Histology

Question 1

What is histology

Answer 1

Looking at tissues

Question 2

What do we use to look at cells and tissues?

Answer 2

Light microscope

Question 3

What are the steps in preparing a sample?

Answer 3

1. Tissue collection
2. Fixation (10% formation) & trimming
3. Dehydration, use a series of alcohols up to 100% concentration
4. Paraffin embedding
5. Sectioning with microtome (tend to curl up)
6. Straighten sections on water bath

Question 4

What measurements does microtome section it to?

Answer 4

3-4um

Question 5

What are the two different counter stains most commonly used and what are their colours?

Answer 5

Haematoxylin —> blue
Eosin—> pink

Question 6

What does haemolotoxin stain

Answer 6

Genetic material, so DNA and RNA

Question 7

What does eosin stain?

Answer 7

Proteins

Question 8

What is the epithelium?

Answer 8

The tissue that covers all of the internal and external surfaces of the body

Question 9

What do all epithelium sit on?

Answer 9

Basement membrane

Question 10

Does epithelium tissue contain blood vessels?

Answer 10

No

Question 11

What are apical modifications/

Answer 11

When outer surface is specialised in one way

Question 12

What is single epithelium

Answer 12

Every cell attached to basement memtsne

Question 13

How can we classify epithelium?

Answer 13

1. Morphology —> cell shape
2. Function —> glandular vs non glandular

Question 14

What are the four different types of simple epithelium

Answer 14

1. Simple squamous —> single flat layer —> round blood vessels
2. Simple cuboidal —> renal tubules
3. Simple columnar —> tend to have apical modifications —> gall bladder
4. Simple pseudostratified columnar—> nucleus at different levels so doesn’t really look like one layer —>trachea

Question 15

What are endothelium?

Answer 15

Epithelium that line the blood vessels

Question 16

What are stratified epithelium?

Answer 16

More than one cell layer

Question 17

What are the different examples of stratified epithelium?

Answer 17

1. Stratified squamous —> older more mature cells move up the layer and become flat —> oesophogus
2. Stratified cuboidal —> nipple
3. Stratified columnar —> nipple
4. Transitional epithelium —> can change shape to allow tissue to stretch —> urinary bladder

Question 18

What are some uses of simple cuboidal cells

Answer 18

Secretion/ absorption
In kidney, thyroid, ducts

Question 19

What are some uses of simple columnar epithelial cells?

Answer 19

Secretion/ absorption
Intestine, female reproductive tract

Question 20

What is the function of simple pseufodtratified epithelial cells

Answer 20

Secretion/ movement of particles along tubular organs
Trachea, bronchi etc.

Question 21

What is stratified squamous epithelium used

Answer 21

Most common
Protects underlying tissues
Covers most external body parts

Question 22

What is the difference in kerstinisation in small vs large animal?

Answer 22

Small —> in skin, outer layers. Doesn’t occur where tissues remain moist e.g. vagina, oral cavity (not internally)
Large —> in skin, oral cavity, oesphogous and non glandular part

Question 23

What is the uses of stratified cuboidal and columnar epithelia?

Answer 23

Not abundant
In areas of transition between simple and stratified epithelia
Respiratory ducts
Ducts if exocrine glands

Question 24

What can we classify epithelial glands

Answer 24

1. Method of secretion (endocrine vs exocrine)
2. Type of secretion (for exocrine0
3. Shape
4. Cell numbers

Question 25

What are endocrine glands

Answer 25

Glands that lack a duct system and no connections to external or internal surfaces Produce hormones Near blood vessels

Question 26

What are exocrine glands

Answer 26

Secrete to a lumen or free surface

Question 27

What are the two classifications of exocrine glands

Answer 27

Number of cells —> unicellular vs multicellular Shape of the secretory component —> tubular bs acinar Shape of tubular system —. Simple (one unbranched tube) or compound (branched tubules) Type of secreatory product —> serous (clear watery fluid) or mucous (more viscous fluid like goblet cells) or mixed

Question 28

What are the three different types of secretion?

Answer 28

Merocrine —> exocytosis (cell membrane remains intact) most common Holocene —> cell membrane ruptures (cell dies) Apocrine —> decapitation secretion (pinches off)

Question 29

What are the different types of apical modifications

Answer 29

Cillia-> motile (move)—> respiratory tract or oviduct Microvilki —> don’t move —> increase SA for absorption Stereocilla —> long villi —> male reproductive tract

Question 30

What are adherent junctions

Answer 30

Anchoring Cells must bind to each other and to the connective tissue Forms the mechanical stiffness of the tissue Cells together —> desmosomes Cells to the extra cellular matrix (basement membrane) —> hemidesmosomes

Question 31

What are tight junctions

Answer 31

Cells are involved in what enters the body Entrance of nutrients and compounds must be controlled Para cellular —> between the cells (controlled by epithelium) Trans cellular —> through epithelium cells

Question 32

What are gap junctions

Answer 32

Cells that must communicate with each other Aqueous channels allowing small molecules to pass through