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Chapter 6: Osseous Tissue and Bone Structure

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Axial Skeleton contains:
skull, vertebral column, rib cage
Appendicular skeleton includes:
pectoral and pelvic girdles, arms and legs
What are the 5 functions of the skeletal system?
support, storage of mineral and lipids, blood cell production, protection of internal organs, and leverage for muscular movement
What is hemopoiesis?
blood cell production
What mineral is vital for the proper function of membranes, neurons, and muscle cells (especially heart cells) and is the most abundant in the body?
Calcium
What are sutural bones?
These bones are small, irregular bones. Can be found between the flat bones of the skull.
What bone classification would the spinal vertebrae and pelvic bones have? (complex shapes)
Irregular bones
What bones are small and thick? (ankle and wrist bones)
Short bones
Describe flat bones
These bones are thin with parallel surfaces. Examples include the sternum, ribs, scapulae, and also can be found in the skull.
What bones are long and thin and are found in the arms, legs, hands, feet, fingers, and toes?
Long bones
Describe sesamoid bones:
These bones are small and flat and develop inside tendons near joints of knees, hands, and feet. Example: Patella
In relation to classification based on markings what runs along the bone surface?
depressions or grooves
Describe elevations or grooves
These markings are where tendons and ligaments attach and are at articulations with other bones.
What are tunnels in reference to markings of the bone?
These markings are where blood and nerves enter the bone
The structure of a long bone contains:
Diaphysis, epiphysis, and metaphysis
Describe diaphysis in accordance to the structure of a long bone:
This portion of the long bone is known as the shaft of the long bone, has a heavy wall of compact bone aka dense bone, and a central space called medullary (marrow) cavity
Describe epiphysis in accordance to the structure of a long bone:
This portion of the long bone is the wide part at each end, articulates with other bones. It is mostly spongy (cancellous) bone and is covered with compact bone (CORTEX).
Describe metaphysis in accordance to the structure of a long bone:
This part of the long bone is where diaphysis and epiphysis meet
Describe the structure of the flat bone:
The parietal bone of the skull. It resembles a sandwich of Spongy bone between two layers of Compact bone. It is within the cranium.
What is the name of the layer of spongy bone between the compact bone in the parietal bone?
Diploe
Describe osseous (bone) tissue:
This tissue is dense, supportive connective tissue. It contains specialized cells and produces a solid matrix of calcium salt deposits. Mineral deposits form around collagen fibers.
What is dense matrix?
This characteristic of bone tissue contains deposits of calcium salts, osteocytes (cells) within lacunae organized around blood vessels.
What is canaliculi?
This characteristic of bone tissue has pathways for blood vessels and exchanges nutrients and wastes.
Break down the proportions of bone weight:
Matrix is 98% of bone weight and cells are 2%.
Describe osteocytes:
These bone cells are mature and maintain the bone matrix. They live in lacunae and cytoplasms connect through canaliculi in lamellae. These cells do not divide.
What are the two major functions of osteocytes?
Maintain protein and mineral content of matrix and help repair damaged bone.
Describe osteoblasts:
These bone cells are immature and secrete matrix compounds (osteogenesis). These cells surrounded by bone become osteocytes and produce osteoid.
What is osteogenesis?
the formation of bone; the development of bone.
What is osteoid?
matrix produced by osteoblasts, but not yet calcified to bone
Describe osteoprogenitor cells:
These bone cells have mesenchymal stem cells that divide to produce osteoblasts and assist in fracture repair. These cells are located in the endosteum and in the inner cellular layer of periosteum.
What bone cells are giant, multi-nucleated cells that secrete acids and protein-digesting enzymes. It also dissolves bone matrix and releases stored minerals and is derived from stem cells that produce macrophages?
Osteoclasts
What is osteolysis?
the pathological destruction or disappearance of bone tissue.
What is homeostasis in bone tissue?
Osteoblasts build bone, osteoclasts break down bone and this requires a balance between both.
What happens when there is an imbalance in homeostasis?
When this happens there is too much breakdown and the bones become weak. Exercise (weight-bearing) increases bone building.
What is osteon?
This part of compact bone structure is a basic structural unit of compact bone. Osteocytes are arranged in concentric lamellar rings around a central canal containing blood vessels and have perforating canals.
What are perforating canals?
Perpendicular to the central canal and carries blood vessels into bone and marrow.
What is lamellae wrapped around the long bone and binds osteons together?
Circumferential lamellae
Periosteum by definition is?
a membrane that covers the outside of bone and covers all bones except parts that are enclosed in joint capsules. Is composed of outer, fibrous and inner cellular layer.
What are the collagen fibers of the periosteum that connect with collagen fibers in the bone and fibers of joint capsules?
Perforating fibers
These collagen fibers of the periosteum that connect to bone and joint capsules can run out of periosteum and they attach to tendons and ligaments
Perforating fibers
The structure of compact bone is described as?
This bone structure is surrounded by periosteum, and surrounded internally by endosteum.
What are the functions of periosteum?
Isolates the bone from surrounding tissue, route for circulatory and nervous supply, and assists with bone growth and repair.
