Week 1 - Intro to histology

Question 1

What is histology

Answer 1

Microscopic anatomy

Question 2

What is a prokaryote

Answer 2

A cell that has no nucleus, for example bacteria

Question 3

What is a eukaryote

Answer 3

Cells that have a nucleus and cytoplasm

Question 4

What are the 3 main things that make up a cell and what are they

Answer 4

Cytosol (intracellular fluid)
Cytoskeleton (network protein filaments which give structure)
Organelles (a sub cellular structure which carries out one or more function)

Question 5

What 3 roles of the cell membrane

Answer 5

To maintain the structure of the cell
To adhere to other membranes in order to form a barrier in skin cells for example
To maintain homeostasis

Question 6

What is a cellular projection and name 2 examples

Answer 6

A cellular protuberance (dendrites, axons, cilia

Question 7

What is the definition of a tissue

Answer 7

Groups of similar cells working together to carry out a common function

Question 8

What 2 things make up tissues

Answer 8

Cells and extracellular matrix

Question 9

What is a tissue containing the same type of cell

Answer 9

Simple tissue

Question 10

What is a tissue containing multiple types of tissue

Answer 10

Compound tissue

Question 11

What do you call a tissue that carries out a specific function in an organ

Answer 11

Parenchyma (working tissue)

Question 12

What do you call a tissue that provides scaffolding and nutrition

Answer 12

Stroma tissue

Question 13

What is an organ

Answer 13

Several tissue types which perform a specific function

Question 14

What is an organ system

Answer 14

A system of organs that work together (e.g urinary system comprises of ureters, bladder)

Question 15

Name 4 types of tissue and their function

Answer 15

Connective - supports and protects
Epithelial - lines/covers body surfaces
Nervous - generates electrical signals in response to environment
Muscle - contains cells which contract to generate a force

Question 16

Describe briefly the process of epithelial cancer

Answer 16

One of the epithelial cells despecialises due to a genetic mutation. Cancerous cell proliferates. Cancerous cell spreads from the initial site/primary site to another part of the body through metastasis

Question 17

What is metastasis

Answer 17

the spread of disease from primary site to secondary site

Question 18

What is dissemination

Answer 18

Spread of disease

Question 19

What are the 4 stages of tissue processing for histology and give a brief description of each step

Answer 19

Fixation - freezing sample (-80 degrees) or use an aldehyde such as formaldehyde
Embedding - sample is embedded in paraffin wax which provides support for sectioning
Sectioning - using a microtome to cut thin sections
Staining - specific and non-specific staining

Question 20

What is the most common stain and what does each component target

Answer 20

H+E (haematoxylin and eosin) H is basic and therefore targets acids such as DNA
E is acidic and therefore targets bases such as the cytoplasm

Question 21

What does PAS target and what does PAS stand for

Answer 21

Periodic acid/schiff targets carbohydrates and glycogen thus turning the liver since it contains lots of glycogen, mucus, basement membranes and brush borders

Question 22

What colour do lipids appear as and why

Answer 22

They appear clear in colour since the lipids were dissolved by the paraffin wax (I think)

Question 23

What can be used as an alternative to increase the resolution of histology

Answer 23

Electron microscopy

Question 24

Where are cells joined together when they are bound by membranes?

Answer 24

cell junctions

Question 25

Describe the basic structure of epithelial tissue

Answer 25

Continuous sheets of epithelial cells that are 1 or more layers thick

Question 26

List 3 main epithelial cell locations and give examples

Answer 26

External body surfaces e.g epidermis layer of skin Closed cavities Body tubes e.g respiratory tract Secretory portions of glands and ducts Sensory receptive regions of sensory organs e.g ear/nose

Question 27

Describe the density of epithelial cells

Answer 27

In close contact

Question 28

What are the binding points called between epithelial cells

Answer 28

cell to cell junctions

Question 29

What do gap junctions allow between epithelial cells

Answer 29

communication between cells

Question 30

Where are epithelial cells positioned

Answer 30

They are always attached to the basement membrane

Question 31

Why are epithelial cells bound to basement membrane

Answer 31

Since epithelial cells are polarised

Question 32

What does the basement membrane act as

Answer 32

A selective filtration barrier

Question 33

Describe the energy source of epithelial cells

Answer 33

Avascular so rely on nutrients from connective tissue below

Question 34

Which region of epithelial cell points outwards

Answer 34

The apex

Question 35

What can sometimes be found on the apex of cells

Answer 35

Cilia

Question 36

Name 5 functions of epithelial cells

Answer 36

They can act as a barrier for example skin which is susceptible to abrasion Can protect toxic molecules and microorganisms from entering the body Some epithelium can allow substances through for example diffusion of o2/co2 across the lung epithelial tissue Involved in secretion in the glands Can make special senses such as hearing/smell through combining with nervous tissue

Question 37

What are the 2 main types of epithelia and give a description

Answer 37

Covering epithelia - cover/line all body surfaces, cavities and tubes Glandular epithelia - collections of secretory epithelial cells that synthesise and secrete products.

Question 38

Which body system is glandular epithelia very common in

Answer 38

Gastroenterology

Question 39

Name and describe the two subcategories of glandular epithelia

Answer 39

Exocrine epithelia which remain continuity with surface and secrete via a duct Endocrine glands which lose contact with surface and secrete directly into bloodstream

Question 40

Give an example of an exocrine gland

Answer 40

Salivary gland

Question 41

Give an example of an endocrine gland

Answer 41

Thyroid gland

Question 42

What does simple mean and give description

Answer 42

Single layer- good for absorption but fragile

Question 43

Stratified

Answer 43

2 or more layers - good for protection

Question 44

Pseudostratified

Answer 44

One layer with a mixture of cell shapes (looks stratified but not all cells reach the surface

Question 45

Define squamous

Answer 45

Flat shaped

Question 46

Cuboidal

Answer 46

Cube shaped

Question 47

Columnar

Answer 47

tall cylindrical shape

Question 48

Transitional

Answer 48

will readily change shape

Question 49

Simple squamous epithelium

Answer 49

Flat, nuclei are squashed Used for diffusion, secretion and absorption but little barrier/protection against friction Found in lining of blood vessels

Question 50

Simple Cuboidal

Answer 50

Single layer, cube shaped, some have microvilli Good for diffusion, secretion absorption Found in surface of ovaries

Question 51

Simple Columnar

Answer 51

single layer of tall narrow cells, some have cilia Used for movement of substances, absorption and secretion. More protection Found in glands

Question 52

Stratified squamous

Answer 52

Multiple layers, cube shaped, more flat towards surface. Can be keratinised or non-keratinised (moist) Prevent water loss, protection from abrasion, infection barrier Keratinised=skin Non-keratinized = mouth, throat

Question 53

What makes non-keratinised layer soft

Answer 53

a layer of fluid on outside

Question 54

What makes keratinised stratified epithelium more rough

Answer 54

Keratinised layer with dead cells which have had their cytoplasm replaced by keratin

Question 55

Pseudostratified Epithelium

Answer 55

Single layer but looks like lots of layers since some cells reach free surface and some do not. Usually have cilia. Synthesises and secretes mucus and move foreign particles over the surface Found in the lining of the nasal cavity, sinuses etc

Question 56

Transitional Epithelium

Answer 56

Unique type of stratified epithelium that can change shape - cuboidal/columnar when not stretched/flattened when stretched. Number of layers decreases upon stretching since cells shift on top of each other Used to accommodate fluctuations in the volume of fluid in organs. Protects against caustic effects of urine Located in urinary bladder