Ch 6, bones & skeletal system Flashcards
Where is hyaline cartilage mainly found on the skeleton
- articular joints (covers end of joints)
- costal cartilages (connects ribs to sternum)
- respiratory cartilages (skeleton of larynx)
- nasal catilages
what are the main descriptive properties of hyaline cartilage
Resilience and flexibility
What bones are included in the axial skeleton?
long axis of the body, includes bones of skull, vertebral column, and rib cage
What bones are included in the appendicular skeleton?
included bones of upper and lower limbs and the girdles that attach them ex: arms legs shoulder hip bones ect
Briefly describe long bones, short bones, flat bones, and irregular bones:
- long bones: have a shaft and 2 expanded ends
- short bones: cube shaped (ankles wrists)
- flat bones: thin, flattened, usually curved (sternum, scapulae, ribs and most skull bones)
- irregular bones: complicated shapes (vertebrae, hip bones)
- sesamoid bones: special bone that forms in tendon (patella). can act to change pull of tendon.
List the 7 major functions of bones
1) support 2) protection 3) mineral homeostasis 4) movement 5) Hemopoiesis (production of blood cells and platelets which occurs in the marrow) 6) triglyceride (fat) storage 7) hormone production
What hormone does bones produce and what is its function
bones produce osteocalcin: regulates bone formation; protects against obesity, glucose intolerance, and diabetes mellitus (high blood sugar levels)
What are the main minerals associated with bones
Calcium (Ca) and phosphorus (P) calcium phosphate and calcium carbonate
where is triglyceride stored in bones
in the yellow marrow in bone cavities
what is the matrix on bone
25% water, 25% protein fibres, 50% mineral salts
Describe trabeculae
honeycomb like collection of small flat needles. Are filled with red (flat, irregular) or yellow (long) bone marrow. *in flat bones trabeculae is called dipole.
Where is the diaphysis located on the bone
forms the long axis of bone, the medullary cavity is located in this area. medullary cavity contains yellow bone marrow.
Where is the epiphysis located on the bone
the bony ends, joint surface is covered with hyaline cartilage
Describe the periosteum
- double-layered membrane that covers the entire external surface of bone, minus joint surfaces.
- fibrous outer layer is made of dense irregular connective tissue
- supplied with nerve fivers and blood and lymphatic vessels, which enter the bone though nutrient foramina
- inner osteogenic layer is composed of osteoblasts (forming) and osteoclasts (destroying)
- Sharpey’s fibers - collagen fibres that brake through bone securing periosteum to the underlying bone
Describe the endosteum
- delicate membrane that covers internal surfaces of bones
- covers trabecular of spongy bone and lines canals that pass though compact bone.
- contains osteogenic (undifferentiated stem) cells
what are the 5 bone cells
1) Osteogenic cells: mitotically active undifferentiated cells, found in peritoneum and endosteum.
2) Osteoblasts: bone FORMING cells that secrete the bone matrix
3) Osteoclasts: facilitate DESTRUCTION of bone matrix, found at sites of bone reabsorption
4) Osteocytes: spiderylike mature bone cells that conform to lacunae spaces they occupy and function to monitor and maintain bone matrix.
5) Bone lining cells: flat cells found on bones surfaces when remodelling; similar function to osteocytes.
What is one structural unit of bone called
Osteon or Haversian system
-Osteon = a group of elongated hollow tubes (lamellae) of bone matrix.
What is the function of the central canal or Haversian canal
runs though the core of each osteon allowing small blood vessels and nerve fibres to service the osteon
what is the function and location of perforating canals or Volkmann’s canals
they lie at right angles to the central canal and connect the blood and nerve supply of the periosteum to those in the central canals and medullary cavity
what are lacunae
hollow spaces at the junctions of the lamellae *siper shaped osteocytes occupy these hollow spaces
what are canaliculi
hair like canals that connect the lacunae to each other and the central canal. *canaliculi connect tie all the osteocytes in a mature osteon together facilitating communication and waste and nutrients exchange.
what are the organic components of bones
ALL the bone CELLS: osteogenic cells, osteoblasts, osteoclasts, bone lineing cells, osteocytes.
