Unit 1 Study Guide Flashcards
Compact Bone
- dense connective bone tissue
- composed of circumferential lamellae and intersitital lamellae
Spongy Bone
- located internal to compact bone
- appears porous
- composed of trabeculae and parallel lamellae
Hyaline Cartilage
- cartilage within epiphyseal plates (growth plates)
- covers the ends of some bones–called articular cartilage
- Provides a model for the function of most of the bones in the body
Fibrocartilage
- weight-bearing cartilage that withstands compression
Describe the general functions of bone.
1) Support and Protection
- structural support for entire body
- protect many delicate organs from injury/trauma (Ex: ribs-heart and lungs)
2) Movement
- Bone is the attachment site for skeletal muscles, tissues, and some organs
3) Hemopoiesis-blood cell production
- occurs in red bone marrow connective tissue that contains stem cells that form blood cells and platelets
4) Storage of Mineral and Energy Reserves
- Calcium and phosphate are stored within the bone and then released
What are some of the functions for Calcium in the body?
- muscle contraction
- blood clotting
- release of neurotransmitter from nerve cells
What are some of the functions of Phosphate in the body?
- a structural component of ATP, nucleotides, and phospholipids
- important component of the plasma membrane
What is the most common class/type of bone?
Long Bone
Label the Regions of the Long Bone
Diaphysis
- the Shaft that is made mostly of compact bone and has some spongy bone
Contains:
- Central Medularry Cavity
- Endosteum
- Periosteum
Medullary Cavity
- hollow, cylindrical spce within the diaphysis
- contains red bone marrow in children and yellow bone marrow in adults
Epiphysis
Knobby region of the long bone
- located at each end of the long bone
- composed of an outer thin layer of compact bone and an inner region of spongy bone
- the spongy bone in the epiphysis resists stress that is applied from many directions
What is the cartilage that covers the ends of each bone?
What is the purpose of this cartilage?
- Articular Cartilage-a thin layer of hyaline cartilage
- helps reduce friction and absorb shock in moveable joints
Metaphysis
- region of mature bone
- between the diaphysis and epiphysis
- contains the epiphyseal plate in growing bone (region of hyaline cartilage)
Periosteum
- double layer membrane covering external surface of bone
- attached to compact bone by perforating fibers
- outer protective layer
- inner cellular layer contains: osteoprogenitor cels, osteoblasts, osteoclasts.
What anchors the periosteum to the bone?
Perforating Fibers:
Endosteum
- an incomplete layer of cells that covers all internal surface of the bone
- Contains osteroprogenitor cells, osteoblasts, and osteoclasts
- locations
- lines medullary cavity
- lines canals
- surrounds spongy bone
Label the Flat Bone
- external surface composed of two layers of compact bone covered by periosteum
- internal surface composed entirely of spongy bone
- no medullary cavity
What is the primary component of bone?
Bone Connective tissue
Osteoprogenitor cells
- are stem cells derived from mesenchyme
- divide via cellular division and produces another stem cell and a “committed cell.”
- This commited cell matures into the osteoblast
- located in both the periosteum and the endosteum
Osteoblasts
- formed from osteoprogenitor stem cells
- synthesize and secrete osteoid
What happens to the osteoblast as the osteoid begins to calcifies?
osteoblasts become entrapped within the matrix/calcified osteoid and differentiate into osteocytes
Osteocytes
- are mature bone cells that are derived from osteoblasts after the osteoblast has lost its bone-forming ability when the matrix/osteoid is calcified
- maintain the bone matrix and detect stress on the bone
What happens if stress is dected by the osteocytes?
-osteoblasts are signaled and it may result in the deposition of new bone matrix at the surface
Osteoclasts
- large, multinuclear, phagocytic cells
- are often located within or adjacent to a lacuna
- involved in breaking down bone in bone resorption
What is the organic portion of the bone matrix?
the osteoid
composed of collegen protein plus a semisolid ground substance of proteoglycans and glycoproteins
What is the purpose of the osteoid?
to give the bone tensile strength by resisting stretching and twisting and contributing to its overall flexibility
What is the inorganic portion of the bone matrix? Purpose?
salt crystals of calcium phosphate deposited around collagen fibers
-hardens the matrix and account’s for the rigidity or relative inflexibility of bone that provide its compressional strength
Bone Formation
- begins when osteoblasts secrete the osteoid
- calcification occurs to the osteoid when hydroxyapatite crystals deposit in the bone matrix and creates inorganic portion of the bone
- initiated when the concentration of calcium ions and phosphate ions reach critical levels in the tissue
- requires vit. D, Vit C, calcium, and phosphate
Vitamin D
enhances calcium absorption from the GI tract
Vitamin C
required for collagen formation
Bone Resorption
a process where bone matrix is destroyed by substances released from osteoclasts into the extracellular space adjacent to the bone
In Bone Resorption:
What digests the organic components of the matrix?
Proteolytic enzymes released from lysosomes within the osteoclasts
In Bone Resorption:
What digests the inorganic portions of the matrix?
HCl dissolves the mineral parts (calcium and phosphate) which then enter the blood