Understanding the Skeletal System: Functions, Composition, and Growth
The skeletal system plays a crucial role in supporting body structure and shape, protecting vital organs, enabling movement, storing minerals, and facilitating blood formation. Composed of osseous tissue, it undergoes ossification throughout life, where cartilage is replaced by bone. Bone composition includes compact and cancellous types, while osteoblasts, osteocytes, and osteoclasts contribute to bone maintenance. Key factors for proper bone formation include calcium, phosphorus, and vitamin D. The skeletal system consists of long, short, flat, irregular, and sesamoid bones, all functioning together to provide structural integrity.
Understanding the Skeletal System: Functions, Composition, and Growth
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Presentation Transcript
Functions • Support: body structure and shape • Protection: vital organs surrounded • Movement/Anchorage of Muscles • Mineral Storage: calcium & phosphorus • Blood Formation
Formation and structure • Composed of connective tissue called osseous tissue and rich supply of blood vessels and nerves • Osseous tissue is composed of : _______________
Bone Formation • Skeleton fully formed by 2nd month of fetal development (all cartilage) • Ossification (replacement of cartilage with bone cells and calcium salts) begins after 8th week of fetal development • Childhood and adolescence: ossification ______ bone loss • Early adulthood through middle age: ossification ______ bone loss • After age 35: bone loss _______ ossification
Bone Formation/Ossification Ossification: replacement of cartilage with bone • Cells: • osteoblast: produce immature bony tissue that replaces cartilage (the “builders”) • osteocyte: nourishes and maintains bone • osteoclast: reabsorb or digest bone (the “remodelers”) • Osteoblasts and osteoclasts work to deposit and tear down bone throughout life
Bone Growth • Grow in length at the epiphyseal line • Grow in width by addition of bone to the surface • Controlled by anterior pituitary (GH)
Bone Composition • Proper formation of bone depends on sources of calcium, phosphorous, and vitamin D. • Vit. D helps with absorption of ________ • Once Calcium and phosphorous are in the blood osteoblastic activity forms the enzyme Calcium phosphate • Calcium phosphate: gives bone its characteristic _________________ • Collagen: chief organic constituent (protein)
Bones (cont’d.) • Bone is the reservoir for calcium storage • Calcium necessary for nerve transmittal to muscle When insufficient, it interferes with nerve transmission causing muscle weakness and spasms • Ca level maintained by the _______________, which secretes a hormone to release calcium from bone
Types of Bones Based on Composition • Compact • Cancellous
Compact Bone (Cortical) • Dense, Stress Bearing • Haversian Systems: system of small canals which contain blood vessels that bring _____and _____ to bone and remove waste products • Medullary cavity: central shaft of long bone composed of _______ marrow (stores fat cells)
CancellousBone (spongy/trabecular) • Light, spongy • Found at ____________, ribs, sternum, hips, vertebrae, cranium spaces • Contain red bone marrow with elements for blood formation
Bone Markings - Purpose • Join one bone to another • Provide a surface for attachment of muscles • Create an opening for passage of blood vessels and nerves • Use as landmarks
Major types of Bone Markings •Processes/Projections: serve as attachments for muscles and tendons • Depressions: openings or hollow regions help join bones or serve as passageways __________________ • Ridges - ____________________
Bones by Shapes Reference: Gerdin, Judith. Health Careers Today. 3rd edition. Mosby, 2003
Extremities (Femur, tibia, fibula, humerus, ulna, radius, clavicle Act as ______ Epiphysis: at the _____; covered with hyaline cartilage for articulating bones (provides ______); cancellous bone Epiphyseal line or plate: growth plate Diaphysis: shaft, covered with periosteum, contains ______bone marrow Medullary cavity – located in the shaft of a long bone. This cavity is surrounded by compact bone and lined with endosteum and contains _______ bone marrow Metaphysis: flared portion of the bone Long Bones
Periosteum • Dense, fibrous membrane covering bone • Contains blood vessels • Essential for bone cell survival and bone formation
Bone Structure (cont’d.) (A) Divisions of a long bone and interior structure (B) composition of compact (cortical) bone
