SM 219a - Bone Histology

Question 1

What is the structural unit of compact bone?

Answer 1

Haversian System (aka Osteon)

Question 2

What is the source of new material for the growth in length of a bone?

Answer 2

Dividing cartilage cells

Question 3

Which part of the bone is indicated by #6?

Answer 3

Cortex

Made up of lamellar (compact) bone

Question 4

What structure is #1 pointing to?

Answer 4

Osteoid

(An unmineralized, organic portion of the matrix)

Question 5

What kind of bone is predominant in this image?

Answer 5

Lamellar bone

(aka Mature Bone or Compact Bone)

The bone is organized into lamellae (layers)

Question 6

Which cells in the bone are multinucleated giant cells?

Answer 6

Osteoclasts

They reabsorb bone

Question 7

Which part of the bone is indicated by #7?

Answer 7

Medullary Cavity

Made up of trabecular (spongey) bone

Question 8

What structure is #2 pointing to?

Answer 8

Woven Bone (aka Immature Bone)

Mineralized, but not organized into lamellae

Question 9

What substance initiates mineralization of bone?

Answer 9

Small vescicles exocytosed by ostoblasts filled with alkaline posphatase and pyrophsophate

Question 10

What is osteoid?

Answer 10

Organic matrix that is not yet mineralized (but will be)

Osteoid -> Mineralized to woven bone -> Matures into lamellar bone

Question 11

Which part of the bone is indicated by #4?

Answer 11

Epiphysis

(also #5)

Question 12

What structures run through the “canal” of the Haversian System?

Answer 12

Blood vessels and nerve fibers

https://peir-vm.path.uab.edu/wsi.php?slide=UAB-Histology-00009

Question 13

Osteoid in a malignant tumor indicates what kind of tumor?

Answer 13

Osteosarcoma

(patho-pneumonic)

Question 14

Which structure is indicated by #3?

Answer 14

Osteocyte Lacunae

https://peir-vm.path.uab.edu/wsi.php?slide=UAB-Histology-00009

Question 15

Which structure is indicated by #2?

Answer 15

Canal

Contains blood vessels and nerve fibers

https://peir-vm.path.uab.edu/wsi.php?slide=UAB-Histology-00009

Question 16

What are the cellular components of bone?

Answer 16

Osteoblasts - Synthesize bone

Osteocytes - Mature osteoblasts

Osteoclasts - Resorb bone

Question 17

Describe what is happening in Zone 3

Answer 17

Cartilage cells are proliferating

This is the Zone of Proliferation

https://peir-vm.path.uab.edu/wsi.php?slide=UAB-Histology-00068

Question 18

Which ossification process does this statement describe?

“New bone develops directly from a capsule of undifferentiated connective tissue”

Answer 18

Intramembranous ossification

Occurs in the flat bones of the face, cranial bones, and clavicles

Question 19

In which zone will you find non-active cartilage?

Answer 19

4 - Reserve Cartilage

https://peir-vm.path.uab.edu/wsi.php?slide=UAB-Histology-00068

Question 20

Which part of the bone is indicated by #1?

Answer 20

Metaphysis

(also #3)

Question 21

What kind of bone cell is B pointing to?

Answer 21

Osteoblast

Osteoblasts sit on the surface and synthesize bone

Question 22

Which hormone stimulates bone resorption?

Answer 22

Parathyroid hormone

Question 23

Which part of the bone is indicated by #2?

Answer 23

Diaphysis

Question 24

Describe what is happening in Zone 2

Answer 24

Cartilage cells are undergoing hypertrophy

This is the Zone of Hypertrophy

https://peir-vm.path.uab.edu/wsi.php?slide=UAB-Histology-00068

Question 25

Which part of the bone is indicated by #3?

Answer 25

Metaphysis | (Also #1)

Question 26

Which ossification process does this statement describe? "New bone develops from and replaces hyaline cartilage"

Answer 26

Endochondral ossification Occurs in long bones, in the bones at the base of the skull, short bones in the hands and feet

Question 27

Which structure is indicated by #1?

Answer 27

Osteocyte canaliculi Canaliculi = little pathways that connect the lacunae of osteocytes so they can share nutrients and excrete waste https://peir-vm.path.uab.edu/wsi.php?slide=UAB-Histology-00009

Question 28

Which part of the bone is indicated by #5?

Answer 28

Epiphysis | (Also #7)

Question 29

Which cells synthesize bone?

Answer 29

Osteoblasts

Question 30

What is the difference between osteoid and woven (immature) bone?

Answer 30

* Ostoid is not yet mineralized * Immature bone is mineralized, but no yet organized into lamellae

Question 31

What kind of bone makes up most of our body?

Answer 31

Long bones

Question 32

Describe what is happening in Zone 4

Answer 32

Not much! Zone 4 contains **Reserve cartilage** - non-active cartilage that is just resting https://peir-vm.path.uab.edu/wsi.php?slide=UAB-Histology-00068

Question 33

In which section are cartilage cells turning into bone?

Answer 33

1 - Zone of Ossification https://peir-vm.path.uab.edu/wsi.php?slide=UAB-Histology-00068

Question 34

What kind of bone cell is **A** pointing to?

Answer 34

Osteocyte Osteocytes sit within lacunae They are conencted by canaliculi to diffuse nutrients and waste

Question 35

Describe what is happening in Zone 1

Answer 35

Cartilage cells are turning into bone This is the **Zone of Ossification** https://peir-vm.path.uab.edu/wsi.php?slide=UAB-Histology-00068

Question 36

In which section are cartilage cells proliferating?

Answer 36

3 - Zone of Proliferation https://peir-vm.path.uab.edu/wsi.php?slide=UAB-Histology-00068

Question 37

What structure is indicated in this diagram?

Answer 37

An Osteon aka Haversian System * Structural unit of compact bone * Osteocytes in concentric layers surround a central canal that carries blood vessels and nerve fibers * Concentric rings are layers of bone laid down by osteoblasts

Question 38

What is the periosteum?

Answer 38

The outer layer of dense connective tissue surrounding bone

Question 39

Which cells in the bone release Ca2+ into the serum?

Answer 39

Osteoclasts They resorb bone

Question 40

Describe the composition of an osteon (aka Haversian system)

Answer 40

An osteon is made up of... * Osteocytes surrounding a central canal * The canal carries blood vessels and nerve fibers * The osteocytes form concentric rings * The rings are layers of bone that are laid down by osteoblasts

Question 41

What is the purpose of the canaliculi in bone?

Answer 41

Canaliculi are little pathways that connct osteocyte lacunae in order to diffue nutrients and waste They are basically a complex series fo gap junctions

Question 42

Bone is constantly remodeled. Which part of the bone is remodeled?

Answer 42

The surface Ostoblasts lay down bone, osteoclasts resorb bone

Question 43

A bone gets turned over completely about every ____ years

Answer 43

A bone gets turned over completely about every **_5_** years

Question 44

Which type of collagen is most common in bone?

Answer 44

Type I

Question 45

In which section are cartilage cells hypertrophy-ing?

Answer 45

2 - Zone of Hypertrophy https://peir-vm.path.uab.edu/wsi.php?slide=UAB-Histology-00068

Question 46

What kind of bone cells are the arrows pointing to?

Answer 46

Osteoclasts Osteoclasts are multinucleated giant cells

Question 47

Where the the primary location of lamellar bone? 1. Fetal skeleton 2. Primary center of ossification 3. Epiphyseal plate 4. Cortical bone

Answer 47

d. Cortical bone

Question 48

What kind of bones make up the skull bones, facial bones, and clavicles?

Answer 48

Flat bones