Cartilage and Bone Flashcards
How do nutrients reach cartilage?
Cartilage is avascular. Nutrients/waste materials pass to and from the cells through the matrix.
What is the function of cartilage?
Support soft tissues and guide the development and growth of long bones.
What are the three types of cartilage?
hyaline, elastic, and fibrocartilage
Where is hyaline cartilage located?
articular ends of long bones in adults, walls of respiratory system, the ventral ends of ribs, and temporarily skeleton for the fetus
What is the hyaline cartilage matrix comprised of?
homogenous, amorphous ground substance with proteoglycan aggregates and chondronectin embedded type II collagen
What is the name of the area adjacent to the chondrocytes? Describe this region’s contents.
Territorial (capsular) Matrix. Poor in collagen but rich in glycosaminoglycans.
How will the territorial matrix stain?
Basophillic and metachromatic. More intensely with PAS stain compared to interrerritorial (intracapsular) matrix.
What is the perichondrium?
A layer of dense irregular connective tissue surrounding hyaline cartilage (except at joints).
Describe the two layers of the the perichondrium.
Outer Fibrous Layer – Type I Collagen, Fibroblasts, Blood Vessels
Inner Cellular Layer – Chondrogenic cells
What provides blood flow for the avascular cartilage?
Perichondrium
What are chondrocytes? Where are they found?
Mature cartilage cells. Embedded in lacunae.
Describe the cellular stages required to form a chondrocyte.
Chondrogenic Cells –> Chondroblasts (Produce Matrix) –> Chondrocytes (Once totally surrounded by matrix)
What cells are responsible for maintaining the cartilage matrix?
Chondrocytes
What are isogenous groups?
When chondrocytes divide, they may stay in the same lacunae (forming pockets of 2-8 cells)
Where in the body can elastic cartilage be found?
External ear, eustachian tube, epiglottis, larynx
Is elastic or hyaline cartilage more prone to degrade?
Hyaline Cartilage
What is unique about the make up of elastic cartilage?
A network of elastic fibers, which provide a yellowish color
What types of cartilage has a perichondrium?
Hyaline and Elastic. Fibrocartilage does not have a perichondrium.
Describe the cellular make-up of Fibrocartilage.
Alternating rows of chondrocytes and thick type I collagen fibers. The cells may align on lines of stress.
Where in the body can fibrocartilage be found?
Intervertebral discs, articular disks, pubic symphysis, tendon and ligament insertions.
What is fibrocartilage often confused for?
Dense regular connective tissue
What types of locations is fibrocartilage most often needed?
Where support and tensile strength are needed in conjunction with hyaline cartilage.
What is the function of bone?
Protects vital organs, supports fleshy structures, provides Ca reserve.
What is bone?
A specialized connective tissue with a calcified extracellular matrix with osteocytes embedded in the matrix that makes up the adult skeleton.
What is the bone matrix comprised of?
Primarily hydroxyapatite crystals.
What can be found in the inorganic portion of bone?
Calcium, phosphate, bicarbonate, citrate, magnesium, potassium, and sodium.
What can be found in the organic portion of bone?
Type I Collagen (95%), chondroitin sulfate, and keratan sulfate
What is a primary bone?
First bone formed in fetal development and repair
What two types of secondary bones are there?
Compact bone and spongy bone
Where can compact bone be found?
With the outer circumferential lamellae, inner circumferential lamellae, and around osteons.
What connects osteons?
Volkmann’s canals
What is bone periosteum?
A layer of noncalcified connective tissue covering the bone on external surfaces (except at joints)
What is the periosteum comprised of?
An outer, fibrous dense collagenous layer and an inner, cellular layer.
What connects the periosteum and the bone?
Sharpey’s fibers (Type I Collagen)
What is the endosteum?
Thin specialized connective tissue lining marrow cavities. It is the source of osteoprogenitor cells and osteoblasts for bone growth and repair.
What are osteoprogenitor cells?
Inner layer of periosteum and endosteal cells that line marrow cavity. Flattened/Spindle Shaped. Become osteoblasts.
What are osteoblasts?
Cells that secrete collagen, ground substance, and osteoid that regulate the mineralization of bone. They are cuboidal in shape and in a single layer at locations bone is forming.
What is an osteocyte?
Cells that reside in the lacunae that maintain bone matrix through minimal acts of synthesis and resorption of matrix.
How do osteocytes communicate?
Via processes that extend through canniculi and gap junctions with other cells
Describe the staining of an osteoclast.
Multinucleated cell, acidophilic
Describe the function of osteoclasts
They actively resorb bone by releasing lysosomes into extracellular space.
What is Howship’s lacuna
A depression in bon created by an osteoclast. The cell seals off the area, acidifies, and secretes acid hydrolases to resorb bone.
What is osteoporosis?
A decrease in bone mass associated with a normal mineral to matrix ratio due to decreased bone formation, increased bone resorption, or both.
List a few possible reasons for developing osteoporosis.
Diminished growth hormone secretion, lack of physical stress on bone, diminished estrogen secretion
What is osteomalacia?
Deficient calcification of newly formed bone and decalcification of calcified bone due to calcium deficiency.
What is often a cause for osteomalacia?
Pregnancy (from the little one leeching the life force from the mother)
What is Rickets?
Osteomalacia in children due to Vitamin D deficiency or calcium deficiency. Often accompanied with deformation of bone spicules in epiphysial plates.
What is acromegaly? How does it present?
Excess pituitary hormone in adults. Characterized by very thick bones in the extremities and facial skeleton.
