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The Skeletal System
Bone is Connective Tissue• The skeletal system
– The framework of bones and cartilage that provides support, protects our organs and allows us to move
– The skeletal system consists of several types of connective tissue:
• cartilage, • bone,• red and yellow bone marrow, • periosteum, and the endosteum.
Functions of Skeletal System• Support- for muscles, organs, body, teeth
• Protection- for soft organs
• Movement- locomotion, breathing
• Blood formation- red marrow
• Electrolyte balance- mineral reservoir, Ca+, PO4
• Acid-base balance- buffers blood with alkaline salts
• Detoxification- removes heavy metals from blood
Bone parts
• Collagen- – protein material (fibers) secreted by
osteoblasts– Becomes bone when calcium phosphate
harden within the collagen fibers
• Osteocytes- bone cells– Osteoblasts- build new bone (if fractures)– Osteoclasts- clean up damaged bone
Haversion Canals
• Osteoblasts lay down collagen• Calcium phosphate hardens in the collagen
fibers• Osteoblasts become osteocytes• Osteocytes are arranged in concentric circles• Central canal is called Haversion Canal• Haversion Canal contains blood vessels and
nerves. Oxygen and wastes are carried by the blood to the osteocytes.
Osteocytes
More bone
periosteum
• Tough outer covering of the bone
• Not on the ends of bones
• Makes new bone for growth and repair
• Point of attachment for muscles
Bone Tissue- Two Types
• Spongy (cancellous)• consists of an irregular
latticework of thin blades of bone called trabeculae. The spaces between the trabeculae contain blood vessels and red marrow which produces blood cells. The spaces between the trabeculae can be seen with naked eye and give spongy bone tissue its "spongy" look.
• Compact (dense)• consists of precise
arrangements of microscopic cylindrical structures called osteons. The matrix and osteocytes of osteon are laid down in concentric rings around a central (Haversian) canal that contains blood vessels and nerve.
Spongy Bone
Compact Bone
Marrow
• Red Marrow– Found in the spaces within spongy bone– Makes red blood cells, platelets, and WBC– Found in vertebrae, ribs, breastbone, cranium
and long bones
• Yellow Marrow– Made of fat cells– Found in long bones
Cartilage
• Type of connective tissue
• Bends easily
• When first born the skeleton is mostly cartilage. Slowly changes into bone by process of ossificationossification
• gives support with a bit of cushion
The Skeleton
• Axial Skeleton
– Skull
– Vertebrae
– Ribs
– Breastbone (sternum)
• Appendicular skeleton– Arms– Legs– Pectoral girdle
• Scapula• clavicle
– Pelvic girdle• Ilium• Ischium • pubis
Joints
•Where bone meets bone in an organism
Types of Joints1. Immovable joint2. Ball-and-socket joint3. Hinge joint4. Gliding joint5. Pivot joints
Immovable Joint
• Bones that are tightly fitted together
Ball and Socket joints
• Can move in all directions
Hinge Joint
• Permits back and forth motion
Gliding Joint
• Provides limited flexibility in all directions
Types of joints
Tendons and Ligaments
• Ligaments– Connect bone to bone– Example: cruciate ligaments connect tibia to
femur
• Tendons– connect bone to muscle– Example: Achilles tendon connects the calf
muscle to the heel
Muscles
MusclesThree types of muscle:
Skeletal muscle
Smooth muscle
Cardiac muscle
Skeletal Muscle• Voluntary (can be
controlled)
• Involved in locomotion
• Attached to bone
• Striated in appearance (striped)
• Function as antagonistic pairs
Striated muscle
• Muscle fibers are made up of myofibrils
• Myofibrils are made up of protein filaments– Thick myosin– Thin actin
..\Desktop\49-31-MuscleContraction.mov
Antagonistic Pairs• Muscles work as
opposites Ex: 1. Bicep
contracts then triceps relaxes
2. Triceps contracts then the bicep relaxeshttp://www.innerbody.com/anim/arm.html
Summary• When the bicep contracts,
the arm bends upward (flexes) and therefore the bicep is known as a flexor
• When the triceps contracts, the arm extends outward and therefore the triceps is known as an extensor
Disorders of Locomotion
1. Arthritis- inflammation of the joints
2. Tendonitis- inflammation of a tendon, usually where it is attached to the bone
Smooth Muscle• Smooth are not striated in
appearance• InvoluntaryInvoluntary (cannot control
movement)• Found in: -walls of digestive organs -walls of arteries and veins -walls of internal organs
Cardiac Muscle
• Found only in the heart
• Striated in appearance
• Involuntary• Intercalated
discshttp://www.mco.edu/cci/movies/cardiacEM.mov