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79 Cards in this Set
- Front
- Back
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Skeletal system |
made up of: -bone -cartilage (covers joint surfaces/"pre-bone") -ligaments (holds bones together at joints)
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functions of the skeletal system |
support protection movement electrolyte balance- Ca & P ion storage acid base balance- buffers blood blood formation - red bone marrow > blood cells |
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Is bone a tissue or an organ? |
both; tissue: contains cells, fiber, ground substance organ: contains many types of tissues (osseous, cartilage, nervous, fibrous, adipose) |
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is a tendon a part of the skeletal system? |
no, tendons attach muscles to bone and are therefore not considered a part of the skeletal system |
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What is bone? |
"osseous tissue"
-connective tissue with matrix hardened by calcium phosphate and other minerals -continually remodels -interacts with other organ systems -permeated with nerves and blood vessels |
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axial skeleton |
skull, vertebral column, ribs |
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appendicular skeleton |
appendages, coxal bones, pectoral girdle |
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Parts of a long bone |
-outer shell of compact bone -marrow cavity -spongy bone @ ends -2 epiphyses & diaphysis -articular cartilage -nutrient foramina -endosteum & periosteum - epiphyseal line/plate |
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Epiphysis |
enlarged ends of long bones
functions; anchor, joints, tendon/ligament attachment |
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diaphysis |
shaft of long bone, houses the medullary (marrow) cavity
used for leverage |
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articular cartilage |
hyaline cartilage at the epiphyses
covers the joint surface to reduce friction |
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periosteum |
a fibrous layer of collagen that covers the outside of a bone |
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endosteum |
thin layer of reticular tissue that lines the marrow cavity |
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epiphyseal line/plate |
adults (line): body scar that shows former place of growth
children (plate): site of bone growth in length |
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flat bone |
spongy bone sandwiched by compact bone
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diploe |
spongy layer in cranium that absorbs shock |
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Types of bone cells |
4 types: -osteogenic -osteoblasts -osteocytes -osteoclasts |
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Osteogenic Cells |
-stem cells found in the endosteum, periosteum, and central canals -embryonic mesenchymal cells -multiply continuously to create new osteoblasts |
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stress and fractures cause rapid multiplication of what type of bone cell? |
osteogenic cells |
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osteoblasts |
-bone forming cells -nonmitotic -lines up in single layer under endosteum and periosteum -synthesizes soft organic matter of matrix to harden by mineral deposition |
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osteocytes |
- former osteoblast that became trapped in the matrix they deposited - reside in lacunae, connected by canaliculi can deposit or reabsorb bone matrix - produce biochemical signals when stressed to regulate bone remodeling - homeostatic mechanism: bone density, calcium phosphate ions |
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osteoclasts |
-bone dissolving cells -have "ruffled border" -found in resorption bays on bone surface -developed from bone marrow stem cells -large (formed by fusion of stem cells) |
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Bone Matrix |
ground substance + fibers -is a composite: made of a ceramic & a polymer |
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Hydroxyapetite |
;crystalized calcium phosphate salt
inorganic
ceramic component of the bone matrix - allows bone to support body weight
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Collagen |
organic
polymer component of the bone matrix - gives bone its flexibility |
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rickets |
calcium salt deficiency in children
bones bend, unable to support body weight not enough calcium int die or vitamin D deficiency |
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osteogenesis imperfecta |
"brittle bone disease"
lack of protein, collagen decreased bone flexibility |
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organic components of the bone matrix |
-made by osteoblasts -collagen -glycosaminoglycans -proteoglycans -glycoproteins |
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inorganic components of the bone matrix |
- 85% hydroxyapetite - 10% calcium carbonate - other minerals: fluoride, sodium, potassium, magnesium |
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Characteristics of compact bone |
-osteon (central canal + concentric lamellae) -canaliculi (connects osteons) -circumferential lamellae -interstitial lamellae (irregular regions; old osteons) -vascular (nutrient foramina, perforating & central canals) |
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Characteristics of spongy bone |
-sponge-like but actually calcified & hard -spicules (slivers of bones) -trabeculae (thin plates formed along stress lines) -red bone marrow -few osteons, no central canals |
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bone marrow |
soft tissue in marrow cavity & inbetween trabeculae
can be: red yellow |
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red bone marrow |
hemopoetic tissue (prodcues blood cells) found in most bones in children
in adults: most changes to fatty yellow. still in skull, vertebrae, ribs, sternum, part of pelvic girdle, proximal heads of humerus and femur |
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yellow marrow |
found in adults
doesnt produce blood
previously red marrow, can change back if needed |
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How does the human fetus & infant develop bone? |
intramembranous ossification endochondral ossification |
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intramembranous ossification |
bones develop within sheets of dense fibrous connective tissue
4 stages
ex. flat bones of the skull & clavicle |
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mesenchyme |
embryonic connective tissue |
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Intramembranous Ossification (Stage 1) |
-mesenchymal cells condense -differentiate into osteogenic cells -begin formation of trabecular network -dense supply of blood capillaries |
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Intramembranous Ossification (Stage 2) |
-osteogenic cells -> osteoblasts -lay down osteoid tissue at surface -formation of periosteum |
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Intramembranous Ossification (Stage 3) |
-spongy bone matures -osteoclasts resorb and remodel trabeculae to form marrow cavity |
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Intramembranous Ossification (Stage 4) |
compact bone forms on outside via bone deposition |
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Endochondral Ossification |
bone develops from pre-existing cartilage model -most bones in body
6th week of fetal development - early 20's
6 stages |
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Endochondral Ossification (Stage 1) |
