Bones and Joints - Lecture Exam 2 Flashcards
What are the tissues and organs that compose of the skeletal system?
- Osseous tissue is a connective tissue with a matrix hardened by calcium phosphate and other minerals
- Mineralization/calcification is the hardening process of bones
- Bones is an organ composed of bone tissue, bone marrow, cartilage, adipose tissue, nervous tissue, and fibrous connective tissue
Describe the general features of a long bone
- A long bone is the bones of appendages, longer than wide, rigid levers, and crucial for movement
- Articular cartilage, made up of hyaline cartilage, is at the ends of bones
- Epiphysis are the ends of the long bone; Diaphysis is the shaft of a long bone
- periosteum is the outermost membrane of the bone, endosteum is the inner membrane of the bone also known as the lining of the bone marrow cavity
- Medullary cavity: the hollow region of the diaphysis where red or yellow bone marrow is found
- Epiphyseal plate/growth plate: area of hyaline cartilage that separates epiphyses and diaphyses of children’s bones, enables growth in length
- Nutrient foramina: minute holes in bone surface that allows blood vessels to penetrate
Compact bone vs Spongy bone
Compact bone: dense outer shell of bone
Spongy (cancellous) bone: loosely organized bone tissue. Found in center of ends and center of shafts of long bones and in middle of nearly all others. Covered by more durable compact bone
Periosteum vs. Endosteum
Periosteum—external sheath covering most of bone
– Outer fibrous layer of collagen. Some fibers continuous with tendons
• Perforating fibers: penetrate into bone matrix
– Inner osteogenic layer of bone-forming cells
• Important to bone growth and healing of fractures
Endosteum—thin layer of reticular connective tissue lining marrow cavity
– Has cells that dissolve osseous tissue and others that deposit it
What are the shapes of bone?
Flat bones: cranium
- Thin, curved plates
- Protect soft organs
Long bones: bones of the appendages
- Longer than wide
- Rigid levers acted upon by muscles; crucial for movement
Short bones: wrists and ankles
- Approximately equal in length and width
- Glide across one another in multiple directions
Irregular bones: vertebrae, some face/cranial bones
-Elaborate shapes that do not fit into other categories
What are the functions of the skeletal system?
• Support—limb bones and vertebrae support body; jaw bones
support teeth; some bones support viscera
• Protection—of brain, spinal cord, heart, lungs, and more
• Movement—limb movements, breathing, and other
movements depend on bone
• Electrolyte balance—calcium and phosphate levels
• Acid–base balance—buffers blood against large pH changes
by altering phosphate and carbonate salt levels
• Blood formation—red bone marrow is the chief producer of
blood cells
Osteogenic Cells
stem cells in endosteum and inner layer of periosteum. They arise from embryonic mesenchyme, and multiply continuously to give rise to most bone cell types
Osteoblasts
- bone forming cells
- single layer of cells under endosteum and periosteum
- nonmitotic
- synthesize soft organic matter of matrix which hardens by mineral deposition
Osteocytes
- former osteoblasts that are trapped in the matrix they deposited
- contains strain sensors that produce biochemical signals that regulate bone remodeling when stressed (shape and density changes that are adaptive)
- also gap junctions that are a passage of nutrients, waste and signals
Osteoclasts
- bone dissolving cells found on bone surface
- develops from same bone marrow stem cells that produce blood cells, not the same as other bone cells
- fusion of several stem cells forms large cells with multiple nuclei in each cell with a ruffled border
The matrix of bone tissue
Organic matter: synthesized by osteoblasts, provides flexibility with collagen fibers.
-Contains collagen, carb-protein complexes like proteoglycans, glycoproteins, and glycosaminoglycans
Inorganis matter: provides structure
- 85% hydroxyapatite
- 10% calcium carbonate
- other minerals: fluoride, sodium, potassium and magnesium
State the importance of each constituent of bone tissue
- osteons (haversian systems)
- central canal
- concentric lamellae surround a central canal running longitudinally
- preforating canal: transverse or diagonal passages
- circumferential lamellae fill outer region of dense bone
- interstitial lamellae: fill irregular regions between osteons
- lacunae: tiny cavities where osteons reside
- canaliculli: litttle channels that connect lacunae
Distinguish between the two typesof marrow
Bone Marrow: soft tissue occupying marrow cavities of long bones and small spaces of spongy bone
Red Bone Marrow: (myeloid tissue) contains hemopoietic tissue that produces red blood cells.
- Every bone in a child.
- In adults, red bone marrow is found in skull, vertebrae, ribs, sternum, part of pelvic girdle, and proximal heads of femur/humerus
Yellow Bone Marrow: found only in adults.
- fatty marrow that does not produce blood
- may transform back to red marrow in the event of chronic anemia
Compare the histology of the two types of bone tissue
Spongy bone:
-few osteons with no central canal, osteocytes close to bone marrow
-lattice of bone covered with endosteum
>slivers of bone:spicule, thin bone plates trabeculae
-spaces filled with red bone marrow
-provides strength with minimal weight
Compact bone:
-contains osteons, haversian systems.
Describe intramembranous ossification (inside membrane)
- in a membrane, mesenchyme cells gather, differentiate into osteogenic cells
- Osteogenic cells divide into osteoblasts.
- osteoblasts gather at the borders of blood vessels - osteoblasts secrete osteoid, collagen fibers appear, Ca3(PO4)2 calcium phosphate hardens/calcifies the osteoid surroundings
-Produces flat bones of skull and clavicle in fetus, thickens long bones throughout life.
