Chapter 6 bone and bone tissue
bone. without it inorganic matrix
( minerals) cannot resit compression
Perforating fibers
(Sharpey's fibers) - made of collagen; anchors periosteum firmly to underlying bone surface by penetrating deep into bone matrix
epiphyseal plates
(growth plates); line of hyaline cartilage found in developing bones of children
-Medullary cavity
(marrow cavity) within diaphysis contains either red or yellow bone marrow, depending on bone and age of individual
Zone of calcification
(second to last region) - dead chondrocytes; some calcified
Zone of reserve cartilage
- (closest to epiphysis) cells that are not directly involved in bone growth but can be recruited for cell division if needed
Osteopetrosis ("marble bone disease")
- defective osteoclasts ( to degrade bone);
Flat bones
- thin and broad bones; include ribs, pelvis, sternum(breastbone), and most skull bones
•Skeletal system includes
-Bones, joints, and associated supporting tissues
endosteum
-Bony struts of spongy bone and all inner surfaces of bone are covered by thin membrane contain different populations of bone cells involved in maintenance of bone homeostasis
hormone estrogen
-Increases rate of longitudinal bone growth; inhibits osteoclast activity -When estrogen levels spike in teen years an accompanying "growth spurt" occurs in females -Accelerates closure of epiphyseal plate at much faster rate than testosterone; leads to average height differences between genders
3 types of cells found in bone
-Osteoblasts -Osteocytes -Osteoclasts
steps for bone remodeling
1. hematoma fills the gap between the bone fragments 2.fibroblast and chondroblast infiltrate the hematoma and soft callus forms 3.osteoblast build bone callus 4. the bone callus is remolded and primary bone is replaced with secondary bone
bone structure
5 classes despite diversity of bone appearance. All 206 bones fit into categories based on shape.
short bones
Also named for shape rather than size, Roughly cubed- shaped as long as they are wide; includes bones of wrist or carpals and ankle taraslas.
Bones
Main organ system
osteoblasts
Have a blast making cells
One of the main factors affecting bone growth is group of chemicals called
Hormones
5 different zones
Zone of reserve cartilage Zone of proliferation Zone of hypertrophy and maturation Zone of calcification Zone of ossification
Zone of proliferation (next region)
actively dividing chondrocytes in lacunae
most bones complete process by
age 7
Mineral storage and acid-base homeostasis
bone is most important storehouse for calcium, phosphorus, and magnesium salts; minerals are also present in blood as electrolytes, acids, and bases; critical for electrolyte and acid-base maintenance
Fat storage
bones also contain yellow bone marrow; made up of fat cells (adipocytes); storetriglycerides; fatty acids from breakdown of triglycerides can be used as fuel by cells
•(appositional growth)
bones grow in width
Blood cell formation
bones house red bone marrow - specialized connective tissue involved in formation of blood cells (hematopoiesis)
movement
bones serve as sites for attachment of most skeletal muscles; when muscles contract, they pull on bones; generates movement at joint
•Long bones lengthen
by longitudinal growth; involves division of chondrocytes (not osteocytes or osteoblasts) in epiphyseal plate
Zone of ossification (last region)
calcifiedchondrocytes and osteoblasts
What canals connect lacunae together?
canaliculi;
bones come from
cartilage
compact bone
cells are highly compacted not easily breakable
1.Protection-
certain bones (skull, sternum (breastbone), ribs, and pelvis) protectunderlying organs; Structure-Function Core Principle
Bonne without organic matrix
collagen is brittle and easily shatters
organic matrix (osteoid)
collagen--helps bone resist torsion (twisting) and tensile (pulling or stretching) forcesflexiable
Epiphyseal plate
composed of hyaline cartilage that did not ossify; five different zones of cells:
inorganic matrix
consists of a calcium hydroxyapatite, which is in a crystalline structure.
osteoblast
create osteocytes
Charlie has a break in the shaft of his thigh bone. He broke the:
diaphysis
The long, tubular shaft of a long bone is called __________.
diaphysis.
