diversity of cells Flashcards
what are the 4 basic tissue types?
- epithelium
- connective tissue
- muscle
-nervous tissue
where are epithelia?
cover surfaces of body and line surface, cavities and tubes and hollow organs (also form many solid organs & glands like liver)
why are epithelia perfect to cover space and line body cavities?
because of strong adhesion between cells which makes sheet with minimum intra-cellular space
what is basal lamina?
layer of extracellular matric component at basal surface of epithelia (attached to the cells)
are epithelial cells polarized?
yes - apical = top and basal = bottom
what are the functions of epithelia?
Mechanical barrier (e.g. skin)
Chemical barrier (e.g. lining of stomach)
Absorption (e.g. lining of intestine)
Secretion (e.g. salivary gland)
Containment (e.g. lining of urinary bladder)
Locomotion (by cilia) (e.g. oviduct)
Minor functions include: sensation (neuroepithelium, e.g. taste buds) and contractility (myoepithelial cells)
what are the 3 types of epithelia cell shape?
- squamous (squashed - flattened)
- cuboidal (cube)
- columnar (column- tall & thin)
nuclei in squamous = bulge out in distinct way
nuclei in columnar = elongated
what are different layers of epithelia cells?
- simple = 1 layer
- stratified = multiple layers
- pseudostratified = looks like multiple layers but actually just nuclei sporadically placed as when look closely, all cells have contact with basal lamina)
what can be on surface of epithelia?
- cilia
- microvilli (smaller than cilia)
- presence of layers of keratin proteins = keratinized (helps support skin, heal wounds & keep nails/hair healthy)
what specialised cell types can be in epithelia?
goblet cells = single cell mucous glands that secrete mucous
what is function of glandular epithelia?
produce secretory products like sweat, milk, oil, hormones, mucous, enzymes etc
what are endocrine glands?
product secreted towards basal end of cell and then product distributed by vascular system throughout body
- termed “ductless” (secretions are released directly into the blood, not to any tubes or ducts)
- have lots of capillaries to disperse around body
what are exocrine glands?
product secreted towards apical end of cell either into lumen of internal space, a duct or body surface
- termed “ducted glands” (tube or passageway that helps transfer secretiona)
what is connective tissue?
forms the framework and support of the body
- has a dynamic role in development, growth & homeostasis of tissues and via fat, energy store
- protects against disease, transports substances and helps repair damage
what are the types of connective tissue and examples?
soft = tendons. ligaments, mesentary (stomach membrane), stroma (like cytoplasm but for organelles) of organs
hard = bone & cartillage
- type determined by relative amounts of extracellular matrix & cells