Busy. Please wait.
or

show password
Forgot Password?

Don't have an account?  Sign up 
or

Username is available taken
show password

why


Make sure to remember your password. If you forget it there is no way for StudyStack to send you a reset link. You would need to create a new account.
We do not share your email address with others. It is only used to allow you to reset your password. For details read our Privacy Policy and Terms of Service.


Already a StudyStack user? Log In

Reset Password
Enter the associated with your account, and we'll email you a link to reset your password.

Remove ads
Don't know
Know
remaining cards
Save
0:01
To flip the current card, click it or press the Spacebar key.  To move the current card to one of the three colored boxes, click on the box.  You may also press the UP ARROW key to move the card to the "Know" box, the DOWN ARROW key to move the card to the "Don't know" box, or the RIGHT ARROW key to move the card to the Remaining box.  You may also click on the card displayed in any of the three boxes to bring that card back to the center.

Pass complete!

"Know" box contains:
Time elapsed:
Retries:
restart all cards




share
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.

  Normal Size     Small Size show me how

Bone and Bone growth

QuestionAnswer
What are the functions of bone? Enables movement- attach of muscles. Protection of vital organs. Structural support. Storage of minerals (Ca2+, Mg, PO43-) Haematopoiesis- blood cell formation.
What is bone made out of? Osteoblasts, osteocytes and osteoclasts.
What is the structure of collagen? Fibre framework in a mucopolysaccharide rich semisolid gel "ground substance.
What is the function of collagen? Gives bone its tensile strength.
How is bone different to cartilage? Bone is hardened by precipitation of calcium phosphate (hydroxyapatite) crystals within matrix.
What is the function of the hydroxyapatite? Gives bone it compressional strength.
What are the four sections of a long bone? Epiphysis, Metaphysis, Diaphysis and Periosteum.
What is the epiphysis? Head- articular surface, covered by hyaline cartilage.
What is the metaphysis? Between epiphysis and diaphysis- region of growth in childhood.
What is the diaphysis? Shaft- hollow cylinder, contains bone marrow in marrow cavity (Red blood cell formation).
What is the periosteum? Fibrous connective tissue sheath covering external surfaces.
What cells are included in the periosteum? Fibroblasts (synthesize collagen), Mesenchymal cells (can differentiate into osteoblasts and chondroblasts) and osteoclasts.
What are the descending layers of bone? Periosteum, Shaft of compact bone and Medullary cavity.
What are the two major kinds of long bone? Trabecular (Cancellous) and Cortical.
Describe the structure of trabecular bone. Spongy and porous.
What is the function of trabecular bone? Gives supporting strength to the ends of weight bearing bone. Allows distribution of stresses. Have high SA for metabolism (e.g. regulation of calcium ions).
What is the structure of cortical bone? Solid.
What are the functions of cortical bone? Bone on the outside forms the shaft of the long bone. Provides stiffness and strength.
Describe the blood supply to a bone. Haversian canals carry blood along the long axis of the bone. Volksman's canals carry blood perpendicularly. Majority of cells in very close contact to blood vessels.
How are the cells arranged in cortical bone? Concentric circles (like an onion). Inside each layer are collagen fibres.
How is spongy (cancellous/trabecular) bone different to compact bone? Fewer lamellar layers in the "spongy" trabecular region. Less coordinated (weaker and more flexible) than compact bone. More open, less dense, site of haemopoiesis in bone marrow.
What is the composition of the bone matrix? Organic matrix, crystallised mineral salts and water.
What constitutes the organic matrix? Mostly protein fibres-collagen. Collagen is highly organised in parallel arrangement (in cortical and trabecular bone).
What constitutes the crystallised mineral salts? Hydroxyapatite- Ca10(PO4)6(OH)2
What causes rickets? Vitamin D deficiency- failure of Ca2+ absorption.
What causes scurvy? Vitamin C deficiency- lack of collagen.
What is the definition of an osteoblast? Bone forming cell. They cover the surface of bone forming an osseous matrix in which it becomes enclosed as an osteocyte.
What is an osteoclast? Osteophage- a large, multinucleated cell derived from haematopoietic cells. In response to mechanical stresses and physiological demands they resorb bone matrix by demineralization.
What is an osteocyte? Bone cell-trapped, "retired" osteoblasts. Mature bone cells- embedded in lacunae, relatively inactive. Maintain bone matrix through cell to cell communication (via projections in canaliculi) and influence bone remodelling.
What are osteoprogenitor cells? Stem cell population, gives rise to osteoblasts (as well as other cells).
What is the function of osteoblasts? When stimulated to form bone, they will deposit organic matrix (collagen) then hydroxyapatite. Some become entombed in this process and mature into osteocytes.
What is the function of an osteoclasts? Form a "sealing zone" on bone- release H+ and hydrolytic enzymes that dissolve the mineral, liberate calcium and break down the extracellular matrix. Regulated by hormones and osteoblasts.
What controls the actions of osteoblasts and osteoclasts? Equilibrium between osteoblast and osteoclast activity is controlled by signalling between the different cells in bone and via the actions of hormones.
Which hormones control the osteoblast-osteoclast equilibrium? Calcitonin and Parathyroid hormone (PTH).
What is the function of Calcitonin? Decreases activity of osteoclasts, i.e. decreases blood Ca2+ levels.
What is the function of Parathyroid hormone? Increases the activity of osteoclasts, releases Ca2+.
What is the process of trabecular bone remodelling cycle? Resorption by osteoclasts. Surface exposed to osteoprogenitors. Osteoblasts differentiate. Osteoblasts lay down new bone. Quiescence.
Is bone dynamic and remodelled throughout life? Yes indeed.
What is the affect of excessive mechanical stimulation on bones? Bone mass and density can increase.
Why can bone mass and density decrease? Non-weight bearing (immobilisation). Sex-hormone deficiency (e.g. menopause). Endocrine/nutritional disorders.
What is Wolff's law? Bone adapts to the load under which it is placed.
What are common examples of Wolff's law? Weight-bearing exercise, orthodontic braces, (Amerindian) head binding.
Describe bone growth from fetus to adult. Cartilage model->Replaced by bone (ossification). Bone growth begins in the shaft during fetal life.
What is the Cartilage model? Formed by chondroblasts then reshaped chondrocytes.
What is ossification? The replacement of cartilage by bone. Endochondral (long bones). Intramembranous (flat bones).
Where does ossification begin? In the diaphysis.
Is the Primary ossification centre active before birth? Yes indeed.
What is the secondary centre of ossification called? Epiphysis. After birth bone begins to develop in the ends of bone.
Describe the process of bone growing in the epiphyseal plate. Bone is laid down in the shaft of the hand. The bony parts are separated by a plate of cartilage. As long as the plate of cartilage is present and active the bone will increase in length.
What is a chondroblast? Site where chondrocytes are formed in the growing matrix.
When does the fusion of epiphyseal plates occur? At the end of puberty.
How long does a fracture usually take to heal? 2-4 weeks dependent on severity and position and age.
How does a fracture heal? Inflammation and additional blood flow lead to callus formation and lamellar bone is laid down.
What is involved in callus formation? Osteoblasts quickly form woven bone, to bridge the gap. Woven bone is weak as the collagen fibres are irregular.
What happens when lamellar bone is laid down? Collagen is organised in regular sheets to give strength and resilience.
Created by: robertspedding