Skeletal System
appendicular skeleton
126 bones; include: pectoral girdle, upper and lower limbs, and pelvic girdle
alkaline phosphatase
An enzyme derived from bone, liver, gallbladder, kidney, GI tract, and placenta. Higher levels seen during growth spurts in children and teens. Also may be elevated with healing fractures , osteomalacia, malignancy
hematopoiesis
Blood cell formation
Remodeling
Bone restored close to original shape
epiphyseal fracture
Occurs where the matrix is undergoing calcification and chondrocytes are dying; usually seen in children
Bony callus
Osteoblasts invade, hard callus fills space
Cartilaginous callus
Phagocytes remove debris, fibrocartilage invades
functions of bones
Provide shape to body, support body structures, protect body structures, aid body movements, contain tissue that produces blood cells, and store inorganic salts
inorganic salts
Sources of necessary ions; have important roles in metabolism, make up 2/3 of bone weight
communited fracture
complete and fragments the bone
oblique fracture
occurs at angle to axis of bone
zone of proliferating cartilage
rows of young cells undergoing mitosis
zone of calcified cartilage
thin layer of dead cartilage cells and calcified matrix then ossification begins below
osteoid
unmineralized/organic bone matrix composed of proteoglycans, glycoproteins, and collagen
fragility fracture
Any fall from a less than standing height, sign of low bone density
transformation zone
Area of the exo/endocervix where cells transition from squamous to columnar epithelial cells; most common place for cervical cancer
Compound (open) fracture
Fracture in which the bone is exposed to the outside through opening in skin (or mucous membrane)
diploe
In flat bones this is what spongy bone is called.
Physical Stress
Stimulates bone growth
cavitation
The formation of cavities in an organ or tissue; frequently seen in some forms of tuberculosis.
endochondral bones
begins as masses of hyaline cartilage, most bones of skeleton include: phalanges, femur, epiphyseal plates, and bone collar formation
calcitonin works to decrease what?
blood calcium levels
spiral fracture
caused by excessive twisting of bone
inorganic salts include:
crystals of calcium phosphate, magnesium, potassium, carbonate, and sodium ions
mesenchyme on outside forms _
periosteum
collagen gives bone _
resilience
lacunae
small cavities in bone that contain osteocytes
open reduction
surgical realignment of broken bone ends
ossification center
the cluster of mesenchymal cells that differentiate into osteoblasts at the site where bone will develop during intramembranous ossification
osteopenia
bone loss
osteoblasts/ bone deposition
bone-forming/building cells that deposit bone matrix around themselves, more active when blood calcium levels are high-calcitonin
sharpey's fibers
connect periosteum to compact bone
spongy bone
consist of branching plates called trabeculae, somewhat flexible, nutrients diffuse through canaliculi, light weight, higher rate of bone turnover, abundant in bone epiphysis
calcium is vital in what?
nerve impulse conduction and muscle contraction
closed reduction
nonsurgical realignment of broken bone ends and splinting of bone
calcitonin causes an increase in what?
number of osteoblasts (greater rates of bone deposition)
parathyroid hormone causes an increase in what?
number of osteoclasts(greater rates of bone resorption) and blood calcium levels
compression fracture
occurs when the bone is pressed together (compressed) on itself
zone of hypertrophic cartilage
older, enlarging cells, matrix calcifies- chondrocytes /cartilage cells die
Vitamin A
osteoblast & osteoclast activity; deficiency retards bone development
what decreases blood calcium?
osteoblasts, calcitonin, living at a northern latitude
what increases blood calcium?
osteoclasts, parathyroid hormone, calcium absorption, inhibition of osteoblasts, vitamin D, calcium reabsorption from kidneys, and bone resorption
when blood calcium decrease it causes the release of what?
parathyroid hormone
blood calcium level is regulated by what?
parathyroid hormone and calcitonin
osteomalacia
softening of bone
Growth hormone
stimulates cartilage cell division - Insufficiency in a child can result in pituitary dwarfism - Excess causes gigantism in child, acromegaly in adult
Parathyroid Hormone (PTH)
stimulates osteoclasts, bone breakdown
yellow bone marrow
stores fat but does not produce blood cells
wolff's law
structure and adaptation (change bone shape by changing the forces you put on them)
trabeculae
supporting bundles of bony fibers in cancellous bone
examples of bone protection
1. skull bones- protect brain, ears, and eyes 2. bones of rib cage and shoulder girdle- protect heart and lungs 3. bones of pelvic girdle- protect internal reproductive organs, lower abdominal bones, 4. vertebrae- protects spinal cord
axial skeleton
80 bones; include: skull, middle ear bones, hyoid bone, vertebral column, and thoracic cage
Simple (closed) fracture
Fracture protected by uninjured skin (or mucous membrane)
In a growing long bone, diaphysis is separated from epiphysis by _
epiphysial (growth) plate
largest to smallest cavity size
medullary cavities, central canals, lacunae, canaliculi
with age red bone marrow is replaced by what?
