Bone tissue Flashcards
What is the composition of cartilage?
- avascular, devoid of nerve fibers
- ground substance contains glycosaminoglycans (chondroitin sulfate and hyaluronic acid)
- collagen fibers
- 80% water
- small cavities in matrix
What are perichondrium?
layer of dense connective tissue surrounding cartilage like gridle
- in damage areas it causes scar tissue
What is the difference between chondroblasts, chondrocytes and lacunae?
CB - immature cartilage cells - actively form cartilage
CC - mature cartilage cells - maintain cartilage
L - localized clusters of chondrocytes in cartilage
Why are lacunae in clusters?
could be the way cartilage grows
What is elastic cartilage made of, its function and location in the body?
- like hyaline cartilage, but more elastic fibers
- maintain shape, flexibility
- external ear, epiglottis
What is hyaline cartilage made of, its function and location in the body?
- collagen, glassy blue-white chondrocytes, lots of ECM
- firm support and pliability
- nose, trachea and larynx
How do bones respond to force and what does it respond to calcium?
- when force is applied, bone increases in density (deposition) and roughness or decreasing it (resorption)
- stores calcium - reabsorbed and transferred to bloodstream when needed (forms new blood)
What is fibrocartilage made of, its function and location in the body?
- rows of chondrocytes with collagen
- tensile strength
- intervertebral discs, discs of knee joints
What are the 7 functions of bones?
- support
- protection
- anchorage and movement (attach to muscles)
- mineral storage
- blood cell formation (bone marrow)
- fat storage (bone marrow)
- hormone production (bone metabolism)
What is the function of bone calcium salts and what does bone hold inside?
- gives hardness and strength for support/ protection of soft tissue
- cavities for fat storage and synthesis of blood cells
What is the cell bone tissue from WBC lineage?
osteoclast - bone resorbing cell/ tissue
- breaks down matrix
What are the stages of bone cell lineage?
- osteoprogenitor cell - stem cells
- osteoblasts - bone growth
- osteocyte - mature bone cell
What are the layers of bone?
periosteum: outer fibrous layer + inner osteogenic layer
endosteum: covers trabeculae of spongy bone and lines canal of compact bone
Calcified tissue - what is the difference in compact bone and spongy (trabecular) bone?
CB - dense, outer layer - strength and support
SB - trabeculae - middle region (red marrow in spongy bone)
What are the 2 main divisions of the skeleton?
- axial skeleton (central axis)
- appendicular skeleton (limbs)
How are bones classified and the types?
by shape
1. long
2. short
3. flat
4. irregular
Explain what flat bones shape, composition, location and function?
thin, flattened and sometimes curved
- 2 layers of compact bone with spongy middle
- skull, ribs, sternum
- protection/ muscles attachment
Explain what long bones shape, composition, location and function?
longer than wide with 2 ends
- mostly compact bones with marrow cavity
- spongy near joint ends
- weight bearing/ movement
Explain what irregular bones shape, composition, location and function?
irregular shape
- mostly spongy bone + thin layer of compact bone
- hip bone, vertebrae
- protection of nervous tissue and movement
Explain what short bones shape, composition, location and function?
cube-like shape
- mostly spongy bone + thin compact bone
- wrist, ankle
- range of movement + flexability
What is the structural parts of a typical long bone?
- diaphysis (shaft)
- epiphyses (bone ends)
- membrane
What is the function of the epiphyses and what is its composition?
- expanded for joining of bones (joints)
- compact and spongy bone with hyaline on the outer surface (reduces friction and increases shock absorption)
What does the diaphysis surround and what does it contain?
marrow cavity (medullary cavity)
- contains fat (yellow marrow)
Where is the epiphyseal located, where does it come from and what happens to it once you reach adulthood?
- between diaphysis and each epiphysis
- epiphyseal (growth) plate - longitudinal growth
- cartilage turns into bone
How is the structure of short, irregular and flat bone similar?
periosteum (attaches to muscle) - covers outside of compact bone
endosteum (maintenance and repair) - inside portion medullary cavity
What does flat, short and irregular bones lack?
