Types of tissues are defined by morphology (anatomy) which influences their function

Abundance of tissue types

Epithelia: - Sheets of cells, polarized

Epithelial cells are tightly connected

Types of epithelia

Squamous epithelium -Simple squamous is delicate, lines ventral body cavities, provides lubrication Stratified squamous is used in areas of mechanical stress

Cuboidal epithelium is often used to make tubes, glands -Nuclei are evenly spaced -Make tubes/ducts -Stratified cuboidal is rare - sweat and mammary glands

Columnar epithelia -Apical end often contains microvilli -Used in absorption

Transitional epithelium is stretchy -Combination of squamous, cuboidal, columnar

Glandular secretions occur in several ways Exocrine - secrete into a lumen Endocrine - secrete into interstitial fluid -mode of secretion varies

Connective tissue -Cells secrete abundant extra-cellular matrix -ECM = fluid + proteins (usually fibrous) -“Proper” - loose and dense -Fluid - blood -Supportive - cartilage and bone

Loose connective tissue Various fibrous proteins + fluid -Areolar - “animal packing material” - very common -Adipose tissue - stores fat -Reticular - Thick network of fibers, strong (structural component of liver, kidney, etc.)

Dense connective tissue -More fibers than fluid -Regular dense CT is very strong, resists forces in 1 direction -Irregular dense CT resists forces in all directions -Elastic dense CT is flexible, can deform

Fluid connective tissue - ECM consists of more fluid than protein

Cartilage is a supporting connective tissue -ECM made of collagen and other fibers -Fibers link together, resists shearing, analogous to rope -Subtypes are more or less flexible Cartilage is avascular, difficult to heal

Bone is a supportive connective tissue -ECM is similar to cartilage (predominantly cartilage) -Collagen fibers bind various calcium salts, acts like glue -Analogous to rope covered with glue -Bone ECM resists torsion, compression Bone is vascularized, can heal