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What are the six basic functions of bone?
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How does a bone provide support?
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A&P chpt. 7
| Question | Answer |
|---|---|
| What are the six basic functions of bone? | Support, Protection, Movement, Mineral homeostasis, Blood cell production, storage of energy. |
| How does a bone provide support? | Bone provides a framework for the body by supporting soft tissues and providing points of attachment or most of the skeletal muscles. |
| How does a bone provide protection? | -- Bones protect many internal organs from injury very well, such as the brain and spinal cord. In addition, the heart, lungs, and reproductive organs are given some degree of protection. |
| How does a bone Move? | -- Most skeletal muscles attach to bones. When the muscles contract, they pull on bones to activate lever systems, and move-ment is produced. |
| Describe Mineral homeostasis | -- Bone tissue stores a number of minerals, particularly calcium and phosphorus. Under control of the endocrine system, bone releases the minerals into the blood or stores the minerals in bone matrix to maintain critical mineral balances. |
| How does a bone produce Blood cells? | -- In all bones of the infant and certain bones of the adult, a connective tissue known as red marrow produces blood cells by the process of hematopoiesis. |
| Diaphysis | The diaphysis of a long bone is its shaft or long main portion. |
| Epiphysis | The epiphysis of a long bone is its end. The two ends together are called the epiphyses. Each epiphysis is covered with articular cartilage. |
| Metaphysis | The metaphysis of a long bone is the region of mature bones where the diaphysis meets the epiphysis |
| Epiphyseal plate | In a growing bone, the epiphyseal plate is formed of hyaline cartilage divided into four zones of cells. Under the influence of growth hormone, the plate continues to grow, giving length to the bone. When bone growth exceeds cartilage growth, beginning |
| Articular cartilage | Articular cartilage is a thin layer of hyaline cartilage covering the articular surfaces of the epiphysis at a joint. |
| Medullary cavity | The medullary (marrow) cavity is the space within the bone containing either red or yellow bone marrow. Red bone marrow consists of blood precursors while yellow marrow consists of adipose tissue. |
| Periosteum | The periosteum is the double-layered connective tissue surrounding the bone except where the articular cartilage is present. It is divided into an outer fibrous layer and an inner osteogenic layer. |
| Fibrous periosteum | The outer fibrous layer of the periosteum is composed of dense irregular connective tissue containing blood vessels, lymphatics, and nerves that pass into the bone. |
| Osteogenic periosteum | The inner osteogenic layer of the periosteum contains elastic fibers and various bone cell types, particularly osteoprogenitor cells, that give rise to new osteoblasts when stimulated. |
| Periosteal functions | The periosteum functions in bone growth, repair, and nutrition. In addition, it provides attachment points for skeletal muscles. |
| Endosteum | The endosteum is a single layer of osteoprogenitor cells lining the medullary cavity. |
| Compare spongy bone with compact bone. | SB (lamellae of bone matrix,in an irregular latticework of thin plates of bone (trabeculae).Spaces between trabeculae are a part of the medullary cavity. CB contains very few spaces. Layers of bone matrix packed together tightly, forming osteons. Forms |
| Osteoprogenitor cells | Osteoprogenitor cells are immature quiescent cells lining the bone surfaces. When stimulated, they enter mitosis, giving rise to a new cell type called the osteoblast. |
| Osteoblast | Osteoblasts, once differentiated, lose their mitotic ability, and begin producing new bone matrix in a process known as osteogenesis. |
| Osteocytes | Osteocytes are mature bone cells completely embedded in bone matrix, are incapable of mitosis, and probably do not secrete new matrix. Their role in bone homeostasis is poorly understood. |
| Osteoclasts | Osteoclasts reside scattered along the endosteal surfaces. They function in a process known as bone resorption, the destruction of bone matrix. This process is required for normal bone function. |
| How does the matrix of bone differ from other connective tissue? | Unlike the other connective tissues, the matrix of bone contains an abundance of mineral salts embedded into an homogeneous frame work of extracellular materials. |
| Identify the three main components of bone matrix | 1. Tricalcium phosphate (hydroxyapatite--50% of total matrix), 2. Ground substance (25% of total matrix is water), 3. Collagen fibers (25% of total matrix) |
| Briefly describe the process of ossification (mineralization or calcification). | Main mineral salt is tricalcium phosphate (hydroxyapatite, ~50%, also calcium carbonate, magnesium hydroxide, fluoride, and sulfate. Salts deposited into framework of ground substance and collagen fibers, they crystallize, the tissue hardens or ossifies. |
| Although the hardness of the bone depends upon the crystallized mineral salts, without the collagen the matrix would be very brittle (ex: an egg shell). Why? | Collagen fibers provide pliability and tensile strength to resist being stretched or torn apart. The mineral salts are crystallized onto the collagen fibers, giving bone its hardness. |
| Did you ever see the experiment in which a chicken bone is placed into vinegar for a few weeks? When the bone was pulled from the vinegar, it could be bent and twisted, even tied into a knot. Why? | Because the acetic acid in the vinegar dissolved the mineral salts from the bone, leaving only the collagen framework. |
