Chapter 3 - Histology Flashcards
Tissue
Collection of similar cells grouped together to function as a unit
Four types of tissues: epithelial, muscular, connective, and nervous
Characteristics of epithelial tissue
Covers the body surface, covers, lines internal organs, and forms glands
Functions in protection, absorption, and secretion
Cells are tightly packed together, forming layers and sheets, means that epithelial tissue has a free or exposed surface called apical surface; opposite surface that sits on a basement membrane, is called the basal surface
Epithelial tissue is avascular (no direct blood supply)
Most types of epithelial tissue are named based on two characteristics: number of layers and shape of individual cells
What are the two characteristic that gives certain types of epithelial tissue their names
Number of layers and shape of cells
Simple
Single layer
Stratified
Multiple layers
Squamous
Flat
Cuboidal
Tall as it is wide (cube)
Columnar
Taller than it is wide (column)
Apical surface
Free, exposed edge (top)
Lateral surface
Contacts adjacent epithelial cells (under apical surface)
Basal surface
Contacts basement membrane (under lateral surface)
Basement membrane
Connects epithelial tissue to underlying tissue (bottom)
Simple squamous epithelium
Single layer of flat cells
Forms very thin and delicate membranes
Allows for easy movement of molecules across the membrane via processes such as osmosis and diffusion
Found in the kidney glomeruli, alveoli of the lungs, lining of the heart, blood vessels, lymphatic vessels, and serous membranes
Simple cuboidal epithelium
Single layer of cube-shaped cells
Capable of secretion and absorption
Found in kidney tubules, small ducts and glands, covering the ovaries
Simple columnar epithelium
Single layer of column-shaped cells
Capable of absorption and secretion
Found lining most of the digestive tract, gallbladder, ducts of large glands, small bronchi, and uterine tubes
Secretions if the digestive tract lining possess microvilli
Bronchi and uterine tube lining is cilliated
Microvilli
Called a brush border
Short slender cell processes that increase the surface area available for absorption of nutrients
Cilia
Hair-like
Beat in unison to propel substances: mucus in the bronchi and ova in the uterine tubes
Stratified squamous epithelium (keratinized)
Many layers of flat cells
Deepest layers are almost cuboidal in shape and actively dividing
Cells become flatter as they are pushed toward the surface by newer cells
Supper layers are dead and filled with keratin
Found in the epidermis of the skin