Chapter 2- Tissue types (3) Flashcards
Where do all epithelial sheets rest?
On a basement membrane that helps it resist stretching and tearing.
What is the basal surface?
The side of the epithelium that rests on the basement membrane
What is the apical surface?
The other free side of the epithelium
Most apical surfaces are covered with what?
Microvilli or cilla- hairs that are important for movement and sensation, e.g, hearing
How is covering epithelia classified?
1- Based on the shape of the cells
2- The number of layers
What are the three primary types of shape for covering epithelia?
1- Squamous
2- Cuboidal
3- Columnar
What are the two types of layers for covering epithelia?
1- Simple layer- one layer
2- Stratified layer- multiple layers
What is simple epithelia useful for?
When an exchange of substances is required
What is stratified epithelia useful for?
Protection
Always found in areas subject to abrasion, e.g, skin, cornea
Stratified epithelia are usually what in humans?
Squamous
Altogether, there are 8 types of epithelia. Give some examples
Simple squamous, Simple cuboidal, simple columnar, etc.
The other two types of epithelia are what?
1- Pseudo stratified- simple columnar epithelia that look stratified
2- Transitional- cells that are round in shape when the organ is relaxed, but flatten when there is pressure e.g, the bladder
What forms the various glands of the body?
Glandular epithelial cells
What is a gland?
A group of cells that make and secrete a particular product
What is the gland involved in?
The production and release of many different secretory products, such as sweat, saliva, and hormones.
What are the types of glandular secretion?
1- Serous- a watery substance often containing proteins, e.g, saliva
2- Mucous- a thick, sticky substance
3- Sebaceous- an oily substance, e.g, in the armpit
Glands are classified as either…
1- Exocrine glands- secrete their products onto the epithelial surface
2- Endocrine glands- secrete hormones into the interstitial fluid, where they go on to enter the blood.
Give an overview of endocrine glands
Structurally diverse and most are multicellular.
Generally ductless
Their secretions are varied
In multicellular exocrine glands, where do secretions travel?
Up to the surface via a series of connecting cells that form a duct.
What is a unicellular exocrine gland?
When a single cell produces and secretes
What is the most common example of a unicellular exocrine gland?
Mucus secreting goblet cell.
Where are goblet cells found?
In the epithelium of the trachea and digestive tube (to protect/ lubricate)
What is a multicellular exocrine gland?
Consists of groups of secretory cells connected to a free surface by ducts.
If there is only a single duct in a multicellular exocrine gland, what is it called?
Simple
If there are multiple ducts in a multicellular exocrine gland, it is called?
Compound
Multicellular exocrine glands can be classified based on:
1- Shape of their secretory units
2- Mode of secretion
What are the different shapes of secretory units?
1- Tubular- if secretory units form tubes.
2- Alveolar- if secretory units form small hollow cavities.
3- Can also be a bit of both- tubuloalveolar
What are the different modes of secretion for multicellular exocrine glands?
1- Merocrine- if the product is released via exocytosis
2- Holocrine- if whole cell ruptures to release product.
3- Apocrine- tip of cell is shed and cell repairs the damage.
