Bones and Bone tissue

Question 1

Function of Bones

Support

Answer 1

• Provides a framework, and provides attachment points for muscle and tendons; ligaments connect bone to bone

Question 2

Funtion of bones

Protection

Answer 2

Containment of valuable organs

Question 3

Funtion of bones

Assistance in movement

Answer 3

Muscle provides the power; skeleton provides the movement; tendons connect

Question 4

Funtion of bones

Mineral storage and release

Answer 4

• Blood/bone Calcium and phosphorous levels maintained
• Homeostasis of moving substance from bone to blood

Question 5

Funtion of bones

Blood cell production

Answer 5

Red marrow present in certain bones use haematopoesis to produce RBCs, white
cells, platelets

Question 6

Axial bones

Answer 6

• Found along the axis
• Essentially houses
  the vital parts of the
  body

Question 7

Appendicular

Answer 7

• Appendages that enable movement (locomation)

Question 8

Types of bones

Answer 8

• Sesamoid ( lie within tendons)
• Short bones
• Flat bones
• Long bones
• Irregular bones

Question 9

Compact bone

Answer 9

• Dense and solid in appearance
• Protection and strength
• Repeating circular units
• Osteons
• Outer portion

Question 10

Cancellous (spongy) bone

Answer 10

• Has open space
• Partially filled with needle-like structures such as trabeculae
• Strength without weight
• Inner portion

Question 11

Long bone structure

Diaphysis

Answer 11

• Hollow
• outside compact bone
• Inner - spongy

Question 12

Long bone structure

Epiphyses

Answer 12

• Both ends are Cancellous / spongy

Question 13

Inorganic salts

Hydroxyapatite

Answer 13

• Chemical crystals of
  Calcium and Phosphate
• Compression strength

Question 14

Organic matrix

Answer 14

• Composite of collagen (ropelike) fibres and proteoglycans
• Flexible strength

Question 15

Bone marrow

White Bone marrow

Answer 15

• Specialized type of soft, diffuse connective tissue; called myeloid tissue
• Site for the production of blood cells- Haematopoiesis
• Found in medullary cavities of long bones and in the spaces of spongy bone

Question 16

Bone marrow

Red bone marrow

Answer 16

• Found in virtually all bones in an infant’s or child’s body
• Produce red blood cells

Question 17

Bone marrow

Yellow bone marrow

Answer 17

• As an individual ages, red marrow is replaced by yellow marrow
• Marrow cells become saturated with fat and are no longer active in blood cell production

Question 18

Major bone cells

Progenitor cells

Answer 18

• Differentiating into cells that belong to the same tissue or organ
• Type of stem cell

Question 19

Osteoblasts

Answer 19

• Bone-forming cells found in all bone surfaces
• Ossifiction/osteogenesis
• Secretes organic component – collagen
• Produce vesicles: release Ca2+ and phosphate ions
  which contribute to hydroxyapatite formation
• Osteoid

Question 20

Osteocytes

Answer 20

• Differentiated mature non-dividing osteoblasts
• Trapped in lacuna and serve mainly as
  mechanosensors/ mineral homeostasis

Question 21

Osteoclasts

Answer 21

• Giant cells
• Resorb bone through dissolving mineral and
  breaking down collagen
• The “macrophages” of bone that are develop from blood cells called monocytes and
  macrophages)

Question 22

Bone Remodelling

Answer 22

• Removal of existing bone by osteoclasts and the deposition of new bone by osteoblasts
• Grow and change in bone shape
• Adjust in response to bone stress, bone repair and calcium ion regulation in body fluids

Question 23

Regulation of blood calcium levels

Skeletal system

Answer 23

• Calcium moves into and out of blood
• Bone formation of osteoblasts remove calcium
  from blood
• Bone breakdown of osteoclasts release calcium
  into blood

Question 24

Calcium homeostasis

Answer 24

• Decrease in blood stimulates PTH secreation from the para thyroid gland
• PTH stimulates osteoclasts and breaks down bone and release Ca2+ into blood
• In kideneys, the PTH increases calcium ions reabsorbtion from the urine, PTH also stimulates active vitamin D formation
• Vitamin D promotes Ca2+ absorbtion from the small intestine into the blood
• Increased blood Ca2+ stimulates Calcatonin secreation from the thyroid gland
• Calcatonin inhibits osteoclasts wich allows for enhanced osteoblast uptake of Ca2+ from the body to deposit bone

Question 25

Aging skeleton

Answer 25

• Decreased collagen makes bones more brittle
• Cancellous bone lost first
• Decrease in no of trabeculae
• Followed by compact (lesser)
• Incomplete remodelling

Question 26

Osteoporosis

Answer 26

• Bone resorption exceeds bone deposition.
• First Line Therapy is oral bisphosphonates e.g. alendronic acid and risedronate sodium
• induce osteoclast apoptosis (death) and suppress bone resorption