Bone Cells and Tissue

Yesterday’s Question Why are cats able to fall from great heights and not break bones? Reduce velocity from 130 to 60 mph by extending their legs like a flying squirrel. At the time of impact they reduce the tension in their leg muscles. However, the chest bones absorb much of the impact and lung damage often occurs.

Bone Cells Osteoprogenitor cells differentiate into osteoblasts. 1.Osteoprogenitor cells- stem cells of bone Osteo = Bone, Geni = beginning. Spindle shaped Oval nucleus Pale cytoplasm Found in the covering of the bone, and lining of inner cavity of bone.

2. Osteoblasts- make the extracellular matrix. –Osteoblasts differentiate into osteocytes. Cells are more columnar have well developed Golgi bodies Blast = sprout

3. Osteocytes- maintain the matrix. Note how osteocytes are connected to each other. They live in small spaces in the matrix called lacunae. Cytes = Cell

4.Osteoclasts- secrete acid that breaks down mineralized matrix Multinucleated Large After bone is broken down, what cell will invade the area and deposit new bone matrix? Osteoblast

Bone Tissue Compact bone Found in the shafts of our long bones and on the inner and outer surface of our flat bones. Provide strength. Canaliculi- small tubes in the matirx that connect bone cells Central/Haversion canal- contains blood vessels Lacuna- Cavity that holds an osteocyte Lamellae- layers of matrix Osteon- cylinder shaped unit

What is the bone matrix made of? -25% water -25% collagen fibers (provide strength, resilience) -50% inorganic salts- calcium and phosphorus (hard, resistant to crushing)

The Structure of Bone Spongy (cancellous) bone. Found within flat bones and in the ends of long bones. Stores red bone marrow How do you think compact and spongy bone got their name?

Bone marrow aspiration and biopsy.

Cartilage Hyaline cartilage - found at ends of long bones between joints -important in bone growth, protects ends of bones Fibrocartilage -found between vertebrae -cushions

Dense Regular Connective tissue Covering of a bone Allows for attachment of tendons and ligaments

Blood Found throughout the bone Brings nutrients, removes wastes

-Nervous tissue Found in the covering of the bone Sends and receives messages

Together these tissues function in... 1.Support and Movement (Explain) –Our bones provide support for sitting and standing. –Our bones act as levers for our muscles to pull against. 2.Protection (Explain) –Our skulls protect our brain. –Our vertebrae protects our spinal cord. –Our ribcage acts as a shield to protect our important thoracic organs (heart and lungs).

3. Storage (What is bone storing?) –Our skeletal tissue stores minerals that can be released as needed- calcium and phosphorous –Adult long bones store yellow marrow, an energy reserve 4.Hematopoiesis -formation of blood cells