Muscle skeleton

Muscle skeleton

1. Muscle skeleton

   • Bone diseases
     • Rickets
       • Condition affecting bone development in CHILDREN
       • Bones become soft and weak- bone deformities
       • Also known as osteomalacia
       • Can cause: -bone pain -poor growth - deformities of the skeleton such as: -bowed legs -curvature of the spine -thickening of the ankles, wrists and knees
       • More likely to also fracture bones
       • Common cause us lack of vitamin D or lack of calcium
         • Calcium- found in dairy products and green vegetables
         • Vitamin D- is a fat soluble vitamin found in foods such as butter, eggs and fish liver oils Also synthesised by skin from the UV in sunlight
     • Brittle bone dieases
       • Is a rare genetic disorder that causes bone to feature easily Gene is usually inherited or a genetic mutation can cause it
       • Defect in the end that produces type 1 collagen- a protein to create bone
         • Causes an imbalance between organic and inorganic components in the matrix of the bone
           • Organic ( including collagen)
           • Inorganic ( including calcium hydroxyapatite)
       • Symptoms
         • -Broad forehead -possible deafness -white part of eyes begin to look blue - poor teeth - barrel chest and rounded back - bones bent and shortened from many fractures
       • Treatment
         • There is no cure for it but treatment is available
           • Drugs such as Biphosphonates can be prescribed- this increases bone mass and reduces bone pain and fractures
           • Children with frequent fractures have a rodding operation in which rods and inserted into shafts of bones
       • Similar to brittle bone disease but for adults also
     • Osteoporosis
       • Children bone growth and repair is quick but with adults it slows down with age as bone density is gradually lost from the age of 35
         • Women who enter menopause lose bone density rapidly after the cycle has ceased
       • Further risk factors
         • - heavy drinking and smoking - long periods of inactivity - patients with rheumatoid arthritis - BMI is less than 19 - family history of osteoporosis - conditions of hormone producing glands
       • Lifestyle advice
         • - exercise - quit smoking - limited alcohol intake - dieting include calcium and vitamin D
       • Treatment
         • - drug treatment to increase bone density - vitamin D and calcium supplements - hormone replacement therapy for women entering menopause - prevention of falls and fractures
   • Cartilage
     • It is a hard but flexible, compressible and elastic tissue. It’s found at joints and between bones
     • Consists of specialised cells called chondrocytes embedded in a matrix present in a group of 2-4 cells. Each cell lies in a fluid called lacuna
     • It does not contain blood vessels but covered in a membrane called perichondrium which derives blood supply. This slows it down long enough so that the nutrients and oxygen must move by diffusion through the matrix in order to reach the chondrocytes
     • Hyaline
       • Consists of collagen fibres embedded in a clear glassy tough ground substance called a matrix
       • It’s firm and elastic and found at the ends of long bones as articular cartilage in the nose, larynx, trachea and bronchial tubes
       • The cells are arranged in a small group set up in a tough matrix
     • Fibrous cartilage
       • The matrix contains large number of fibres
         • There are 2 types of fibrous cartilage
           • White fibro- cartilage
             • Small amount of matrix of cartilage is packed with large number of bundles of thick white fibres- is the toughest, strongest and the least flexible It’s is the least flexible
             • It has no perichondrium It’s is found on intervertebral disc as shock absorbers
           • Yellow fibro- cartilage
             • Matrix is packed with yellow or elastic fibres Appears yellow or opaque Yellow pet is what makes it flexible
             • Found in epiglottis, pinna of ear and tip of the nose

2. Bone/ bone cells

   • There are 2 types of bone in the human skeleton
     • Compact bone
       • Is found on the outside of most bones. It’s is the hard outer layer that gives bones their smooth and white appearance
       • It has a much greater mass than the spongy bone
       • It is found in places such as the joints and at the end of bones
     • Spongy bone
       • Is lighter and fills all the inside of the bone
   • Bone cells are embedded in a firm calcified matrix 30% is organic 70% is inorganic bone salts
     • Organic material mostly contains collagen
     • Inorganic material mainly consists of needle like crystals called hydroxyapatite- form of calcium phosphate
   • Functions of organic/ inorganic
     • Type of component
     • Function
     • Helps to resist bone fractures
     • Helps prevent bone compression
     • Organic ( collagen)
     • Inorganic ( hydroxyapatite)

3. Osteocytes

   • Bones begin life as cartilage. from birth until old age, the skeleton hardens and breaks
   • Ossification is the process of hardening cartilage into bone
     • Ossification is achieved by bone-forming cells called osteoblasts
       • The old osteoblasts produce bone tissue and secrete the enzyme phosphatase which allow calcium salts to be deposited into the new formed bone tissue making the tissue hatd
       • Osteoclasts are responsible for breaking down the bone matrix so that new bone can be made in that place
         • Minerals such as calcium move into the bloodstream for use by the body. As reabsorbtion occurs, new bone cells form

4. Haversian system

   • It provides a transport system in the bone It’s found in the compact bone of humans
   • It’s a system of concentric circles called lamellae There is a hollow tube down the middle called the haversian canal
     • Each compact bone has many Haversian systems next to each other creating a dense structure
     • Within the lamellae of each system there are spaces called lacunae which hold the osteocytes
       • From each lacuna there are many channels called canaliculi
         • These provide nutrients to living bone tissue. Nerves and lymph vessels can be found in the canals
           • These accessory tissue help with immune response in the bones and also pick up he signals from different stimuli
     • Within the canals there is a vein and an artery
       • Capillaries branch from the canals and pass through the canaliculi to the lacunae