Skeleton (Skeletal Tissue/System (Types of bone (Spongy: Presents as a…
Functions: The skeleton serves to support our framework for soft connective tissue, assistance in locomotion, protection of major organs, storing minerals, forming blood, and storing energy.
Major structures: The skeleton can be divided into organic and inorganic material. The organic components are composed of bone (made up of osteocytes and extracellular matrix) and connective tissue. Inorganic materials consist of minerals. The skeleton is also divided regionally into the axial (thoracic cage and central nervous system) and appendicular system (pelvis and extremities)
Types of bone
Spongy: Presents as a porous type of bone with the processes being called trabecula. Spongy bone is more flexible compared to compact bone and allows blood to flow through.
Compact: Is a dense bone filled with organic extracellular matrix and inorganic salts. Compact bone makes up 80% of the skeleton.
Long: Long bone is composed of both spongy and compact bone. The ends of long bone are considered epiphyses while the shaft itself is the diaphysis. Long bones are also vascularized and has a cavity filled with yellow bone marrow called the medullary cavity. The periosteal is the connective tissue membrane that covers the bone.
Red bone marrow: The location that produces new blood cells and is highly vascularized.
Yellow bone marrow: Converted from red bone marrow, yellow bone marrow is made of primarily adipose tissue located in the medullary cavity.
Types of bone cells
Osteogenic cells: The stem cells that form into osteoblasts.
Osteoblasts: Produces that organic components that make up the extracellular matrix and later grow into osteocytes.
Osterocytes: Function to keep the bone matrix healthy.
Syndesmoses: This joint is held together by a ligament that has fibrous tissue that's longer than sutures.
Gomphoses: Fibrous joint that is a socket whose periodontal ligament holds the tooth.
Sutures: Found in the bone of the skull, uses short interconnecting fibers to connect bone edges.
Synchondroses: The use of hyaline cartilage that forms junctions such as epiphyseal plates and makes these joints immovable.
Symphyses: Firbocartilage that include intercertebral discs and the pubic symphysis of the pelvis.
Synovial joint components: The synovial joints consist of articular cartilage, articular cavity, articular capsule, synovial fluid, reinforcing ligaments, nerves and vessels, articular discs, and bursae and tendon sheaths.
Synovial joint types
Plane: Provides nonaxial movement supported by flat articular surfaces that provides gliding.
Ball-and-socket: Formed by a ball and socket, provides multiaxial movement that provides flexion, extension, adduction, abduction, and rotation.
Hinge: Provides uniaxial movement supported by a cylinder and a trough that allows flexion and extension.
Pivot: Uniaxial movement supported by a sleeve and axle that provides rotation.
Saddle: Biaxial movement supported by articular surfaces that has a concave and a convex that provides adduction, abduction, flexion, and extension.
Condylar: Biaxial movement supported by oval articular surfaces that provides flexion, extension, adduction, and abduction.
Functions: Skeletal muscle is able to produce movement, open and close body passageways, maintain posture, stabilize joints, and generate heat.
Properties: Skeletal muscle has the properties of being able to contract, extend,be able to recoil with elasticity, and receive nerve signals with excitability.
Connective tissue layers: Skeletal muscle has the other layer of irregular connetive tissue called the epimysium. The kayer below that covers fascicles is the perimysium. Endomysium is the loose connective tissue that covers the reticular fibers.
Components of skeletal fibers: Each skeletal muscle fiber is covered by a membrane called the sarcolemma that contains mitochondira, myofibrils, and nuclei. On each myofibril there are repretitive units called sarcomeres that have z-discs separating the units. Actin extends from the z-disc towards the center of the sacromere which overlaps with myosin that release energy required for muscle contraction. There are I bands, A bands, M lines, and H zones that distinguish various parts of the filament. Myofibrils are surrounded by sarcoplasmic reticulum. At the terminal cisterns at A-I junction there are T tubules that form deep invaginations that conduct impulses down the surface of the cell.