Module 2A: Tissues; Epithelial Flashcards
What are tissues?
Groups of cells that are:
- similar in structure
- perform a common or related function
What is histology?
The study of tissues
- subset of microscopic anatomy
What are the four main types of tissues in the human body?
- Epithelial tissue
- Connective tissue
- Muscular tissue
- Nervous tissue
What is the role of epithelial tissue?
Protects
What is the role of connective tissue?
Supports and attaches things together
What is the role of muscular tissue
Moves
What is the role of nervous tissue?
Controls
What are the two types of epithelial tissue? What do they do?
- Covering/lining epithelium: forms outer layer of skin and internal structures (lining around stomach as well)
- Glandular epithelium: forms glands of body (ex. Salivary glands)
- both form boundaries and decides what crosses the boundary
What are the four functions of epithelial tissue?
- Physical protection
- Absorption
- Sensation
- Secretion
What does physical protection from epithelial tissue do?
Stops harmful substances from entering the body or particular organs
Epithelial tissues can form what that allows some things to pass and some things to not
A selective barrier
- when epithelial does this, it’s called absorption
What does epithelial tissue do for sensation?
Forms some specialized receptors
- have hairlike extensions that can detect changes in temperature, chemical composition, if there’s too little oxygen, or if something too big comes through that tube.
- when hairlike extensions are bent, it sends sensory responses to brain to say that it’s not good
What is a gland with respect to epithelial tissue?
Group of one or more modified epithelial cells that make or secrete a particular substance
Where does secretion occur?
In glands
What are the two types of glands?
Endocrine and exocrine
What is an endocrine gland?
- secrete products directly in bloodstream
Ex. Thyroid, pituitary glands, pancreas
What is an exocrine gland?
Secrete products into ducts (channels/tunnels)
Ex. Sweat, earwax, saliva
What happens to a substance if it is put into the blood?
It can go anywhere in the whole body
what is the basement membrane?
a thin, delicate membrane of protein fibers and glycosaminoglycans separating an epithelium from underlying tissue
Which type of glands has a thicker basement membrane? (Membrane surrounding membrane of nucleus of secretory cell of sweat gland)
Exocrine gland. Endocrine needs secretion or diffusion across the cells into the nearby blood vessels so this makes sense as to why the basement membrane is thicker in exocrine cells. Exocrine does not want product to leave the gland.
What side of epithelial tissue is exposed to the external environment or cavity of organ?
Apical (free) surface
- often have microvilli or cilia
Where is the basal surface of epithelial tissue?
The anchored bottom surface of the cells and is attached to the basal lamina which is apart of the basement membrane when the epithelial tissue is connected to connective tissue
What does basal lamina do?
Acts as a filter. Decides what can and cannot travel into or out of the epithelial layer of that tissue.
- joins epithelial tissue to connective tissue
When the epithelial tissue is connected to connective tissue, what is the basement membrane made up of?
Basal lamina and reticular lamina
Does epithelial tissue fit closely together to form, continuous sheets
Yes
What protects and gives structural support to epithelial tissue?
Connective tissue
What does avascular mean?
Blood vessels, arteries and veins do not go directly to them
True or false: epithelial tissue is avascular?
True
How does epithelial tissue get their nutrients?
From nearby blood vessels and when they are anchored to connective tissue, the blood vessels in connective tissue is where their nutrients come from
While epithelial tissue has no direct contact with arteries or veins, what do they have direct contact with?
Nerves
- epithelial tissue can pass information from this tissue layer to the brain
Epithelial tissue has high regenerative capacity as long as?
They receive adequate nutrition. They can replace lost cells by cell division
What are the three different types of arrangement of layers in epithelial tissue?
- Simple - one layer where all touch basement membrane
- Pseudostratified - one layer elongated where all touch basement membrane
- Stratified- multiple simples on top of one another where only first layer touches basement membrane
What are the three types of cell shapes in epithelial tissue?
- Squamous- thin, fiat, wide
- Cuboidal- cells are cube shaped; all approx same size
- Columnar- tall, thin, rectangular, shaped like columns
- you can have a mix and match of the types within a tissue
What does more layers on epithelial tissue mean?
More protection
What is cilia often helpful for in epithelial tissue?
Often helpful in moving substances or involved in sensation
Where in our body will we have simple squamous epithelium?
Small intestine.
- whenever we need absorption or secretion
Which type of epithelium tissue layer and shape is for absorption of fluids?
Simple cuboidal epithelium
what is a miotic spindle?
a structure that forms during cell division and separates duplicated chromosomes
what is the two varieties of simple columnar epithelium?
nonciliated and ciliated
what is nonciliated simple columnar epithelium?
simple columnar epithelium with microvilli on the surface to increase the surface area
- goblet cells and mucous production
- typically seen in the digestive system
what is ciliated simple columnar epithelium?
simple columnar epithelium that is covered with cilia at the top
- goblet cells and mucous production
- typically seen in uterus
where is stratified squamous epithelium found?
areas where many layers are needed because protection is important
in stratified squamous epithelium, bottom layers have nuclei and top layers dont, why is this?
top layers are dead
- like dead skin for example
stratified tissue is going to regenerate from where?
below, by the basement membrane and basal surface, pushing the cells upward
where would stratified cuboidal epithelium be found?
- esophagus
- lining of sweat glands
- salivary glands
where can stratified columnar epithelium be found?
- male urethra
- conjunctiva of the eyeball (front of eyeball)
- lining of pharynx
is the pseudostratified ciliated columnar epithelium usually ciliated and/or have goblet cells?
yes and yes
where is pseudostratified ciliated columnar epithelium typically found?
respiratory system to help move things along the walls
what does a transitional epithelium look like?
stratified layers of cells that change shape depending on where they are and what loads are applied to them
the inner bladder tissue is a transitional epithelium.
1. what happens to the inner layers of cells when your bladder is full?
2. what happens when your bladder is later emptied?
- inner layers of cells are going to flatten to make more space inside the bladder to hold more urine.
- cells bounce back and look more cuboidal
What is the lumen of a gland?
In exocrine glands, the lumen forms the ducts for products to be transported to a SPECIFIC location
Together, the basal and reticular lamina (the basement membrane) decides what in terms of the two tissues?
What passes through the two tissues
What is simple squamous specialized for?
Moving molecules across
