Microscopic Anatomy: Bone Connective Tissue
LEARNING OBJECTIVE 7. Name the four types of bone cells and their functions. 8. Describe the composition of bone's matrix. 9. Explain bone matrix formation and resorption. 10. Compare the structure of compact bone and spongy bone.
Terms in this set (27)
The primary component of bone is "bone connective tissue" also called?
connective tissue: osteoprogenitor cells, osteoblasts, osteocytes, and osteoclasts
Four types of cells are found in bone?
Cells of Bone (heading)
- are stem cells derived from mesenchyme (see section 5.2c). When they divide through the process of mitosis, another stem cell is produced along with a "committed cell" that matures to become an osteoblast. As previously described, these stem cells are located in both the periosteum and the endosteum.
- Makes bones
(blast = germ) are formed from osteoprogenitor stem cells.
Often, _____ are positioned side by side on bone surfaces.
Active ______ exhibit a somewhat cuboidal shape and have abundant rough endoplasmic reticulum and Golgi apparati, reflecting the activity of these cells.
_______ perform the important function of synthesizing and secreting the initial semisolid organic form of bone matrix called osteoid (os′tē-oyd; eidos = resemblance).
Osteoid later calcifies as a result of salt crystal deposition. As a consequence of this mineral deposition on osteoid, ______become entrapped within the matrix they produce and secrete, and thereafter they differentiate into osteocytes.
- it comes after osteoblasts
- maintain bones when osteoblasts makes some.
cyt = cell) are mature bone cells derived from osteoblasts that have lost their bone-forming ability when enveloped by calcified osteoid.
Connections between the original neighboring osteoblasts are maintained as they become_____.
________maintain the bone matrix and detect mechanical stress on a bone. If stress is detected, osteoblasts are signaled, and it may result in the deposition of new bone matrix at the surface.
- 22 your bone stop growing
(os′-tē-ō-klast; klastos = broken) are large, multinuclear, phagocytic cells. They are derived from fused bone marrow cells similar to those that produce monocytes (described in section 18.3c). These cells exhibit a ruffled border where they contact the bone, which increases their surface area exposure to the bone.
An _____ is often located within or adjacent to a depression or pit on the bone surface called a resorption lacuna (Howship's lacuna). ______are involved in breaking down bone in an important process called bone resorption (described shortly).
- is an organic material and made of collagen fibers
- is composed of both collagen protein plus a semisolid ground substance of proteoglycans (including chondroitin sulfate) and glycoproteins that suspends and supports the collagen fibers.
- These organic components give bone tensile strength by resisting stretching and twisting, and contribute to its overall flexibility.
Composition of the Bone Matrix (heading)
- minerlization of matrix
- Natural mineral structure that the crystal lattice of bone and teeth closely resembles.
- is a calcium phosphate salt deposited within the bone.
- These crystals deposit around the long axis of collagen fibers in the extracellular matrix. The crystals harden the matrix and account for the rigidity or relative inflexibility of bone that provide its compressional strength.
- it begins when osteoblasts secrete the initial semisolid organic form of bone matrix called osteoid
Bone Matrix: Its Formation and Resorption (heading)
- Also called mineralization: the process of deposition of mineral salts such as calcium and magnesium phosphates into a tissue.
- or mineralization, subsequently occurs to osteoid formation when hydroxyapatite crystals deposit in the bone matrix.
- ______occurs when the concentration of calcium ions and phosphate ions reach critical levels and precipitate out of solution, thus forming the hydroxyapatite crystals that deposit in and around the collagen fibers.
- The entire process of bone formation requires a number of substances, including vitamin D (which enhances calcium absorption from the gastrointestinal tract) and vitamin C (which is required for collagen formation), as well as calcium and phosphate for calcification.
- the process by which osteoclasts break down bone and release the minerals, resulting in a transfer of calcium from bone fluid to the blood
- is a process whereby bone matrix is destroyed by substances released from osteoclasts into the extracellular space adjacent to the bone.
- Proteolytic enzymes released from lysosomes within the osteoclasts chemically digest the organic components (collagen fibers and proteoglycans) of the matrix, while hydrochloric acid (HCl) dissolves the mineral parts (calcium and phosphate) of the bone matrix. The liberated calcium and phosphate ions enter the blood. Bone resorption may occur when blood calcium levels are low (described in detail later in this chapter).
connective tissue: osteoprogenitor cells, osteoblasts, osteocytes, and osteoclasts
- Hard, dense bone tissue that is beneath the outer membrane of a bone
- is composed of small cylindrical structures called osteons, or Haversian systems.
Compact Bone Microscopic Anatomy (heading)
- is the basic functional and structural unit of mature compact bone
- or Basic structural unit of bone
- are oriented parallel to the diaphysis of the long bone. When an ____ is viewed in cross section, it has the appearance of a bull's-eye target. An ____ has several components: The central (Haversian) cana, Concentric lamellae , Osteocytes, Lacunae, and Canaliculi.
- is a cylindrical channel that lies in the center of the osteon and runs parallel to it.
- Traveling within the ______l are the blood vessels and nerves that supply the bone.
- are rings of bone connective tissue that surround the central canal and form the bulk of the osteon.
- Each lamella contains collagen fibers oriented at an angle in one direction; adjacent lamellae contain collagen fibers oriented at an angle that is 90 degrees different from both the previous and next lamellae. This alternating pattern of collagen fiber direction gives bone part of its strength and resilience.
are mature bone cells found in small spaces (see next) between adjacent concentric lamellae. These cells maintain the bone matrix.
are the small spaces that house an osteocyte.
- Extensions of osteocyte
- are tiny, interconnecting channels within the bone connective tissue that extend from each lacuna, travel through the lamellae, and connect to other lacunae and the central canal.
- ______ house osteocyte cytoplasmic projections that permit intercellular contact and communication. Nutrients, minerals, gases, and wastes can travel through the cytoplasmic extensions within these passageways between the blood vessels of the central canal and the osteocytes.
- it helps communicate
- They contain blood vessels and nerves, they run perpindicular to the central canals and help connect multiple central canals, creating a vascular and innervation connection among the multiple osteons
- (Volkmann canals) resemble central canals in that they also contain blood vessels and nerves. However, _____ run perpendicular to the central canals and help connect multiple central canals within different osteons, thus creating a vascular and innervation connection among the multiple osteons.
Dictionary ( no answer)
Intersecting at or forming right angles
- located deep to periosteum and superficial to endosteum and extend around entire circumference of the diaphysis and resist twisting of long bone
- are rings of bone immediately internal to the periosteum of the bone (external circumferential lamellae) or internal to the endosteum (internal circumferential lamellae)
- Both external and internal circumferential lamellae run the entire circumference of the bone itself (hence, their name).
are either the components of compact bone that are between osteons or are the leftover parts of osteons that have been partially resorbed—thus they often look like a "bite" has been taken out of them. The interstitial lamellae are incomplete and typically have no central canal.
(HEADING: Spongy Bone Microscopic Anatomy)
Unlike compact bone, ____ contains no osteons (figures 7.7c, 7.8c) Rather its structure is an open lattice of narrow rods and plates of bone, called trabeculae
A thin plate or layer of tissue, particularly those found in spongy bone is called.....
- layers of bone connective tissue that compose the trabeculae of spongy bone
- composed of bone matrix. Between adjacent lamellae are osteocytes resting in lacunae, with numerous canaliculi radiating from the lacunae. Nutrients reach the osteocytes by diffusion through cytoplasmic processes within the canaliculi that open onto the surfaces of the trabeculae.
Spongy Bone Microscopic Anatomy (Headings)