Connective Tissue II

Question 1

Fx. of bone and cartilage?

Answer 1

1. ) Protection of critical organs
2. ) Mechanical support for locomotion
3. ) Ca and phosphate homeostasis (bone is a Ca reservoir)
4. ) To house, protect, regulate stem cell precursors of blood cells (hematopoietic system)

Question 2

Mineralized

Answer 2

Calcium and phosphate crystals

Question 3

Bone is…

Answer 3

dynamic, vascularized, constantly turned over/remodeled. Has a population of precursor cells that can divide/differentiate into new bone cells. Required to adjust blood ca and phosphate levels, to allow damage repair, to allow changes in structure in response to stimuli.

Question 4

Cartilage is…

Answer 4

less dynamic. Avascular (diffusion nec). Limited in repair ability.
Can still be converted to bone in adults.
In adulthood it’s in articular surfaces of bones and nose, ear, trachea etc.

Question 5

Cartilage main fx

Answer 5

Provide resilient/pliable support structure

Direct formation/growth of bone

Question 6

Chondrocytes

Answer 6

Make cartilage matrix and tissue. Can arise from mesenchymal cells or from external layer of connective tissue around the cartilage (perichondrium).
They secrete ECM components around themselves, become isolated into compartments called lacuna.
Proliferative chondrocytes = chondroblasts.
After growth they remove from cell cycle, but retain ability to secrete cartilage matrix at low rate

Question 7

3 types of cartilage

Answer 7

distinguished by matrix:
Hyaline
Elastic
Fibrocartilage

Question 8

Hyaline cartilage

Answer 8

contains collagen that forms thin fibrils, irregular 3D pattern. Ground susbtance is rich in proteoglycans and hyaluronic acid (hydration and flexibility). Hyaline:

• allows metabolites to readily diffuse tissue
• resiliency to compression during joint movement
• growth of chondrocytes and matrix from w/in the matrix
• During growth can calcify and attract cells that initiate bone formation

Question 9

Elastic cartilage

Answer 9

Contains thin collagen fibrils and proteoglycans too. But is distinguished by abundant elastic fibers/ interconnecting sheets (lamellae) of elastic material.
External ear, epiglottis, larynx.
Designed for elasticity, flexibility.
Doesn’t calcify.

Question 10

Fibrocartilage

Answer 10

Large bundles or regularly arranged collagen that is similar to dense regular connective tissue (continuation of it in tendons, intervertebral discs).
ECM designed to resist compression/sheer forces.