Tissues Flashcards
What is a tissue
Groups or layers of similar specialised cells with common function
What are organs
2 or more tissues combined
What do organs consist of
a. Parenchyma: the functional element
b. Stroma: supportive framework
Epithelial tissue definition
Forms outer layer of a body, lines alimentary canal and other hollow structures and makes up glands
Epithelial tissue functions
Secretion, barrier, absorption, protection, transcellular transport, sensing
Epithelial tissue characteristics
Have polarity: portion of the cell exposed to the lumen One or many sheets Highlight cellular Cell to cell contacts Avascular Nerve supply Cells resting on basement membrane
Basement membrane
Made of collagen fibres and glycoproteins
Sits on a bed of loose connective tissue
Anchors epithelium to loose connective tissue
Forms organised scaffold to provide structural support
Simple squamous epithelium
Fast absorption
Diffusion
Make thin membranes
Simple cuboidal epithelium
Absorb nutrients
Produce secretions
Nucleus very circular and central
Simple columnar epithelium
Absorb nutrients
Produce secretions
Nuclei elliptical
Simple epithelium
Simple = one layer thick
Stratified epithelium
Stratified = many stacked layers
Keratinised stratified squamous epithelium
Special features of epithelial tissue
Keratin:
Fibrous structural protein that protects epithelial cells from damage or stress
Extremely insoluble in water and organic solvents
Key structural material making up the outer layer of human skin
Keratin function
Adheres cells to each other
Forms a protective layer on the outside of the skin
Psuedostratified epithelium
Looks like several layers, but is one
Cells connect to the basement membrane