Chapter 5 - Section 5.3 - Study Guide - Assess Your Learning Outcomes - Page 173: 9

**Osseous tissue**, also known as bone tissue, is a specialized and dynamic connective tissue that forms the skeletal system in vertebrates. It provides structural support, protection of vital organs, and serves as a reservoir for minerals like calcium and phosphate. There are several defining characteristics of osseous tissue as a class: **Defining Characteristics of Osseous Tissue:** 1. **Mineralized Matrix:** Osseous tissue has a mineralized extracellular matrix composed primarily of hydroxyapatite crystals, which are calcium phosphate compounds. This mineralization gives bone its hardness and strength. 2. **Collagen Fibers:** Collagen fibers, primarily type I collagen, are present in the matrix and provide flexibility and tensile strength to the bone. 3. **Osteocytes:** Bone cells called osteocytes are embedded within small cavities called lacunae in the bone matrix. Osteocytes are responsible for maintaining bone tissue and monitoring mechanical stresses. 4. **Haversian Systems:** Osseous tissue is organized into repeating structural units known as Haversian systems (or osteons in compact bone), which consist of concentric layers of bone tissue surrounding a central canal containing blood vessels and nerves. These units help in nutrient and waste exchange within the bone. 5. **Periosteum:** The outer surface of bone is covered by a dense connective tissue layer called the periosteum, which contains blood vessels, nerves, and osteoprogenitor cells. The periosteum plays a crucial role in bone growth, repair, and nourishment. **Distinction between Spongy and Compact Bone:** 1. **Compact Bone:** - **Appearance:** Compact bone appears dense and solid. It forms the outer layer of most bones and provides strength and protection. - **Structure:** It is composed of Haversian systems (osteons), which are tightly packed and aligned parallel to the long axis of the bone. The central canals within each osteon contain blood vessels and nerves. - **Function:** Compact bone is designed to withstand mechanical stress and distribute loads evenly along the bone's length. 2. **Spongy (Cancellous) Bone:** - **Appearance:** Spongy bone has a porous and trabecular (spongy) appearance. It is located deep to the compact bone and typically fills the interior of bones. - **Structure:** It consists of a network of thin, bony trabeculae (struts or plates) with spaces between them. These spaces are filled with bone marrow. - **Function:** Spongy bone is involved in red and yellow bone marrow production, which is essential for blood cell formation and fat storage. It also reduces the overall weight of bones while maintaining strength. **Relationship of the Periosteum to Bone:** The **periosteum** is a vital connective tissue layer that covers the outer surface of most bones. It serves several functions: 1. **Nutrient Supply:** The periosteum contains blood vessels that supply nutrients and oxygen to the bone tissue. These blood vessels also carry away metabolic wastes. 2. **Bone Repair:** The periosteum contains osteoprogenitor cells, which can differentiate into osteoblasts (bone-forming cells). This is essential for bone growth and repair after injury. 3. **Attachment for Tendons and Ligaments:** Tendons (muscle to bone) and ligaments (bone to bone) often attach to the periosteum, anchoring muscles and stabilizing joints. 4. **Sensory Function:** The periosteum contains nerves and sensory receptors that allow for the perception of pain and other sensations related to the bone. In summary, osseous tissue is characterized by its mineralized matrix and collagen fibers. It can be classified into compact and spongy bone, each with distinct structures and functions. The periosteum is a crucial layer covering the outer surface of most bones, serving functions related to bone nutrition, repair, attachment, and sensation.

**Osseous tissue**, also known as bone tissue, is a specialized and dynamic connective tissue that forms the skeletal system in vertebrates. It provides structural support, protection of vital organs, and serves as a reservoir for minerals like calcium and phosphate. There are several defining characteristics of osseous tissue as a class: **Defining Characteristics of Osseous Tissue:** 1. **Mineralized Matrix:** Osseous tissue has a mineralized extracellular matrix composed primarily of hydroxyapatite crystals, which are calcium phosphate compounds. This mineralization gives bone its hardness and strength. 2. **Collagen Fibers:** Collagen fibers, primarily type I collagen, are present in the matrix and provide flexibility and tensile strength to the bone. 3. **Osteocytes:** Bone cells called osteocytes are embedded within small cavities called lacunae in the bone matrix. Osteocytes are responsible for maintaining bone tissue and monitoring mechanical stresses. 4. **Haversian Systems:** Osseous tissue is organized into repeating structural units known as Haversian systems (or osteons in compact bone), which consist of concentric layers of bone tissue surrounding a central canal containing blood vessels and nerves. These units help in nutrient and waste exchange within the bone. 5. **Periosteum:** The outer surface of bone is covered by a dense connective tissue layer called the periosteum, which contains blood vessels, nerves, and osteoprogenitor cells. The periosteum plays a crucial role in bone growth, repair, and nourishment. **Distinction between Spongy and Compact Bone:** 1. **Compact Bone:** - **Appearance:** Compact bone appears dense and solid. It forms the outer layer of most bones and provides strength and protection. - **Structure:** It is composed of Haversian systems (osteons), which are tightly packed and aligned parallel to the long axis of the bone. The central canals within each osteon contain blood vessels and nerves. - **Function:** Compact bone is designed to withstand mechanical stress and distribute loads evenly along the bone's length. 2. **Spongy (Cancellous) Bone:** - **Appearance:** Spongy bone has a porous and trabecular (spongy) appearance. It is located deep to the compact bone and typically fills the interior of bones. - **Structure:** It consists of a network of thin, bony trabeculae (struts or plates) with spaces between them. These spaces are filled with bone marrow. - **Function:** Spongy bone is involved in red and yellow bone marrow production, which is essential for blood cell formation and fat storage. It also reduces the overall weight of bones while maintaining strength. **Relationship of the Periosteum to Bone:** The **periosteum** is a vital connective tissue layer that covers the outer surface of most bones. It serves several functions: 1. **Nutrient Supply:** The periosteum contains blood vessels that supply nutrients and oxygen to the bone tissue. These blood vessels also carry away metabolic wastes. 2. **Bone Repair:** The periosteum contains osteoprogenitor cells, which can differentiate into osteoblasts (bone-forming cells). This is essential for bone growth and repair after injury. 3. **Attachment for Tendons and Ligaments:** Tendons (muscle to bone) and ligaments (bone to bone) often attach to the periosteum, anchoring muscles and stabilizing joints. 4. **Sensory Function:** The periosteum contains nerves and sensory receptors that allow for the perception of pain and other sensations related to the bone. In summary, osseous tissue is characterized by its mineralized matrix and collagen fibers. It can be classified into compact and spongy bone, each with distinct structures and functions. The periosteum is a crucial layer covering the outer surface of most bones, serving functions related to bone nutrition, repair, attachment, and sensation.