Skeletal Systems I: Bone Histology Flashcards
function of bone
- support
- protection
- movement
- blood cell production
- storage
bone support
- structural framework
- supports/supported by soft tissues (muscles, organs)
bone protection
-protects internal organs
bone movement
- muscle to bone via tendons
- contraction muscle causes bone to move
bone blood cell production
- medullary cavity
- “red marrow”
bone blood cell production medullary cavity
-hollow space inside bones
bone blood cell production red marrow
-produces new blood cells
bone storage
-consists of fats and minerals
bone storage fat
- “yellow marrow” of long bones
- in medullary cavity
bone storage minerals
- in matrix of bone tissue
- mostly calcium and phosphate
- other minerals in smaller amounts
bone matrix composition
- inorganic matrix (nonliving portion)
- organic matrix (living portion)
bone matrix composition inorganic matrix
- 2//3 of total bone mass
- calcium and phosphate salts –> hydroxyapatite crystals
- crystals deposit around collagen fibers
- principle source of rigidity and strength against compression
bone matrix composition organic matrix
- 1/3 of total mass
- cells, collagen, and intercellular matrix
- provides resistance to twisting and stretching
- provides degree of elasticity
types of bone arrangement
- compact (cortical) bone
- spongy bone (cancellous)
compact bone
- dense and solid
- comprises outer surface of bones
- primary component of long bone shafts
- bone shafts are very close together
spongy bone
- contains wide spaces in bone that resemble “holes” in a sponge
- holes are filled with red marrow
bone membrane types
- periosteum
- endosteum
periosteum bone membrane
- protective outer CT covering
- entry point: nerves/vessels
endosteum bone membrane
-inner lining of bone found within medullary cavity (hollow space within)
bone cell types
- osteocyte
- osteoblast
- osteoclast
- chondroblasts and chondrocytes
osteocyte
-mature bone cell, resides in a space called lacunae
lacunae
-cell sized empty spaces
osteoblast
- cell which helps form bone by producing osteoid (the organic component of bone matrix
- produces osteocytes (found in lacunae)
osteoclast
- resorption
- freed minerals enter blood stream
resorption
-break down bone with enzymes
chondroblasts and chondrocytes
- lay down cartilage model which ossifies (connected to bone)
- active during phases of growth and repair (constantly repairing)
another name for osteon
-haversian system
osteon definition
-the basic functional and structural unit of mature bone
osteon characteristics
- long cylindrical structures
- oriented parallel to the long axis of a bone
- arranged in a pattern that allows bone to withstand compression and torsion (“miniature weight bearing pillars”)
torsion
another name for twisting
structural components of an osteon
- concentric lamellae
- haversian (central) canal
- canaliculi (small channels)
- perforating (volkmann’s) canals
- *all have a rich blood supply
osteogenesis
-bone formation and development
processes of bone formation
- ossification
- calcification
ossification
-osteoblasts secrete osteoid (inorganic part of matrix)
calcification
- deposition of insoluble calcium salts (inorganic component of bone)
- results in hardening of bone
types of bone formation
- intramembranous bone
- endochondral bone
intramembranous bone formation
- osteoblasts form bone in a connective tissue membrane
- early in fetal development
- in bones, required for protection
intramembranous bone formation example
-flat bones of the skull
endochondral bone formation
- begins with hyaline cartilage model
- osteoblasts gradually replace model with bone
- process may occur up to age 25
- most of the skeleton is formed this way
endochondral bone formation example
- rib
- femur
- phalanges
factors regulating bone growth
- nutritional requirements
- hormonal regulation
nutritional requirements regulating bone growth
- calcium and phosphate salts
- vitamins A and C
- vitamin D
nutritional requirements: vitamin A and C
-healthy osteoblast production
nutritional requirements: vitamin D
-affects calcium absorption and transport
types of hormones that regulate bone growth
- parathyroid hormone
- calcitonin
- growth hormone
- sex hormones
parathyroid hormone
-stimulates osteoclasts and increases Ca absorption in GI system
calcitonin
- inhibits osteoclasts
- produced in thyroid gland
growth hormone
-promotes growth
sex hormones
- estrogen and testosterone
- ->stimulate osteoblasts
types of bones
- flat bones
- long bones
- short bones
- irregular bones
- sesamoid bone
flat bone
-composed of layer of spongy bone surrounded by two plates of compact bone
flat bone examples
- parietal
- sternum
- rib
long bone
- longer, narrower
- shaft=compact one (diaphysis)
- ends (epiphysis) primarily spongy
long bone examples
- femur
- humerus
- phalanges
short bone
-spongy bone surrounded by compact bone (like spongy candy)
short bone examples
- cuboid bone
- carpal and tarsal bones
irregular bone
-shape and structure do not fit into other categories (not long, short, or flat)
irregular bone examples
-vertebrae
sesamoid bone
-forms with tendons
sesamoid bone examples
-patella
what is the most functionally important structure in the skeleton?
-long bones
structure of a typical long bone
- diaphysis
- epiphysis
- epiphyseal plate
- medullary cavity
- periosteum
- endosteum
- articular cartilage
- nutrient vessels
diaphysis
- shaft of long bone
- primarily compact bone
epiphysis
- ends of long bone
- primarily spongy bone
epiphyseal plate
- plate of cartilage in growing bones
- lengthwise bones grow here
medullary cavity
- cavity with diaphysis
- mostly yellow bone marrow
periosteum
- fibrous, protective outer membrane of bone
- isolates the bound surrounding the tissue
- provides a route for the circulatory and nervous supply
- actively participates in bone growth and repair
- dense connective tissue
endosteum
-inner membrane of bone containing cells involved of bone formation
articular cartilage
-hyaline cartilage located on the ends of long bones for protection
nutrient vessels
-blood vessels that penetrate bone to supply it with nutrients
