Chapter 4.1 (Human Anatomy) Epithelial Tissue Chapter 4.1 (Human Anatomy)
Histology is the branch of anatomy that studies the structure of animal tissue on a microscopic level.
What is a tissue? A group of cells that all perform the same specific function Example: cardiac, muscle, or nerves
4 Types of Tissues 1) Epithelial Tissue – covers body surfaces and organs, lines body cavities 2) Connective Tissue – binds and supports body parts
3) Muscular Tissue – contracts producing movement 4) Nervous Tissue – responds to stimuli and transmits nerve impulses
Epithelial Tissue Tightly packed cells Readily divides (mitosis) producing new cells to replace old or damaged cells Lacks blood vessels Exists on the skin and on the surface of organs, blood vessels, and body cavities
Function: - Externally – protects body from drying out, injury, and bacterial invasion - Internally – protects, sweeps up impurities, secretes mucus, absorbs
Covers surfaces and lines cavities Has a free surface Other surface attached to underlying tissue by the basement membrane Free Surface Nucleus Basement membrane Cytoplasm Free Surface Nucleus Basement membrane
Simple Epithelial Tissue – composed of a single layer of cells Stratified Epithelial Tissue – composed of 2 or more layers of cell
Types of Epithelial Tissues 1] Squamous Epithelium: simple and stratified 2] Cuboidal Epithelium 3] Columnar Epithelium 4] Pseudostratified Epithelium 5] Transitional Epithelium
Squamous Epithelium 2 types of squamous epithelium: * Simple Squamous Epithelium * Stratified Squamous Epithelium
SIMPLE SQUAMOUS EPITHELIUM: – Single layer of flattened cells – Function: secretion, absorption, and filtration – Location: lines the lungs, blood vessels and heart
Simple Squamous Epithelium Cytoplasm Nucleus Simple Squamous Epithelium
STRATIFIED SQUAMOUS EPITHELIUM – Many layers of flattened cells – Function: protection – Location: outer layer of skin, lining the various orifices of the body
Stratified Squamous Epitlelium
Cuboidal Epithelium Location Function Glands secretion Kidney tubules Simple Cuboidal Epithelium: - single layer of cube-shaped cells attached to a basement membrane Stratified Cubiodal Epithelum: two or more layers of cube-shaped cells Location Function Glands secretion Kidney tubules Secretion & absorption
Simple Cuboidal Epithelium Basement membrane Nucleus Free Surface Simple Cuboidal Epithelium
Simple Columnar Epithelium Composed of cells that are longer than wider Nucleus found in the lower half of the cell Location Function Digestive organ Absorption Uterine tubes Propel egg to uterus
Free Surface Nucleus Basement membrane
Pseudostratified Epithelium Cells appear to be layered due to irregularly placed nuclei but each cell touches the basement membrane May contain cilia – aids in movement of particles Function: protection, secretion, movement of mucus and sex cells Location: respiratory tract, reproductive tract
Pseudostratified Epithelium Cilia Nucleus Basement membrane Pseudostratified Epithelium
Transitional Epithelium Tissue that changes in response to tension Found in organs that need to stretch Location: urinary bladder, ureters, urethra
Transitional Epithelium Basement membrane Nucleus Free Surface Transitional Epithelium