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AP Bone Ch 6
Excelsior AP ch 6 bone tissue and structure
Question | Answer |
---|---|
skeletal system includes... | bone, cartilage, ligaments |
Five functions of the skeletal system | 1. structural support 2. storage of lipids and minerals 3. blood cell production 4. protection of vital organs 5. leverage with the force of muscles |
sutural bone shape | small, flat, irregularly shaped bones between the flat bones in the skull. resemble jigsaw puzzle pieces |
irregular bones | complex shapes with short, flat, notched or ridged surfaces. ie- vertebrae,pelvic bones, some skull bones |
short bones | small and boxy. ie- carpals in wrists and tarsals in ankles |
flat bones | have thin parallel surfaces. ie- sternum, ribs, scapulae |
long bones | long and slender. ie- femur, humerus, radius, ulna, phalanges, etc |
largest, heaviest bone in the body | femur |
sesamoid bones | small, flat, shaped somewhat like a sesame seed. develop inside tendons and are mostly found at joints. ie- patella |
process (bone marking) | projection or bump on bone surface where tendons/ligaments attach |
trochanter | large rough projection where tendon/ligaments attach |
tuberosity | small rough projection where tendon/ligaments attach |
spine (bone marking) | pointed or narrow projection (process) |
foramen | round passageway in bone through which blood vessels and nerves pass |
canal | duct or channel |
meatus | passageway through bone |
fissure | elongated cleft or slit |
sinus | a chamber within bone, normally filled with air |
diaphysis | tubular shaft of long bone |
epiphysis | head, expanded area at either end of long bone |
metaphysis | neck, narrow connection between epiphysis and diaphysis (head and shaft) |
medullary cavity (marrow cavity) | central space inside some bones that contains the marrow |
compact bone | dense bone that contains parallel osteons |
cancellous bone | spongy bone as in the epiphysis (head) of a long bone |
epiphysis (head) of long bone is made of ___ bone | spongy (cancellous) |
cortex (cortical bone) | thin layer of compact bone that surrounds spongy bone |
matrix of osseous tissue is made up of... | crystallized calcium salts, protein (collagen) fibers and ground substance containing specialized cells |
calcium phosphate makes up approx ___ of the weight of all bone in the body | 2/3 of the weight |
collagen fibers make up approx ___ of the weight of all bone in the body | 1/3 of the weight |
bone gets its hardness from ___ ___ | calcium salts |
bone gets its flexibility from ___ ___ | collagen fibers |
four types of bone cells | 1. osterocytes 2. osteoblasts 3. osteoprogenitor cells 4. osteoclasts |
osteocytes | mature bone cells. largest population of bone cells. |
lacunae | pocket that encloses each osteocyte |
lamellae | concentric layers of bone matrix matrix in an osteon (bulls eye) |
canaliculi | narrow passageways between matrix of bone that connect osteocytes in lacunae to one another and to blood vessels |
functions of osteocytes | 1. maintain protein and mineral levels in matrix 2. repair damaged bone by converting to less specialized cells |
osteoblasts | produce new bone matrix (osteogenesis/ossification)[blast and build both start with B] |
osteogenesis/ossification | production of new bone matrix (by osteoblasts) |
osteoid | new, incomplete bone matrix that doesn't yet have calcium deposits. |
osteoprogenitor cells | (ancestor) stem cells whose daughter cells differentiate into osteoblasts |
osteoclasts | dissolve and recycle bone matrix (osteolysis) |
osteolysis | erosion of bone matrix |
osteon | the functional unit of mature compact bone. made up of concentric layers of lamellae, central canal, perferorating canals and collagen fibers |
central canal | run parallel to bone surface. contain vessels that supply the osteon |
perforating canals | run perpendicular to bone surface, supply deeper bone tissue and medullary cavity |
which type of bone has a structure arranged in osteons? | compact bone |
spongy bone structure | matrix is an open network of fibers called trabeculae. spongy bone is located where bones are not heavily stressed or where stress is applied from many directions |
trabeculae | fibers that form the interwoven network of spongy bone |
network of trabeculae in spongy bone supports and protects ___ ___ | bone marrow |
