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Chapter 5. the Skeletal System. Divided into: the axial skeleton - forms the longitudinal axis of the body the appendicular skeleton - bones of the limbs and girdles. Also includes joints, cartilages, and ligaments. Functions. support protection movement
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Chapter 5 the Skeletal System
Divided into: • the axial skeleton- forms the longitudinal axis of the body • the appendicular skeleton- bones of the limbs and girdles. • Also includes joints, cartilages, and ligaments.
Functions • support • protection • movement • storage- fat and minerals (Ca2+) and P • blood cell formation- hematopoiesis • Occurs within bone marrow cavities of certain bones
Structure of the Long Bone • Diaphysis- shaft, most of bone’s length, compact bone. • Periosteum- fibrous connective tissue that covers and protects the diaphysis. • Epiphysis- ends of the long bone; thin layer of compact bone encloses spongy bone; covered with hyaline cartilage.
Structure of the Long Bone • Epiphyseal plate- a flat plane of hyaline cartilage that allows lengthwise growth. After puberty, this is replaced with bone and is called the epiphyseal line. • Medullary cavity- cavity of the diaphysis; is primarily a storage area for adipose (fat) tissue in adult bones; called yellow marrow. In infants, these areas form red blood cells and are called red marrow. In adult bones, red marrow is found the spongy bone of flat bone and the epiphyses of some long bones.
More background information • The adult skeleton is composed of 206 bones • 2 types of bone tissue: • Spongy – spiky, open pockets • Compact – very dense
Four Groups of Bones • Long • Short • Flat • Irregular
Microscopic Anatomy • Osteocytes – mature bone cells found within the matrix in tiny cavities called lacunae
The lacunae are arranged in concentric circles called lamellae around central (Haversian) canals
Each complex consisting of central canal and matrix rings is called an osteonor Haversian systemHaversiancanals, are interconnected with one another via Volkmann's canals and contain a blood vessel, a nerve and a lymph vessel.
Tiny canals, canaliculi, radiate outward from the central canals to all lacunae.The canaliculi form a transportation system that connects all the bone cells to the nutrient supply through the hard bone matrix.
Volkmann’s canals, are perforated areas which run into the compact bone at right angles to the shaft.These canals provide communication between the outside of the bone to its interior.
The calcium salts deposited in the matrix give bone its hardness, which resists compression. • The organic parts (especially the collagen fibers) provide for bone’s flexibility and great tension strength. • What does organicmean ? • Containing carbon
Do you know the parts in a micrograph? Haversian Canal Canaliculi Lamellae Lacunae