Epithelia

Question 1

What is the difference between ‘simple’ epithelia and ‘stratified/compound’ epithelia?

Answer 1

Simple epithelia are one cell layer thick, while stratified/compound epithelia are more than one cell layer thick

Question 2

What is the basement membrane?

Answer 2

The thin, flexible layer that separates the epithelium from surrounding connective tissue

Question 3

What type of epithelia line vascular structures (blood vessels, lymph vessels)? What is this referred as?

Answer 3

Simple squamous epithelia line vascular structures - it is known as the endothelium

Question 4

What are the crypts of Lieberkuhn? What type of epithelia line theses structures?

Answer 4

The crypts of Lieberkuhn are structures in the large intestine that absord water and remaining electrolytes - simple cuboidal epithelia line these structures

Question 5

Where in the body are simple pseudostratified epithelia most commonly found?

Answer 5

In the upper airways of the respiratory tract

Question 6

List 2 places in the body where you might find non-keratinised stratified squamous epithelia.

Answer 6

The lining of the vagina

The oesophagus

Question 7

List 2 functions of non-keratinised stratified squamous cells.

Answer 7

Protection from abrasion

Protection against water loss (yet still remain moist)

Question 8

What is the epidermis? What is its outermost layer?

Answer 8

The epidermis is the outermost layer of the skin - the outermost layer of the epidermis is called the stratum corneum

Question 9

List the 4 layers of the epidermis.

Answer 9

Stratum corneum (horny layer)
Stratum granulosum (granular layer)
Stratum spinosum (prickle cell layer)
Stratum basalae (basal layer)

Question 10

What is a keratinocyte? Where does keratinocyte mitosis occur?

Answer 10

Keratinocytes produce keratin, which contribute to the strength of the epidermis - keratinocyte mitosis occurs in the basal layer (stratum basalae) of the epidermis

Question 11

What are transitional epithelia?

Answer 11

Epithelia consisting of multiple layers of epithelium cells that can contract and expand (distend)

Question 12

What cells does the stratum corneum mainly consist of? How are the developed, and what is their function?

Answer 12

The stratum corneum mainly consists of corneocytes - these develop from keratinocytes (after the keratinocyte loses its plasma membrane) in the corneum basalae, and play a major role in skin barrier function

Question 13

Where are transitional epithelia commonly found? What is their main function?

Answer 13

The urinary tract (bladder, urethra etc) - distensibility, allowing them to hold varying volumes

Question 14

What is the difference between and endocrine and an exocrine gland?

Answer 14

An endocrine gland secretes its hormones directly into the bloodstream (is ductless), while an exocrine gland has ducts into which the hormone is first secreted

Question 15

What are melanocytes?

Answer 15

Dendritic cells that secrete melanin at the basal layer of the epidermis, giving skin its pigmentation

Question 16

What is a langerhans cell?

Answer 16

A dendritic cell located in the prickle cell layer of the epidermis, which have a specialised capacity to present antigens to T lymphocytes, and therefore play a role in immune reactions (rashes etc)

Question 17

List 6 ways that a gland may be defined by its structure.

Answer 17

Unicellular
Multicellular
Acinar
Tubular
Coiled
Branched

Question 18

List 4 functions of the keratinised stratified squamous epithelia at the epidermis.

Answer 18

Protection against abrasion/trauma
Protection against invasion ofmicrobe
Prevents water loss
Protection against UV light

Question 19

In individuals with darker skin pigmentation, are there more melanocytes, or is more melanin being produced?

Answer 19

The number of melanocytes remains the same - they are just producing more melanin

Question 20

Define a gland.

Answer 20

An epithelial cell (of collection of epithelial cells) specialised for the secretion of a substance

Question 21

What are serous membranes?

Answer 21

A serous membrane is a thin, 2-part membrane which line closed body cavities - they secrete a lubricating fluid which reduces the friction of the structures they surround

Question 22

List the 3 ways in which a gland can be defined by their method of secretion. Briefly describe each method.

Answer 22

Merocrine - exocytosis
Appocrine - secretion droplets covered by plasmalemma
Holocrine - where the whole cell breaks down

Question 23

How is the respiratory tract affected in cystic fibrosis?

Answer 23

An abnormal CFTR cannot be properly inserted into the apical membrane of the epithelium of the respiratory tract - Cl- ion transport is compromised, and so water cannot also be transported across the epithelial surface - mucus in the respiratory tract is not adequately hydrated, and so is severely viscous

Question 24

Name the serous membranes that encompass the following structures:

• the heart
• the lungs
• the abdominal cavity

Answer 24

The pericardium
The pleura
The peritoneum

Question 25

How can highly vicious mucus affect the gastrointestinal tract of cystic fibrosis sufferers?

Answer 25

In newborns, it can make the first stool to pass extremely difficult, while in older individuals it can lead to general constipation

Question 26

What are the specific names for the outer and inner membranes of the serosa?

Answer 26

The inner membrane of the serosa is called the visceral pleura
The outer membrane of the serosa is called the parietal pleura

Question 27

How are sweat glands affected in cystic fibrosis?

Answer 27

Absence of the CFTR within sweat glands at the dermis means that there is poor reputable of Cl- ions - as a result sweat has abnormally high levels of Cl- and Na+, giving sweat a salty taste

Question 28

Is the pancreas regarded as an exocrine or an endocrine gland?

Answer 28

Both

Question 29

What are the 3 main salivary glands?

Answer 29

Parotid
Submandibular
Sublingual

Question 30

How is the pancreas affected in cystic fibrosis?

Answer 30

Secretions from the exocrine pancreas contain too little water and are therefore more viscous - ducts are blocked, and the alimentary canal receives little pancreas secretions, resulting in malabsorption - the pancreas becomes inflamed (pancreatitis) and becomes fibrotic

Question 31

How is the endocrine pancreas affected in cystic fibrosis compared to the exocrine pancreas?

Answer 31

The endocrine pancreas is not as severely affected in cystic fibrosis as the exocrine pancreas

Question 32

Are cells on the layer of the stratum cornea dead or alive?

Answer 32

Cells on the stratum corneum are all dead