Histology Flashcards
What is the difference between keratinized and non-keratinized tissue?
Presence or absence of a protective, apical layer of dead squamous cells containing keratin, an intermediate filament, that provides protection from abrasion and desiccation
Define endothelium
Squamous epithelial cells lining the lumen of blood or lymph vessels
Define mesothelium
Squamous epithelial cells lining body cavities and free surfaces of organs
What are the four basic types of tissue?
Epithelial, connective, muscular and nervous tissue
What are some general characteristics and functions of epithelial tissue?
Highly cellular and regenerative
Exhibits polarity with an apical side and a basal side
Avascular, receives nutrients and oxygen via diffusion from capillaries in underlying connective tissue
What are the two components of the basement membrane and from what cells do these components originate?
Basal lamina - apical layer, originates from epithelial cells
Reticular lamina - basal layer, originates from fibroblasts in connective tissue
What is the common function of simple columnar epithelium?
Absorption and secretion in small intestine and kidney
Associated with microvilli
What is the function of goblet cells and with what type of epithelial cells do they often associate in parallel?
Mucous secretion, prevents epithelial desiccation
Often seen in parallel with columnar epithelial cells in small intestine
Define pseudostratified columnar epithelium and where is this tissue observed?
Nuclei are located at different levels but all cells connect to the basement layer
Observed in the respiratory and reproductive tracts
What is the function of fibroblasts? What is an identifying characteristic?
Main cell type of connective tissue
Synthesize and secrete fibers and ground substances
Have dark, elongate nuclei
What is the function of mast cells?
Involved in immune responses such as allergic reactions
usually located near small blood vessels
don’t need to identify
What is the function of lymphocytes and what is an identifying characteristic?
Responsible for immunologic surveillance
Found in peripheral blood, lymphatic organs and loose CT
Identified by dark, round nuclei
