Epithelial cells
Importance:
1. Protective layer, protects you skin from dehydration,damages and entry of pathogen.
2. Secretion of enzyme,hormones,mucus,sweat, when epithelial cells are modified into glandular tissues
3. Selectively permeable, allows only absorption of certain substances.
Types of epithelium:
Shape
1. Squamous, flat and looks like fish scales,fast absorption and diffusion
2. Cuboidal,shapes like cube,wide, absorbs nutrients and produce secretions
3. Columnar,tall and thick like column,cushions underlying tissues,absorbs nutrients and produce secretions
Layering
1. Simple,only one layer of cells
2. Stratified,many cells stack on each other
3. Pseudostratified,only one layer of cell but different sizes
The type of cells depend on the functions.
As mentioned above,epithelial cells can be modified to form glands which consists of secretory cells.
There are 2 different types of glands,
i)Exocrine glands-release chemical substances through ducts to outside the body such as sweat,saliva
ii)Endocrine glands-release chemical substances into the boodstream and carry to target cells,they are the hormones!
PYQ STPM 2016
Describe the distribution and functions ot three types of simple epithelial tissues. (9)