yellow bone marrow
process after the release of calcitonin
1. When levels of blood calcium increase, calcitonin is released from the C cells of the thyroid gland 2. The circulating calcitonin inhibits osteoclasts and stimulates osteoblasts within minutes. 3. The effects on osteoclasts cause a decrease in bone resorption and a concurrent increase in bone deposition due to osteoblasts. 4. The decline in bone breakdown and increased mineralization causes blood calcium to decrease back to normal levels
Vitamin D
calcium absorption: deficiency causes rickets, osteomalacia
what is the process of endochondral ossification
1. begins as hyaline cartilage 2. chondrocytes (cartilage cells) enlarge, lacunae grow 3. matrix breaks down, chondrocytes die 4. osteoblasts invade area, deposit bone matrix 5. osteoblasts form spongy then compact bone 6. once encased by matrix, osteoblasts are now osteocytes
Steps of repairing a fracture
1. blood escapes from the broken vessels and forms a hematoma 2. cartilaginous callus: spongy bone forms in region close to developing blood vessels 3. a bony callus replaces fibrocartilage 4. Remodeling: osteoclasts remove excess bony tissue, causing restoration of new bone structure (osteogenesis)
osteoporosis
A condition in which the body's bones become weak and break easily (loss of bone mineralization)
osteon
A structural unit of compact bone consisting of a central canal surrounded by concentric cylindrical lamellae of matrix
harversian/central canal (osteon)
A tiny channel found within the spinal cord and inferior medulla oblongata; contains blood vessels, lymphatic vessels, and nerves
growth zone/epiphyseal plate
Cartilage cells undergo mitosis, pushing the epiphysis away from the diaphysis
bones support..
body weight (lower limbs, pelvis, and vertebral column)
impacted fracture
broken ends of bone are pushed into each other
when calcium blood levels increase it causes the release of what?
calcitonin
osteoclasts/ bone resorption
carry out bone- breaks down calcified matrix, parathyroid hormone makes it more active
Thyroid Hormone
causes replacement of cartilage with bone in epiphyseal plate, osteoblast activity
paget's disease
chronic bone disorder where there is enlarged, deformed bone; can cause pain in the bones or joints, headaches and hearing loss, pressure on nerves, increased head size, bowing of limb, or curvature of spine
Vitamin C
collagen synthesis; deficiency results in slender, fragile bones
transverse fracture
complete, break occurs at right angle to axis of bone
organic matrix
contains collagen, protein, provides strength, resist tensile (pulling) forces
intramembraneous ossification
flat skull bones are forming between sheets of primitive connective tissue, contain parietal and occipital bones
compact/cortical bone
found where bones are heavily stressed; consist of cylindrical units called osteons, strong and solid, weight bearing, resits compression, visible central canals, forms superficial regions of all bones (abundant in bone diaphysis)
inorganic salts make bones _
hard
bone provides shape for..
head, face, thorax, limbs
inorganic matrix
hydroxyapatite, calcium carbonate, resists compressive (crushing) forces, provides hardness
fissured fracture
incomplete longitudinal break
greenstick fracture
incomplete, break occurs on convex section of bend in the bone
hematoma
large blood clot
zone of resting cartilage
layer closest to end of epiphysis, anchor epiphyseal plate to epiphysis
lamellae
layers of matrix around central canal
endochondral ossification
long bones and most of skeleton are forming from hyaline cartilage models
Osteocytes
mature bone cells that occupy chambers called lacunae and exchange nutrients and waste via cell processes within tiny passageways called canaliculi, encased in matrix
depressed fracture
name of fracture where a broken piece of skull moves inward
intramembranous bones
originate within sheetlike layers of connective tissue, broad flat bones (mesenchyme)
Sex Hormones (estrogen, testosterone)
promote bone formation; stimulate ossification of epiphyseal plates
functions of skeletal system
provide attachment for muscles-aid in body movement, store inorganic salts, provide shape, support and protect body structures, and contain tissue that produces blood cells
red bone marrow produces what?
red and white blood cells and platelets
where does blood cell production occur
red bone marrow