Epithelia Tissue

Question 1

What is the function, locality and proteins involved with adheren cell junctions?

Answer 1

Function = “Belt desmosome” appearance. Plaque layer of proteins on inside of cell to join actin to cadherins. Prevent cell seperation from forces.

Locality = places where organs contract ie heart or muscles

Proteins = Cadherins link to actin via catenins

Question 2

What is the function, locality and proteins involved with tight cell junctions?

Answer 2

Function = Restrict flow of substances through plasma membrane between cells.

Locality = stomach, intestines &urinary bladder

Proteins = claudins and occludins. ZO-1 joins cytoskeleton of cells to actin

Question 3

What is the function, locality and proteins involved with desmosome cell junctions?

Answer 3

Function = Resist shearing forces and have a plaque

Locality = muscles, lateral wall, skin epithelium and cardiac cells of the heart

Protein = Cadherins span the gap, BUT link cell surface to keratin. Keratin spans from one desmosome to another on the other side of a cell.

Question 4

What is the function, locality and proteins involved with gap cell junctions?

Answer 4

Function = transfer of small molecules from cell to cell

Locality =

Protein = connexIN

6 connexIN = 1 connexON/hemichannel
2 hemichannels make up 1 gap junction

Question 5

What is the function, locality and proteins involved with hemidesmosome cell junctions?

Answer 5

Function =. Connect EPT to BM. Links cellular basal intermediate filament keratin to BM.

Locality = basal surface

Protein = Intergrin linker protein binds to laminin in BM and to keratin

Question 6

What forms a junctional complex?

Answer 6

tight junction, adherens junction and desmosome

Question 7

What are the 2 parts the BM is composed of? And what are those components made up of?

Answer 7

Reticular lamina and Basal lamina

Reticular lamina = produced by fibroblasts in CT and made up of fibrous proteins fibronectin collagen etc

Basal lamina = secreted by EPT, contains collagen, laminin, proteoglycans, glycoproteins etc

Question 8

What is the function of the BM?

Answer 8

Support
provide a surface for migration during wound healing.
physical barrier
participates in the filtration of subs in the kidney

Question 9

How does EPT receive nutrients and get rid of waste?

Answer 9

EPT is avascular, therefore receives nutrients from the CT via diffusion

Question 10

Explain how the BM acts as a barrier for malignant melanoma? What does ABCD stand for?

Answer 10

Once the BM has been penetrated, the chance of metastasis increases.

Concept of ABCD
A asymmetrical
B border irregularity
C colour
D diametre

Question 11

What are the 2 types of EPT?

Answer 11

1. Covering and lining - outer lining of skin and some organs, inner lining of BV, ducts and body cavaties, respiratory. digestive, urinary and reproductive systems
2. Glandular (exocrine and endocrine) - constitute the secretory portion of glands

Question 12

Explain simple, stratified and pseuodstratified epithelia in terms of arrangement and function

Answer 12

Simple = singler layer of cells. secretion; absorption; filtration

stratified = two or more layers. protective

pseudostratified = “fake” appears to have many layers but only has one due to all nuclei touching BM. not all cells reach the apical surface. Actually a simple E therefore role is secretion.

Question 13

Which shape allows for diffusion?

Answer 13

Squamous - flat and thin

Question 14

which shape is more tall than wide? and what is its function?

Answer 14

Columnar = increase S.A for capacity to absorb and secrete substances

Question 15

which SHAPE of epithelia cells are found in the urinary bladder and why?

Answer 15

Transitional - because at a relaxed state the shape is cuboidal and stretches to flat once the bladder is full.

Question 16

What are the roles of Mesothelium and Endothelium?

Answer 16

Mesothelium = lines pericardial, pleural, peritoneal cavaties

Endothelium = lines inside of heart, blood and lymphatic vessels.

Question 17

what is a location of simple squamous epithelium?

Answer 17

Bowmans capsule of kidney
cardiovascular and lymphatic systems
alveoli of lungs
visceral cavity linings
inside heart and BV

Question 18

What are the locations of simple cuboidal epithelium?

Hint* their role is secretion and absorption

Answer 18

pancreas ducts, parts of kidney tubules, smaller ducts of many glands, secretory chambers of thyroid, anterior surface of lens, pigmentated epithelium at posterior of retina, secretory part of some glands like thyroid

Question 19

Explain the features/appearance and subtypes of simple columnar epithelium

Answer 19

Features = elongated (nucleus also) therefore more organelles

subtypes = cilia (movement) or microvili (increase S.A or “brush border”)

Question 20

A modified columnar cell (non-ciliated) can contain what?

Answer 20

Goblet cells which secret mucous

Question 21

Where can ciliated simple columnar epithelium be located?

Answer 21

Fallopian tubes, bronchioles, sinuses, central canal of spinal cord, ventricles of brain

Question 22

Where can the subtypes keratinised and non-keratinised occur in EPT?

Answer 22

Stratified squamous epithelium (where stress often occurs)

Keratinised = skin
non-keratinised = mouth, throat, tongue, oesophagus, anus, and vagina

Question 23

where do endocrine glands secrete onto? And give an example

Answer 23

directly into the blood via traversing interstitial fluid

Pituitary, pineal, thyroid, parathyroid

distant strong effects

Question 24

where do exocrine glands secrete onto? And give an example

Answer 24

into ducts that empty onto the surface of covering or lining epithelium

sweat and salivary glands; oil glands; wax glands; pancreas

local effects