Chapter 6 A&P

Osteoblasts

Bone- building cells. They synthesize and secrete collagen fibers and other organic components needed to build an extra cellular matrix of bone tissue

What are the 4 steps in the repair of a bone fracture. What is meant by the reduction of a fracture?

1.Formation - of fracture hematoma 2.Fibro cartilaginous - callus formation 3.Bony callus formation - lump on bone 4.Bone remolding - reduction of a bone is where the bone is brought back into alignment

Two types of bone remodeling

Bone deposition - the addition of minerals and collagen Tissue involves bone resorption - removal of minerals and collagen

Briefly describe how spongy bone differs from compact bone. What are trabeculae?

Doesn't contain osteons, trabeculae, lamellae that are arranged in an irregular pattern of thin columns

Describe the epiphyseal (growth) plate. Where is it found? What is it made of? What does it ultimately become? When?

Epiphyseal plate layer of hyaline cartilage at age 18-21 it becomes the epiphyseal line ends of long bones

What are Osteoclasts? What do they do?

Huge cells derived from the fusion of as many as 50 monocytes and are concentrated in the endosteum. Bone side deeply folded into a ruffled border deposit slip

What is bone resorption?

Is part of the normal development maintenance and repair of bone

Briefly describe the following types of fractures:

Open (compound) - goes through skin Closed (simple) - doesn't break skin Comminuted - bone is splintered, crushed Greenstick - one side of the bone is fractured Impacted - bone is force fully into the interior of the other Pott's - fracture of distal end lateral leg bone (injury of distal tibia) Colles'- forearm bone distal fragment displaced posteriorly Stress - microscopic fissures

Osteogenic cells

Stem cells derived from mesenchyme, tissue that all connective tissue is formed, only one to go under cell division inner portion of the periosteum in the endosteum and within the canals within bone

What is osteoarthritis?

The degeneration of articular cartilage such that the bony ends touch

What is the significance of "lines of stress" in compact bone?

They change as a person learns to walk and in response to repeated strenuous physical activity. Can also change because of fractures or physical deformity

Why is exercise so important for bone health?

To put stress on bones to increase deposition of mineral salts and production of collagen fibers by osteoblasts (makes bones stronger)

What is the nutrient foramen? Where is it usually found? What goes through it?

a hole in a compact bone that allows veins & arteries in & out

Concentric lamellae

are circular plates of mineralized extracellular matrix in the central canal

Interstitial lamellare

areas between neighboring osteons (muscles and nerves)

Endochondral ossification

bone forms within hyaline cartilage, develops from mesenchyme

Osteoporosis

bone resorption outpaces bone deposition

Perforating (Volkmann's) canals

connected with the medullary cavity

Where is Yellow bone marrow found and what important function does it serve?

consists of adipose cells that stores triglycerides chemical energy reserve

Osteons

consists of concentric lamellae arranged around

Lacunae

contain osteocytes (little lake)

Canaliculi

filled with extracellular fluid (fingerlike, little canals)

Where is red bone marrow found and what important function does it serve?

found within some bones this produces red blood cells and platelets. This process is called hemopoiesis

Central (Haversian) canals

looks like growth rings on a tree

Osteocytes

mature bone cells, main cells in bone tissue and maintains its daily metabolism, do not undergo cell division. Carve out bone.

circumferential lamellae

outer and inner of the shaft of the bone

Osteopenia

reduced bone mass due to a decrease in the rate of bone synthesis to a level too low to compensate for normal bone resorption

Bone remodeling

replacement of old bone

Briefly describe the extracellular matrix of bone.

•15% water 30% collagen fibers, and 55% crystallized mineral salts.

Is bone tissue very pain sensitive? Periosteum?

•Bone tissue is very sensitive •Periosteum is rich in sensory nerves the bone does not

List and briefly describe the seven parts of a long bone.

•Diaphysis - bone shaft, main portion of bone •Epiphysis - proximal and distal end of the bone •Metaphysis - the region between the diaphysis and epiphysis growth plate, hyaline cartilage allow the diaphysis to grow ages 18-21 •Articular Cartilage - thin layer of hyaline cartilage covering part of the epiphysis where the bone forms a joint with another bone reduces friction, and absorbs shock at freely moveable joints lacks a perichondrium and blood vessels repair is limited •Periosteum - tough connective tissue sheath and blood supply that surrounds the bone surface at places where it is not covered with has an outer fibrous layer and an inner osteogenic layer, enables bone growth in thickness assists in fracture repair •Medullary Cavity - hollow cylindrical space contains fatty yellow bone marrow and blood vessels in adults minimizes bone weight •Endosteum - thin membrane lines the medullary single layer of bone - forming cells and small amount of connective tissue

Describe intramembranous ossification. What bones are formed by this method?

•Flat bones of skull, most facial bones, mandible and medial part of clavicle are formed this way. •Intramembranous ossification - involves the formation of bone within mesenchyme arranged in sheet like layers that resemble membranes

Differentiate interstitial from appositional growth.

•Interstitial - within. Increase in length. •Appositional growth - outer. Bones are formed from cartilage

Briefly describe the hormones PTH, CT and Calcitriol, including where they come from and what effect they have on calcium.

•PTH - increases CA2 level •CT - speeds blood CA2 intake level •Calcitriol - promotes absorption of calcium from foods (active form of vitamin D)

What is articular cartilage, where is it found and what is it made of?

•a thin layer of hyaline cartilage covering the part of the epiphysis where a bone forms an articulation (joint) with another bone.