Skeletal system Flashcards
Functions of the skeletal system
- Supports and gives shape to the body
- protects internal organs (ex. ribcage, pelvis, skull)
- helps make movements possible when bones at movable joints are pulled by muscles
- stores calcium - too much in the blood -> stored in bone, not enough calcium -> takes from bone
- hematopoiesis - blood cell formation in red bone marrow
5 shapes of bones
- long bones (ex. femur, humerus)
- short bones (ex. carpals- wrists)
- flat bones (ex. skull)
- sesamoid (ex. patella - knee cap)
- irregular (vertebra)
Anatomy of a long bone
- Diaphysis (hollow shaft of hard, compact bone - main part of the bone)
- Epiphysis (end of a bone, spongy bone that contains red bone marrow)
- Metaphysis (cone like flared portion between end and shaft)
- Epiphyseal line or plate growth plate where cartilage replaced by bone for bone growth in length. Line in adult bones and plate in children’s)
- Articular cartilage (covers epiphyses and acts like a cushion)
- Periosteum (outer layer of the bone, very hard)
- Endosteum ( inner lining of the bone cavity)
- Medullary cavity (hollow space in the diaphysis that contains yellow bone marrow)
Compact bone
Hard bone, contains haversian systems for blood vessels, nerves and yellow bone marrow (mostly fat)
Cancellous
Spongy/trabecular bone, spaces contain red bone marrow with elements for blood formation
Anatomy of a flat bone
- Spongy (cancellous) bone layer sandwiched between two compact (hard) bone
Yellow vs red bone marrow
Yellow - mostly fat, fills the hollow of the diaphysis
Red - rich with blood vessels and immature and mature blood cells; later in life replaced with yellow marrow . Hematopoiesis. Found in the cancellous bones of the epiphyses of long bones and flat bones
What is trabeculae?
Needlelike threads of bones surrounded by a network of open spaces (spongy, cancellous or trabecular bones). Usually found in epiphyses of bones and contains red bone marrow
What are osteons?
Structural units of hard bones/compact bones. Calcified matrix arranged in multiple layers or rings called Concentric lamella. Bone cells are called osteocytes and are found inside spaces called lacunae
Cartilage
- Cell type called chondrocyte
- Matrix is gel-like and lacks blood vessels
What is endochondral ossification?
Replacement of cartilage with bone
What are osteoblasts?
Produce immature bony tissue that replaces cartilage (BUILDS BONES)
What are osteoclasts?
Reabsorb or digest bone (remodels bone) (BREAKS DOWN BONE/COLLAPSE)
What are osteocytes?
Nourishes and maintains bone. Bone cells (inactive osteoblast)
What is ossification?
The process of of depositing and tearing down bone throughout life
Calcium
- The skeleton is a source of calcium.
- Proper formation of bone depends on sources, phosphorus and vitamin D
- Calcium is necessary for nerve transmittal to muscle, including heart muscle and muscles attached to bones
What does the parathyroid gland do in bone formation? What does the thyroid gland do?
Parathyroid - secretes a hormone to release calcium from bone.
Thyroid - decreases blood calcium and stores it in blood and stores it in bone
What is a bone process?
Serves as attachments for muscles, tendons and ligaments
What are depressions?
Openings or hollow regions help join bones or serve as passageways for nerves and/or vessels
What are the 2 divisions of the skeleton?
- Axial skeleton (skull, spine, thorax and hyoid bone)
- Appendicular skeleton (upper extremities and lower extremities)
What are sinuses?
Air cavities located in facial and cranial bones lighten the skull and warm and moisten the air as it passes into the respiratory system
What are vertebrae?
- 26 bone segments from base of skull to tailbone in 5 divisions and separated by pads of cartilage called intervertebral disks
- Cervical, thoracic, lumbar, sacral and coccyx
What bones are in the thorax?
- Clavicle (collarbone)
- Scapula (shoulder)
- Sternum
- Ribs
What bones are in the arm and hands?
- Humerus
- Ulna
- Radius
- Carpals
- Metacarpals
- Phalanges
