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Transcript of Your Bones
Vertebrae, the skull and rib cage – primarily used as protection of CNS and organs
The Appendicular Skeleton
Includes the movable limbs and supporting girdles
5 different types of bones
The Skeletal System
The adult body has 206 bones in total
The largest bone
The smallest bone
Play a role in phosphate & Calcium regulation
The Role of the Skeleton:
Works in conjunction with muscles to create movement but also provides protection
Red blood cells are produced in the marrow of the long bones
Different from quadrupeds in the vertebrae of the lower spine
Most of the body’s muscles originated from here
80 bones in total
126 bones in total
Pectoral girdle (shoulder) & pelvic girdle (hip)
eg: skull, pelvis
These bones are thinner and begin as fibrous membranes
Irregular Shaped Bones
While bones of similar type may be somewhat similar in shape, these bones have unique shapes and features.
eg: humerus, femur
These are the classic shaped bones that have a medullary cavity for red blood cell production
eg: carpals, tarsals
Thee bones have the same basic construction but no medullary cavity
Sesmoid Shaped Bones
These bones are embedded in a tendon or fibres for leverage purposes
The process by which bone is actually made is called ossification. Compact bone (the hard outer bone) begins as cartilage - osteoblasts secrete a gelatin-like osteoid which absorbs minerals to create bone.
The bone in the interior of the epiphysis is a sponge-like network of tubules that reduce the weight while maintaining strength.
Short bones have single ossification center in the middle while Long bones have 3 – one in middle and one in each epiphysis (growth plates) - where the ossification begins.
Cancellous bone (like flat bones) begin as fibrous membranes – osteoblasts cause sponge-like bundles of bone that will form plates of compact bone like in the skull.
Bones do not grow by cell division like other tissue but rather a process called bone remodeling - a process of breakdown-absorption AND re-ossification.
Remodeling is most active when we are children then slowly declines until around age 35 when reabsorption exceeds production resulting in a 5-10% loss in bone mass per decade.
Your bones are the source of 99% of body’s calcium (vital dietary need) so we need regular source of vitamin D to assist with this. We make Vit D naturally in sunlight.
Resistance training stimulates bone growth – NOT heavy weights though - by stressing the epiphysial plates. Epiphyseal plates (black lines seen on x-ray) are the growth areas of long bones.
Stress Fractures occur when muscles become to fatigued to support the bones and all the stress of activity impacts the bone causing a tiny crack usually from a change in training or training surface
Issues with bone strength can be attributed to nutrition, infection and accidents.
Physical activity is essential to maintaining the health of the skeleton.
Symptoms of fractures include sharp pain, tenderness, swelling, bruising, grating-grinding feeling.
Bones heal by rebuilding the same as ossification.
Serious issues surround breaks located near joints which can can lead to later bone loss or osteoarthritis.
Fractures can be classified as:
Simple (Fracture is contained to the bone)
Compound (Fracture extends through the bone)
Comminuted (Bone is shattered)
Fractures can be classified as:
Greenstick (Fracture like a green tree branch)
Impacted (Fractured ends are rammed together)
Some issues are inherited (osteogenesis imperfecta or hypophosphatasis).
Diseases range from problems re abnormal stress (dislocation) or metabolism-growth issues (rickets & osteomalacia) or infections (osteomyelitis)
Osteoporosis is often called the “silent disease” because people often do not know something is wrong until a break occurs.
(a) The structure of bone is optimized to be strong but light
(b) Cortical or Compact bone is hard outer shell - composed of OSTEOCYTES
- Osteocytes have concentric lamellae which helps to resist bending
(c) Trebecular bone is spongy with a network of tissue
- Network of lattice-like portions resists compression but weighs less
(d) The center of long bones is called MEDULLARY CAVIITY
- Cavity is filled with bone marrow (red + yellow)
- Red marrow is the site of RBC regeneration
Modelling and Remodelling:
(a) Bone formation and growth happens primarily in childhood
(b) OSTEOCLASTS = reabsorb via acidic action
(c) OSTEOBLASTS = refill cavities left by Osteoclasts - release Osteoid (gel) which absorbs Ca+ and Ph+ to form new bone
(d) REMODELLING is used for repair and replacement while MODELLING is new growth perhaps in response to activity (proper nutrition and exercise increases bone mass)
80 in the AXIAL skeleton & 126 in the APPENDICULAR skeleton