two types of bone marrow | 1. red bone marrow- produces blood cells 2. yellow bone marrow- adipose tissue |
red bone marrow | located in the epiphysis (head) of long bones and in large bones like sternum, ilium, etc. Surrounded by spongy bone. produces blood cells. |
yellow bone marrow | adipose tissue that serves as an energy reserve. |
body weight compresses the ___ side of femur while the ___ portion resists stretching under tension | medial portion is compressed. Lateral portion resists stretching |
periosteum | the two layer fibrous membrane that wraps the outside of bone |
two layers of periosteum | 1. fibrous outer layer 2. cellular inner layer |
endosteum | incomplete cellular layer that lines the medullary cavity and trabeculae of spongy bone. made up of layer of osteoprogenitor (stem) cells and exposed matrix. |
calcification | deposition of calcium salts during ossification |
ossification/osteogenesis | bone formation |
two types of ossification | 1. endochondral 2. intramembranous |
endochondral ossification | in a developing fetus, the skeleton is initially made of hyaline cartilage. it is gradually replaced by bone during development. |
intramembranous ossification | bone develops from mesenchyme. usually occurs in dermis (creating dermal bones). responsible for growth of flat bones in skull, clavicles, mandible |
epiphyseal cartilage | cartilage that separates the epiphysis and diaphysis of a bone |
appositional bone growth | cells of inner layer of periosteum differentiate into osteoblasts and increase bone width by adding superficial layers of circumferential lamellae to bone. |
ossification center | location where ossification (bone formation) begins in tissue |
spicules | small struts of bone that grow outward from ossification center |
three major sets of blood supplies to bone | 1. nutrient artery/vein- supplies diaphysis 2. meathyseal vessels- supply inner surface of epiphyseal cartilage where growth occurs 3. perostial vessels- originate at periosteum and supply superficial osteons of diaphysis |
nutrient foramina | the opening in the diaphysis of a bone where the nutrient artery/vein enters the bone |
remodeling | continuous recycling and renewal of the organic and mineral components of the bone matrix by oseoclasts and osteoblasts |
bone has a high turnover rate with approx __ of skeleton being replaced each year | 1/5 |
when a bone is stressed, mineral crystals generate tiny ___ ___ which draws osteoblasts to the site to strengthen the bone. | electrical fields |
as muscle strength increases bumps and ridges where muscles attach... | increase in size |
bone that is not subjected to stress ___ | deteriorates |
calcitrol | hormone required for calcium absorption in GI tract. synthesized in kidneys from cholecalciferol (vit D3) |
cholecalciferol | vitamin D3- used by the kidneys to synthesize calcitrol which is required for absorption of calcium in GI tract |
Vitamin C | required for many enzymatic reactions including collagen synthesis |
vitamin A | stimulates building of bone by stimulating osteoblasts |
Vitamin K and B12 | required for protein synthesis in normal bone |
growth hormone | produced by pituitary gland, stimulates bone growth |
thyroxine | produced by thyroid gland, stimulates bone growth |
sex hormones (androgen and estrogen) | both stimulate bone growth ultimately causing the closure of the epiphyseal cartilage. estrogen causes faster growth causing the cartilage to close in women before androgen does in men. thus, women usually shorter than men. |
calcitonin | decreases calcium content in body fluids. produced by the thyroid gland, inhibits osteoclast activity, promotes calcium loss by kidneys. |
parathyroid hormone (PTH) | increases calcium concentration in body fluids by stimulating osteoclast activity, increases Ca++ absorption in GI tract, decreases Ca++ excretion in kidneys |
calcitonin effect on calcium concentration in plasma | decreases calcium levels in plasma. promotes bone growth. |
parathyroid hormone effect on calcium levels in plasma | increases calcium levels in plasma. promotes bone breakdown. |
most abundant mineral in the human body | calcium |
if calcium level in body fluids gets too high | neurons and muscle cells become unresponsive |
if body fluid calcium level drops too low | neurons become excitable and convulsions occur |
a 50% decrease in plasma calcium concentration can cause | death |