Chapter 6 Flashcards
What is bone made up of?
Osseous tissue, cartilage, dense connective tissue, epithelium, adipose tissue and nervous tissue
What are the basic functions of the skeletal system?
- Support
- Protection
- Assistance in moving
- Mineral homeostasis (storage and release)
- Blood cell production
- Triglyceride storage
What does red bone marrow produce?
Red blood cells, white blood cells, platelets
What is hemopoiesis?
Hemopoiesis is the process when red bone marrow produces red blood cells, white blood cells, or platelets
What does yellow bone marrow do?
Stores triglycerides
What is a long bone?
A bone whose length is greater than its width
What parts does a typical long bone consist of?
- Diaphysis
- Epiphyses
- Metaphases
- Articular cartilage
- Periosteum
- Medullary cavaty
- Endosteum
Diaphysis
The bone shaft. the long, cylindrical, main portion of the bone
Epiphyses
The proximal and distal ends of the bone
Metaphyses
The regions between the diaphoresis and the epistasis contains epiphyseal (growth) plates
Epiphyseal (growth) plate
A layer of hyaline cartilage that allows the diaphysis of the bone to grow in length when it stops growing the cartilage in the epiphyseal plate is replaced by bone
Epiphyseal line
The cartilage in the epiphyseal plate that is replaced by bone is known as this
Articular cartilage
A thin layer of hyaline cartilage covering the part of the epiphysis where the bone forms an articulation with another bone this cartilage reduces friction and absorb shock at freely moveable joints
Periosteum
A tough connective tissue associated with blood supply composed of outer fibrous layer and an inner osteogenic layer attached to the underlying bone by perforating fibres
Perforating fibres or sharpies fibres
Six bundles of collagen that extend from the periosteum into the bone extra cellular matrix
Medullary cavity
A hollow cylindrical space within the dyphisis that contains fatty yellow bone marrow and numerous blood vessels minimizes weight of the bone
Endosteum
A thin membrane that lines the medullary cavity contains a single layer of bone forming cells in a small amount of connective tissue
Osseous tissue
Connective tissues with an abundant extracellular matrix
Hydroxyapatite
Calcium phosphate combined with another mineral salt calcium hydroxide which form crystals of hydroxyapatite
How is calcification initiated?
By bone building cells called osteoblasts
What’s it called when mineral salts which are deposited into the extra cellular matrix crystallize and the tissue hardens?
Calcification
What are the four types of cells that are present in bone tissue?
- Osteoprogenitor cells
- Osteoblasts
- Osteocytes
- Osteoclasts
Osteoprogenitor cells
Unspecialized bone stem cells derived from mesenchyme
undergo cell division resulting in osteoblasts
found along the inner portion of the Periosteum, in the endosteum, and in the canals within bone that contains blood vessels
Osteoblasts
Bone building cells
synthesize and secrete collagen fibres and other organic components needed to build the extracellular matrix
Osteocytes
Mature bone cells
main cells in the bone tissue and maintain its daily metabolism such as the exchange of nutrients and waste within blood
do not undergo cell division
Osteoclasts
Huge cells
concentrated in the endosteum releases powerful lysosomal enzymes and acids that digest the protein in mineral components of the underlying extracellular bone matrix
help regulate blood calcium levels
Compact bone tissue
Contains few spaces and is the strongest form of bone tissue provides protection and support and resist the stress is produced by weight and movement
What is compact bone tissue composed of?
Osteons
What do osteons consist of?
- Concentric lamellae
- Ostionic canal
What is the concentric lamellae?
Circular plates of mineralized extra cellular matrix of increasing diameter surrounding a small network of blood vessels and nerves located in the central canal
Lacunae
Small spaces between the concentric lamellae which contain osteocytes
Canaliculi
Radiate from the lacunae And are filled with extra cellular fluid connect lacunae with one another and with the central canals providing many routes for nutrients and oxygen to reach the osteocytes
Osteons in compact bone tissue are aligned in the same direction and are _______to the length of the diaphysis?
Parallel
Interstitial lamellae
Located between neighbouring osteons and are fragments of old osteons that have been partially destroyed during bone rebuilding or growth
Interosteonic canals
Blood vessels and nerves from the periosteum that penetrate the compact bone And connect the medullary cavity, periosteum, and central canals
What are the lamellae arranged around the entire outer and inner circumference of the shaft of a long bone?
Circumferential lamellae
What other circumferential lamellae directly deep to the periosteum called?
External Circumferential lammellae
 What do perforating fibres connect?
Sercombe Franchel Lammle and periosteum
What is the Circumferential lamellae that lines the medullary cavity called?
Internal circumferential lamellae
What is spongy bone tissue also referred to as?
Trabecular or cancellous bone tissue
Trabeculae
Consists of Lammle that are arranged in an irregular pattern of thin columns
What does trabecula consist of?
- Concentric lamellae
- Osteocytes that lie in lacunae
- Canaliculi that radiate outward from lacunae
What is spongy bone always covered in And why?
A layer of compact bone for protection
What are the two ways spongy bone tissue is different from compact bone tissue?
- Weight
- The trabeculae of spongy bone tissue support and protect the red bone marrow
Periosteal arteries
Small arteries accompanied by nerves supply the periosteum and outer part of the compact bone
Nutrient artery
Near the centre of the dyphisis and passes through a hole in compact bone called the nutrient foramen. supplies the inner part of the compact bone tissue of the diaphysis, spongy bone tissue and red bone marrow
Metaphyseal arteries
Enter the metaphyses of a long bone and with the nutrient artery supply the red bone marrow and bone tissue of the metaphyses
Epiphyseal arteries
Enter the epiphyses of a long bone and supply the the red bone marrow and bone tissue of the epiphyses
What three places are veins evident in the long bone?
