Transcript the skeletal system

THE SKELETAL
SYSTEM
The Skeletal System
 The
skeleton is a framework of bones held
together by _________ to form movable
_________. There are 206 bones in the
adult skeleton.
Functions

The skeletal system has 5 main functions





Framework – the skeleton gives our body its shape
Movement – the bones are leavers upon which
muscles pull
Protection – the skeleton protects vital organs
Blood cell formation – the long bones contains bone
marrow which produces all red blood cells and some
white blood cells
Storage – the skeleton stores mineral salts, especially
calcium
SKELETAL DIVISIONS
APPENDICULAR – 126 BONES
EXTREMETIES,SHOULDER GIRDLE, PELVIS
AXIAL – 74 ( SKULL, VERTEBRAE, RIBS)
- 6( AUDITORY OSSICLES)
COMPACT VS. SPONGY
2 MAIN TYPES OF BONE
COMPACT: Regions of high stress
SPONGY : Light weight, ‘ mesh’, bone
marrow , low stress ( skull)
BONE STRUCTURE
3 MAIN CELLS
Osteocytes: mature bone cells
Osteoblasts: build and repair bone
Osteoclasts: help reshape in response to
stress.
BONE GROWTH
INTRAMEMBRANOUS OSSIFICATION
-
Osteoblasts secrete bone matrix and trap osteocytes
Appearance is spongy bone, compact bone develops
ENDOCHONDRAL OSSIFICATION
-
Cartilage models form and replaced by bone tissue.
Formation begins in the middle of the diaphysis( shaft) and
continues to the epiphyseal regions ( end of bones)
CATEGORIES OF BONE
( BASED ON SHAPE p. 35)
Diet:

Vitamin A: important for bone growth:
• Milk fat, egg yolks, dark green / yellow vegetables;

Vitamin C: important for collagen giving
bones strength:
• Citrus fruits;

Vitamin D: Promotes calcium absorption:
• Milk, Fish-liver oils;

Calcium: Creates bone rigidity:
• Dairy products.
BONE DISEASE
INFLAMMATORY AND
DEGENERATIVE CONDITIONS
 Osteoporosis-bone
mass loss
 Bursitis- inflammation of bursa
 Tendonitis-overuse and repetition
 Sprain-stretched or torn ligament
 Cartilage-Tears in cartilage
 Arthritis- degenerative disease
 Dislocation- bones displace
AXIAL :The spine/vertebral
column
33 individual Vertebrea
Made up of five groups:
 Cervical spine (7);
 Thoracic spine (12); Ribs and Muscles
 Lumbar spine (5); Weight of body
 Sacrum (5 fused); Muscle attachment
 Coccyx (4 fused); Muscle attachement

Top two vertebrae are the atlas and axis; Rotation

Vertebrae are stacked on top of each other to create
a canal in which the spinal cord runs down;

Vertebrae are separated by discs that absorb shock.
APPENDICULAR
PECTORAL GIRDLE
Clavicle (collar bone)
Scapula ( shoulder blade)
UPPER LIMBS
Upper Arm: Humerus
Forearm :
Ulna (pinky, medial)
Radius (thumb, lateral)
Hand:
Carpals ( 8)
Metacarpals ( 5)
Phalanges ( 14)
APPENDICULAR
PELVIC GIRDLE
COXAL BONES=
illium, ischium,
LOWER LIMB =
femur, patella,
fibula (pinkie toe
side), tibia (big toe
side) tarsals (7),
metatarsals (5),
phalanges(14)
Structures of the Skeletal System
– joints (articulations) occur when
two or more bones meet
 There are 3 types:
 JOINTS



Immovable – bones are fused together and no
movement is possible
Slightly movable – joined by cartilage and
small amounts of movement are possible
Freely movable – synovial joints where there
is movement in at least one direction
Joints - examples
Structures cont’d
 CARTILAGE





A glassy, smooth, slightly elastic tissue
Reduces friction between bones
The ends of bones in synovial joints are
coated with hyaline cartilage
The vertebrae of the spine are separated by
discs of cartilage.
The hard part of the ear and tip of the nose
are also cartilage
Cartilage
Structures cont’d
 LIGAMENTS




Slightly elastic tissue that joins bones together
Their function is to provide stability to the
joint, preventing dislocation
When ligaments are torn they need to be
repaired surgically
Frequent dislocation of the same joint results
in overstretched ligaments that are no longer
able to do their “stability” job correctly
Ligaments
Structures cont’d
 TENDONS



Tendons join muscle to bone
They are elastic and very strong
They allow movement to take place, as they
help pull across the joints on the bone
Tendons