06: The Skeletal System: Bone Tissue

Question 1

Bone

Answer 1

• An organ made up of several different tissues that work together
  
  • bone
  • cartilage
  • dense connective tissue
  • adipose
  • nervous tissue

Question 2

Functions of the Skeletal System

Answer 2

• Provides support
• Protects the internal organs (brain, heart, etc.)
• Assists body movements (in conjunction with muscles)
• Mineral homeostasis - stores and releases calcium and phosphorus
• Participates in blood cell production (hemopoiesis)
• Stores triglycerides in adipose cells of yellow marrow

Question 3

Long Bone

Answer 3

• Diaphysis (bone shaft)
• 2 epiphyses (both ends of the bone at the joints)
• 2 metaphyses (region between diaphysis and epiphysis)
• Articular cartilage covering both epiphyses
• Periosteum (connective tissue surrounding the diaphysis)
• Medullary cavity (hollow space within diaphysis)
• Endosteum (thin membrane lining the medullary cavity)

Question 4

Structure of Bone

Answer 4

Question 5

Extracellular Matix

Answer 5

• Bone contains an abundant extracellular matrix that surrounds widely separated cells
  
  • 15% water
  • 30% collagen
  • 55% crystalized mineral salts

Question 6

Osteoprogenitor cells

Answer 6

• bone stem cells able to differentiate into the other types of cells

Question 7

Osteoblasts

Answer 7

• bone-building cells that secrete matrix

Question 8

Osteocytes

Answer 8

• Mature bone cells

Question 9

Osteoclasts

Answer 9

• Remodel bones
• Cause them to release calcium

Question 10

Compact Bone

Answer 10

• Provides protection and support

Question 11

Spongy Bone

Answer 11

• Lightweight
• Provides tissue support

Question 12

Blood and Nerve Supply of Bone

Answer 12

• Periosteal arteries (accompanied by nerves) enter the diaphysis through Volkmann’s canals.
  
  • accompanied by periosteal veins.
• A nutrient artery enters the center of the diaphysis through a nutrient foramen.
• Nutrient veins exit via the same canal.
• The metaphyses and epiphyses have their own arteries and veins.

Question 13

Blood and Nerve Supply

Answer 13

Question 14

Ossification (osteogenesis)

Answer 14

• The process of bone formation.
• Bones form in 4 situations:
  
  • During embryological and fetal development
  • When bones grow before adulthood
  • When bones remodel
  • When fractures heal

Question 15

Intramembranous Ossification

Answer 15

• Occurs in flat bones when a connective tissue membrane is replaced by bone.

Question 16

Endochondral Ossification

Answer 16

• Replaces cartilage with bone in the developing embryo and fetus

Question 17

Phases of Bone Repair

Answer 17

• Reactive phase
  
  • early inflammatory phase.
• Reparative phase
  
  • formation of a fibrocartilaginous callus first
  • bony callus second
• Bone remodeling phase
  
  • The bony callus is remodeled.

Question 18

Open (compound) Fracture

Answer 18

• The broken ends of the bone protrude through the skin.
• Conversely, a closed (simple) fracture does not break the skin.

Question 19

Comminuted Fracture

Answer 19

• The bone is splintered, crushed, or broken into pieces at the site of impact, and smaller bone fragments lie between the two main fragments.

Question 20

Greenstick Fracture

Answer 20

• A partial fracture in which one side of the bone is broken and the other side bends
  
  • similar to the way a green twig breaks on one side while the other side stays whole, but bends;
• occurs only in children
  
  • whose bones are not fully ossified
  • contain more organic material than inorganic material.

Question 21

Impacted Fracture

Answer 21

• One end of the fractured bone is forcefully driven into the interior of the other.

Question 22

Pott Fracture

Answer 22

• Fracture of the distal end of the lateral leg bone (fibula)
• with serious injury of the distal tibial articulation.

Question 23

Colles Fracture

Answer 23

• Fracture of the distal end of the lateral forearm bone (radius)
• which the distal fragment is displaced posteriorly.

Question 24

Bones Role in Calcium Homeostasis

Answer 24

• Bones store 99% of the body’s calcium.
• The parathyroid gland secretes parathyroid hormone (PTH) when calcium levels drop.
• Osteoclasts are stimulated to increase bone resorption and calcium is released.
• PTH also stimulates the production of calcitriol by the kidneys to increase calcium absorption in the intestines.

Question 25

Homeostatic Imbalances

Answer 25

• Bone Scan (diagnostic tool)
• Osteoporosis
• Rickets
• Osteomalacia