Histology - Brodski Flashcards
What are the three types of cartilage in the body?
Hyaline cartilage: most abundant in the body, type II collagen
- Found in articular ends of long bones (joints), larynx, trachea, bronchi
- Composed of isogenous groups: Represent cell divisions from an original chondrocyte
- Surrounds bone in joints
Elastic cartilage: type II collagen and elastic fibers
-Found in ear, epiglottis and nose
Fibrocartilage: withstands tensile forces, type I collagen
- No perichondrium (nor in articular hyaline)
- Found in intervertebral disks, articular discs, pubic symphysis, insertion of some tendons
What are the two types of histogenesis and growth of cartilage?
What is the difference between them?
- Interstitial Growth
Mesenchymal cells retract their processes, round up and differentiate into chondroblasts which secrete matrix around them.
Chondroblast become entrapped in their own matrix and form a compartment called lacunae.
Lengthens the bone
Only present in development - Appositional Growth
Mesenchymal cells at the periphery of the developing cartilage differentiate to fibroblasts forming the perichondrium.
Inner cell layer of perichondrium harbors chondroblasts producing matrix
Present throughout life to grow and repair cartilage in the remainder of the body (outside of bone)
What are the components of intervertebral discs?
How does it change during the day?
Nucleus Pulposus (Resists forces of compression): cells derived from notochord are scattered in extracellular matrix which consists of ground substance only
Anulus Fibrosus (Resists tensile forces): Concentric layers of fibrocartilage (lamellae) are layered throughout the anulus
Make up a buffering cushion
The largest avascular structure in the human body
Diurnal Change:
- During the day discs get compressed and dehydrated because of the gravity and physical activity (shrink down some 20%)
- During night discs get decompressed, swell with water plus nutrients and expand back to their fully hydrated state.
What are the components of periosteum?
What is their importance?
Covers external surfaces except at synovial articulations
Outer layer of dense fibrous connective tissue
Inner cellular layer of osteoprogenitor (osteogenic) cells
Important for growth and repair
Sharpey’s fibers are collagen fibers binding the periosteum to the bone
What are the two typse of bone formation/histogenesis?
Where do they occur?
What is the difference?
Intramembranous Bone Formation:
Occurs within mesenchymal tissue
Mode of development for most of flat bones
Present in the pelvis, scapula, skull
Mesenchymal cells differentiate into osteoblasts that secrete bone matrix, forming a network of trabeculae
Endochondral Bone Formation:
requires the presence of a cartilage template
Mode of development for most of the long and short bones
Primary Center of Ossification (Diaphysis)
Hyaline cartilage model of bone is developed
Diaphysis of cartilage becomes vascularized, chondrogenic cells become osteoprogenitor cells forming osteoblasts
Osteoblasts secrete bone matrix, forming the subperiosteal bone collar
The bone matrix becomes calcified to form a calcified cartilage/calcified bone complex.
Secondary Centers of Ossification (Epiphysis)
Begin to form at the epiphysis at each end of the forming bone
Similar to that in the diaphysis, except that a bone collar is not formed.
Osteoprogenitor cells invade the cartilage of the epiphysis, differentiate into osteoblasts and begin secreting matrix
The articular surface of the bone remains cartilaginous throughout life.
After birth, growth in the length of long bones occurs through the secondary ossification center
The continued lengthening of bone depends on the epiphyseal plate
What are the types of movement between bones of a joint?
Synarthroses:
closely bound together with only a minimum of movement between them
Three types of synarthroses (more to less rigid):
1. Synostosis: There is little if any movement, no joint uniting tissue (e.g. skull bones)
2. Synchondrosis: Little movement and joint uniting tissue is hyaline cartilage (e.g. joint of first rib and sternum)
3. Syndesmosis: Joints are connected by dense connective tissue (e.g. pupic symphysis)
Diarthroses:
Bones are free to articulate over a fairly wide range of motion
Most of the joints of the extremities
Bone making up these joints are covered by persistent hyaline cartilage
What are the components of the joint capsule? What are they made of?
- Outer fibrous layer:
Dense connective tissue, which is continuous with the periosteum - Inner cellular synovial layer/membrane (site of rheumatological pathophysiology):
A. Type A cells: Macrophages, remove debris from joint space
B. Type B cells: Resemble fibroblasts, secrete synovial fluid (supplying nutritiens and oxygen to chondrocytes and serves as lubricant for joint)
How does rheumatoid arthritis differentiate from osteoarthritis on a cellular level?
RA:
Increase in number of synovial lining cells.
Infiltration with mononuclear cells.
Acute inflammatory process in the synovial fluid
Cartilage and bone destruction
OA:
Mechanical issue. Cartilage (smooth surface) wears away, debris enters the joint, osteophytes appear at the edges of joints, bone can become exposed
What are the components of the Havaersian canal and the surroundings?
Haversian canal contains a vein and artery
Osteocytes located in surrounding lacunae connected by canaliculi
Osteoblasts for bone synthesis in cavities and osteoclasts for degradation in the periphery
