Epithelia and connective tissue Flashcards
What is epithelial tissue
- It covers and protects surfaces both inside and outside of the body. it can form glands
- It is mostly composed of cells with little extracellular matrix between them.
- it is nonvascular - blood vessels in the underlying connective tissue do not penetrate inside. Gases and nutrients enter the epithelia via diffusion
- They can regenerate using stem cells and acts as a barrier
- They can secrete and absorb substances
What are the classifications of Epithelial tissue
- Simple epitheliium= consist of a single layer of cells
- Stratified epithelium= more than one layer of cells but only the basal layer is in contact with the basement membrane.
- Pseudostratified columnar epithelium = appears stratified but is not, one layer of cells with all cells attached to the basement membrane. some cells extend to the free surface some do not.
- Transitional epithelium = shape of cells changes from cuboidal and columnar to squamous when stretched
What are the three shapes of epithelium
- Squamous = cells are flat
- Cuboidal = cube-shaped
- Columnar = more taller than they are wide
What is the nomenclature of epithelium
- The first name indicates the number of layers.
2. The second name indicates the shape of the cells at the free surface eg Simple squamous.
What can stratified epithelium be composed of
They can be squamous, cuboidal or columnar. They can also be non-keratinized or keratinized.
State the function and location of Simple squamous epithelium
Function = Diffusion, filtration, some secretion and absorption, protection against friction
Location =
1. The lining of blood vessels, the heart and lymphatic vessels (endothelium)
- alveoli of the lungs and portion of the kidney tubules
- lining of serous membranes (mesothelium) of body cavities (pleural, pericardial and peritoneal)
- Inner surface of the tympanic membranes (eardrum)
State the function and location of Simple cuboidal epithelium
Function =
1. Secretion and absorption by cells of the kidney tubules
- Secretion by cells of the glands and choroid plexus (brain)
- Movement of particles embedded in mucus out of the terminal bronchioles by cilia.
Location =
- Kidney tubules and glands and their ducts
- Choroid plexuses of the brain
- lining of the terminal bronchioles of the lungs
- surfaces of the ovaries
State the function and location of Simple columnar epithelium
Function =
- Movement of particles out of the bronchioles of the lungs by ciliated cells.
- Partially responsible for the movement of oocytes through uterine tubes
- Secretion in the stomach and intestines
- Absorption by cells of the small and large intestines
Location =
1. glands and some ducts
- Bronchioles of the lungs
- auditory tubes
- uterus and uterine tubes
- stomach, intestines, gallbladder, bile ducts and the ventricles of the brain.
State the function and location of stratified squamous epithelium
Function =
- Protect against abrasion
- Acts as a barrier against infection
- Reduction of water loss from the body
Location =
- Keratinized - primarily in the skin
- Non-keratinized - mouth, pharynx, larynx, oesophagus, anus, vagina, cornea, inferior urethra
State the function and location of Stratified cuboidal epithelium
Function =
- Secretion, absorption and protection against infection.
Location =
- Sweat gland ducts, ovarian follicular cells and salivary gland ducts
State the function and location of Stratified columnar epithelium
Function = Potection and secretion
Location = Mammary gland ducts, larynx and a portion of the male urethra
State the function and location of Pseudostratified columnar epithelium
Function =
- Synthesize and secrete mucus onto the free surface
- Move mucus that contains foreign particles over the surface of the free surface and from passages
Location =
- Trachea, bronchi of the lungs and lining of the nasal cavity
- Nasal sinuses, auditory tubes and pharynx
State the function and location of Transitional epithelium
Function =
- accommodate fluctuations in the volume of fluid in organs or tubes
- Protect against the corrosive effects of urine
Location =
- lining of the urinary bladder, ureters and superior urethra.
