Skeletal System - The body Flashcards
Bone constitution
Living & calcified connective tissue
Has an intercellular calcified matrix with collagen fibers
Is vascular and innervated
There is 1 nutrient artery per bone that enters to the spongy bone
Covered externally by a fibrous connective tissue membrane (periosteum) except for where joint because there’s cartilage
Periosteum can form new bone
Nerves also accompany the vessel that supply the bone and the periosteum (vasomotor fibers for blood flow)
Bone has few sensory
Periosteum has lots of sensory and is sensitive to injury
Bone function
Supportive structures for the body
Protects vital organs
Calcium and phosphorous storage
Levers for muscles to produce movement
Containers for blood-producing cells.
Cartilage constitution
Extracellular fibers embedded in a matrix that have cells that are localized in small cavities
Heavy weight-bearing areas will have lots of collagen to make the cartilage touch
Light weight-bearing areas will have less collagen and more elastic fibers instead
Is full nourished by diffusion (avascular)
Cartilage function
Support soft tissues
Provide a smooth, gliding surface for bone articulations at joints
Enable the development and growth of long bones
Bone types
Compact (trabecular) bones
Spongy (cancellous) bones
Compact (trabecular) bones
The outer shell of all bones that surrounds the spongy type.
Spongy (cancellous) bones
The spicules of bones that enclose cavities containing marrow (blood-forming cells)
Classification of bones by shape
Tubular = long bones
Cuboidal = short bones
Flat bones = two compact bone plates separated by spongy bone
Irregular bones = various shapes
Sesamoid bones = round or oval and they develop in tendons.
Explain how bone tissue is broken down and rebuilt
Continuous process known as bone remodeling, maintains bone strength and repairs microdamage. Also keeps mineral homeostasis
Osteoclasts digest old bones by secreting acid
After some mononuclear cells appear on the surface preparing for new bone formation and look for osteoblast precursors
Osteoblasts lay down new bone matrix that is then over time ossified
Understand how bone grows
Two main mechanisms
Regulated by hormones, nutrition, physical activity and mechanical stress.
/ 2 extra mechanisms
Intramembranous ossification (flat bone formation)
Mesenchymal cells differentiate into osteoblasts
Ossification centers form where osteoblasts secrete osteoid
Osteoid calcifies into bone matrix
Trabecular bone is developed, which then becomes compact.
Endochondral ossification (lone bone growth and development)
Hyaline cartilage model formed
Cartilage matrix in the diaphysis is calcified
Blood vessels bring osteoclasts and blasts
Calcified cartilage becomes spongy bone
Longitudinal bone growth
Grow bones in length on the epiphyseal growth plate
Basically make cartilage cells and then ossify.
Appositional growth
increasing bone growth in diameter (complex)
Red marrow (myeloid tissue)
Erythrocytes (red blood cells), platelets and white blood cells from red marrow
Body is mostly red marrow at birth, as ages it becomes yellow (especially in medulla of long and flat bones)
Yellow marrow
Some white cells are made. Dominated by FAT globules
Hemopoietic stem cells
rise white blood cells, red blood cells and platelets
Mesenchymal stem cells
differentiate into structures that form bone, cartilage and muscle.
Synovial joints (separated by a cavity)
Narrow articular cavity
Have a layer of hyaline cartilage covering skeletal elements (dont touch each other)
Joint capsule with an inner synovial membrane and an outer fibrous membrane.
Synovial membrane (synovial)
Highly vascular and produces synovial fluid. Lubricating the movement.
Closed sacs of the membrane occur on outside joins where they form “synovial bursae” or “tendon sheaths”
intervene between structures to reduce the friction of one structure moving over the other.
Fibrous membrane (synovial)
Dense connective tissue
Stabilizes the joint
Can thicken to form ligaments
Additional structures (synovial)
Articular discs = can absorb compression and adjust to changes during movement.
Fat pads = move into and out of regions.
Tendons.
Solid joints (held together by connective tissue)
Linked together by fibrous connective tissue or cartilage usually fibrocartilage
Sutures (fibrous joint)
Skull, where adjacent bones are linked by a thick layer of sutural ligament connective tissue
Fibrous joint (solid joint)
Sutures
Gomphoses
Syndesmosis
Gomphoses (fibrous joint)
Between teeth and adjacent bone (short collagen tissue fibres run between root of tooth and bony socket)
Syndesmosis (fibrous joint)
Two adjacent bones are linked by a ligament. (i.g ulna and radius in forearm)
Cartilaginous (solid joints)
Synchondroses
symphyses
Synchondroses (cartilaginous joint)
Two ossification centers in a developing bone are separated by a layer of cartilage. Allow bone growth and complete ossification occurs eventually.
Symphyses (cartilaginous joint)
Two separate bones are interconnected by cartilage
Usually midline and pubic symphysis.
