Specialized Connective Tissue

Question 1

What is cartilage ?

Answer 1

It is a form of connective tissue composed of cells called chondrocytes and highly specialized extracellular matrix.

Its avascular, 95% is extracelluar matrix.

Question 2

What are characteristics of cartilage?

Answer 2

Cells of cartilage consists of chondrocytes and chondroblasts that are round cells with a large nucleus and cytoplasms that is most glycogen.

Extracellular matrix: gelatinous amorphous ground substance .

Question 3

What is dense connective tissue (vascular) composed of cells that resemble fibroblasts surrounding cartilage.

Answer 3

Perichondrium

It serves as a source for new cartilage cells.
(chondrocytes/chondroblasts)

cartilage mesenchymal cells are from the mesodermal layer.

Question 4

What are the three different growths of cartilage?

Answer 4

Interstitial growth: new cells arise from the division of chondrocytes within their lacunae.

Appositional growth: new cells are derived form the inner portion of the surrounding perichondrium. Cells resemble fibroblasts in form and function.

Nutrition: cartilage is avascular so it is dependent upon diffusion from the perichondrium.

Question 4

What are the three different growths of cartilage?

Answer 4

Interstitial growth: new cells arise from the division of chondrocytes within their lacunae.

Appositional growth: new cells are derived form the inner portion of the surrounding perichondrium. Cells resemble fibroblasts in form and function.

Nutrition: cartilage is avascular so it is dependent upon diffusion from the perichondrium.

Question 5

What are the three types of cartilage?

Answer 5

1. Hyaline cartilage: most common type.
   Functions: precursor of bones that develop by endochondrial ossification, calcifies with age. surrounded by perichondrium.
2. Elastic cartilage:
   Elastin in cartilage matrix
   Does not calcify with age.
   found in the external ear, eustachian tube of ear.
3. Fibrocartilage: No surrounding perichondrium

Question 6

What is bone?

Answer 6

Connective tissue characterized by a mineralization of the extracellular matrix.

Mineralization forms calcium phosphate in the form of hydroxyapatite crystals.

Question 7

Cells:

Answer 7

within a cell are spaces call lacunae, each contains a osteocyte.

Osteocytes maintain the viability of the bone.

Osteoprogenitor cells: cells from the mesenchymal stem cell that give rise to osteoblasts.

Osteoblasts secrete the extracellular matrix and once surround by the matrix become an osteocyte.

Osteoclasts: are the bone resorbing cells which are on the surface of bone. very large multinucleate cells located in Howship’s lacunae which are shallow bays in bone located directly under the osteoclast

Question 7

Cells:

Answer 7

within a cell are spaces call lacunae, each contains a osteocyte.

Osteocytes maintain the viability of the bone.

Osteoprogenitor cells: cells from the mesenchymal stem cell that give rise to osteoblasts.

Osteoblasts secrete the extracellular matrix and once surround by the matrix become an osteocyte.

Osteoclasts: are the bone resorbing cells which are on the surface of bone. very large multinucleate cells located in Howship’s lacunae which are shallow bays in bone located directly under the osteoclast

Question 8

Process of endochondrial ossification

Answer 8

starts with the proliferation of the mesenchymal cells
Mesenchymal cells express type II collagen and also differentiate into chondroblasts.
Chondroblasts then produce the cartilage matrix
Cartilage matrix then calcifies to form bone.
Cartilage acts as a template (hyaline)

Question 8

Process of endochondrial ossification

Answer 8

starts with the proliferation of the mesenchymal cells
Mesenchymal cells express type II collagen and also differentiate into chondroblasts.
Chondroblasts then produce the cartilage matrix
Cartilage matrix then calcifies to form bone.
Cartilage acts as a template (hyaline)

Question 9

What are the types of adult bone?

Answer 9

compact/dentse: hard/compact layer that forms the outside of bones - cortical plate.

Spongy: spongle like meshwork consisting of trabeculae that forms the interior of bones.

Question 10

How are bones classified by shape?

Answer 10

Long bones (tibia)
Short bones (carpal bones of the hand)
Flat bones (sternum, skull cap)
Irregular bones (vertebra, ethmoid bone)

Question 11

How are bones classified by shape?

Answer 11

Long bones (tibia)
Short bones (carpal bones of the hand)
Flat bones (sternum, skull cap)
Irregular bones (vertebra, ethmoid bone)

Question 12

Connective tissue covering most bones except in areas where it articulates with another bone. (contains osteoprogenitor cells)

Answer 12

Periosteum

Question 13

Lines tissue of both the compact bone facing marrow cavity and the trabeculae of the spongy bone.

Answer 13

Endosteum

Question 14

Lines tissue of both the compact bone facing marrow cavity and the trabeculae of the spongy bone.

Answer 14

Endosteum

Question 15

What are the two different kinds of bone marrow ?

Answer 15

Red Marrow: stir of blood formation, consists of blood in different stages of development.

Yellow Marrow: with age the blood forming cell are replaced with fat cells giving its yellow color. Can revery back to blood forming function if and when need arises.

Question 16

What is the canal system?

Answer 16

There is intricate canal system that handles nutrients , blood , and nerves.

Periosteum —> Volkmann’s canals –> canaliculi–> Haversian canals–> Endosteum.

Question 17

Hormonal Regulation of Blood Calcium levels:

Answer 17

hormones secreted by the parathyroid gland.

Question 18

Parathyroid Hormone:

Answer 18

acts on bone to raise low blood calcium levels to normal.

Question 19

Calcitonin:

Answer 19

acts to lower blood calcium levels by inhibiting bone resporptin.

Question 20

Pituitary growth hormone

Answer 20

stimulates the growth of the epiphyseal cartilage and bone. Acts on osteoprogenitor cells stimulating them to divide and differentiate.

Question 21

Osteoporosis

Answer 21

Caused by an imbalance between osteoclasts (bone resorbing) and Osteoblast (bone forming) resulting in decrease in bone mass/density.

Question 22

Therapy for Osteoporosis

Answer 22

Estrogens: increases the risk of cardiovascular disease and breast cancer.

Biphosphonates: inhibits osteoclastic activity and induces osteoclast apoptosis resulting in an imbalance in the bone remodeling process. associated with osteonecrosis of the jaw.

Question 22

Therapy for Osteoporosis

Answer 22

Estrogens: increases the risk of cardiovascular disease and breast cancer.

Biphosphonates: inhibits osteoclastic activity and induces osteoclast apoptosis resulting in an imbalance in the bone remodeling process. associated with osteonecrosis of the jaw.

Question 23

What are similarities between bone and cartilage?

Answer 23

cells occupy lacunae
intercellular substance
both can calcify
connective tissue covering

Question 24

What are some differences between bone and cartilage?

Answer 24

bone is highly vascular
more collagen to mucopolysaccharides in bone
ossification differences.
different functions