-Osteoid= organic part of matrix consisting of round substance (proteoglycans and glycoproteins) and collagen fibres (provides flexibility and tensile strength) *
what are the inorganic components of bones
HYDROXYAPATIES or Mineral Salts account for 65% of bone mass
-mostly calcium phosphate which is present as tightly packed crystals providing exceptional hardness and resistance to compression *
what is osteogenesis
= ossification = process of bone formation
what does osteogenesis lead to
- bony skeleton of embryos
- bone growth until early adulthood
- bone thickness, remodelling, and repair
- early fetal skeleton is made of hyaline cattily and fibrous membranes - ossification doesn’t start until week 8
what are the two main patterns of bone growth
1) intramembraneous ossification: bone development from fibrous membranes = membraneous bone
2) Endochondral ossification: bone developed by replacing cartilage = endochondral bone = most bones
Describe the steps of Intramembranous ossification
- formed by fibrous membranes
1) ossificiation centre forms from osteoblasts
2) Bone matrix secreted by ossification centre and is mineralized by hydroxyapatite formation tapping osteoblasts in lacunae
3) bone matrix forms around blood vessels and periosteum forms trabulae are formed
4) outer trabeculae thicken and form compact bone; trabeculae remain in spongy bone which then becomes heavily vascularized and red marrow forms
what is the most common type of bone formation called
endochondral ossification (forms hyaline cartilage)
what are the five stages of endochondral ossification
- formation of bone collar
- cavitation (formation of an empty space in a solid) of hyaline cartilage
- invasion of internal cavities by periosteal bud and spongy bone formation
- formation of the medullary cavity; appearance of secondary ossification centre in the epiphyses
- ossification of the epiphyses with hyaline cartilage remaining only in the epiphyseal plates.
briefly describe growth in length of long bones
- cartilage on the side of the epiphyseal plate closest to the epiphysis is relatively inactive
- cartilage abutting the shaft of the bone organizes into a pattern that allows fast, efficient growth
- cells of the epiphyseal plate proximal to the resting cartilage form four functionally different zones
what are the four functional zones in long bone growth
- proliferation zone
- hypertrophic zone
- calcification zone
- ossification zone
describe the four zones in long bone growth
- proliferation: cartilage cells undergo mitosis
- hypertrophic: older chondrocytes enlarge
- calcification: the matrix becomes calcified, chondrocytes die, and the matrix begins to deteriorate
- ossification: new bone formation occurs
steps of Appositional (width) bone growth (4)
- osteoblasts beneath the periosteum secrete bone matrix, forming ridges that follow the course of periosteal blood vessels
- As the bony ridges enlarge and meet, the groove containing the blood vessel becomes a tunnel
- the periosteum lining the tunnel is transformed into an endosteum and the osteoblasts just deep to the tunnel endosteum secrete bone matrix, narrowing the canal
- as the osteoblasts beneath the endosteum form new lamellae, a new odeon is created. Meanwhile new circumferential lamellae are elaborated beneath the periosteum and the process is repeated, continuing to enlarge bone diameter.
what happens to bones during remodelling
bone is resorbed and added by appositional growth.
- adjacent osteoblasts deposit bone and osteoclasts resorb bone at the periosteum and endosteum surfaces.
- bone is removed from the inside and added to the outside - this maintains bone proportions between epiphysis and diaphysis
what is needed to bone deposition
- occurs where bone is injured to extra strength is needed
- requires a diet rich in protein, vitamins c,d and a, calcium, phosphorus, magnesium, and manganese
what mineral is essential for mineralization of bone
alkaline phosphatase
sites of new matrix deposition are revealed by:
- osteoid seam: unmineralized band of bone matrix
2. calcification front: abrupt transition zone between the osteoid seam and the older mineralized bone
what are the common types of fractures
- open: bone penetrates skin
- closed: skin not perforated
- incomplete: doesn’t extend across the bone
- complete: does
- displaced: bone ends are out of normal position
- nondisplaced: bone ends stay in place
