Chapter 6 - Bone Tissue Flashcards
Osteology
Study of Bone
Arthrology
Study of joints
Kinesiology
Study of musculoskeletal movement
Difference in ligaments and tendons?
Ligaments - bone to bone
Tendons - boen to muscle
How does the skeletal system help with support?
Limbs and vertebral column support other organs/things
Ex: mandible and maxilla support teeth
How does the skeletal system help with protection?
Protects brain, spinal cord, lungs, heart, pelvic viscera, and all that good stuff
How does the skeletal system help with movement?
Helps with attachment/leverage, ventilation
How does the skeletal system help with blood formation?
Forms RBCs and immune cells
How does the skeletal system help with storage?
Reservoir for calcium and phosphorous (released PRN)
Bone marrow - reserve of stored fuel/fat
Electrolyte, acid/base balances
What are long bones and what are the 2 major structures within them?
Most limb bones (help with leverage and movement)
Diaphysis (shaft)
Epiphysis (head)
Where is the medullary cavity found and what is found inside it?
Found in diaphysis, made up of yellow bone marrow (red marrow in kids)
What is the outer sheath of bone called? Inner lining?
Periosteum (collagen)
Endosteum (reticular CT)
What are flat bones and where are they found?
Protective plates, found around the sternum, heart, and the cranial bones
What makes up flat bones?
Two layers of compact bone (periosteum) surrounding a middle layer of spongy bone (endosteum)
What are the 4 types of bone cells?
- Osteogenic cells
- Osteoblasts
- Osteocytes
- Osteoclasts
What is the function of osteogenic (osteochondral progenitor) cells?
Develop from mesenchymal cells
Form the endosteum
Stem cells that form osteoblasts
What are the functions of osteoblasts?
To build bone
Single layer on bone surface (endosteum or periosteum)
Produce collagen and proteoglycans
What is ossification?
Formation of bone by osteoblasts
What are the functions of osteocytes?
Mature bone cells (former osteoblasts)
Trapped in lucunae (connected by canaliculi)
Maintain the matrix
What are the functions of osteoclasts?
Bone crushers (bone dissolving cells)
Develop from bone marrow stem cells (monocytes)
LARGE cells with MANY nuclei
Where is the bone matrix found?
Surrounds osteocytes and lacunae
Describe compact bone and the cells/structures found inside it
Opaque
Arranged in microscopic cylinders (osteons)
- surround central canals (blood vessels, nerves)
- run longitudinally through shaft
Lamellae
- concentric layers of deposited bone matrix (tree rings/onion slice)
Osteocytes
- occupy cavities (lacunae) between lamellae
What is the difference in circumferential lamellae and insterstitial lamellae? What type of bone is it found in?
Circumferential lamellae - outer surface of compact bone
Interstitial lamellae - fill irregular regions between osteons (remnants of remolded lamellae)
What makes up spongy bone?
trabecular (thin plates) and spicules (rods/spines)
What does compact bone have that spongy bone lacks?
Osteons/central canals
What is the purpose of spongy bone?
Provides strength while adding minimum weight (oriented along stress lines)
What are the two main types of bone marrow?
Red marrow (Myeloid tissue) Yellow marrow
What is the purpose of red marrow and where is it found/ who is it found in?
Hemopoietic tissue (produces blood cells)
Found in almost every bone of the child
Found in the skull, vertebrae, ribs, sternum, part of pelvic girdle, and proximal head of humerus and femur
What is the purpose of yellow marrow and where is it found/who is it found in?
Fatty marrow, does not produce blood
Found in adults
What are the 3 types of cartilage?
- hyaline cartilage (lines synovial joints)
- elastic cartilage (ears, nose, etc)
- hyaline and elastic cartilage are surrounded by perichondrium (fibrous dense irregular CT) - fibrocartilage (discs in your back)
What are the general functions of cartilage?
Support, frameworks and attachments
Protection
Structural models for developing bones
What types of cells make up cartilage?
