bone tissue

Describe intramembranous and endochondral ossification

-Intramembranous Ossification- Occurs in flat bones when a connective tissue membrane is replaced by bone. Sheet like layers, develop ossification center 1. Calcification 2. Formation of trabecular 3. Development of periosteum -Endochondral Ossification- Replaces cartilage with bone in the developing embryo and fetus. Bone formed in hyaline cartilage. 1. Cartilage 2. Growth of cartilage 3. Develop medullary cavity 4. Development secondary ossification centers.

Why is cartilage white? Know the 3 types of cartilage and where they are found.

-No blood vessels or nerves. -Hyaline- Articular cartilage- covers ends of long bones, Costal cartilage- ribs to sternum, -Respiratory cartilage-larynx, trachea, Nasal cartilage. -Elastic- elastic fibers, external ear, epiglottis -Fibrocartilage- compressible (menisci of the knee, intervertebral discs.

Know the four types of cells present in bone tissue and their function

-Osteoprogenitor cell- bone stem cells able to differentiate into the other types of cells. -Osteoblasts- bone building cells that synthesize & secrete collagen fibers & ground substance for matrix. They initiate calcification and get trapped in secretions and become osteocytes. -Osteocytes- mature bone cells that are responsible for maintaining daily metabolism and exchanging nutrients with blood. They do not undergo mitosis. -Osteoclasts- remodel bones and cause them to release calcium. They are usually in the Endosteum and are a type of monocyte (WBC). They respond to low blood Ca levels and bone stressors to release enzymes and acids that digest and break down bone. (These cells are target for the treatment of osteoporosis)

Know the blood and nerve supply of bone

-Periosteal arteries (accompanied by nerves) enter the diaphysis through Volkmann's canals. They are accompanied by periosteal veins. -A nutrient artery enters the center of the diaphysis through a nutrient foramen. -Nutrient veins exit via the same canal. The metaphyses and epiphyses also have their own arteries and veins.

List and describe the major functions of the skeletal system

-Provides support as a framework for soft tissues and attachment for skeletal muscles. -Protects internal organs (brain, heart, lungs) -Assists body movement (muscles allow the bones to function as levers) -Mineral homeostasis- stores and releases calcium and phosphorus between bone tissue and blood. You have to have calcium to have any nervous system function. Has an ionic matrix for strength. -Participates in blood cell production (hemopoiesis) (red bone marrow, yellow marrow is fat housed in long bones) -Blood cell production (hemopoiesis) in red bone marrow of RBC's, WBC's, and platelets.

Define skeletal system. Know that bones, ligaments, and cartilage make up the skeletal system. what attaches to what.

-The entire framework of bones and their cartilage constitute the skeletal system. -Cartilage covers ends of bones -Ligaments attaches bone to bone -Bone is an organ made up of several tissues (bone, cartilage, dense connective tissue, adipose, and nervous tissue) working together.

how are fractures repaired or treated

A fracture is a break in bone. Many different types of fractures may occur. The healing process involves 3 different phases in 4 steps. The reactive phase is an early inflammatory phase that includes hematoma formation The reparative phase includes formation of a fibrocartilageinous callus first and a bony callus second The bone remodeling phase is that last step as the bony callus is remodeled Treatment Reduction- bring fractured ends into alignment. Closed reduction- skin intact, bring fractured ends into alignment by manual manipulation. Open reduction- surgery to align fracture with screws, plates, pins, rods, and wires. Immobilize patient with cast, sling, splint, elastic bandage, etc.

Describe the roles of bones in calcium homeostasis. Know the hormones involved and their function

Bones store 99% of the bodies Ca2+ Parathyroid hormones (PTH) Vit-D Calcitonin(CT) Negative Feedback system (Low blood calcium) ↓ Stimulates release of PTH into blood stream ↓ Activates osteoclasts which ↓ releases Ca2+ into blood stream High Blood Calcium ↓ Stimulates release of Calcitonin into blood stream ↓ Osteoblasts build bone ↓ And Ca2+ is stored in bone matrix ↓ This lowers Ca2+ in blood

Describe bone remodeling and the cells involved. What factors affect bone growth and remodeling?

Bones thicken thanks to the cooperative action of osteoblasts and osteoclasts. Growth in thickness- Osteoblasts add to surround surface of bone and the bone grows in diameter. As osteoblasts deposit bone on the outer surface osteoclasts widen the medullary cavity from within. Osteoclasts- Dissolve bone (monocyte), use enzymes and acids, Ca, minerals, into blood, resorption, chewers. Osteoblasts- Lay down bone, store ca minerals in bone, builders. As a response to mechanical stress Traebeculae form along lines of stress, Large, bony projections occurs where heavy, active muscles attach.

Describe compact and spongy bone. Know the difference between them and where the two types are located in the skeletal system.

Compact bone- is good at providing protection and support (thick part of femur & humerus) Composed of osteons. Diaphysis aligned with directions of stress, associated with long bones. Strongest of the bone types, protects, supports, resists stress. 80% of skeleton is compact bone. Spongy bone- is light weight and provides tissue support (bones that contain a lot of red bone marrow, humerus, femur) 20% of bone is spongy, Includes short, flat, and irregular bones, interior of epiphyses in long bones. Lightens bones.

Label the structures of a long bone

Diaphysis (bone shaft) 2 epiphyses (both ends of the bone at the joints) Articular cartilage covering both epiphyses Periosteum (connective tissue surrounding the diaphysis) outer coving of bone Medullary cavity (hollow space within diaphysis) contains yellow bone marrow that is fat Endosteum (thin membrane lining the medullary cavity) contains red bone marrow

Be able to describe how bones grow in length and thickness

Endochondral ossification also occurs in epiphyseal plates of long bones as they grow in length (Zones of stem cells) Epiphyseal plate Zone of resting cartilage Zone of proliferating cartilage Zone of hypertrophic cartilage Zone of calcified cartilage

Describe red bone marrow, its function, the cells found in it, and where in the skeletal system red bone marrow is found.

Is a net of reticular fibers, Bone marrow is a spongy substance found in the center of the bones. It manufactures bone marrow stem cells and other substances, which in turn produce blood cells. Red blood cells carry oxygen to tissues in the body. Found in pelvis, ribs, sternum, vertebrae, skull, ends of long bones.

how fractures are classified

Position of bone ends after fracture, completeness of break, orientation of bone to long axis, wether the bones ends penetrate the skin.

Know the effects the sex hormones have on bone growth

Testosterone, estrogen, and progesterone slow the resorption of old bone by slowing osteoclast function, boost new bone deposit by speeding osteoblast function. (Menopause)

functions of calcium in the body

Transmission of nerve impulses, myocardial contractions, blood clotting, formation of teeth and bone, and muscle contractions.

Describe extracellular matrix

is about 15% water, 30% collagen, and 55% crystalized mineral salts.