Bone Tissue and Bone Cells Overview

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Questions and Answers

What is the main function of osteoblasts in bone tissue?

Endosteum formation

Matrix synthesis (correct)

Bone resorption

Bone marrow formation

What is the name of the structure through which osteocytes communicate with blood capillaries?

Gap junctions

Osteons

Lacunae

Canaliculi (correct)

What happens to osteoblasts when they are engaged in matrix synthesis?

They have a cuboidal to columnar shape (correct)

They undergo apoptosis

They become osteoclasts

They lose their ultrastructure

What is the function of gap junctions in osteocytes?

To allow for the exchange of molecules between cells Signup and view all the answers

What is the name of the cell type involved in bone resorption?

Osteoclasts Signup and view all the answers

What is the composition of the bone matrix synthesized by osteoblasts?

Type I collagen fibers, proteoglycans, and glycoproteins Signup and view all the answers

Where are osteocytes located in bone tissue?

In the lacunae within the bone matrix Signup and view all the answers

What happens to the bone matrix when osteocytes die?

It is resorbed Signup and view all the answers

What is the role of alkaline phosphatase in endochondral ossification?

Alkaline phosphatase promotes the death of chondrocytes, leading to the formation of a porous structure. Signup and view all the answers

What is the primary function of osteoclasts in bone remodeling?

Osteoclasts break down bone tissue through the release of enzymes and the creation of an acidic environment. Signup and view all the answers

What is the key difference between endochondral and intramembranous ossification?

Endochondral ossification involves a cartilage model, while intramembranous ossification directly forms bone on fibrous connective tissue. Signup and view all the answers

Which of the following correctly describes the role of the periosteum in bone?

The periosteum is a dense connective tissue membrane that covers bone surfaces and aids in bone repair. Signup and view all the answers

Which of the following bone types is NOT formed through endochondral ossification?

Flat bones Signup and view all the answers

What is the primary difference between the primary and secondary ossification centers in endochondral ossification?

The primary ossification center forms the shaft of the bone, while the secondary ossification center forms the ends of the bone. Signup and view all the answers

Which of the following statements accurately describes the process of bone growth in length?

Bone growth in length occurs through the replacement of cartilage by bone in the epiphyseal plate. Signup and view all the answers

What is the significance of the porous structure formed during the primary ossification center?

The porous structure provides space for the passage of blood vessels and nerves. Signup and view all the answers

Study Notes

Bone Tissue Overview

Bone tissue provides structural support for fleshy structures, organ cavities, and houses bone marrow.
Specialized connective tissue composed of calcified intercellular matrix known as bone matrix.
Contains three primary cell types: osteocytes, osteoblasts, and osteoclasts.

Bone Cells

Osteocytes
- Located in cavities between layers of bone matrix.
- Communicate with blood capillaries via canaliculi, facilitating metabolite exchange.
- Maintain the bony matrix; their death leads to matrix resorption.
- Found in small chambers called lacunae.
Osteoblasts
- Responsible for synthesizing the bone matrix, composed of Type I collagen, proteoglycans, and glycoproteins.
- Usually cuboidal to columnar in shape, located on the bone's surface.
- Active in protein synthesis, surrounded by their secretions, mature into osteocytes.
- Communicate through gap junctions, allowing molecular exchange for nourishment.
Osteoclasts
- Giant multinucleated cells of macrophage origin involved in bone resorption.
- Release collagenase and enzymes to create an acidic environment for hydroxyapatite dissolution.

Bone Types

Different types of bones include long, short, flat, irregular, and sesamoid (round).
Vascularized and innervated, typically supplied by one artery entering the marrow directly.
Covered by periosteum, a membrane that supports and protects the bone.

Bone Formation

Bone growth occurs through two processes:
- Endochondral Ossification: Bone forms on a cartilage model, replacing it.
- Intramembranous Ossification: Bone forms directly on fibrous connective tissue without an intermediate cartilage stage, occurring in specific locations like the parietal bone.

Endochondral Ossification Process

Takes place within hyaline cartilage matching the future bone shape.
Two stages involved: primary ossification center and secondary ossification center.
Primary Ossification Center:
- Bone appears via osteoblast activity creating a collar around the cartilage model.
- Collar obstructs nutrient diffusion to cartilage, leading to cartilage degradation.
- Chondrocytes produce alkaline phosphatase, compressing the matrix and initiating ossification.
- Death of chondrocytes results in a porous structure from remaining collagen ECM, followed by osteoblasts laying down primary bone.
Secondary Ossification Center:
- Bone enlarges and organizes into rows.
- Increased matrix production causes cells to spread further apart.
- Calcareous material is deposited between rows, leading to increased calcification of the matrix.

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Description

Learn about the structure and functions of bone tissue, including its composition and the three primary cell types: osteocytes, osteoblasts, and osteoclasts.