-mesenchyme turns into hyaline cartilage covered with perichondrium
-perichondrium produces chondrocytes which thicken the cartilage |
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Endochondral Ossification (Stage 2) |
-bony collar forms
- perichondrium produces osteoblasts > now considered the periosteum
-chondrocytes enlarge to form primary ossification center |
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Endochondral Ossification (Stage 3) |
-blood vessels penetrate bony collar & invade primary ossification center -osteoblasts line the cavity & deposit osteoid tissue -osteoclasts dissolve calcified cartilage from the inside out - secondary ossification center forms |
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Endochondral Ossification (Stage 4) |
-secondary marrow cavity forms by enlargement & then death of chondrocytes in epiphysis - enlarged primary marrow cavity -metaphysis forms
*appearance of bone at birth |
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Endochondral Ossification (Stage 5) |
-epiphyseal plate(wall of cartilage) forms at distal end
-epiphyses fill with spongy bone |
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Endochondral Ossification (Stage 6) |
-gap between epiphysis & diaphysis close ~ plate > line
-1 cavity, no more growth in length
*typical adult bone |
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Growth in long bones of hands & fingers |
there is only a single epiphyseal plate in these bones. only grows in length outward |
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Which lamellae are the newest, the ones closest to the central canal or the ones farther away? |
the lamellae closest to the central canal are the newest. Bone deposition goes from inside to out |
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bone elongation |
via interstitial growth
cartilage growth from within @ epiphyseal plate |
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bone thickening |
via appositional growth
the widening of bones because of deposition of new tissue at surface |
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what is the metaphysis? |
a transitional zone on each side of the epiphyseal plate facing the marrow cavity where cartilage is replaced by bone
5 zones: zone of reserve cartilage, proliferation, hypertrophy, calcification, bone deposition |
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zone of reserve cartilage |
closest to the epiphyseal plate
hyaline cartilage |
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zone of proliferation |
chondrocytes multiply and form columns of flat lacunae |
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zone of hypertrophy |
chrondrocytes enlarge |
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zone of calcification |
mineral deposited in matrix between lacunae
temporary support for cartilage |
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zone of bone deposition |
chrondrocytes die columns fill with osetoblasts & blood vessels osteoclasts dissolve calcified cartilage osteoblasts create spongy bone and osteons |
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which two zones are responsible for the growth in height of children? |
2. zone of proliferation 3. zone of hypertrophy |
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dwarfism |
achondroplastic: long bones stop growing in childhood (normal torso, short limbs)
pituitary: lack of growth hormone (normal proportions, short stature) |
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bone remodeling |
combined action of mineral deposition by osteoblasts and mineral resorption by osteoclasts
10% of skeleton per year
repairs microfractures, releases minerals into blood, reshapes bone for function |
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wolffs law |
bones adapt and shape is determined by stresses |
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mineral deposition |
creating bone
osteoblasts lay down collagen > hydroxyapetite crystals form (crystallization) > seed crystals recruit (positive feedback) > calcification |
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mineral resorption |
process of using osteoclasts to dissolve bone, leaking minerals into the blood
acid phosphatase digests collagen > HCL dissolves bone minerals |
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how do bones regulate blood calcium and phosphate levels? |
minerals can be deposited or withdrawn when needed |
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Ways in which our body utilizes phosphate |
ATP DNA phospholipid bilayer pH buffers |
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ways in which our body utilizes calcium |
muscle contraction blood clotting neuron communication exocytosis |
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How much calcium does our body have? |
1100g , 99% is in skeleton --stable hydroxyapatite reserve
we exchange 18% with blood each year |
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calcium homeostasis |
keeps desirable levels of calcium in blood
regulated by hormones calcitonin, calcitriol, and parathyroid hormone
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Concentration of calcium in blood plasma |
9.2-10.4 mg/dL slight changes cause serious consequences
depends on diet, urinary/fecal losses, exchanges with osseous tissue |
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calcitriol |
homeostatic control of calcium -raises blood calcium concentration (bone resorption, promotes kidney reabsorption, promotes absorption by small intestine) -form of vitamin D -found in fortified milk
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calcitonin |
homeostatic control of calcium -lowers blood calcium concentration (osteoclast inhibition, osteoblast stimulation) -secreted by c cells of thyroid when calcium is too high -important in children, weak effect in adults |
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calcium ion imbalances |
hypercalcemia: excess calcium, nerve/muscle cells less excitable, rare
hypocalcemia: calcium deficiency, more excitable, caused by vit D deficiency, pregnancy/lactation, diarrhea, tumors *negative feedback loops |
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parathyroid hormone |
homeostatic control of calcium -raises blood calcium (increases osteoclast activity, decreases osteoblast activity, promotes reabsorption by kidneys & calcitriol synthesis) -lowers blood phosphate levels by promoting excretion in urine |
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Types of bone fractures |
stress fracture: abnormal trauma, sports related
pathological fracture: fracture in bone that is already weakened by another disease (stress wouldnt normally break bone) ex. osteoporosis, bone cancer |
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classification of bone fractures |
nondisplaced: still aligned displaced: out of line comminuted: broken in 3+ pieces greenstick: incompletely broken on one side, bent on opposite side (twig) |
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Steps of healing a fracture |
1. hematoma formation - invasion of cells and capillaries 2. soft callus formation - deposition of collagen & fibrocartilage 3. hard callus formation - osteoblasts deposit bony collar(unites broken pieces) 4. bone remodeling - fragments removed by osteoclasts - osteoblasts deposit spongy bone > compact |
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Fracture treatments |
closed reduction (no surgery) open reduction (surgery) cast (immobilizes healing bone) STIM (accelerates repair, supresses PTH) traction (overrides force of muscles to align fracture)
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Bone anatomy - articulations |
condyle facet head |