Short Bones • _____-shaped • Allows ____________ • Cancellous bone covered by compact bone • Carpals, metacarpals, tarsals, metatarsals, phalanges
Flat Bones • Flat plates • Protect ____________ • Provide broad surface area for attachment of ________ • Cranial bones, Facial bones, Scapula, Sternum
Irregular Bones • Peculiarly shaped to provide support and protection with ____________ • Vertebrae, Ribs, Ear, Hip, Hyoid • Includes Sesamoid bones
Sesamoid Bones • Extra bones found around ________i.e. Patella
CARTILAGE • Smooth, rubbery, white connective tissue • Acts as a _____________ between bones • Makes up the flexible parts of the skeleton as well as the ____________________ • ___________– covers the surfaces of the bones that form joints • __________– curved, fibrous cartilage found in some joints (knee and jaw)
JOINTS • _________ – jagged lines where bones joint that does not move (top of an adult’s skull – coronal /Sagittal sutures) • __________ –Cartilaginous joint –2 bones join and are held firmly together; function as one (pelvic symphyses) • ______________– movable • Ball and socket (hip) • Hinge (knee, elbow)
Bursae • Closed sacks of synovial fluid with a synovial membrane located near, but not within a joint. Needed where sliding must take place • Common sites: • between tendons (connective tissue connecting muscle to bone) and bones • between ligaments (binding bone to bone) and bone • between skin and bones (with prominent bony anatomy)
SKELETON • AXIAL SKELETON (80 BONES) • Skull • Spinal Column • Ribs • Sternum • APPENDICULAR SKELETON (126 bones) • Upper extremities • Lower extremities
Skull - Cranium • Houses and protects the brain • _______: forms forehead • ________: forms roof of nasal cavity • _______right & left; form sides and roof of skull • ________: right & left; forms temple, cheek, ear openings
_______: back of skull; inferior portion has foramen magnum (opening for spinal cord) and 2 condyles to articulate with atlas • _________: fills space between orbital plates; depression called sella turcica holds the pituitary gland; bat shaped
Cranial Sutures • Unite the bones of the cranium • As the child grow, irregular bands of connective tissue ossifies and turns into hard bone
Sutures • _________Suture: between the frontal and parietal bones • _________ Suture: between right and left parietal bones • ________Suture: between the parietal and occipital bones • _________ Suture: between temporal and parietal bones
Fontanels • Fusion of the cranial bones is not complete at birth • Space between the bones remains • Anterior (Bregmatic): “soft spot”, closes at ___months • Posterior (Occipital): triangular, closes at _____ months
Facial Bones Continued • ______ (2): cheek bones • ______ (2): small bones form medial wall of each eye socket • _______ (2): forms back roof of mouth and floor of nose • ________(2): forms curved ledge inside side wall of nose
Ear Bones • Malleus (2): the hammer • Incus (2): the anvil • Stapes (2): the stirrup
Hyoid Bone • U-shaped bone • In neck • At base of tongue • Only bone in body that does NOT articulate with another bone
SPINAL/VERTEBRAL COLUMN • 26 Vertebrae • Five divisions • C1 to C7 = Cervical • T1-T12 = Thoracic • L1-L5 = Lumbar • Sacrum (5 bones fuse when young) • Coccyx (4 bones fused together)
Functions • Supports trunk and _____. • Protects ____________ • Multiple joint spaces allow for ______ and twisting
BONES OF THE THORACIC CAVITY • RIBS – 12 pairs, called ______ (first 7 = true, RIBS 8-12 = false ribs; last 2 pairs = floating) • _________– breast bone • Manubrium • Body • Xiphoid process (cartilage)
Functions • Protect and support heart and ______ • Supports bones of pectoral girdle • Plays leading role in ________ • Ribs and sternum aid in RBC formation
Shoulder Girdle • Clavicles (2): collar bones • ________(2): shoulder blades • Acromion: extension of the scapula/high pt
Upper Extremities • Humerus: ____________ • Radius: _____side of forearm • ______: little finger side of forearm • Olecranon process (funny bone)
WRISTS AND HANDS • Carpals (8) = ______ • Metacarpals (5) = _______________ • ______ (14) = fingers • Distal • Medial • Proximal
Os Coxae (2): contains the acetabulum (hip socket) 3 components: _________ – upper blade of the pelvic girdle Sacroiliac – slightly moveable articulation betw. sacrum and ilium Ischium – ______, posterior portion Also, contains the sacrum PELVIC GIRDLE
LOWER EXTREMITIES • Femur: ________ • Patella: kneecap • Tibia: _________ • Fibula: lateral bone of lower leg