Chapter 7 - Bones Flashcards
What are the two most durable components of your body?
Bones and teeth (especially the enamel)
Do we have a dead or living skeleton?
Living
True or false: The skeletal system constantly remodels itself and interacts with other organ systems of the body
True
______ is the study of bone
Osteology
What are the 3 main components of the skeletal system?
Bones, cartilages, and ligaments
Define cartilage, ligaments, and tendons
Cartilage is forerunner of bone formation and coats ends of bones.
Ligaments connect bone to bone
Tendons connect muscle to bone
What are the functions of the skeleton?
Support, protection, movement, electrolyte balance, acid-base balance, and blood formation
How does the skeleton aid in support, protection, and movement?
Support: limb bones and vertebrae support body; jaw bone supports teeth; bones support viscera
Protection: of brain, spinal cord, heart, lungs etc
Movement: of limbs, breathing – action of muscles on bones
How does the skeleton aid in maintaining electrolyte and acid base balances, and how does it aid in blood formation?
Electrolyte balance: calcium & phosphate levels
Acid–base balance: buffers blood against large pH changes by altering phosphate and carbonate salt levels
Blood formation: red bone marrow makes red blood cells
Define bone (osseous tissue)
A connective tissue with its matrix hardened by calcium phosphate and other minerals
Define mineralization/ calcification
The hardening process of bone
What do individual bones consist of?
Individual bones (organs) consist of bone tissue, bone marrow, cartilage, adipose tissue, nervous tissue, and fibrous connective tissue
Define sesamoid and sutural bones
Sesamoid (type of short bone) and sutural (wormian) bones
Sesamoid bones develop in a tendon (or ligament) in response to a need for more leverage
Sutural bones are the extra bones in the sutures (especially the lambdoid suture) of the skull
Define compact bone
Has a dense outer shell of bone
Define spongy (cancellous) bone
Made up of an internal honeycomb of trabeculae filled with red or yellow bone marrow
The skeleton’s weight is made up of ___% compact bone and _____% spongy bone
75% compact bone; 25% spongy bone
Define diaphysis and epiphyses
Diaphysis—shaft that provides leverage
Epiphyses—enlarged ends of a long bone
Define the epiphyseal line (metaphysis) and marrow cavity (medullary cavity)
Epiphyseal line: separates diaphysis from epiphysis (aka metaphysis)
Marrow cavity: space in the diaphysis of a long bone that contains bone marrow (aka medullary cavity)
Define articular cartilage
A layer of hyaline cartilage that covers joint surface and allows the joint to move more freely
Describe the two layers of the periosteum
Outer fibrous layer made 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
Define the periosteum
2 layers covering most of bone
Define the endosteum
A thin layer of reticular connective tissue lining marrow cavity
Contains osteoblasts and osteoclasts
The nutrient foramina is penetrated by what?
Blood vessels
Describe the epiphyseal plate (growth plate)
Area of hyaline cartilage that separates epiphyses and diaphyses of children’s bones
Enables growth in length
When growth is finished turns into Epiphyseal line
List the 8 features of long bone
Epiphyses Diaphysis Compact bone Spongy bone Marrow cavity Articular cartilage Periosteum Endosteum
Describe the anatomy of a flat bone
Bones with a sandwich-like structure: two layers of compact bone with a middle layer of spongy bone (diploë)
Define and describe the diploë of flat bones
Diploë is the spongy middle layer found in flat bones. It absorbs shock and the marrow spaces are lined with endosteum
Define osteogenic cells
Stem cells (cell division) and develop into osteoblasts
Define osteoblasts
Bone-forming cells
Describe how osteoblasts do their job
Osteoblasts secrete collagen (and other carbohydrate-protein complexes) to form a soft fibrous matrix. This matrix hardens with mineral deposition. They make bone by mitosis and differentiation of osteogenic cells
What two organelles are particularly abundant in osteoblasts?
Rough ER and golgi complexes.
What stimulates osteogenic cells to multiply rapidly? What does this do?
Stress stimulates osteogenic cells to multiply rapidly, which increases the number of osteoblasts which reinforce bone
Define and describe osteocytes
Defined as mature bone cells
They’re found in pockets called lacunae, and connected to each other by canaliculi and gap junctions
Some reabsorb bone matrix & others deposit it; regulates bone remodeling
Describe the role of osteocytes when under stress
They act as strain sensors; when stressed, they produce biochemical signals that regulate bone remodeling (shape and density changes that are adaptive)
Define and describe osteoclasts
Defined as bone-dissolving cells found on bone surface
Derived from fusion of multiple white blood cells (WBC’s)
Usually multinucleate
Secrete enzymes and acids for the break down of bone (resorption)
True or false: Dissolving bone is a part of bone remodeling
True
What are the two main parts of the matrix, and what fraction of the matrix do they each make up?
Organic portion (1/3) and inorganic portion (2/3)
Describe the organic part of the matrix
Synthesized by osteoblasts
Composed of collagen and carbohydrate–protein complexes
Responsible for the flexibility of bone
Makes up 1/3 of the matrix
Describe the inorganic part of the matrix
85% hydroxyapatite (calcium phosphate) 10% calcium carbonate 5% other minerals (fluoride, sodium, potassium, magnesium) Responsible for the hardness of bone Makes up 2/3 of the matrix
If there is a mineral deficiency, what happens to the bone?
Rickets disease
Describe Rickets disease
A disease caused by mineral deficiency and resulting in soft, deformed bones
If there is a defect in collagen deposition, what happens to the bone?
Osteogenesis imperfecta (brittle bone disease)
Describe osteogenesis imperfecta (brittle bone disease)
Results from a defect in collagen deposition
Histology of compact bone reveals that they have _____
Osteons (haversian systems)
Describe the 3 elements of the haversian system of an osteon
1) Lamellae
Columns of the matrix (mainly collagen) that are weight bearing
Run concentric, circumferential, and interstitially
2) Central (Haversian canal)
Contains blood vessels and nerves
3) Perforating (Volkmann’s) canals
Channels that connect blood and nerves from periosteum to the central (Haversian) canal
Describe lamellae in osteons
Columns of the matrix (mainly collagen) that are weight bearing. The columns run concentric, circumferential, and interstitially
Describe the central (Haversian) canal of the osteon
Contains blood vessels and nerves
Describe the perforating (volkmann’s) canals of osteons
Channels that connect blood and nerves from periosteum to the central (Haversian) canal
Run transverse or diagonal
Where do trabeculae develop in spongy bone?
They develop along the bone’s lines of stress