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Lecture 15

MEDT220 Lecture 15: Chapter 15 – musculoskeletal system

11 Pages
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Department
Medical Laboratory Sciences
Course Code
MEDT220
Professor
kimberlyarnold

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Chapter 15 – musculoskeletal system
Musculoskeletal System
Provides form, support, stability, and movement to the body
Bones (oste/o)
Provide framework on which the body is constructed
Protect and support attachment for muscles
Ligaments: bind bone to bone
Muscles (my/o, muscul/o)
Attached to bones or to internal organs and vessels
Provide movement
Tendons: bind muscle to bone
Joints (arthr/o)
Places bones come together
Type of joint in a location determined by need for greater or lesser flexibility of
movement
Bones
Complete organs composed of dense, hard connective tissue, rich supply of blood
vessels and nerves
Osseous (L/Gk = bony) tissue: connective tissue
Osteocytes: bone cells
Collagen
Intercellular calcium salts
Bones of fetus are composed of cartilage
More flexible and less dense due to lack of intercellular calcium salts
During embryo development, calcium salts are deposited in cartilage
Ossification
Bone formation
Gradual replacement of cartilage and its intercellular substance by immature bone cells
and calcium deposits
Bone cells
Cells: oste/o = bone
Osteoblast: immature osteocyte
produces immature bony tissue that replaces cartilage
Osteoclast: -clast: Gk = to break
Large cells that reabsorb or digest bone
“Bone phagocytes”
Digest bone tissue form the inner sides enlarging the inner cavity so
bones do not become overly thick and heavy
Osteocyte: osteoblast encased in bony matrix
Skeletal maintenance
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42 billion osteocytes
Bone remodeling
Bone is a dynamic tissue constantly being reshaped by osteoblasts and osteoclasts
Bone remodeling makes bone a living tissue
Osteoblasts and osteoclasts work together to tear down and rebuild bone
Allows bone to respond to mechanical stress placed on it
Keep bones strong and in good repair
Broken bones??
Osteoblasts lay down mineral bone matter (calcium salts)
Osteoclasts remove excess bone debris (smooth bone)
Needed for bone formation
Absorbed into body from digestive system
Calcium
Makes hard structure of bone tissue
Calcium stored in bones
Present in the blood – muscles and nerves
Parathyroid gland maintains calcium levels in the blood
Too much PTH weakens bones
Absorbed into body from digestive system
Calcium
Vitamin D
Enhances calcium absorption from the small intestine
Phosphorous
High in beans, seeds, nuts, pork, beef, salmon, milk
Consumption of too much causes release of calcium from bones to restore
balance
Osteoblasts produce enzyme that forms calcium phosphate
Major calcium salt
Gives bone hard quality (ossified)
Types of bones
206 bones in the body
Long bones
Thigh, lower leg, upper & lower arm
Very strong
Broad at the ends where they join other bones
Large surface areas for muscle attachment
Short bones
Wrist & ankle
Small with irregular shapes
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Flat bones
Skull, shoulder blades, ribs, pelvic bone, sternum
Cover soft body parts
Sesamoid bones
Small, rounded bones shaped like a sesame seed
Found near joints
Increases the efficiency of muscles near a joint
Patella (kneecap): largest sesamoid bone
Bone structure – long bones
Inner core
Composed of hematopoietic tissue
Outer parts
Storage areas for minerals necessary for growth, such as calcium and
phosphorus
-physis = to grow
Diaphysis (growing through)
Shaft, middle region
Epiphysis (growth upon)
End of long bone
Metaphysis (beyond + growth)
Flared portion of the bone between end and shaft
Epiphyseal line or plate
Growth plate
Where cartilage replaced by new bone as bone grows
Responsible for lengthening bones in children
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Description
Chapter 15 musculoskeletal system Musculoskeletal System Provides form, support, stability, and movement to the body Bones (osteo) Provide framework on which the body is constructed Protect and support attachment for muscles Ligaments: bind bone to bone Muscles (myo, musculo) Attached to bones or to internal organs and vessels Provide movement Tendons: bind muscle to bone Joints (arthro) Places bones come together Type of joint in a location determined by need for greater or lesser flexibility of movement Bones Complete organs composed of dense, hard connective tissue, rich supply of blood vessels and nerves Osseous (LGk = bony) tissue: connective tissue Osteocytes: bone cells Collagen Intercellular calcium salts Bones of fetus are composed of cartilage More flexible and less dense due to lack of intercellular calcium salts During embryo development, calcium salts are deposited in cartilage Ossification Bone formation Gradual replacement of cartilage and its intercellular substance by immature bone cells and calcium deposits Bone cells Cells: osteo = bone Osteoblast: immature osteocyte produces immature bony tissue that replaces cartilage Osteoclast: clast: Gk = to break Large cells that reabsorb or digest bone Bone phagocytes Digest bone tissue form the inner sides enlarging the inner cavity so bones do not become overly thick and heavy Osteocyte: osteoblast encased in bony matrix Skeletal maintenance
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