Bones and Skeletal Tissues

Question 1

What is the role of fibrocartilage? Where is it found? (3)

Answer 1

Transferring weight to our body for our lower limbs

• cartilage intervertebral disc
• Pubic symphysis
• Meniscus

Question 2

Where is elastic cartilages found?
(2)

Answer 2

• Epiglottis
• Eustachian tube (external ear)

Question 3

Where is hyaline cartilages found?

Answer 3

Most in our body
- costal cartilage
- articular cartilage of a joint

Question 4

How does growth of a cartilage work? (2)

Answer 4

1. Appositional growth
   - occurs at surfaces
2. Interstitial growth
   - Expand cartilage from within

Question 5

Why does cartilage calcification occur?

Answer 5

• Sites where cartilage connects with bone
• It is about to be replaced by bone
• Cartilage has lack of nutrition/oxygen

Question 6

How does cartilage calcification occur? (3)

Answer 6

1. Chondrocytes get big and & secrete enzymes to wear away extracellular matrix
2. calcium phosphate is deposited & matrix crytsalizes
3. Chondrocytes die (leave space

Question 7

What is the spongy bone texture called?

Answer 7

Trabeculae

Question 8

What are the 2 layers of the periosteum?
What is it secured by?

Answer 8

1. Fibrous
2. Osteogenic

Perforating fibers

Question 9

What covers the trabeculae of spongy bone, compact bones canals, marrow cavity?

Answer 9

Endosteum

Question 10

Describe Lamellaes

Answer 10

-column-like matrix tubes
- fibers in 1 lamellae run in the same direction but not all tubes run in the same direction

Question 11

What is the role of the perforating canals?

Answer 11

Come in at 90 degree angles and connects blood vessels & nerves

Question 12

What is the microscopic anatomy of compact bone?

Answer 12

Lacunae
- small cavities that contain osteocytes

Canaliculi:
- hairlike canals that connect lacunae to each other

Question 13

What is the microscopic anatomy of spongy bone?

Answer 13

Trabeculae
- contain irregularly arranged lamellae, osteocytes, canaliculi
(NO OSTEONS)
- Capillaries in endosteum supply nutrients

Question 14

What is the structure of a long bone

Diaphysis
Epiphyses

Answer 14

Diaphysis (shaft)
- Yellow bone
- Bone marrow

Epiphyses (ends)
- red marrow
- has articular (hyaline) cartilage

Question 15

Where do nerve fibers, and blood vessels enter bone?

Answer 15

via nutrient foramina

Question 16

What is the role of the following organic chemical composition of bone:

Osteogenic/genesis
Osteoblast
Osteocyte
Osteoclast

Answer 16

Osteogenic/genesis
- active stem cels in periosteum
- bone tissue formation

Osteoblast
- synthesize osteoid (the matrix)
In matrix:
- Osteocytes
- Bone lining cells

Osteoclast
- break down the matrix

Question 17

What type of bone is the most common in our body?
What does it have the most of?

Answer 17

Inorganic bone
- Biggest contributor to calcium

Question 18

What does organic bone mainly consist of?

Answer 18

Mostly collagen

Question 19

What are 3 stages of bone development? when does it occur?
What helps with bone tissue formation?

Answer 19

Osteogenesis (ostification)

1. Bone formation (2nd month prenatal)
2. Postnatal bone growth (until early adulthood)
3. Bone remodeling and repair
   (lifelong)

Question 20

What occurs during step 1 bone formation?

Answer 20

1. Endochondral ossification
   - bone forms by replacing hyaline cartilage
2. Intramembranous ossification
   - bone develops from fibrous membrane
   - Forms flat bones

Question 21

What occurs during step 2 of postnatal bone growth?

What are the 4 important functional zones in the epiphyseal plate?

Answer 21

Interstitial growth
- Increase length of long bone

1. Proliferation
2. Hypertrophic
3. Calcification
4. Ossification

Appositional growth
- increase thickness while actual amount of bone shaft does not change
(osteoclast break down endosteum)

Question 22

What occurs during step 3 of bone remodeling?
How many years is spongy bone replaced? what about compact?

Answer 22

-Spongy bone replaced every 3-4 years

• Compact bone replaced every 10 years

Question 23

How does osteoid calcifies?
Bone deposit

Answer 23

-Proteins of osteoid bind Ca2+
-osteoblasts release vesicles with phosphate

Question 24

How does bone resorption occur

Answer 24

• Osteoclasts break compact bone
• Osteoblasts come in to make the matrix and remodel it

Question 25

Where does GH stimulate growth
What modulates this hormone?

Answer 25

At epiphyseal plate

• Thyroid hormone

Question 26

What is calcium necessary for in terms of hormonal control of blood calcium?

Answer 26

1. transmission of nerve impulses
2. Muscle Contraction
3. Secretion by glands & nerve cells
4. Blood coagulation
5. cell division

Question 27

Which hormone increases blood calcium level?
How (4)?

Answer 27

Parathyroid hormone

1. Osteoclasts degrade bone matrix & release calcium
2. Osteoblasts will decrease their activity
3. Increase calcitriol to increase Ca absorption in intestine
4. Decrease urinary Ca2+ excretion & increase urinary Pi excretion

Question 28

Which hormone decreases blood calcium level?
How (2)?

Answer 28

Calcitonin (tone down calcium)

1. Osteoclast activity inhibited
   (osteoblast not affected)
2. Calcitonin inhibit CA2+ reabsorption in kidneys

Question 29

What is Wolff’s law?

Answer 29

A bone grows or remodels in response to forces or demands placed upon it