- shaft
- marrow cavity
- epiphyses
What is an osteon, what is it also called and what is its function?
structural unit of compact bone
- lamellae
- run parallel which act to bear weight
What is compact bone also called and what does it consist of?
lamellar bone
1. osteon (haversian system)
2. canals and canaliculi
3. interstitial and circumferential lamellae
What are the 3 canals of compact bone?
- osteons
- haversian (central) canal
- Volkmann’s (perforating) canal - perpendicular to long axis of bone + Have canal
What is the difference between osteocytes and canaliculi?
O - mature bone cells that are in cavity (lacunae) with bony matrix - maintain bone tissue
C - small canals that connect lacunas - connected to Have system
What is the difference between interstitial lamellae and circumferential lamellae?
IL - fill gaps between forming osteons or are leftovers of osteons that were partially destroyed by bone remodeling
CL - sheets of bone located just deep to periosteum and extend around entire shaft
What is intramembranous ossification and when does it start?
bone development from fibrous CT membrane containing mesenchymal cells
- 8 weeks embryo
What is the composition of spongy bone and why does its location served a function?
trabeculae, lamellae, osteocytes and canaliculi
- trabeculae runs along stress lines to help bone to resist stress
What does spongy bone lack and how does nutrients enter into the bone?
- osteons
- thorough canaliculi from marrow space between trabeculae to osteocytes
What is ossification and what are the 3 steps?
bone tissue formation
1. formation of bony embryotic skeleton
2. postnatal bone growth during childhood and adolescents
3. bone remodeling and repair throughout life
Which bones are affected by intramembranous ossification and what is it also called?
flat bones (cranial and clavicles)
- membrane bones
What is endochondral ossification and what are its bones called?
development via replacement of hyaline cartilage model
- cartilage bones
When does endochondral ossification start and what does it form?
2nd month of embryo
- forms most skeleton/ all bones below skull (except clavicles)
How does the bone grow longer and wider?
longer - by interstitial growth of epiphyseal plates
wider - thickness by appositional growth
Which bones continue to growth after early adulthood?
some facial bones
- nose, lower jaw
What are the regions of the epiphyseal plate?
- resting zone
- proliferation zone (cartilage cells)
- hypertrophic zone (older cart. cells enlarge)
- calcification zone (cartilage dies)
- ossification zone (new bone development)
What is the locational difference between epiphyseal plates and diaphysis?
EP - wider part of bone
D - shaft (which grows longer to support EP)
What is the role of osteoclasts and osteoblasts in bone growth?
OC - destroy bones
OB - lay down cells on inner and outer surface
What is unique about the size of the epiphyseal plate throughout childhood and what happens in adulthood - name??
- stays the same size
- stops growing (epiphyseal plate closure)
What is the function of the primary osteoblast and primary osteoclasts?
OB - on periosteal side secrete bone matrix
OC - on endosteal side remove bone
What causes osteoporosis, what are the consequences and what are the areas that are most likely affected?
imbalance between bone resorption (more) and formation (less)
- bone more porous (more likely to fracture)
- spine, neck of femur
How does the parathyroid control calcium levels?
if levels fall, para releases PTH which make osteoclasts degrade bone matrix and release Ca2+ into blood
What are the 4 major stages of fracture repair?
- hematoma formation - localized formation of blood outside blood vessels (inflammation)
- fibrocartilaginous callus formation - macrophages clean area - osteoclasts reabsorb - the blasts lay down collagen and tissue
- bony callus formation - converted to trabeculae bone
- bone remodeling - extra bone material is removed - bone regains original shape
What are the risk factors of osteoporosis and what are the contributing factors?
- age/ testosterone and estrogen
- lack of exercise, diet poor in Ca bad protein/ bad Vit D receptors, smoking
What is the importance of bone markings?
- identification of bone
- understanding how they join
