Integrated Histology Tissue

Question 1

What are the 4 general characteristics of Epithelium tissue?

Answer 1

-Polar Orientation
-Lateral surfaces that are connected to neighbouring cells by anchoring junctions
-Avascular
-Innervated

Question 2

What is meant by apical surface (apex)?

Answer 2

The surface that faces the lumen or body cavity

Question 3

What is a basal surface or basement membrane?

Answer 3

The side of the cell that anchors the epithelium onto the body by attching istelf to underlying tissue

Question 4

Briefly explain what desmosomes are.

Answer 4

The are a form of anchoring junction binding the epithelia cells together

Question 5

Briefly explain what hemidesmosomes are.

Answer 5

They are a form of anchoring junction binding the epithelia to the basement membrane

Question 6

What are the functions of anchoring junctions?

Answer 6

Assure tissue cohesion (strength)

Question 7

What are tight (occluding) junctions?

Answer 7

Two pathways:
-Paracellular (between adjacent plasma membranes)
-Transcellular pathway (through the cell)

Question 8

What is the function of a tight junction?

Answer 8

Control the entrance of specific compounds (nutrients/oral therapeutics) that have come from the intestinal lumen & must diffuse towards the blood vessels

-Limit paracellular movement of water & other molecules

Question 9

What are Gap junctions?

Answer 9

Aqueous channels allowing small molecules (Molecular Weight ≤ 1000Da) to pass between adjacent cells.

They also allow for electrical impulses to directly pass through

Question 10

What is the main function of gap junctions?

Answer 10

Allow for communication between the cells

Question 11

What are the 3 main atypical modifications of epithelia?

Answer 11

Cilia
Microvilli
Stereocilia

Question 12

What is the function of cilia?

Where is cilia located?

Answer 12

They a motile, long cell processes that move substances along

They are commonly found in the respiratory tract, oviduct & uterus)

Question 13

What is the function of microvilli?

Where is it located?

Answer 13

Non motile, tiny projections whihc are specialised for absorption by increasing SA

Found in kidneys & intestines

Question 14

Wat is the function of stereocilia

Where is it found?

Answer 14

Non motile, long villi whihc increase SA for absorption

Found within both parts of the male reproductive tract

Question 15

What are the two things we classify epithelia by?

Answer 15

Morphology (cell shape & arrangement)

Function (glandular or non glandular)

Question 16

What is simple epithelium?

Answer 16

Single layer of cells all attached to the basement membrane

Question 17

What is stratified epithelium?

Answer 17

Multiple layers of cells

Question 18

Relate the properties of simple squamous cell to its function

Answer 18

Flat thin cells so they are ideal for passive transport

-Found lining blood vessels and in Alveoli

Question 19

Relate the properties of simple columnar & simple cuboidal cell to their functions

Answer 19

Square like cells (columnar go slightly deeper than cuboidal). They are markedly polarised and often have atypical modifications making them ideal for absorption and secretion

-Simple Cuboidal: Thyroid, Kidney, Lung, Ovary, Ducts & Secretory portions of many glands

-Simple Columnar: Intestine, Female reproductive tract, Many Exocrine glands

Question 20

Relate the properties of simple pseudostratified columnar cells to their functions

Answer 20

Nuclei are not orientated in one level, giving the impression of multilayers. These are ideal for the secretion & movement of particles along tubular organs

-Found in trachea, bronchi, male reproductive tract

Question 21

Relate the properties of stratified squamous cells to their functions

Answer 21

Start off on the basement membrane edge then as they mature and move up become flatter. Forms a stratified squamous epithelium on the surface that protects underlying tissues and prevents their desiccation

It can be keratinised or no keratinised

Question 22

Relate the properties of stratified cuboidal & columnar cells to their functions

Answer 22

Not abundant & tend to cover transitional areas between simple and stratified epithelium

-Respiratory Tract, Ducts of Exocrine glands (bilayers)

Question 23

Relate the properties of transitional epithelium cells to their functions

Answer 23

As the bladder distends and fills with urine these cells flatten out going from the appearance of thick stratified columnar to thin stratified squamous
Some of the surface cells are binucleated
Allow for great change in volume for an
Organ whilst retaining watertight

Found in Renal Pelvis, Ureter, Urinary Bladder, Urethra

Question 24

What of the 5 classifications of epithelial glands?

Answer 24

Method of Secretion
Type of Secretion
Type of Secretion Product
Shape
Cell Numbers

Question 25

What are endocrine glands?

Answer 25

Glands that lack a duct system and have no connections to external or internal surfaces

-Produce hormones
-Near blood vessels

Question 26

What are exocrine glands?

Answer 26

Glands that posses ducts and secrete product to a lumen or free surface

Question 27

What do Exocrine glands secrete?

Answer 27

-Merocrine: exocytosis, cell membrane intact (most glands are merocrine; e.g. pancreas)

-Holocrine: cell membrane rupture: detachment and cell death (e.g. sebaceous glands)

-Apocrine: “decapitation” secretion (e.g. mammary glands, sweat glands)

Question 28

What types of secretion product to exocrine glands produce?

Answer 28

-Serous: Clear, watery fluid (e.g. exocrine pancreas)

-Mucous: more viscous fluid (e.g. goblet cells, sebaceous glands)

-Mixed: mixture of serous and mucous (e.g. some salivary glands)

Question 29

Describe the shapes of Endocrine glands

Answer 29

High diversity in morphology

-Simple tubular
-Simple acinar
-Compound acinar

Question 30

Describe the shapes of exocrine glands

Answer 30

-Of the secretory component: Tubular or acinar

-Of the tubular system: Simple (one unbranched tube) or compound (branched tubules)

Question 31

Outline the 8 stages of preparing a histological slide

Answer 31

Tissue Collection

Fixation
-10% Formalin- prevents rotting
-Trimming- Rids of any unwanted parts

Dehydration
-Series of alcohol with increasing concentration up to 100%
-Usually be handled by a Pathologists team

Paraffin Embedding
-Rigidify the specimen

Sectioning
-Use a microtome to section (3-4µm)

Straightening
-Begin to curl due to the sectioning, use a water bath to straighten them

Transferring to a slide
-Stain to view
-Coverslip to protect

Staining & Cover slipping

Question 32

What are the two stains generally used on a histological slide?

Answer 32

Haematoxylin & Eosin

Question 33

What does Haematoxylin stain?

Answer 33

Stains mainly genetic material (DNA/RN)

Blue

Question 34

What does Eosin stain?

Answer 34

Stains mainly proteins (mostly in the cytoplasm)

Pink

Question 35

Outline 5 benefits of staining

Answer 35

View the architecture of the tissue by looking at the cellular level
-locations & position of the cell
-cell size
-Contours & shapes of cells
-staining intensity of cells and their nuclei