BSI Lecture 46 Bone Structure Flashcards
What are the functions of the bone and skeletal system?
a) Supports soft tissues and provides attachment for skeletal muscle
b) protects internal organs
c) Assists in movement
d) Mineral homeostasis
e) Blood cell production
f) triglyceride storage
g) endocrine function
What are the different parts of the long bone?
a) diaphysis
b) epiphyses
c) metaphyses
d) periosteum
e) medullary cavity
f) nutrient artery
What is the diaphysis?
The shaft of the long bone
What are the epiphyses?
The distal and proximal ends of the long bone
What kind of cartilage does the epiphyses contain?
Articular cartilage
What is articular cartilage?
Hyaline cartilage covering the epiphyses
What are the two parts of the metaphyses?
The epiphyseal plate and the epiphyseal line
What is the difference between the epiphyseal plate and epiphyseal line?
the plate is the layer of hyaline cartilage that allows for bone to grow in length, whereas the line is cartilage replaced with bone.
What is the periosteum?
It is the sheath of dense irregular connective tissue that surrounds the surface of the bone.
What are the functions of the periosteum?
The periosteum protects bone, assists in fracture repair, helps nourish bone tissue, and serves as an attachment point for ligaments and tendons.
What is the medullary cavity, and what does it contain?
It is the space within the diaphysis that contains the endosteum.
What is the endosteum and where is it located?
It is the thin membrane that lines the medullary cavity . It is located within the medullary cavity.
What is the nutrient artery?
It is the principle artery that supplies the shaft of the bone.
Where do the branches of the nutrient artery go through?
They snake through the canals of haversian systems and other cavities of the bone.
Where does the nutrient artery enter?
It enters the diaphysis via the nutrient foramen.
What is the bone matrix consisted of?
inorganic mineral salts deposited on organic framework (osteoid).
What is the bone matrix comprised of?
25% water
25% collagen fibers
50% mineralized salt
What is the most abundant protein making up the organic matrix?
collagen fibers
What are the inorganic mineral salts in bone?
hydroxyapatite
magnesium hydroxide
fluoride
sulfate
What is hydroxyapatite comprised of?
Calcium phosphate and calcium carbonate
What is the most abundant mineral salt in bone?
hydroxyapatite
What do crystallized salts give the bone?
The crystallized salts give the bone hardness
What does collagen give to the bone?
Collagen gives the bone its flexibility and tensile strength
What are the four types of cells in bone tissue?
osteogenic cells
osteoblasts
osteocytes
osteoclasts
What are osteogenic cells also considered?
“pre-osteoblast” cells
What do osteogenic cells differentiate into?
Osteoblasts
What are undifferentiated stem cells?
osteogenic cells are derived from the mesenchyme, which is the tissue that all connective tissues are derived from
Where are osteogenic cells found?
They are found along the inner portion of the periosteum, endosteum, and its canals within bone that contain blood vessels.
What are osteoblasts?
They are bone building cells that synthesize and secrete collagen fibers and other components of the matrix.
How do osteoblasts initiate calcification?
They secrete alkaline phosphatase
What are osteocytes?
Mature bone cells (senescent osteoblasts)
What do osteocytes act as?
Mechanosensory receptors
T/F? Osteocytes undergo cell division.
FALSE
What do osteocytes play a major role in?
orchestrating bone remodeling
Where are osteoclasts derived from?
stem cells in the bone marrow that gives rise to monocytes
T/F? Differentiation and fusion of the monocytes in osteoclasts form single-nucleated osteoclasts.
FALSE, multinucleated
What are osteoclasts responsible for?
Bone resorption
What are the steps of bone resorption?
- Ruffled border forms a seal with bone surface.
- Releases lysosomal enzymes and acids to digest matrix.
- When the osteoclast is active, the ruffled border is more pronounced.
What are the regions of bone classified as?
Compound bone, and spongy bone
What is compact bone also considered?
cortical bone
What is the compact bone arranged in?
Units called osteons (aversion systems)
What are the various units of compact bone called?
osteons
What are the five osteons?
- central (haversion) canal
- perforating (volkmans) canal
- concentric lamellae and inner and outer circumferential lamellae
- lacunae
- canaliculi
What is the central (haversion) canal?
a canal that runs longitudinally through bone and through osteon; it contains blood vessels, lymphatic vessels and nerves
What is the perforating (volkmans) canal?
canal that connects the central canals to one another, to medullary cavity, and to the periosteum
T/F? Concentric lamellae and inner and outer circumferential lamellae are the rings of the hard calcified matrix.
TRUE
What are the lacunae?
They’re the spaces in the matrix that house the osteocytes.
What are the canaliculi?
They are small channels that are filled with extracellular fluid connecting adjacent lacunae.
What do the canaliculi contain?
They contain fingerlike processes of osteocytes, which communicate via gap junctions with neighboring osteocytes.
What are two other names for spongy bone?
Cancellous or trabecular bone
What is a big difference between spongy and compact bone, in relation to their structure?
Spongy bone contains more spaces
T/F? Spongy bone is arranged in osteons.
FALSE; it is NOT arranged in osteons
T/F? In certain bones, spongy bone houses RBCs.
True
How is the bone tissue arranged in spongy bone?
Bone tissue is arranged in lamellae
What does spongy bone contain?
- trabeculae
- lacunae
- canaliculi
What is trabeculae?
It is an irregular lattice work of columns of bone
What part of the bone does spongy bone make up?
makes up most bone tissue of short, flat, irregularly shaped bones, epiphyses of long bone, and narrow rim around the medullary cavity.
What are the two kinds of bone marrow?
Red bone marrow and yellow bone marrow
What does red bone marrow contain?
It contains developing blood cells, adipocytes, fibroblasts, and macrophages within a network of reticular fiber.
What does red bone marrow produce?
It produces red and white blood cells and platelets.
Where is yellow bone marrow located?
It is located within the medullary cavity.
How does red bone marrow produce red and white blood cells and platelets?
Via hemopoiesis
What does yellow bone marrow contain?
Mostly contains adipocytes
What does yellow bone marrow store?
triglycerides for energy reserve
T/F? With increasing age, much of the bone marrow changes from yellow to red.
FALSE. It changes from red to yellow.
What is the bone richly supplied with?
Blood vessels
How are pain messages transmitted within the bone?
Nerves follow vessels into bone tissue, where they sense damage and then transmit pain messages
How are osteocytes provided for?
Nutrient artery and vein pass through nutrient canal and send branches into the central canals of osteons to provide for osteocytes.
Which hormone is secreted from bone?
Osteocalcin, which functions to regulate blood glucose levels.
What is the major organic component of the bone matrix?
Collagen
What is the ultimate function of osteoclasts?
Bone resorption
How do osteoclasts arise?
Fusion of monocytes
What do osteoclasts secrete?
Lysosomal enzymes
How do osteoblasts arise?
Differentiation of pro-osteogenic cells
What do osteoblasts secrete?
secrete collagen and alkaline phosphatase
How do osteocytes arise?
maturation of osteoblasts
T/F? Bones are considered epithelial tissue.
FALSE; they are connective tissue
T/F? Compact bone and spongy bone are both organized into osteons.
FALSE. Spongy bone is arranged in lamellae.
