Lecture 1 - Histology

Question 1

why do we need to study histology?

Answer 1

we can correlate pathological changes in function to changes in tissue and its components

Question 2

Histology is relevant at what levels?

Answer 2

mostly tissue and cellular and partially molecular, from around 1mm to 1um

Question 3

connective tissue =?

Answer 3

cells + extracellular matrix

Question 4

Extracellular matrix =?

Answer 4

ground substance + fibres

Question 5

describe briefly the extracellular matrix

Answer 5

it is a 3d network consisting of molecules and minerals that provide biochemical support to surrounding tissues

Question 6

what are the major cells of connective tissue?

Answer 6

fibrocytes (CT proper)
chondrocytes (cartilage)
osteocytes (bone)

Question 7

are fibers a part of the ground substance?

Answer 7

no, fibers are a separate component of the ECM

Question 8

what is ground substance primarily composed of?

Answer 8

water and large organic molecules (glycosaminoglycans, glycoproteins and proteoglycans)

Question 9

what are GAGs?

Answer 9

polysaccharideds that trap water, giving the ground substance its gel-like texture.

Question 10

what is the role of proteoglycans and glycoproteins?

Answer 10

provide structure to the ground substance and attaches components of the GS to each other and cells.

Question 11

what type of sugar attachement does a glycoprotein have?

Answer 11

oligosaccharide

Question 12

what type of sugar attachment does a proteoglycan have?

Answer 12

polysaccharide

Question 13

what is chondroitin sulfate?

Answer 13

a type of GAG, which is the polysaccharide attachment of a proteoglycan

Question 14

what is the main difference in non fibrous components of areolar tissue vs dense regular tissue

Answer 14

there are far less non fibrous components in dense regular tissue than areolar tissue.
(e.g. less ground substance and PGs and GPs)

Question 15

the amount of ground substance in a type of connective tissue directly relates to its….?

Answer 15

function

Question 16

what are the three types of fibers of the ECM?

Answer 16

collagen, reticular and elastic

Question 17

describe the features of collagen fibers

Answer 17

• long and unbranched
• stretches a little but not much (~20%)
• provides strength
• a bit flexible

Question 18

describe the features of reticular fibers

Answer 18

• contains collagen type III but are thinner and branched
• strong but flexible
• allows movement of cells while maintaining structure e.g. spleen

Question 19

describe the features of elastic fibres

Answer 19

• branched
• allows tissue to stretch (200%)
• elastin
• allows for movement

Question 20

list the main functions of areolar tissue

Answer 20

• holds organs in place and provides cushioning
• attaches epithelia to underlying tissue
• allows cell movement (e.g phagocytic cells which provide defense against pathogens)

Question 21

why would areolar connective tissue require cell movement of phagocytic cells?

Answer 21

exposure to environment: such as pathogens and injury

Question 22

what is the function of adipose connective tissue?

Answer 22

• provides cushioning
• insulation
• stores energy
• heat production?

Question 22

where is there areolar (loose) connective tissue?

Answer 22

in the dermis of the skin and the lamina propria of the small intestine

Question 23

is there a higher % of GS or fibres in areolar connective tissue?

Answer 23

more GS and therefore more proteoglycans

Question 24

in adipose tissue, how does the % of cells relate to GS?

Answer 24

hardly any ground substance present due to large lipid filled cells. - this related directly to its functions

Question 25

what other type of connective tissue is found in adipose tissue in trace amounts?

Answer 25

reticular connective tissue

Question 26

what are the main functions of reticular connective tissue?

Answer 26

- fibres form a supporting skeleton for organs - allows movement of cells and fluids

Question 27

where is adipose connective tissue commonly found?

Answer 27

in the skin and intestine

Question 28

is there a higher % of GS or fibres in reticular connective tissue?

Answer 28

more GS than fibres, but the fibres create a network for cell movement

Question 29

where is reticular connective tissue commonly found?

Answer 29

in the liver. the reticular tissue provides structure but also allows movement which cannot be provided by areolar or dense connective tissues

Question 30

what are the functions of dense regular connective tissue?

Answer 30

- provides firm attachment - strength in one direction - stabilize position of bones

Question 31

is there a higher % of GS or fibres in dense regular connective tissue?

Answer 31

more collagen fibres (usually type I)and hardly any ground substance and therefore very little proteoglycans

Question 32

what are the functions of dense irregular connective tissue

Answer 32

- provides strength - resistant to forces from different directions

Question 33

where is dense irregular connective tissue commonly found?

Answer 33

skin and intestines, as these locations move and require force resistance from different directions

Question 34

what is the supporting connective tissue classes?

Answer 34

- hyaline - elastic - and fibrocartilage

Question 35

what are the functions of hyaline cartilage?

Answer 35

- reduces friction - allows for compression - provides flexible support

Question 36

is there a higher % of GS or fibres in hyaline cartilage

Answer 36

more ground substance and therefore proteoglycans

Question 37

what produces cartilage?

Answer 37

condrocytes in lacunae in the ECM

Question 38

where is hyaline cartilage commonly found?

Answer 38

Joints - flexible support which allows for compression and reduces friction

Question 39

describe the main functions of elastic cartilage

Answer 39

- provides support and flexibility - allows tissue to distort but return to its original shape

Question 40

where is elastics cartilage commonly found?

Answer 40

in the ear

Question 41

what are the main functions of fibrocartilage

Answer 41

- resists compression - provides cushioning

Question 42

where is fibrocartilage commonly found?

Answer 42

intervertebral disks

Question 43

why is the fibrocartilage at the intervertebral disks but not at the knee joints?

Answer 43

the main role of hyaline cartilage at joints is to reduce friction. the fibrocartilage is rougher and would not be as adequate for this reason.