| Is a bone a solid mass? | No, we tend to think of bone as a solid mass of calcified matrix, but it is instead riddled with microscopic spaces through which blood vessels pass and fluids percolate. |
| Volkmann’s canal | A Volkmann’s canal is a minute passageway by means of which blood vessels and nerves from the periosteum of a bone penetrate into compact bone. |
| Haversian canal | An Haversian (central) canal is a circular channel running longitudinally in the center of an osteon of mature compact bone. It contains blood and lymphatic vessels and nerves. |
| Concentric lamellae | Concentric lamellae are rings of calcified bone matrix surrounding the Haversian canals of compact bone. |
| Lacunae | A lacunae (“little lake”) is a small hollow space within bone matrix wherein resides an osteocyte. They are located between concentric lamellae. |
| Canaliculus | A canaliculus is a small channel or canal connecting two lacunae in compact bone. Each canaliculus contains a cellular process of an osteocyte. |
| Osteon | An osteon (Haversian system) is the basic unit of structure in adult compact bone. Each consists of a central canal with its concentrically-arranged lamellae of matrix, lacunae, osteocytes, and canaliculi. |
| Interstitial lamellae | Interstitial lamellae are fragments of older compact bone found between newer osteons. They have been partially destroyed during bone replacement. |
| What is the process of bone remodeling? | Remodeling is the ongoing replacement of old bone tissue by new bone tissue. It occurs as a delicate balance between bone resorption by osteoclasts and bone formation by osteoblasts. |
| What does bone remodeling accomplish? | 1. Changes the way bone matrix resists stress, 2. Removes worn or injured bone, 3. Provides a reservoir for body calcium |
| Functions of bones | 1) support 2) protection 3) movement 4) mineral storage * calcium & phosphorus 5)blood cell formation 6)detoxification of heavy metals |
| GROSS ANATOMY OF BONES | 1) compact bone dense outer layer2) spongy bone - honeycomb of trabecualae filled w/ yellow or red bone marrow |
| STRUCTURE OF LONG BONES | Diaphysis - shaft - of compact bone surround the meduallary cavity filled w/ yellow or red marrowEpiphysis- head, exterior is compact bone internal is spongy-covered w/ articular (hyaline cartilage)- while growing it becomes the EPIPHYSEAL PLATE- EPIPHYSE |
| Diaphysis | shaft of long bone- of compact bone surround the meduallary cavity filled w/ yellow or red marrow |
| Epiphysis | Head of long bone, exterior is compact bone internal is spongy-covered w/ articular (hyaline cartilage)- while growing it becomes the EPIPHYSEAL PLATE- EPIPHYSEAL LINE |
| BONE MEMBRANE | Periosteum- double layer protective membrane white*outer fibrous layer - dense regular connective tissue * Major site of OSTOBLAST (bone forming cells)* Richly supplied with nerve fibers, blood, elyphatic vessels enter via nutrient foramina)* seamed to th |
| ENDOSTERM | INSIDE OF BONE*the delicate membrane covering internal surface of bone |
| Periosteum- around | OUTSIDE OF BONE (woven bone)*double layer protective membrane white*outer fibrous layer - dense regular connective tissue *vascularized mesenchyme condenses on the external face of the woven bone to become... |
| OSEOCLAST | dissolve bone |
| OSTEOBLAST | build new bones |
| MESENCHYMAL CELLS | Embryonic cell centrally located clusters become Osteoblasts - forming an ossification center |
| OSTEOCYTE | trapped osteoblast become ...matrure |
| OSSIFICATION & OSTEROGENESIS | process of bone formation (boney skeleton) then bone grown and repair |
| STRUCTURE OF BONE | Osteon or Haversian systemlamella - lemele haversian canal or central canalvolkman's canals |
| OSTEON OR HAVERSIAN SYSTEM | the structural unit of compact bone (one group of circles section of bone cross sectional view) |
| OSTEOID | unmineralized bone matrix composed of proteoglans, glucoproteins and collagen |
| LAMELLALAMELE (plural) | weight bearing section of bone - column like a matrix tubes composed mainly of collagen(One ring) |
| HAVERSIAN CANAL OR CENTRAL CANAL | canal of bone length wise that contains blood vessels and nerves(eye of the storm) |
| VOLKMANN'S CANAL | Channels in bone lying at right angles to the central cannal (Haversian canal). Connecting blood and nerves supply of the perlosteum to the Haversian canal (central canal). Also called the perforating canal. |
| LACUMAE | small cavities in bone that contain osteocytes |
| CANALICULI | hair like canals that connect lacunae to each other and central canal (Haversian canal). |
| STRUCTURE OF SHORT, IRREGULAR & FLAT BONES | * thin plates of PERIOSTEM COVERED OUTSIDE compact bone w/ ENDOSTEUN COVERED INSIDE spongy bone* have no diaphysis or epiphysis* contain bone marrow between the trabecule * sandwich like |
| LOCATIONS OF HEMATOPIETIC TISSUE (RED MARROW) | Infants- found in the medullary cavity and all areas of spongy boneAdults- found in the spongy (dipole) of flat bones and the head of the femur and humours |
| Inorganic part of bone | Hydroxyatatile Ca+ (Po4) 6 (OH) 2 85%calcium carbonate 10% |
| BONE DEVELOPMENT | ostergeneisis and ossifacaiton - (hayline will turn into bone and then break) the process brake, clean up , bind |
| 4 STAGES OF INTRAMEMBRANOUS OSSIFICATION | 1) Mesecchymal cells - differentiate into osteoblast2) Osteroblast secrete ostercytes then become osteocyte (mature)3) Perioseum forms=woven bone4) blood vessels invade the bone tissue |
| ENDOCHONDRAL OSSIFICATION | * begins the 2nd month of development* uses hayline cartilage "bones" as a model of bone* requires breakdown of haylaine cartilage prior to ossification |
| 5 STAGES OF ENDOCHODRAL OSSIFICATION | 1) formation of bone collar2) cavitations of the hayline cartilage3) invasion of internal cavities by blood vessels (spongy bone formation will occur)4) formation of medullary cavity5) ossification of the epiphysis - wit hayaline cartlage remaining only |
Created by:
SKinnan