APES: histology
Tissue
Groups of specialised cells that are similar in structure and perform similar functions
The multicellularity can be an advantage because it has a longer lifespan, specialisation and
production & repair of damaged cells by employing other cell types.
Cell -> tissue -> organ -> organ system
Epithelial, connective, muscle and nervous tissue.
Cell junctions hold adjacent cells together
- tight junctions: seal plasma membranes tightly together (digestive tract + bladder lining)
- adhesion junctions: permit some movement between cells, allow tissues to stretch and
bend (skin)
- gap junctions: protein channels enable movement of materials between cells (liver + heart)
Epithelial Tissue
Polarised: apical (faces external environment or lumen of a tube where it is often involved in
absorption/secretion) and basal (mediates attachment to underlying tissue or surface via
integrins)
Tightly packed sheets of cells
Basement membrane: noncellular layer directly beneath epithelial tissue composed of
proteins secreted by epithelial cells & connective tissue. Provides structural support to
overlying cells and attaches epithelial layer to underlying tissues
Simple (single layer, adapted for diffusion across cell barriers) vs. stratified (multiple layers,
provide protection)
Simple squamous Lines blood vessels and alveoli.
Permits exchange of nutrients, wastes and
gases.
, APES: histology
Simple cuboidal Lines kidney tubules and glands.
Secretes and reabsorbs water and small
molecules.
Simple columnar Lines most digestive organs.
Absorbs nutrients & produces mucous.
Stratified squamous Outer layer of skin, mouth + vagina.
Protects against abrasion, drying out and
infection.
Stratified cuboidal Lines ducts of sweat glands.
Secretes water and ions.
Stratified columnar Lines epididymis, mammary glands + larynx.
Secretes mucous.
Tissue
Groups of specialised cells that are similar in structure and perform similar functions
The multicellularity can be an advantage because it has a longer lifespan, specialisation and
production & repair of damaged cells by employing other cell types.
Cell -> tissue -> organ -> organ system
Epithelial, connective, muscle and nervous tissue.
Cell junctions hold adjacent cells together
- tight junctions: seal plasma membranes tightly together (digestive tract + bladder lining)
- adhesion junctions: permit some movement between cells, allow tissues to stretch and
bend (skin)
- gap junctions: protein channels enable movement of materials between cells (liver + heart)
Epithelial Tissue
Polarised: apical (faces external environment or lumen of a tube where it is often involved in
absorption/secretion) and basal (mediates attachment to underlying tissue or surface via
integrins)
Tightly packed sheets of cells
Basement membrane: noncellular layer directly beneath epithelial tissue composed of
proteins secreted by epithelial cells & connective tissue. Provides structural support to
overlying cells and attaches epithelial layer to underlying tissues
Simple (single layer, adapted for diffusion across cell barriers) vs. stratified (multiple layers,
provide protection)
Simple squamous Lines blood vessels and alveoli.
Permits exchange of nutrients, wastes and
gases.
, APES: histology
Simple cuboidal Lines kidney tubules and glands.
Secretes and reabsorbs water and small
molecules.
Simple columnar Lines most digestive organs.
Absorbs nutrients & produces mucous.
Stratified squamous Outer layer of skin, mouth + vagina.
Protects against abrasion, drying out and
infection.
Stratified cuboidal Lines ducts of sweat glands.
Secretes water and ions.
Stratified columnar Lines epididymis, mammary glands + larynx.
Secretes mucous.
