11. Skeletal System

Question 1

Functions of Skeletal System

Answer 1

• Supports the body
• Facilitates movement
• Protection of internal organs
• Haematopoiesis
• Stores and releases minerals and fat

Question 2

Organic Nature of Skeletal System

Answer 2

• Osteogenic cells, osteoblasts, osteocytes, osteoclasts

• Osteoid—organic bone matrix secreted by osteoblasts
  
  • Ground substance
  • Collagen fibers: Provides tensile strength and flexibility

Question 3

Inorganic Nature of Skeletal System

Answer 3

• Mineral salts
  * 65% of bone by mass
  * Mainly calcium phosphate crystals
  * Responsible for hardness and resistance to compression

Question 4

Histology of Bone

Answer 4

Osteoprogenitor Cell -> Osteoblast -> Osteocyte | Osteoclast

Question 5

Osteoprogenitor Cell

Answer 5

Develops into Osteoblast

Question 6

Osteoblast

Answer 6

-Develops into osteoblasts
-Forms bone extracellular matrix
-LOCATION: Growing portions of bone, including
periosteum and endosteum

Question 7

Osteocyte

Answer 7

• Maintains bone tissue
• Maintain mineral concentration of matrix
• LOCATION: Entrapped in matrix

Question 8

Osteoclast

Answer 8

-Functions in resorption, the breakdown of bone
extracellular matrix
-Bone Resorption
-LOCATIONS: Bone surfacesand at sites of old,
injured, or unneeded bone

Question 9

Osteogenic Cells

Answer 9

• Develop into osteoblasts

- LOCATION: Depp layers of the periosteum and bone marrow

Question 10

How many bones do we have?

Answer 10

206

Question 11

5 categories of bones

Answer 11

• Long (greater length than width
• Short (cube shaped)
• Flat (thin layers of parallel plates)
• Irregular (complex shapes)
• Sesamoid (shaped like a sesame seeds)

Question 12

Ossification (osteogenesis)

Answer 12

Formation of bone

Question 13

Bones form in 4 situations

Answer 13

1. During embryological and fetal development
2. Bone growth prior to adulthood
3. When bones remodel
4. When fractures heal

Question 14

Endochondral Ossification

Answer 14

Replaces cartilage with bone in the developing embryo and fetus

Question 15

3 Different Phases of Bone Repair

Answer 15

1. Reactive phase (early inflammation)
2. Reparative phase (includes formation of a fibrocartilaginous callus first and the bony callus second)
3. Bone remodeling phase (last step as the bony callus is remodeled)

Question 16

Calcitonin

Answer 16

Released by thyroid gland to make osteoblasts deposit Ca into bone. Osteoclasts are inhibited. Decrease Ca from intestines; increase excretion to filtration

Question 17

Parathyroid Hormone (PTH)

Answer 17

Secreted by parathyroid glands when Ca is low. Stimulates osteoclasts tk release Ca from bone. Increase Ca uptake from institutes and increase reabsorption from filtrate

Question 18

Chondrocytes

Answer 18

Cells in cartilage. Located in spaces called lacunae

Question 19

Matrix if cartilage contains:

Answer 19

Ground substance composed of proteoglycans which contribute to the flexible, resilient consistency of cartilage

Question 20

Articulate cartilage

Answer 20

• Hyaline cartilage lining many joint surfaces

- Absorbs compression and prevents bone damage

Question 21

Articular discs

Answer 21

• Wedges fibrocartilage in freely movable joints
• improves the fit between irregular bone services
• Improves joint stability

Question 22

Synovial Joints

Answer 22

Two bones are separated by a joint cavity which is enclosed by a fibrous capsule: Freely movable, articulating surfaces of bones lined by hyaline cartilage