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