What is endosteum by definition?
This lining covers the inside of bone (medullary cavity) and has an incomplete cellular level and contains osteoblasts, osteoclasts, and osteoprogenitor cells.
What covers the trabeculae in spongy bone, lines central canals, and is also active in bone growth and repair.
Endosteum
What is the structure of spongy bone?
This bone structure has no osteons, has trabeculae, and bone marrow in space between trabeculae.
What spongy bone characteristic is an open network formed by the matrix and has no blood vessels?
Trabeculae
What bone marrow has blood vessels, supplies nutrients to osteocytes and forms blood cells?
Red bone marrow
What bone marrow is only in some bones and holds fat?
Yellow bone marrow
Supporting weight and force on weight bearing bones (long) requires?
Compact bone and spongy bone
Describe the process of how spongy and compact bone work together in weight bearing bones?
On the femur the weight is applied at the hip, on the head of the femur and it compresses the medial shaft and creates tension laterally. The weight gets diverted and the force is transferred by the trabeculae and then force is resisted by compact bone.
What is bone formation?
Osteogenesis
What is the process of replacing other tissues with bone?
Ossificatioln
Bone growth starts at __ _______ gestation and continuously until __ ______ old.
6 weeks; 25 years
What hardens tissue after the process of depositing calcium salts in tissue and occurs during ossification of bone or other tissue?
Calcification
By definition, what is Endochondral Ossification?
This type of ossification ossifies hyaline cartilage into bone and most bones originate as hyaline cartilage. Starts with formation of a thin layer of bone and is followed by appositional growth.
What thickens compact bone and strengthens long bones with layers of circumferential lamellae?
Appositional growth
There are 6 steps to endochondral ossification, what are they?
In this ossification, 1) chondrocytes and lacuna get bigger, calcify, and then the cell dies leaving holes. 2) Blood vessels grow into perichondrium, first become osteoblasts and then they create a layer (perichondrium is now periosteum). 3) Blood vessels enter space from dead chondrocytes. Fibroblasts in blood supply form more osteoblasts and make spongy bone. The formation spreads. 4) Bone grows, osteoclasts begin remodel. 5) Capillaries and osteoblasts move into epiphyses, creating secondary ossification centers. 6) Epiphyses fill with spongy and articular cartilage and epiphyseal cartilage remains.
After puberty, long bones stop growing, epiphyseal cartilage disappears and leaves an x-ray visible ________?
Epiphyseal line
By definition, what is intramembranous ossification?
This type of ossification is also known as "Dermal Ossification," because it occurs in the dermis and produces dermal bones such as the mandible and clavicle.
What are the 3 steps of intramembranous ossification?
1) Mesenchymal cells aggregate turn into osteoblasts and begin the ossification process. The bone expands into a series of spicules. 2) Spicules interconnect and trap blood vessels. 3) Then over time, the bone assumes structure of spongy bone. May be remodeled to create medullary cavities or compact bone.
By remodeling, the adult skeleton must:
Maintain itself, replace mineral reserves, recycle and renews bone matrix.
Vitamins tend to function as:
Co-Factors
What is the turn over rate in bone remodeling?
If deposition is faster than removal, the bones get stronger and if removal is faster than deposition, bones will get weaker.
What nutrients or vitamins are required for normal bone growth and maintenance?
Calcium, phosphate, vitamin D3, vitamin C, vitamin A, vitamin K, and vitamin B12.
What vitamin(s) is/are required to absorb calcium?
Vitamin D3
What vitamin(s) is/are required to build collagen?
Vitamin C and Vitamin A
A lack of this vitamin will cause scurvy:
Vitamin C
A lack of vitamin C will cause what disease?
scurvy
What vitamin(s) is/are required for enzamatic processes?
Vitamin K and Vitamin B12
Describe nutrient artery and veins in regards to types of blood supply to bones:
This type of blood supply to the bones is a single pair of large blood vessels and enters the diaphysis through the nutrient foramen. One exception is the femur it has 2 pairs.
Describe metaphyseal vessels in regards to types of blood supply to bones:
This type of blood supply to the bones supplies blood to the epiphyseal cartilage where bone growth occurs.
Describe periosteal vessels in regards to types of blood supply to bones:
This type of blood supply to the bones supplies it to superficial osteons where secondary ossification centers are.
What type of fracture is completely internal and can only been seen on x-rays because the skin is intact?
Closed (simple) fracture
What type of fracture projects through the skin and is more dangerous due to uncontrolled bleeding and infection risk?
Open (compound) fracture
What are the 4 steps of fracture repair?
1) The fracture ruptures blood vessels, fracture hematoma, and the bone cells die in the area. 2) The activation of endosteum and periosteum cells divide and migrate, then calluses of cells stabilize. 3) Osteoblasts then form new bone..replaces center of external callus with spongy bone. 4) Osteoblasts and osteoclasts remodel.
What is inadequate ossification of bone and begins between ages 30 and 40?
Osteopenia
What is effected mostly by osteopenia?
The epiphyses, vertebrae, and jaws
What is a reduction in bone mass that compromises normal function?
Osteoporosis
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