Histology Bone

Question 1

What is bone composed of (4 major things)

Answer 1

1. Osteocytes,
2. Lacunae,
3. Type 1 collagen,
4. calcified ground substances.

Question 2

What are the functions of bone?

Answer 2

Support,

protection,

attachment for muscles,

calcium stores,

stimulates osteoclast activity,

Question 3

What does parathyroid hormone do to blood calcium levels?

Answer 3

Raises blood calcium

Question 4

What lowers blood calcium levels?

Answer 4

Calcitonin.

Question 5

What are the 4 classifications of bone?

Answer 5

1. short: wrist 2. Long: Femur 3. Irregular: Vertebre 4. Flat: skull

Question 6

Do all classifications of bone have long and spongy bone?

Answer 6

Yes

Question 7

What are the matrix layers of compact bone? what type of cells ?

Answer 7

lamellae Osteons

Question 8

What allows nutrition from the osteonal artery to reach all the osteocytes in the Osteone?

Answer 8

Canaliculi (means little canals)

Question 9

What are the three matrix layers of compact bones?

Answer 9

1. Haversian System 2. Circumfrential Lamellae 3. Interstitial Lamellae- remnants of the old osteones.

Question 10

How does spongy bone differ from compact bone?

Answer 10

Spongy bone exists in thin plates or fragments. Spongy bone is in thin fragments and does not need Harversian systems.

Question 11

How does nutrition get to the spongy bone?

Answer 11

Diffusion through the usual canaliculi

Question 12

What is around the border of the plate fragments of spongy bone?

Answer 12

Marrow

Question 13

What are the two layers of the periosteam?

Answer 13

Fibrous Layer Cellular Layer

Question 14

What two types of cells make up the periosteam?

Answer 14

Osteoblasts- are on the surface of the bone Osteocytes are buried in the bone.

Question 15

What holds the periosteum to the bone?

Answer 15

Is held to the bone at the location of ligaments and tendons by Sharpey’s fibers (Bundels of collagen that penetrate the outer lamellae), otherwise the collagen runs parallel to the bone

Question 16

What is the endosteum?

Answer 16

Lines the harversian canals and covers the surface of the marrow spaces.

Question 17

What are the two portions of the bone matrix?

Answer 17

Organic and Inorganic

Question 18

What does the organic layer do? what is it made of?

Answer 18

Makes the bone tough. It is make of collagen fibers oriented in perpendicular layers of adjacent lamella. **Contains ground substances (assorted glycosaminoglycans)

Question 19

What is Osteomalicia?

Answer 19

Softening of the bone, Bone is imperfectly calcified **Produced by vitamin D deficiency

Question 20

What is Osteoporosis?

Answer 20

Augmented bone resorption leading to porous bones. Correct chemical structure but less is present. **Increases probability of fracture.

Question 21

What are the two types of bone development?

Answer 21

Intramembranous & Endochondrial

Question 22

(Intra-membranous Development) Mesenchymal Cells

Answer 22

Differentiate into osteoprogenitor cells which act as stem cells for more osteoblasts

Question 23

(Intra-membranous Development) What is appositional growth?

Answer 23

These Osteoblasts line up on the bone and add more bone to the surface. **Osteoid gets laid down then calcifies.

Question 24

Where are osteoblasts abundant ?

Answer 24

Cytoplasm, which is basophilic.

Question 25

What grows together to form a mass of spongy bone?

Answer 25

Bone Spicules

Question 26

What cells line up to form compact bone?

Answer 26

Osteoblasts

Question 27

What cells work together to direct expansion of bone?

Answer 27

Osteoblast & Osteoclast

**Osteoclast remodeling proteins