homeostasis 1. Bone is the major reservoir for calcium in the body. 2. Parathyroid hormone (PTH) secreted by the parathyroid glands increases blood Ca2+ level. Calcitonin (CT) from the thyroid gland has the potential to decrease blood Ca2+ level. Vitamin D enhances absorption of calcium and phosphate and thus raises the blood levels of these substances.  HUMAN SKELETAL SYSTEM ❑ Types of Bones: 1. Long bones 2. Short bones 3. Flat bones 4. Irregular bones 5. Sesamoid bones 6. Sutural bones  HUMAN SKELETAL SYSTEM ❑ Types of Bones: 1. Long bones Generally longer than wide. Have a shaft with heads at both ends. Contain mostly compact bone Examples: Femur, humerus 2. Short bones Generally cube-shape Contain more spongy bone than compact Examples: Carpals, tarsals  HUMAN SKELETAL SYSTEM ❑ Types of Bones: 3. Flat bones Thin and flattened like pancakes. Usually curved have two thin layers of compact bone sandwiching a layer of spongy bone Examples: Skull, ribs, sternum 4. Irregular bones Do not fit into other bone classification categories Irregular shape Example: Vertebrae  HUMAN SKELETAL SYSTEM ❑ Types of Bones: 5. Sesamoid bones Sesame seed like It protects the tendons from excessive wear and tear Example: Patella 6. Sutural bones Classified by location located in sutures (joints) Example: Cranial bones  HUMAN SKELETAL SYSTEM ❑ Divisions of the Skeletal System:  HUMAN SKELETAL SYSTEM ❑ Divisions of the Skeletal System:  HUMAN SKELETAL SYSTEM ❑ The Skull: 1. Cranial bones (8) ✓ form the cranial cavity which encloses and protects the brains. ✓ frontal bone, 2 parietal bones, 2 temporal bones, occipital bone, sphenoid bone, and ethmoid bone 2. Facial bones (14) ✓ forms the face. ✓ 2 nasal bone, 2 maxillae, 2 zygomatic bones, mandible, 2 lacrimal bodies, 2 palatine bone, 2 inferior nasal conchae, and vomer.  HUMAN SKELETAL SYSTEM ❑ Fontanels ✓ Fibrous cartilage between the cranial bones of the fetal skull. ✓ It allows the fetal skull to be compressed during birth and allow the infant’s brain to grow.  HUMAN SKELETAL SYSTEM ❑ Vertebral Column (26) ✓ Divided into five major regions: 1. Cervical vertebrae (7) ✓ neck region 2. Thoracic vertebrae (12) ✓ thoracic cavity 3. Lumbar vertebrae (5) ✓ lower back 4. Sacrum (1) ✓ Fused sacral vertebrae 5. Coccyx (1) ✓ Fused coccygeal vertebrae  HUMAN SKELETAL SYSTEM ❑ Intervertebral Discs(26): ✓ Found between the bodies of adjacent vertebrae from the 2nd cervical vertebra to the sacrum ✓ It consists of pads of elastic cartilage. ✓ Function: Cushion vertebrae and absorb shocks.  HUMAN SKELETAL SYSTEM ❑ Parts of a Typical Vertebra: 1. Vertebral Body 2. Vertebral Arch 3. Several Processes  HUMAN SKELETAL SYSTEM ❑ Parts of a Typical Vertebra 1. Vertebral body ✓ The thick, disc-shaped anterior portion, the weight bearing part of a vertebra. ✓ Anterior and lateral surfaces contain nutrient foramina. 2. Vertebral Arch a. Processes – 2 thick and short b. Pedicles – feet like projections c. Laminae – flat d. Vertebral foramen e. Vertebral (spinal) canal f. Vertebral notches g. Intervertebral foramen – stacked vertebral notches that permits passage of spinal nerve  HUMAN SKELETAL SYSTEM ❑ Parts of a Typical Vertebra 3. Several Processes (7) a. Transverse process (2) b. Spinous process (1) c. Superior articular processes (2) d. Inferior articular processes Intervertebral joints are the articulation formed between the vertebral bodies and articular facets.  HUMAN SKELETAL SYSTEM ❑ Cervical Vertebrae (C1-C7) ✓ Smaller than other vertebrae except those that form coccyx. ✓ Vertebral arches are larger. ✓ Vertebral foramen are larger a. Vertebral foramen b. Transverse foramen ✓ C1 (Atlas) is a ring of bone that lacks spinous process supporting the head and permiting movement. ✓ C2 (Axis) does have a vertebral body permitting side-to-side movement of the head.  