Intro To Histology

Question 1

What are the basic parts of a eukaryotic cell?

Answer 1

• plasma membrane
• nucleus
• cytoplasm

Question 2

Briefly describe the plasma membrane of a eukaryotic cell.

Answer 2

This is a physical barrier which helps to regulate what goes in and out of the cell. It is sensitive to the intracellular and extracellular environment and also provides support to the cell. It is selectively permeable and may have specialisations such as cilia.

Question 3

Briefly describe the nucleus of a eukaryotic cell.

Answer 3

The nucleus contains the DNA of that organism.

Question 4

Briefly describe the cytoplasm of a eukaryotic cell.

Answer 4

The cytoplasm contains cytosol (intracellular fluid), a cytoskeleton and various organelles e.g. mitochondria, ribosomes and Golgi apparatus.

Question 5

Define tissue.

Answer 5

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

Question 6

What is parenchyma?

Answer 6

Parenchyma is ‘working tissue’ e.g. the heart

Question 7

What is simple tissue?

Answer 7

Tissue that is formed from one cell type.

Question 8

What is compound tissue?

Answer 8

Tissue that is formed by different cells e.g. the cortex of the kidney.

Question 9

What is a stroma?

Answer 9

A tissue that provides scaffolding and nutrition e.g. blood vessel

Question 10

Define an organ

Answer 10

An organ is made up of several tissue types comprised in a morphologically recognisable structure and performs a specific set of functions.

Question 11

What are the four types of tissue?

Answer 11

• Connective tissue e.g. blood, cartilage, bones
• Epithelial tissue e.g. epidermis
• Muscle tissue e.g. skeletal, smooth, cardiac
• Nervous tissue e.g. motor neurons

Question 12

List some health problems that are caused at a cellular/tissue level. (7)

Answer 12

• cancer
• cystic fibrosis
• malaria
• meningitis
• Alzheimer’s
• bone fracture
• burns

Question 13

Define metastasis.

Answer 13

The spread of a disease producing agency (such as cancer cells) from the initial or primary site of disease to another part of the body.

Question 14

What are the stages of tissue processing in histology?

Answer 14

1. Fixation (freezing/chemical to preserve tissue)
2. Embedding (paraffin wax most common, to provide support for tissue when sectioning)
3. Sectioning (cut using a microtome, thinner = higher resolution)
4. Staining

Question 15

Discuss the most common method of standing in histology.

Answer 15

H&E = Haemotoxylin and Eosin staining

• haemotoxylin is basic so will stain acidic structures a purplish blue e.g. nucleus
• eosin is acidic so will stain basic structures red or pink e.g. cytoplasm

Question 16

When would PAS staining be used? Give examples.

Answer 16

• Periodic acid/Schiff
• used to stain complex carbohydrates and glycogen
• a tissue stained with PAS is known as PAS+
• e.g. liver is PAS+ as it contains a lot of glycogen so stains magenta
• also stains mucus, basement membranes and brush borders of intestines
• also stains glycocalyx

Question 17

Why do lipids look empty when stained?

Answer 17

Because during fixation the signal large lipid droplet is removed

Question 18

Discuss epithelial tissue.

Answer 18

• cells are in close contact
• cells are polarised (sit on basement membrane)
• not vascularised instead nourished by connective tissue
• covers and protects surfaces, outside and inside the body
• lines internal cavities, blood vessels and respiratory, digestive, urinary and reproductive organs
• forms glandular structures
• forms barriers
• combines with nervous tissue to make special senses (smell, hearing, etc)

Question 19

Name some types of epithelial tissue.

Answer 19

• covering epithelia: cover or lines all body surfaces, cavities and tubes
• glandular epithelia: secretory epithelium arranged into glands, invaginations of epithelium, also glandular organs e.g. salivary glands

Question 20

What is the difference between an exocrine and endocrine gland?

Answer 20

Exocrine glands retain continuity with the surface and secrete via a duct whereas endocrine glands lose contact with the surface and secrete directly into the blood stream e.g. thyroid gland.

Question 21

How can epithelial tissue be classified?

Answer 21

1. By number of layers (simple, stratified, pseudostratified)
2. By shapes of cells (squamous, cuboidal, columnar, transitional)
3. By surface specialisations (e.g. cilia, keratin, etc)

Question 22

Discuss the structure and function on simple squamous epithelium and where it would be found.

Answer 22

Structure: 
	- single layer
	- flat/hexagonal cells
	- nuclei appear very flay 
Function: 
	- diffusion and filtration
	- some secretion and absorption
	- little barrier/protection against friction 
Found: 
	- lining of blood vessels and heart
	- alveoli
	- lining of serous membranes of the body cavities 
	- lining of some kidney tubules

Question 23

Describe the structure, function and location of simple cuboidal epithelium.

Answer 23

Structure: 
	- single layer
	- cube shaped cells
	- may have microvilli (e.g. in kidney tubules)
Function: 
	- diffusion, secretion and absorption 
Location: 
	- kidney tubules
	- glands and their ducts
	- lining of terminal bronchioles of the lungs
	- surfaces of the ovaries

Question 24

Describe the structure, function and location of simple columnar epithelium.

Answer 24

Structure: 
	- single layer
	- tall, narrow cells
	- some have cilia e.g. bronchioles of lungs, auditory tubes, uterine tubes and uterus
	- some have microvilli e.g. intestines
Function: 
	- movement of substances
	- absorption and secretion 
	- offer more protection than flatter cells
Location: 
	- glands and some ducts
	- bronchioles of the lungs
	- auditory tubes
	- uterus, uterine tubes
	- stomach, intestines, gallbladder, bile ducts
	- ventricles of the brain