Chondroblasts - cartilage builders (secrete matrix)
Chondrocytes - mature chondroblasts (trapped in lacunae)
How does nutrition and waste get to cartilage?
Must diffuse through matrix - no blood vessels
What is the mesenchyme?
Embryonic CT
Scaffolding for bone, muscle, blood and others (starting point)
What are the two ways to form bone?
- Intramembraneous
2. Endochondral
What types of bones are formed via intramembraneous ossification?
Flat bones (skull, clavicle, mandible)
What is the purpose of intramembraneous ossification in already grown bones?
Thickening, strengthening, and remodeling
What are the soft spots on the head called?
Fontanels
What is the center of ossification?
Where expansion via intramembranous ossification occurs
What types of bone are formed in endochondral ossification?
Most bones other than flat bones (vertebra, ribs, pelvic bones, limbs, parts of skull
In which type of bone formation does bone develop from a preexisting model?
Endochondral ossifcation
During the first step of endochondral ossification, mesenchyme is turned into hyaline cartilage. What covers this cartilage? What types of cells are involved?
Covered by perichondrium
Chondroblasts –> Condrocytes
During the second step of endochondral ossification, a primary ossification center is starting to form. What is the job of chondrocytes?
They inflate (hypertrophy) and absorb the matrix. Then they release matrix vesicles which initiate formation of hydroxyapatite crystals (calcified cartilage) and then they die. This forms calcified walls/big lacunae
During the second step of endochondral ossification, a primary ossification center is starting to form. At the same time, bony collar formation begins. Describe what is happening with this.
Blood vessels reach the perichondrium. Osteoblasts are formed to start producing bone (and the periosteum). Osteoblasts deposit a layer of bone around the middle of calcified cartilage, forming a “bony collar”
During the third step of endochondral ossification, a primary ossification center is forming. What do the blood vessels do? What is the job of chondrocytes? What is formed in the diaphysis?
Blood vessels invade and deliver to the osteoblasts and osteoclasts.
The osteoclasts do work, hollow out the primary marrow cavity and the blood vessels follow.
Osteoblasts line the cavity with bone.
Chondrocytes hypertrophy and die in both directions
A medullary cavity is formed int he diaphysis
During the fourth step of endochondral ossification, a secondary ossification center is formed. How and where does this occur? What type of bone fills the epiphysis?
It’s formed int he epiphysis (ends of bones)
Development occurs at the end of bones. No medullary cavity is present. The metaphysic is a transitional size between the diaphysis and epiphysis
The epiphysis is filled with spongy bone
During the fifth step of endochondral ossification, the cavities are separated by the epiphyseal plate. What are the two cavities and how/why are they separated?
The epiphysis and the diaphysis are the cavities.
They are separated by a middle layer of hyaline cartilage that acts as a growth zone. The cartilage is transformed into bone. This zone is active throughout childhood and adolescence
During the sixth and last step of endochondral ossification, adults attain their maximum height and stop growing. What is happening internally?
The reserve cartilage in the epiphyseal plate is depleted
Where do bones elongate at and how?
The epiphyseal plate.
Cartilage is turned to bone.
Hyaline cartilage is in the middle with transition zones on each size.
What is interstitial growth?
Growth from within. Cartilage grown within the epiphyseal plate
What are the 5 zones that exists during bone elongation?
(zone one is nearer to the end of the bone, zone five nearer the center)
- Zone of reserve cartilage (hyaline cartilage)
- Zone of cell proliferation (chondrocytes multiply)
- Zone of cell hypertrophy (mitosis stops, chondrocytes enlarge)
- Zone of calcification (cartilage matrix calcifies
- Zone of Bone Deposition (via osteoblasts)
Does bone prefer to grow inwards or outwards?
Outwards
What is Wolff’s Law of Bone?
Architecture of bone is determined by mechanical stressed placed on it
What cells are involved in bone remodeling?
Osteoblasts - deposit new osseous tissue (heavy use/stress)
Osteoclasts - remove bone (unnecessary mass)