- Nutrient veins exit through the diaphysis
- Epiphyseal veins and metaphyseal veins exit through the Epiphyses and metaphyses
- Periosteal veins exit through the periosteum
What accompanies the blood vessels that supply the bones?
Nerves
What is the process by which bones are formed called?
Ossification
What are the two patterns of bone formation?
- Intramembranous ossification
- Endochondral ossification
Intramembranous ossification
Bone forms directly within mesenchyme which is arranged in sheet like layers that resemble membranes
Endochondral ossification
Bone forms within hyaline cartilage that develops from mesenchyme.
The replacement of cartilage by bone
Which bones form from intramembranous ossification?
Flat bones of the skull, most of the facial bones, mandible, medial part of the clavicle, and soft spots that help the fetal skull pass-through the birth canal
How does intramembranous ossification occur?
- Development of the ossification centre
- Calcification
- Formation of trabeculae
4. Development of the periosteum
Steps of endochondral ossification?
- Development of the cartilage model
- Growth of the cartilage model
- Development of the primary ossification centre
- Development of the medullary cavity
- Development of the secondary ossification centres
- Formation of articular cartilage in the epiphyseal plate
Interstitial growth
When the cartilage model grows in length by continual cell division of chondrocytes accompanied by further secretion of the cartilage extracellular matrix
Appositional growth
When the cartilage grows in thickness do mainly to the deposition of extra cellular matrix material on the cartilage surface of the model by new chondroblasts that develop from the Perichondrium
Periosteum
Once the perichondrium starts to form bone
Primary ossification centre
A region were bone tissue will replace most of the cartilage
Secondary ossification centres
Usually develop around the time of birth when branches of the epiphyseal artery enter the epiphyses
What two major events are involved in the growth of length of long bones?
- Interstitial growth of cartilage on the epiphyseal side of the epiphyseal plate and
- replacement of cartilage on the diaphyseal side of the epiphyseal plate with bone by endochondral ossification
What are the four zones of the epiphyseal plate?
- Zone of resting cartilage
- Zone of proliferating cartilage
- Zone is hypertrophic cartilage
- Zone of calcified cartilage
What’s the only way the diaphysis can increase in length?
Activity of the epiphyseal plate
What is the way that bone can grow in thickness?
Appositional growth
What are the steps to bone growth in thickness?
- At the bone surface periosteal cells differentiate into osteoblasts
- Eventually the ridge is full together in fuse and the groove becomes a tunnel that encloses the blood vessel
- Osteoblasts in the Endosteum deposit bone extra cellular matrix forming new concentric lamellae
- As an osteon is forming osteoblast under the periosteum deposit new circumferential lamellae further increasing the thickness of the bones
Bone remodeling
The ongoing replacement of old bone tissue by new bone tissue
Bone reabsorption
The removal of minerals and collagen fibres from bone by osteoclasts
Results in the distraction of bone extracellular matrix
Bone deposition
The addition of minerals and collagen fibres by the bone by osteoblasts
Results in the formation of bone extracellular matrix
What factors affect bone growth and bone remodeling?
- Minerals
- Vitamins
- Hormones like insulin like growth factors (IGS), thyroid hormones (T3 and T4), and insulin
What’s the bodies major calcium Reservoir?
Calcium
Parathyroid hormone (PTH)
Increases blood CA2+ level and operates on a negative feedback system
Calcitriol
A hormone that promotes absorption of calcium from foods into the gastrointestinal tract into the blood which elevate blood CA 2+ level
Calcitonin (CT)
CT inhibits activity of osteoclasts speeds blood Ca2+ uptake by bone and accelerates CA 2+ deposition into bones the net result been CT promotes bone formation and decreases blood CA 2+ level
The periosteum is essential for what?
Growth and bone thickness
bone repair
bone nutrition and also
serves as a point of attachment for ligaments and tendons
What is bone resorption necessary for?
Development, maintenance, and repair of bones
What would happen if the osteonic canal’s were blocked?
Blockage would lead to death of the osteocytes because the osteonic canal’s are the main blood supply
How do periosteal arteries enter bone tissue?
Through perforating interosteonic canal’s
What is the lengthwise growth of the diaphysis caused by?
Cell divisions in the zone of proliferating cartilage and replacement of the zone of calcified cartilage with bone
What depends on proper levels of calcium?
Heartbeat, respiration, nerve cells functioning, enzyme functioning, and blood clotting
________ Is the receptors in the feedback system for the regulation of blood calcium mediated by parathyroid hormone?
Parathyroid gland cells
Which cells in bone tissue are the only sells to undergo cell division?
Osteoprogenitor cells
This zone of _____ cartilage of the epiphyseal plate becomes the “new diaphysis” as it is replaced by bone extracellular matrix through endochondral ossification?
Calcified
What activities is the periosteum involved with?
Providing nourishment to bone tissue, growth of bone in width, assistance in fracture repair
The outer fibrous layer of the periosteum is composed of
Dense irregular connective tissue
The connective tissue sheath on the surface of the bone is?
Periosteum
The epiphyseal plate and growing bones is located where?
Metaphysis
What bone cells help regulate blood calcium levels?
Osteoblast and osteoclast
Obstruction within the perforating canals of the femur will affect blood flow within what artery?
Periosteal
Which bone is rich in sensory nerves?
Periosteum
What process of intramembranous ossification gives rise to spongy bone tissue?
Formation of trabeculae
