Tissue structure Flashcards
what are the three germ cell layers ?
- endoderm (inner)
- mesoderm (middle)
- ectoderm (outer)
which tissue develops from the mesoderm ?
- muscle tissue
- connective tissue
which tissue is formed form all three germ cell layers ?
- epithelial tissue
what tissue develops from ectoderm layer ?
- skin tissue
- nervous tissue
what tissue develops from ectoderm layer ?
- skin tissue
- nervous tissue
what are 3 main function of epithelial tissue ?
- protective layer
-secrete substances - absorption of substances
Structure of epithelial tissue
- basement membrane
- apical surfaces
- blood vessels
- nucleus
Structure of epithelial tissue
- basement membrane
- apical surfaces
- blood vessels
- nucleus
what is the basement membrane made of ?
- basal lamina (selectively permeable) and reticular lamina
what is apical surface ?
- top
- lined with microvilli to inc surface area for absorption eg. small intestine
- cilia to waft mucus in one direction eg. in trachea
what is the function of basement membrane ?
- attaches epithelium to connective tissue
what are the 3 types of layers of epithelia tissue ?
- simple
- stratified
- pseudostratified
what is simple epithelia ?
- one layer
what is stratified epithelia?
- more than one layer, only bottom layer in contact with basement membrane (like bricks)
what is pseudostratified epithelia ?
- appear to be arranged in layers but only one layer
what are the 4 different shapes of epithelia cells ?
- squamous
- columnar
- cuboidal
- transitional
what shape are squamous epithelial cells?
- flat like paving stones
what shape are columnar epithelial cells ?
- taller than they are wider
what shape are cuboidal epithelial cells ?
- similar height, depth and width
- cube like
what are transitional epithelial cells ?
- layers which change shape when they are stretched
function of simple squamous cells ?
- lines blood vessels
- lines alveoli in lungs
function of simple cuboidal epithelial cells ?
- lines kidney tubules
- reabsorbs+ secretes water and small molecules
function of simple columnar cells ?
- lines digestive organs eg. small intestine
- can have cillia + goblet cells that secretes mucus
function of stratified squamous epithelium ?
- protects outer layer of skin from infection etc
function of stratified cuboidal epithelium?
- lines ducts and sweat glands
function of stratified columnar epithelium ?
- lines mammary glands + epididymus ( sperm )
what are the three types of junctions on the surface on epithelial cells ?
- adhesion junctions
- tight junctions
- gap junctions
what are gap junctions ?
- spot like junctions allowing small molecules to pass
what are tight junctions ?
- adjacent apical plasma membranes fuse, preventing substances from passing
what are adhesion junctions ?
- desmosomes create adhesion’s involving cadherin proteins
what is an endocrine gland ?
- secrete into empty tissue spaces then goes to blood
what is an exocrine gland ?
- secretes products into ducts
what are the 3 secretory mechanisms for exocrine glands ?
- merocrine
- apocrine
- holocrine
what is merocrine secretion ?
- secretion passes via exocytosis
- no damage to plasma membrane
- eg. salivary gland
what is apocrine secretion ?
-apical end pinched off to release product into duct
- eg. mammary gland
what is holocrine secretion ?
- death of cells releases its contents
- eg. sebaceous gland
what does an epithelial membrane contain ?
- contains an epithelium and an underlying connective tissue
what are the 4 types of epithelial membranes ?
- mucous (small intestine, nose)
- cutaneous (skin)
- synovial (lines joints, secretes synovial fluid )
- serous (lines body cavities , secrete serous fluid )
