Skeletal System
Chp. 5
Skeletal System
Composed of 3 Types of Connective Tissue
Recall that connective tissue consists of a matrix
with cells suspended w/in it--the type of matrix &
cells determine type of tissue.
1. Bones - hard elements of skeleton.
2. Ligaments - dense, fibrous connective tissue that
serves to bind bone-to-bone.
3. Cartilage - collagen & elastin fibers suspended
in gel-like matrix [ground substance].
5 Functions of Bones
1. Support
2. Movement
3. Protection
4. Formation of blood cells
5. Mineral storage
Skeletal System cont.
1. Bone: hard inorganic matrix of calcium salts
a. Compact Bone:
•
Dense - extracellular deposits of calcium
phosphate matrix w/ living cells
•
Osteocytes- living mature bone cells
that maintain structure of bone
•
forms shafts & covers ends of long bones
•
filled with yellow marrow
•
•
Yellow marrow = Primarily fat for
energy reserves
Contains blood vessels & nerves
Skeletal System cont.
b. Spongy Bone:
• porous bone found inside enlarged knobby
ends of bones [knob = epiphysis]
• Internal latticework makes bones lighter &
stronger
• Trabeculae = latticework of bones made of
calcium minerals + living cells
• red marrow - found in spaces of trabeculae
w/in long bones of upper arms & legs
Stem cells w/in red marrow
produce RBC’s
Osteons [Haversian Systems]
Cylindrical Structures (see text Fig 5.1)
Osteons - as compact bone develops & hardens (ossifies)
the osteocytes are trapped in hollow chambers within
cylindrical osteons in such a way as to maintain contact with
other osteocytes yet provide them a strong matrix to
support them.
Blood vessels traveling through the central Haversian canal
feed the osteocytes via cell-to-cell diffusion. Waste products
Diffuse away from cells, back to blood vessels.
Periosteum
Tough Connective Tissue covering bones
• Contains bone forming Osteoblast cells
Structure of Bone
*
*
*
Human
Biology
*Make note of these
Figure 5.1
Cartilage and Ligaments
Cartilage - fibers of cartilage & elastin in gel-like matrix
Function: support
Types:
• Fibrocartilage - between vertebral disks, in
knee joint
• Hyaline - embryonic “model” for bones, covers
ends of mature bones found in joints.
• Elastic cartilage - outer ear, part of epiglottis
Ligaments- attach bone to bone
Bone Development
[see Fig. 5.2 from text]
Prenatal: cartilage model
Fetus: some conversion to bone
Childhood: primary & secondary ossification sites
formed
Adolescence: cartilage growth plate elongates
Bone Development
(cont.)
Figure 5.2
Mature Bone Remodeling and Repair
Changes in: (1) shape, (2) size, (3) strength
• Dependent on diet, exercise, age
Bone cells regulated by hormones
• Parathyroid hormone (PTH): removes calcium
from bone
• Calcitonin: adds calcium to bone
Repair: hematoma and callus formation
Skeletal System: Frontal View
Blue = Axial Skeleton
[skull, vertebral column, ribs,
Sternum]
Black = Appendicular
Skleton
[pectoral girdle, pelvic girdle, limbs]
Figure 5.5
Axial Skeleton: The Skull [Just make note of the
number of bones in the skull]
Figure 5.6
Axial Skeleton: Vertebral Column
5 areas of Axial skeleton:
cervical, thoracic,
lumbar, scarum,
coccyx
Figure 5.7
Axial Skeleton: Vertebral Column
(cont.)
Vertebral column
• Regions: cervical, thoracic, lumbar, sacral,
coccygeal
• Intervertebral disks: cushion vertebrae; assist
in movement, flexibility
Ribs
• Twelve pairs
• Bottom two pair floating
Sternum: Breastbone
• Three bones fused
Appendicular Skeleton
Pectoral girdle: shoulder
• Clavicle, scapulas
Pelvic girdles: hip
• Coxal bones, sacrum, pubis, ilium, ischium
Limbs
• Arms: humerus, radius, ulna, wrist and hand
bones
• Legs: femur, tibia, fibula, ankle and foot bones
Joints (Articulations)
Classified by degree of movement
• Fibrous joint: immovable (e.g., fontanels)
• Cartilagenous joint: slightly movable, cartilage
connection (e.g., backbone)
• Synovial joint: freely movable (e.g., knee)
Synovial Joints
Figure 5.12A
Synovial Joints
(cont.)
Joint capsule: synovial membrane + hyaline
cartilage
Synovial membrane secretes synovial fluid as
lubricant
Hyaline cartilage cushions
Diseases and Disorders of the Skeletal
System
Sprains: stretched or torn ligaments
Bursitis and tendinitis: inflammation of bursae or
tendons
Arthritis: inflammation of joints