SM 219a - Bone Histology Flashcards
What is the structural unit of compact bone?
Haversian System (aka Osteon)
What is the source of new material for the growth in length of a bone?
Dividing cartilage cells
Which part of the bone is indicated by #6?
Cortex
Made up of lamellar (compact) bone
What structure is #1 pointing to?
Osteoid
(An unmineralized, organic portion of the matrix)
What kind of bone is predominant in this image?
Lamellar bone
(aka Mature Bone or Compact Bone)
The bone is organized into lamellae (layers)
Which cells in the bone are multinucleated giant cells?
Osteoclasts
They reabsorb bone
Which part of the bone is indicated by #7?
Medullary Cavity
Made up of trabecular (spongey) bone
What structure is #2 pointing to?
Woven Bone (aka Immature Bone)
Mineralized, but not organized into lamellae
What substance initiates mineralization of bone?
Small vescicles exocytosed by ostoblasts filled with alkaline posphatase and pyrophsophate
What is osteoid?
Organic matrix that is not yet mineralized (but will be)
Osteoid -> Mineralized to woven bone -> Matures into lamellar bone
Which part of the bone is indicated by #4?
Epiphysis
(also #5)
What structures run through the “canal” of the Haversian System?
Blood vessels and nerve fibers
https://peir-vm.path.uab.edu/wsi.php?slide=UAB-Histology-00009
Osteoid in a malignant tumor indicates what kind of tumor?
Osteosarcoma
(patho-pneumonic)
Which structure is indicated by #3?
Osteocyte Lacunae
https://peir-vm.path.uab.edu/wsi.php?slide=UAB-Histology-00009
Which structure is indicated by #2?
Canal
Contains blood vessels and nerve fibers
https://peir-vm.path.uab.edu/wsi.php?slide=UAB-Histology-00009
What are the cellular components of bone?
Osteoblasts - Synthesize bone
Osteocytes - Mature osteoblasts
Osteoclasts - Resorb bone
Describe what is happening in Zone 3
Cartilage cells are proliferating
This is the Zone of Proliferation
https://peir-vm.path.uab.edu/wsi.php?slide=UAB-Histology-00068
Which ossification process does this statement describe?
“New bone develops directly from a capsule of undifferentiated connective tissue”
Intramembranous ossification
Occurs in the flat bones of the face, cranial bones, and clavicles
In which zone will you find non-active cartilage?
4 - Reserve Cartilage
https://peir-vm.path.uab.edu/wsi.php?slide=UAB-Histology-00068
Which part of the bone is indicated by #1?
Metaphysis
(also #3)
What kind of bone cell is B pointing to?
Osteoblast
Osteoblasts sit on the surface and synthesize bone
Which hormone stimulates bone resorption?
Parathyroid hormone
Which part of the bone is indicated by #2?
Diaphysis
Describe what is happening in Zone 2
Cartilage cells are undergoing hypertrophy
This is the Zone of Hypertrophy
https://peir-vm.path.uab.edu/wsi.php?slide=UAB-Histology-00068
Which part of the bone is indicated by #3?
Metaphysis
(Also #1)
Which ossification process does this statement describe?
“New bone develops from and replaces hyaline cartilage”
Endochondral ossification
Occurs in long bones, in the bones at the base of the skull, short bones in the hands and feet
Which structure is indicated by #1?
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
Which part of the bone is indicated by #5?
Epiphysis
(Also #7)
Which cells synthesize bone?
Osteoblasts
What is the difference between osteoid and woven (immature) bone?
- Ostoid is not yet mineralized
- Immature bone is mineralized, but no yet organized into lamellae
What kind of bone makes up most of our body?
Long bones
Describe what is happening in Zone 4
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
In which section are cartilage cells turning into bone?
1 - Zone of Ossification
https://peir-vm.path.uab.edu/wsi.php?slide=UAB-Histology-00068
What kind of bone cell is A pointing to?
Osteocyte
Osteocytes sit within lacunae
They are conencted by canaliculi to diffuse nutrients and waste
Describe what is happening in Zone 1
Cartilage cells are turning into bone
This is the Zone of Ossification
https://peir-vm.path.uab.edu/wsi.php?slide=UAB-Histology-00068
In which section are cartilage cells proliferating?
3 - Zone of Proliferation
https://peir-vm.path.uab.edu/wsi.php?slide=UAB-Histology-00068
What structure is indicated in this diagram?
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
What is the periosteum?
The outer layer of dense connective tissue surrounding bone
Which cells in the bone release Ca2+ into the serum?
Osteoclasts
They resorb bone
Describe the composition of an osteon (aka Haversian system)
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
What is the purpose of the canaliculi in bone?
Canaliculi are little pathways that connct osteocyte lacunae in order to diffue nutrients and waste
They are basically a complex series fo gap junctions
Bone is constantly remodeled. Which part of the bone is remodeled?
The surface
Ostoblasts lay down bone, osteoclasts resorb bone
A bone gets turned over completely about every ____ years
A bone gets turned over completely about every 5 years
Which type of collagen is most common in bone?
Type I
In which section are cartilage cells hypertrophy-ing?
2 - Zone of Hypertrophy
https://peir-vm.path.uab.edu/wsi.php?slide=UAB-Histology-00068
What kind of bone cells are the arrows pointing to?
Osteoclasts
Osteoclasts are multinucleated giant cells
Where the the primary location of lamellar bone?
- Fetal skeleton
- Primary center of ossification
- Epiphyseal plate
- Cortical bone
d. Cortical bone
What kind of bones make up the skull bones, facial bones, and clavicles?
Flat bones
