Tissues

Question 1

What is a tissue?

Answer 1

A group of cells with the same function.

Question 2

What types of cells are there in the human body?

Answer 2

Epithelial, contractile, neural, connective and haematopoietic.

Question 3

What are the characteristic features of epithelium?

Answer 3

Cells form continuous, cohesive layers with stable cell-cell junctons.

Question 4

What does ‘simple’ mean in terms of epithelium?

Answer 4

Single cell layer

Question 5

What types of simple epithelium are there?

Answer 5

Squamous, cuboidal, columnar

Question 6

If epithelium is not considered to be simple, what could it be?

Answer 6

Stratified, pseudo-stratified

Question 7

What are the different types of cell cell junction?

Answer 7

Tight junction, adherens junction, desmosomes, gap junctions.

Question 8

What is a tight junction?

Answer 8

Form a belt around the apical lateral membrane, to seal the gaps between two cells.

Question 9

What is an adherens junction?

Answer 9

Master junction that controls all the others.

Question 10

What is a desmosome?

Answer 10

In the lateral membrane, provides membrane strength.

Question 11

What are gap junctions?

Answer 11

Form pores between cells.

Question 12

What are the two domains on epithelial cells?

Answer 12

Apical and basolateral

Question 13

What are the major epithelium functions?

Answer 13

Transport, absorptive, secretory

Question 14

What is the difference between exocrine and endocrine secretory epithelial cells?

Answer 14

Exocrine cells have secretory granules in the apical cytoplasm whilst endocrine are in the basal aspects.

Question 15

What is constructive secretion?

Answer 15

Secretory vesicles are formed

Question 16

What is stimulated secretions?

Answer 16

Exocytosis

Question 17

What does the ‘turning over of cells’ mean?

Answer 17

Cells that are lost due to cell death or by mechanical removal are replaced by proliferation of stem cells.

Question 18

What cells replace those lost from intestinal villi?

Answer 18

Cells proliferate in the intestinal crypt.

Question 19

What is a corn/wart?

Answer 19

Thickened layer of epithelium as a result of hyperproliferation.

Question 20

Why may chemotherapy cause gastro-intestinal side effects?

Answer 20

Inhibits proliferation of intestinal crypt stem cells, so enterocytes that are lost can’t be replaced.

Question 21

What is extracellular matrix?

Answer 21

Complex network of macromolecular (fibrillar and non-fibrillar) deposited by cells, that then become immobilised.

Question 22

What are collagens?

Answer 22

A family of fibrous proteins, made up of three alpha chains and can be homo/heterotrimer.

Question 23

How many types of collagens are there?

Answer 23

28

Question 24

What is the primary structure?

Answer 24

Glycine-proline/lysine-hydroxyproline/hydroxylysine

Question 25

What does hydroxylation of the amino acids cause?

Answer 25

It is a post-translation modification which contributes to interchain hydrogen bond formation.

Question 26

What is the process of collagen formation?

Answer 26

Amino acids > tropocollagen > fibrils > fibres

Question 27

What is the basement membrane?

Answer 27

Flexible thin mats of extracellular matrix underlying epithelial sheets and tubes.

Question 28

What is diabetic nephropathy?

Answer 28

Accumulation of extracellular matrix leading to highly thickened BM.

Question 29

What is Alport Syndrome?

Answer 29

Mutations in collagen IV that result in split and laminated GBM.

Question 30

What is the structure of collagen IV?

Answer 30

Network formed as molecules can associate literally between triple helical segments and head-to-head and tail-to-tail between domains.

Question 31

What is scurvy?

Answer 31

Deficiency of vitamin C resulting in underhydroxylated collagens as Prolyl hydroxylase and Lysyl hydroxylase require vitamin c as a cofactor.

Question 32

What are the different types of proteoglycans?

Answer 32

BM proteoglycans, small leucine rich proteoglycans, aggregating proteoglycans and cell surface proteoglycans.

Question 33

What is the general structure of proteoglycans?

Answer 33

Core proteins which are covalently attached to one or more glycosaminoglycan chain.

Question 34

What is the general structure of elastic fibres?

Answer 34

Core of elastin and fibrillin-rich microfibrils. | There are two types segments that