SKELETAL SYSTEM PHYSIOLOGY PORTION

Question 1

long bones

Answer 1

• longer than they are wide

- located mostly in the appendicular skeleton

Question 2

Short bones

Answer 2

• usually long as they are wide
• Cube shaped
• located in the carpals and tarsals

Question 3

Flat bones

Answer 3

• usually thin
• protect internal organs
• broad surfaces for the attachment of muscles
  ex: cranial, sternum and ribs

Question 4

irregular bones

Answer 4

• vary in shape

- protect organs and tendons (patella)

Question 5

What are the 5 major parts of a long bone?

Answer 5

• the diaphysis, epiphyses, periosteum, endosperm, and medullary cavity

Question 6

What is the microscopic structure of compact bone?

Answer 6

• consists of densely packed, microscopic cylinders called osteons.
• Each osteon contains osteocytes and extracellular matrix deposited in rings around a central canal
• blood vessels and nerves occupy the central canal
• osteocytes lie within a chamber called lacunae
• share nutrients with other osteocytes through canaliculi

Question 7

Explain regulation of the concentration of blood calcium

Answer 7

• if blood calcium levels drop, parathyroid hormones stimulates osteoclasts to break down bone and release calcium.
• If blood calcium levels rise, calcitonin (from thyroid glands) stimulates osteoblasts to deposit calcium in the bones

Question 8

What substances are normally stored in bone tissue?

Answer 8

• calcium
• phosphorus
• magnesium, sodium, potassium, carbonate ions

Question 9

What bones are intramembranous?

Answer 9

• skull
• clavicles
• sternum
• some facial bones, including the mandible, maxillae, zygomatic bones

Question 10

Major steps in intramembranous ossification

Answer 10

• sheets of embryonic CT (mesenchyme) appear at the sites of future bones
• mesenchymal cells differentiate into osteoblasts, which deposit bone matrix
• Dense networks of blood vessels supply the developing spongy bone
• osteoblasts become osteocytes when bony matrix completely surrounds them
• mesenchyme on the surface of each developing structure condenses to form periosteum
• osteoblasts on the inside of the periosteum deposit compact bone over the spongy bone

Question 11

Define endochondral ossification

Answer 11

• masses of hyaline cartilage form models of future bones
• cartilage tissue breaks down and periosteum develops
• blood vessels and differentiating osteoblasts from the periosteum invade the disintegrating tissue
• osteoblasts form spongy bone in the space occupied by cartilage
• osteoblasts beneath the periosteum deposit compact bone
• osteoblasts become osteocytes when bone matrix completely surrounds them

Question 12

What effects do hormones have on bone growth?

Answer 12

• growth hormones stimulate mitosis in the cartilage cells of the epiphyseal plates.
• Thyroid hormones stimulates osteoblasts to deposit bone tissue to replace cartilage in the epiphyseal plates
• Parathyroid hormone stimulates osteoclast activity
• Male and female sex hormones stimulate bone growth and ossification of the epiphyseal plate

Question 13

how are male and female pelves different?

Answer 13

• female pelvis, the iliac bones are more flared than that of a male. Also the angle of the pubic arch and the distance between the ischial spines and tuber-sixties are greater in the female than in the male