Chapter 2a - Extracellular Matrix

Question 1

What is the Extracellular Matrix?

Answer 1

A connective tissue synthesized and secreted by cells that live within the tissue

Question 2

What are the differences in composition of epithelial and connective tissues?

Answer 2

Epithelial tissue is mostly cellular, with a small amount of ECM.

Connective tissue is mostly ECM with fewer cells.

Question 3

What is the ECM of epithelial tissue called?

Answer 3

basement membrane or basal lamina.

Question 4

What lies below the epithelial cells?

Answer 4

The lamina propria, a thin layer of loose connective tissue.

Question 5

What constitutes the mucosa?

Answer 5

Epithelium + lamina propria

Question 6

What is submucosa?

Answer 6

A layer of tissue beneath a mucous membrane.

Question 7

What are the categories of extracelular macromolecules?

Answer 7

Glycosaminoglycans (GAGs) & Proteoglycans (these are mostly carbohydrate in structure)

Fibrous proteins (e.g elastin & collagen)

Adhesive proteins (e.g fibronectin and laminin).

Question 8

What are proteoglycans?

Answer 8

Aggregates of proteins and GAG’s (glycosaminoglycans)

Question 9

What are GAGs?

Answer 9

glycosaminoglycans (also known as mucopolysaccharides) are repeating disaccharide chains where 1 sugar is N-acetylated, and the other is acidic sugar. M

Question 10

Give some properties of GAGs

Answer 10

Long unbranched chains

Contain multiple negative charges

Question 11

What is the most common GAG?

Answer 11

Chondroitin Sulfate.

Question 12

What are some properties of proteoglycans?

Answer 12

Due to net negative charge, GAG’s repel, and in solution they slide past each other. Negative charge also causes water to flood into matrix creating turgid pressure - which is balanced by tension from collagen.

Question 13

Name some properties of the cartilage matrix.

Answer 13

Large amount of GAG’s and rich in collagen. It is tough resilient and resistant to compression.

Question 14

How does cartilage matrix function?

Answer 14

When there is compression, water is forced out and GAG’s occupy a smaller volume. When released, water floods back in rehydrating the GAGs like a sponge.

Question 15

What is the change in hydration seen in the ECM called?

Answer 15

Resilience - which is seen in cartilage as well as synovial fluid and vitreous humor of the eye.

Question 16

What is the structure of proteoglycans?

Answer 16

GAG’s are covalently attached to protein and form proteoglycan monomers (exception being hyaluronic acid). Monomer has a core protein with GAGs extending outward and spaced out due to repulsion.

Question 17

What is the shape of a cartilage proteoglycan?

Answer 17

“Bottle brush” or “fir tree” with the GAG chains being the needles and the core protein the branch, and the trunk being hyaluronic acid. It occurs through ionic interactions and stabilized by link proteins.

Question 18

What is used as therapy for osteoarthritis?

Answer 18

Glucosamine

Question 19

What is the most abundant protein in the human body?

Answer 19

25% of all protein is Collagen, found in bone tendons and skin. Over 90% of human collagen is of type I , II, III AND IV out of 28.