HUMAN SKELETAL SYSTEM ❑ Thoracic Vertebrae (T1-T12) ✓ Long and slender spinous processes ✓ Rib facets  HUMAN SKELETAL SYSTEM ❑ Lumbar Vertebrae (L1-L5) ✓ large and sturdy bodies ✓ large, blunt, thick, short spinous processes  HUMAN SKELETAL SYSTEM ❑ Sacrum (S1-S5) ✓ five fused vertebrae ✓ posterior wall of pelvic cavity  HUMAN SKELETAL SYSTEM ❑ Coccyx (Co1-Co4) ✓ Tailbone ✓ Develop as 3-5 separate vertebrae, but fuse into 1 structure between the ages of 20-30 HUMAN SKELETAL SYSTEM  HUMAN SKELETAL SYSTEM ❑ Thoracic Bones 1. Sternum ✓ A typical flat bone and the result of fusion of three bones. a. Manubrium b. Body c. Xiphoid process ✓ Attached to the 1st seven pairs of ribs.  HUMAN SKELETAL SYSTEM ❑ Thoracic Bones 2. Ribs ✓ The 12 pairs of ribs form the wall of the thoracic cage. ✓ All ribs attach to vertebral column posteriorly a. True ribs - superior seven pairs of ribs attach directly to sternum by costal cartilage (1-7) b. False ribs – inferior five pairs of ribs (8-12) ❖ Have cartilages attachment to the sternum that are indirect or are not attached at all. ❖ Ribs 11–12 are known as floating ribs  HUMAN SKELETAL SYSTEM ❑ Divisions of the Skeletal System:  HUMAN SKELETAL SYSTEM ❑ Appendicular Skeleton 1. Pectoral Girdle a. Clavicle ✓ holds the arm away from the thorax. b. Scapula ✓ serves as a site of attachment for many muscles that move the arm and pectoral girdle  HUMAN SKELETAL SYSTEM ❑ Appendicular Skeleton 2. Upper limb a. Humerus b. Radius & Ulna c. Carpals d. Metacarpals e. Phalanges HUMAN SKELETAL SYSTEM  HUMAN SKELETAL SYSTEM ❑ Appendicular Skeleton 3. Pelvic (Hip) Girdle ✓ Formed of the two HIP bones and joined anteriorly at a joint called pubic symphysis. ✓ Each hip bone is formed of three parts : a. Ilium b. Ischium c. Pubis HUMAN SKELETAL SYSTEM  HUMAN SKELETAL SYSTEM ❑ Appendicular Skeleton 4. Lower Limb a. Femur - thigh b. Patella  HUMAN SKELETAL SYSTEM ❑ Appendicular Skeleton 4. Lower Limb c. Tibia and fibula d. Tarsals e. Metatarsals f. Phalanges  HUMAN SKELETAL SYSTEM ❑ Appendicular Skeleton 4. Lower Limb d. Tarsals e. Metatarsals f. Phalanges  HUMAN SKELETAL SYSTEM ❑ Aging and Bone Tissue ✓ The principal effect of aging is demineralization, a loss of calcium from bones, which is due to reduced osteoblast activity. ✓ The decreased production of extracellular matrix proteins (mostly collagen fibers), which makes bones more brittle and thus more susceptible to fracture. ✓ With aging, a decrease in synovial fluid, thinning of articular cartilage, and decreased flexibility of ligaments occur. ✓ Most individuals experience some degeneration in the knees, elbows, hips, and shoulders due to the aging process.  HUMAN SKELETAL SYSTEM ❑ Contribution of the Integumentary System ▪ For all the body systems 1.Bones provide support and protection for internal organs 2.Bones store and release calcium, which is needed for proper functioning of most body tissues.  HUMAN SKELETAL SYSTEM BODY SYSTEM CONTRIBUTION/S MUSCULAR ✓ Bones provide attachment points for muscles and leverage for muscles to bring about body movements ✓ Contraction of skeletal muscle requires calcium ions NERVOUS ✓ Skull and vertebrae protect brain and spinal cord ✓ Normal blood level of calcium is needed for normal functioning of neurons and neuroglia ENDOCRINE ✓ Bones store and release calcium, needed during exocytosis of hormone-filled vesicles and for normal actions of many hormones CARDIOVASCULAR ✓ Red bone marrow carries out hemopoiesis (blood cell formation) ✓ Rhythmic beating of the heart requires calcium ions DIGESTIVE ✓ Teeth masticate (chew) food ✓ Rib cage protects esophagus, stomach, and liver ✓ Pelvis protects portions of the intestines  HUMAN SKELETAL SYSTEM BODY SYSTEM CONTRIBUTION/S LYMPHATIC SYSTEM ✓ Red bone marrow produces lymphocytes,white blood cells that are and IMMUNITY involved in immune responses RESPIRATORY ✓ Axial skeleton of thorax protects lungs ✓ Rib movements assist in breathing ✓ Some muscles used for breathing attach to bones via tendons URINARY ✓ Ribs partially protect kidneys ✓ Pelvis protects urinary bladder and urethra REPRODUCTIVE ✓ Pelvis protects ovaries, uterine (fallopian) tubes, and uterus in females ✓ Pelvis protects part of ductus (vas) deferens and accessory glands in males ✓ Bones are an important source of calcium needed for milk synthesis during lactation INTEGUMENTARY ✓ Bones provide strong support for overlying muscles and skin