Epithelia & Secretion Flashcards
What structure do epithelial cells rest on?
Basement membrane
Are epithelia innervated? Do they have a blood supply?
No they are avascular and not innervated
What is the function of epithelia? What 3 things are they involved in?
They form barriers for:
- Protection - skin
- Absorption - gut
- Secretion - glands
What are the 4 main types of epithelia?
- Simple
- Stratified
- Pseudo-stratified
- Transitional
Where can simple epithelia be found?
(Single layer of cells) in lungs
Where can stratified epithelia be found?
(Multiple layers of cells) in skin
Where can pseudo-stratified epithelia be found?
(Mixture of tall and short cells, looks stratified but single layer) in trachea
Where can transitional epithelia be found?
(When released only bottom cells in contact with BM, when stretched all cells flatten) in bladder
What type of epithelia lines the alveoli of the lung? What is the arrangement of cells in this epithelia? What is the shape and orientation of the cells nucleus? How does its structure relate to its function?
- Simple squamous epithelia
- Single layer of flattened cells
- Parallel, oval nucleus
- Provides a thin barrier for gas exchange to allow rapid diffusion of gases into/out of blood
What type of epithelia lines the kidney tubules? What is the arrangement of cells in this epithelia? What is the shape and orientation of the cells nucleus? How does its structure relate to its function?
- Simple cuboidal epithelia
- Single layer of cuboidal cells
- Central, round nucleus
- Provides a large surface area for absorption of substances from the urine back into the blood
What type of epithelia lines the respiratory airways? What is the arrangement of cells in this epithelia? What is the shape and orientation of the cells nucleus? How does its structure relate to its function?
- Simple columnar epithelia
- Single layer of columnar cells
- Perpendicular, oval nucleus
- Cells have cilia on apical surface to waft mucus up to throat to be swallowed
What are microvilli? Where are they found? How does their structure relate to their function?
- Regular, finger-like projections on the apical surface of absorptive cells
- Found on cells lining the intestinal tract
- They greatly increase the surface area through which absorption can occur
What are cilia? Where are they found? How does their structure relate to their function?
- Regular, motile appendages on apical surface of cells in respiratory tract or female uterine tubes
- Found on cells in respiratory tract and female uterine tubes
- They have filaments that actively beat to waft mucus or egg along the tract
In what type of areas are stratified epithelia found in?
Areas where there is constant abrasion
Features of stratified/compound epithelia
- Protective function
- Composed of many layers of cells
- Continually being worn down
- Worn away cells replaced from below
What are the subtypes of stratified/compound epithelia?
Squamous, cuboidal
What type of epithelia lines the oesophagus/vagina? What is the arrangement of cells in this epithelia? How does its structure relate to its function?
- Stratified squamous non-keratinised epithelia
- Many layers of flattened cells
- Many layers of cells help to protect against damage from constant abrasion the tissue is subject to
What type of epithelia lines the skin? What is the arrangement of cells in this epithelia? How does its structure relate to its function?
- Stratified squamous keratinised epithelia
- Many layers of flattened cells
- Outer cells are no longer alive and are packed full of the protein keratin which makes our skin waterproof
Where can stratified cuboidal epithelia be found?
In large ducts
Is the epithelia in mouth keratinised or non-keratinised?
Non-keratinised
What is the basement membrane composed of?
Collagen IV and fibronectin
What kind of stain are basement membranes positive for?
Periodic Acid Schiff’s (PAS) stain
detects polysaccharides such as glycogen, and mucosubstances such as glycoproteins, glycolipids and mucins in tissues. Magenta colour
What does the basement membrane separate?
Epithelium and connective tissues
What type of gland secretes through ducts?
Exocrine
What type of gland secretes without ducts?
Endocrine
What is an example of a single cell gland? What is its function?
Goblet cell - Secretes mucus in respiratory tract to trap bacteria, which his then wafted up to the throat by cilia and swallowed
What is an example of multicellular gland?
Pancreas
What are the 2 types of glands? What do they each secrete? Give an example for each type
- Mucous gland - secretes mucous - Sublingual gland
2. Serous gland - secretes proteins e.g. enzymes - Parotid gland
Differences between mucous and serous glands
Mucous glands: mucous, pale, round nuclei
Serous glands: proteins, darker, flat nuclei
Which type of gland has flat nuclei?
Serous glands
What is a mixed gland?
A gland that secretes both mucous and proteins e.g. mandibular gland
