Psio Exam 2 (Lecture 10)

Front 1

List and describe the functions of the skeletal system.

Back 1

• Contains bones, cartilage, ligaments, and other connective tissues that attach bones to each other
• Each bone is an organ
• Functions:
o Support
o Protection
o Mineral storage
o Triglyceride storage
o Red and white blood cell formation (hemopoiesis)
o Leverage (assistance in movement)

Front 2

Differentiate between the two divisions of the skeletal system and give examples.

Back 2

• Axial Division
o Skull (cranial-8 and facial portion-14), Thorax (sternum-1 and ribs-24), Vertebral Column (26), Hyoid (1), Auditory ossicles (6)
• Appendicular Division
o Pectoral (Shoulder) Girdle (Clavicle-2 and scapula-2), Upper Limb (humerus-2, ulna-2, raius-2, carpals-16, metacarpals-10, phalanges-28), Pelvic (Hip) Girdle/Coxal Bone (2), Lower Limb (femur-2, patella-2, tibia-2, fibula-2, tarsals-14, metatarsals-10, phalanges-28)

Front 3

Describe the classification of bone based on shape, giving examples for each type.

Back 3

• Long bone
o Length is greater than width example: humerus
• Short bone
o Width is greater than length example: trapezoid, wrist bone
• Flat bone
o Flat shaped with little depth example: sternum
• Irregular bone
o Oddly shaped not like others example – vertebra
• Sesamoid bone
o Bones built with pressure, as little holes example – patella
• Sutural bone
o Bones in the skull

Front 4

Describe the anatomy of a long bone.

Back 4

• Endosteum and periosteum are important for bone growth and remodeling
o Periosteum
• Connective tissue membrane covering external surface of bone
• Contiuous with tendons, connective tissue of joints
• Attached to bone matrix via perforating fibers
• 2 Layers: 1) Outer Fibrous 2) Inner osteogenic
o Endosteum
• Lining inner surface of bone including marrow cavity, trabecullae of spongy bone, canals of compact bone
• Contains osteogenic cells – important for bone growth and remodeling

Front 5

List and describe the functions of the 4 cell types found in bone.

Back 5

• Osteogenic cell
o Develops into an osteoblast
o Stem cells that are formed from mesenchyme (embryonic connective tissue)
o Through mitosis develops into daughter osteogenic cells and then through differentiation develops into osteoblasts
• Osteoblast
o Forms bone matrix
o Important in bone remodeling
o Cells that build bone → bone formation
o Synthesize organic components of matrix
o Initiate calcification – take calcium from blood and deposit it within matrix by exocytosis
• Osteocyte
o Maintains bone tissue
o Mature cells involved in maintenance of bone
• Osteoclast
o Functions in resorption, the breakdown of bone matrix
o Important in bone remodeling
o Break down bone → bone resorption
o Release proteolytic enzymes and acids to degrade collagen and release minerals to blood
o Derived from myloid stem cells (not osteogenic cells)
o Have a ruffled border

Front 6

Discuss modeling and remodeling of bone.

Back 6

• Bone modeling: construction
o The process by which bone is formed by osteoblast without prior bone resorption
• Happens during growth
• Produces change in bone size and shape

• Bone remodeling: reconstruction
o Occurs when bone is first resorbed by osteoclasts and then formed in the same location by osteoblasts
• Happens throughout life
1. Activation: preosteoclats are stimulated and differentiate under the influence of cykines and growth factors into mature active osteoclast
2. Resorption: osteoclast digest mineral matrix (old bone)
3. Reversal: end of resorption; recruitment of osteoblasts
4. Formation: osteoblasts synthesize new bone matrix
5. Quiescence: osteoblast become resting bone lining cells on the newly formed bone surface

• Goal of modeling/remodeling
o Achieve strength for loading and lightness for mobility
o How?
• Strategically deposit bone where it is needed
• Remove bone from where it is not needed to avoid bulk
o During growth
→ To achieve the skeleton’s peak strength
o During adulthood
→ To maintain bone strength by removing damaged bone