FelixNyasimiSkeletal/tissues/jointsandskeletalmuscle.
Skeletal system/tissues
FUNCTIONS 1. Support and protection 2. Movement 3. Storage of mineral and energy reserves. 4. Hemopoiesis.
COMPONENTS 1. Bones 2. Cartilages 3. Ligaments 4. Other connective tissues
Compact bone structural features
Dense or cortical bone
Relatively dense connective tissue
Appears white, smooth, and solid
80% of bone mass
Spongy bone structural features
Cancellous or trabecular bone
Located internal to compact bone
Appears porous
20% of bone mass
Long bone
Proximal epiphysis
Metaphysis
Diaphysis
Distal epiphysis
Red bone marrow or myeloid tissue
Hemopoietic (blood cell forming)
Reticular connective tissue, immature blood cells, and fat
In children it is located in spongy bone and medullary cavity of long bones.
In adults it is located only in selected areas of the axial skeleton: skull, vertebrae, ribs, sternum, ossa coxae, proximal epiphysis of humerus and femur.
Yellow bone marrow.
Product of red bone marrow degeneration as children mature
Fatty substance
May convert back to red bone marrow
Bones cells.
Osteoprogenitor cells
Osteoblasts
Osteocytes
Osteoclasts
Joints
Fibrous joints
Cartilaginous joints
Synovial joints
Bones held together by dense connective tissue
Bones joined by ligaments with fluid-filled joint cavity separating bone surfaces.
Bones joined by cartilage
Connected by dense regular connective tissue
Have no joint cavity
Immobile or only slightly mobile
Either hyaline cartilage or fibrocartilage between bones
Lack a joint cavity
Immobile or slightly mobile
Synchondroses or symphyses
Plane joint
Pivot joints
Condylar joints
Saddle joints
Ball-and-socket joints
Articular surfaces flat
Simplest, least mobile synovial articulation
Uniaxial: limited side-to-side gliding movement in a single plane
Hinge joints
Convex surface within concave depression
Uniaxial
Bone with rounded surface fits into ligamentring.
Uniaxial joint
Oval, convex surface articulating with concave surface.
Biaxial
Convex and concave surfaces resembling saddle shape.
Biaxial
Spherical head of one bone fitting into cup like socket.
Multiaxial, permitting movement in three planes.
The most freely mobile type of a joint
Skeletal muscle Functions.
Body movement
Maintenance of posture
Protection and support
Regulating elimination of materials
Heat production
Properties of skeletal muscle
Excitability: ability to respond to a stimulus by changing electrical membrane potential
Conductivity: involves sending an electrical change down the length of the cell membrane
Contractility: exhibited when filaments slide past each other
Elasticity: ability to return to original length following a lengthening or shortening
Extensibility: ability to be stretched
Connective tissue layers.
Epimysium: Dense irregular connective tissue wrapping whole muscle.
Perimysium: Dense irregular connective tissue wrapping fascicle and houses many blood vessels and nerves.
Endomysium: Areolar connective tissue wrapping individual fiber and it is delicate layer for electrical insulation, capillary support, binding of the neighbouring cells.
Components of skeletal fiber
Sarcoplasm (cytoplasm): Has typical organelles plus contractile proteins and other specializations.
Multiple nuclei (individual cells are multinucleated): Cell is formed in embryo when multiple myoblasts fuse.
Sarcolemma (plasma membrane): Has T-tubules that extend deep into the cell.
Components of neuromuscular junction.
Synaptic cleft
Synaptic knob
Motor end plate
The expanded tip of axon terminal
Contains synaptic vesicles filled with neurotransmitter acetylcholine.
Has Ca2+ pumps and channels embedded in plasma membrane
Specialized region of sarcolemma under the synaptic knob
Has numerous folds
Has vast numbers of acetylcholine receptors
Narrow fluid-filled space
Separates synaptic knob and motor end plate
Contains acetylcholinesterase for the breakdown of acetylcholine molecules