causes of osteoporosis
diet, vitam D defincay,
growth hormone
effects both longitudinal and appositional growth
central canal
endosteum-lined hole in center of each osteon; blood vessels and nervessupply bone
hormone estrogen
female sex hormone
Osteogenic cells
flattened cells; differentiate into osteoblasts when stimulated by specific chemical signals
spongy bone -
has no central or perforating canals supplying blood to trabeculae; obtain blood from vessels in bone marrow
Male sex hormone testosterone
has pronounced effect on bone growth
bone marrow transplant
have improperly functioning hematopoietic cells; benefit from bone marrowtransplantation ( hemotatis ) Makes new red blood cells
What is the function of red bone marrow?
hematopoietic
sinuses
hollow, air-filled spaces
Irregular bones
include vertebrae and certain skull bones; do not fit into other classes because of irregular shapes
yellow bone marrow
is a fat storage
Rings of each tree are made up of thin layers ofbone called
lamella
Which shape of bone contains a medullary cavity and epiphyseal lines?
long
Red bone marrow
loose connective tissue; supports islands of blood-forming hematopoietic( process of creating white and red blood cells.
osteoblast
makes bone
Crystalline structure
makes bone one of hardest substances in body; strong and resistant to compression Allows bone to be both protective and supportive; demonstrates
organic matrix
makes up remaining 35%; consists of collagen fibers and usual ECM components
yellow bone marrow is found
medullary cavity
red bone marrow is found where in children
medullary cavity because they need more to grow
Periosteum
membrane composed of dense irregular collagenousconnective tissue; rich with blood vessels and nerves; surrounds outer surface of long bones ( protection )
inorganic matrix
minerals make up about 65% of bone's total weight
Which of the following functions is associated with the skeletal system? Thermoregulation Vitamin D synthesis Movement
movement
Zone of hypertrophy and maturation
next region closer to diaphysis) - maturechondrocytes
Perforating canals (Volkmann's canals)
originate from blood vessels in periosteum; travel at right angles (perpendicular) to central canals of neighboring osteons;connect them to one another
Compact bone cross section resembles forest oftightly packed trees; each tree is a unit called
osteon
Circumferential lamella
outer and inner layers of lamellae just insideperiosteum; at boundary with spongy bone; add strength
bone / osseous tissue
primary tissue found in bone; composed mostly of extracellular matrix with a smallpopulation of cells scattered throughout
ossification or osteogenesi
process of bone formation
hematopoiesis
process of making new blood cells and platelets, which occurs in the bone marrow.
Functions of skeletal system
protection mineral storage and acid base homeostasis blood cell formation fat storage movement support
spongy bone
provides protective structure for bone marrow tissue
sesamoid bones
red bone marrow
osteoclasts
responsible for bone resorption. will destroy osteocytes, break down bone
Epihyseal lines
separate both proximal and distal epiphyses from diaphysis
Diaphysis
shaft of long bone; each end is epiphysis; covered with thin layer of hyaline cartilage (articular cartilage) found within joints (articulations) between bones
support
skeleton supports weight of body; provides its structural framework
Osteocytes in lacunae
small cavities between lamellae; filled with extracellular fluid
spongy bone
space within the cells things found inside
Sesamoid bones
specialized bones located within tendons; usually small, flat, and oval-shaped; give tendons mechanical advantage; give muscles better leverage; patella (kneecap) is example
Red bone marrow is found in
spongy bone
trabecuale
struts or ribs of bone; covered with endosteum
Bone growth
takes place at epiphysis on side closest to diaphysis
yellow bone marrow
triglycerides, blood vessels, and adipocytes
Internal structure of short, flat,irregular
two outer layers of thin compact bone with middle layer of spongy bone (diploë) and associated bone marrow
-Spongy bone
usually not weight-bearing like compact bone; much lessdensely packed
Osteoporosis
•Most common bone disease in United States; bones become weak and brittle due to inadequate inorganic matrix; increases risk of fractures with decreased rate of healing
Epiphyseal plate
•composed of hyaline cartilage that did not ossify; five different zones of cells:
Growth hormone
•secreted by anterior pituitary gland; enhances protein synthesis and cell division in nearly all tissues, including bone
bones
Dense regular, irregular collangeous tissue and bone marrow
Long bones
Named for overall shape not actual size( some are quite small). Longer then they are wide, includes most bones in arms and legs.
osteocytes
Osteoblasts eventually surround themselves with matrix in small cavities (lacunae); become osteocytes that no longer actively synthesize bonematrix