BIOL 105 Lab 3; Histology Notes

histo = tissue; histology = study of tissue

cell – functional units of life; the organization of the cells determines the structure of the tissue
and its functional capabilities

tissue – ensembles of cells with similar structure and function that together carry out a specific
function; organs are made up of multiple tissue types

cell  tissue  organ  organ system  body

4 major tissue types
- connective tissue: support and protect organs and binds other tissues
o fat and other soft padding tissue
o bone
o tendons, ligaments
o collagen
- epithelial tissue: layered to withstand abrasion
o lining of GI tract organs and other hollow organs
o skin surface
o squamous
o stratified
- muscle tissue: generates force, allows movement
o cardiac muscle
o smooth muscle
o skeletal
- nervous tissue: uses electrical impulses to send signals to coordinate movement /
sensory input
o neurons, microglia, astrocytes
o brain tissue
o spinal cord tissue

structure = function
- cells have differentiated to be able to carry out specific functions
- groups of cells with similar structure and function form tissues
- multiple tissue functions that work together are an organ

epithelial tissue
- layered sheets covering an internal or external surface
o tight junctions – limit movement of substances between cells; relies on passive
transport to keep the balance
o desmosomes – specialized adhesive molecules that hold these same types of
cells / tissues together; integral