Lecture 14 - Cartilage and Bones Flashcards
What are the three types of cartilage and what fibres do they contain?
Hyaline - Collagen II Elastic - Elastin Fibrocartilage (fibrous) - Collagen I mostly and II minimally
What do all cartilage matrices contain?
Proteoglycan in matrix Hyaluronic acid in matrix Chondrocyte cells
What are isogenous groups of Chondrocytes?
“Same origin” Small clusters of chondrocytes as a result of very rare mitotic division of them
What is a lacunae?
“Lake” or empty space between chondrocytes which is full of matrix
What is the epiphyseal plate? How does it form?
During long bone development, hyaline cartilage remains at articulating surfaces of bones. These areas are designed to continuously grow until around 24 years old.
What do chondrocytes do?
Lay down extracellular matrix of cartilage
What is the purpose of the extracellular matrix?
Allows diffusion of materials in/out of the cartilage
What does Hyaluronic Acid do to matrix? Describe matrix.
Matrix is solid and firm, but pliable Hyaluronic Acid assists resilience of matrix from repeated application of pressure
What is the purpose of the proteoglycan structure?
Part of ground substance, makes stiff like gel substance in cartilage.
Compare no. of hyaluronate-proteoglycan aggregates per collagen fibre in cartilage vs CT.
100 in cartilage vs 10 in CT
Where is Hyaline Cartilage found in the body?
Nasal Larynx, Trachea, Bronchi etc. Costal cartilage (ribcage) Intervertebral Disc Articular cartilage of knees (meniscus) Articular cartilage of shoulder, elbows, wrists etc.
Describe appositional growth.
Growth of chondrocytes occurs from outside edge of cartilage, the perichondrium. Perichondrium contains elongated fibroblast-like cells that develop into chondroblasts then chondrocytes. Increases width of cartilage.
Describe interstitial growth.
Growth of chondrocytes occurs within the cartilage lacunae. Increases length and density of cartilage.
How does the fact that the matrix is highly hydrated benefit the Hyaline cartilage?
Water is non-compressible so permits resilience to increase load of pressure.
Describe Trachea cartilage.
C-shaped rings of Hyaline Cartilage that keep trachea open.
Where is elastin found in the body? (Hint: only 3 places)
Pinna of the ear (and external part of Acoustic Meatus) Eustachian Tube (tube of inner ear to oral cavity) Epiglottis
In the Pinna what type of cartilage growth occurs?
Interstitial growth.
What distinction does fibrocartilage have to other cartilage?
Fibrocartilage has fibroblasts
Describe structure of Fibrocartilage.
Combo of dense regular CT and hyaline cartilage Cells distributed in rows No surrounding perichondrium
Where is fibrocartilage found in the body? (Hint: There are 3 places).
Cartilage in intervertebral disc (Sternoclavicular and Temporomandibular)
Meniscus (knee padding)
Pubic Symphasis (joins two pelvic parts)
Function of Fibrocartilage?
Resilience to act as shock absorber and resist shearing forces
What process allows long bones to develop? What do they form from?
Endochondral Ossification
From Hyaline Cartilage Model, Hyaline is precursor for most bones
What are growth plates(epiphyseal plates) on bones? What are they made of?
Parts of bones on ends which are made of hyaline cartilage and continuously grow until 24.
Describe the process of endochondral ossification.
State as much as you know about Osteoprogenitors.
Undifferentiated cells
Exist in inner layer (endosteum) and outer layer (periosteum)
Immature versions of Osteoblasts (need GF)
State as much as you know about Osteoblasts.
Sit on inner layer (endosteum) of spicules
Intermediate cells and cannot divide
Lay down and form new bone
Produce collagen and proteins (Osteocalcin and Osteopontin that make Osteoid)
Mature into Osteocytes
State as much as you know about Osteocytes.
Fully differentiated in bone cell
Trapped in Osteon and occupy Lucanae
No longer lay down matrix - Now maintain tissue
Branch out via extensions that signal w/ other cells to allow movement of substances between them
State as much as you know about Osteoclasts
HUGE cells (50 nuclei)
Formed from WBCs
On surface of bones, responsible for bone resorption and breaking
Work hand in hand with Osteoblasts to make bone strength
When resorpting, lies in resultant depression in bone which proves its function
Describe this diagram
What is Osteoarthritis?
Age related degeneration
Failure of articular cartilage
Leads to bone friction and permits smooth articulation
What is Rheumatoid Arthritis
Autoimmune disease
Inflammation of Synovial Membrane + Thickening of joint capsule
Leads to damage to underlying bone and cartilage
Both disintegrate
