Skeletal System: Tissue and physiology Skeletal tissue is the most distinctive form of connective tissue. Chapter 7 Notes

Functions of Skeletal Tissue  Support Ex. Arch of foot, vertebral column, etc.  Protection Ex. Skull protects the brain, rib cage protects lungs and heart.  Movement Occurs with the help of joints - act as levers Muscle contraction pulls on bones = movement

Functions of Skeletal Tissue  Mineral reservoir o Calcium o Homeostasis of blood calcium levels  Hemopoiesis - blood cell formation oOccurs in red bone marrow »chest »spinal column in adults »base of skull »upper arm and thigh »In infants or child, all bone marrow is red. ADULTS

Bone Shapes Long boneLong bone - consists of 6 parts. Ex. femur, humerus Short boneShort bone - ex. Carpals = fingers and toes Flat BoneFlat Bone – scapula = back (shoulder blade) Irregular boneIrregular bone - vertebrae

Structure of Long Bone Diaphysis –Main shaft –Strong support –Hollow = decrease in weight

Structure of Long Bone Epiphysis –Ends of long bone –Bulbous shape allows for muscle attachment and gives stability to joints –Contains spongy tissue contains marrow - red or yellow Spongy bone Compact bone

Structure of Long Bone Articular cartilage –Covers joint surface of epiphysis –Cushions jars and blows

Structure of Long Bone Periosteum –Dense fiberous membrane –Covers bone except at joints –Tedons interlace with and anchor muscles –Contain many blood vessels (connects with haversian canal) –Osteoblasts (bone forming cells) compose inner layer

Structure of Long Bone Medullary Canal –Tube of diaphysis –Contains marrow Endosteum –Membrane –Lines medullary cavity of long bone

Long Bone Anatomy l

Haversian System Identifies microscopic structure of compact bone in the diaphysis

Haversian System Structure Lamellae (Lah-Mel-e) –cylinder shaped layers of calcified matrix (non-living) Lacunae (la-Kew-nah) –small spaces –contains tissue fluid where bone cells (osteocytes) live –imprisoned between lamellae

Haversian System Structure Canaliculi (Ka-NALi-ku-li) –ultra small canals –radiates out from lacunae to connect each other –connects also to haversian canal Haversian canal –Contains blood vessels and lymphatic tissue –Gives nutrients to lacunae through canaliculi –Gives nutrients to osteocytes

Haversian System

Bone Development and Growth Osteogenesis - the process of bone formation –At 12 weeks the skeleton has formed-made of cartilage and fibrous tissue.

Bone Development and Growth Fontanels - "soft spots" of an infant's skull

Osteogensis Intramembranous Development –Prebone structure of skull and mandible –Takes place within connective tissue –Connective tissue enlarges to form osteoblasts - bone forming cells. –Bone matrix is formed –Matrix is calcified by deposits of calcium and salts. –Flat bones grow by adding to their outside borders.

Osteogensis Continued Endochondral (all other bones) –Begin as cartilage –Cartilage develops periosteum - enlarges into a ring –Cartilage calcifies –Ossification, hardening of bone, progresses toward each epiphysis. (involves addition of Ca+ and Phosphorous ions) –During bone growth, ephiphyseal cartilage remains between ends and shaft = growth plate.

Osteogensis Continued Major stages (a-d fetal, e child, f adult) in the development of the endochondral bone.

Bone Growth Diameter –Osteoclasts - enlarge diameter of medullary cavity by eating away wall. –Osteoblasts - build new bone at periosteum –Occurs throughout life bone/bone5.htm

Bone Growth Continued Childhood –Bone ossification is greater than bone resorption (decomposition) = taller Adulthood –Bone ossification and resorption equal one another. –At 35-40, bone ossification decreases and resorption is greater. Become hollow Vertebrae collapse = height decrease Brittle bones = death

Bone Growth on.aspx?gcid=000112&ptid=17

Bone marrow aspiration, direct removal of a small amount (about 1–5 millilitres) of bone marrow by suction through a hollow needle.bone marrow

Bone Fracture Bone Fracture - break in continuity of bone. –Types Simple - skin remains unbroken Compound - broken ends protrude through skin –Easily infected - osteomyelitis

Bone Fractures Continued A complete fracture is when the bone has broken into two pieces. A greenstick fracture is when the bone cracks on one side only, not all the way through. A single fracture is when the bone is broken in one place. A comminuted (say: kah-muh-noot-ed) fracture is when the bone is broken into more than two pieces or crushed. A bowing fracture, which only happens in kids, is when the bone bends but doesn't break An open fracture is when the bone is sticking through the skin.

Bone Fractures Continued

Repair - fracture healing –Damage to blood vessels begins repair sequence. –Dead bone is removed by osteoclasts-resorption. –Osteoclasts used as framework for repair tissue called callus. –Callus tissue bonds broken ends of bone outside. –Callus tissue binds medullary cavity. –Callus tissue is molded and replaced with bone. Electrically induced osteogenesis - uses electrical stimuli to heal fractures.

Bone Fractures Continued Major steps in the repair of a fracture.

Osteoporosis Loss of calcified matrix & callogenous fibers. Occurs most frequently in elderly, white females. Decrease levels of estrogen and testosterone. –Decreased osteoblast activity –Decreased maintenance of existing bone Bone Degeneration –Spontaneous fractures –Curvature of the spine Treatment –Estrogen therapy - after menopause –Dietary supplement of calcium and vitamin D.

Cartilage Cartilage - connective tissue –Types Hyaline Elastic Cartilage Fibrocartilage

Hyaline Most abundant Semi-transparent- bluish, opalescent Covers articular surface of bone Forms ends of ribs that join to sternum Forms rings in trachea, bronchi of lungs, & nose

Elastic Cartilage Elasticity and firmness Fibers form to external ear, epiglottis, tubes in ear, nasal cavity Yellowish in color

Fibrocartilage Greatest tensile strength Intervertebral disks, point of attachment of some large tendons to bones.

Structure of Cartilage Chondrocytes - cartilage cells. Avascular - contain no blood vessels. –Receive oxygen and nutrients through diffusion. Increase of collagenous fibers and matrix embedded in a gel (not calcified).

Function of Cartilage Shock absorption Resists collapse of passageways Allows bone growth