Cartilage, Bone and Ossification

Frage	Antworten
True or false: cartilage has its own blood supply.	FALSE. Cartilage is avascular. It gets its nutrients by long range diffusion.
Where are chondrocytes found in the matrix of cartilage?	In lacunae.
What did chondrocytes develop from?	Chondroblasts.
What are the three types of cartilage found in the body?	1. Hyaline (most common) 2. Elastic 3. Fibrocartilage
Where can hyaline cartilage be found?	Embryonic skeleton (before ossification), articular ends of long bones, nose, trachea, costal cartilages, larynx.
What four things make up the matrix of hyaline cartilage?	GAGs, proteins, glycoproteins, type II collagen fibrils.
What type of collagen fibrils are found in hyaline cartilage?	Type II
What percentage of hyaline cartilage is tissue fluid (water)? How is it held in place?	75%. It is held in place by gel of the matrix.
What is the function of the high water content of hyaline cartilage?	It allows oxygen and nutrients to diffuse to the innermost chondrocytes.
How are the collagen fibres arranged in fibrocartilage? Why?	They are arranged in parallel to resist stretch.
Where in the body can fibrocartilage be found?	Tendon insertions, articular menisci, pubic symphysis, intervertebral discs.
What are the main functions of fibrocartilage?	To provide tensile strength and absorb shock.
What is the function of elastic cartilage?Where in the body can it be found?	To withstand repeated bending and maintain its shape - it can bend but springs back into position. Supports the larynx, epiglottis and external ear.
What does elastic cartilage contain in addition to collagen fibres?	Elastic fibres.
True or false: bone is a form of connective tissue.	True.
What are the three main functions of bones?	To support, protect and store minerals.
What percentage of the matrix is made up by collagen fibres? What are the collagen fibres embedded in?	95%. Embedded in GAGs and mineral salts.
In what form are the mineral salts found in the matrix of bones?	They are in a crystalline form of calcium phosphate called hydroxyapatite.
What are bone cells called and where can they be found?	Osteocytes. Found in lacunae.
What are canaliculi in bones? What is their function?	Canaliculi are canals tat connect lacunae. They permit tissue fluid to flow between lacunae and bathe the osteocytes.
What are osteoclasts?	Osteoclasts are multinucleate cells that destroy bone matrix and function in bone resorption.
What is haemopoeisis? Where in the bone does it occur?	Formation of blood cells. Occurs in the bone marrow.
What are the two main forms of bones?	Compact and spongy.
What are the three main things that bone marrow contains?	Adipocytes, stromal cells and haemopoietic cells.
Describe the three stage process of intramembranous bone formation.	Undifferentiated mesenchyme cells condense. Cells in the centre of the condensation form osteoblasts. Osteoblasts then produce osteoid (bone matrix).
What happens to the osteoblasts during ossification?	They become osteocytes.
What did bone begin as before it became ossified?	Hyaline cartilage.
What is a diaphysis?	A periosteal bone collar that occurs in the middle of the bone - first stage in endochondral ossification.
When does ossification begin?	At the 3rd prenatal month.
At what age in both males and females are all the bones normally ossified?	23 - females 25 - males
When does bone deposition normally occur? What is required for it to occur? What controls it normally?	When bones are injured or need extra strength. Needs Vitamin A, C, D, calcium, magnesium and an enzyme called alkaline phosphatase. Hormones tend to control the process (significant in osteoporosis - hormone levels have changed).

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Cartilage, Bone and Ossification

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