Animal Tissue Flashcards
Groups of cells that are similar in structure and function are called
Tissues
Four primary tissue types
Epithelium
Connective
Nervous
Muscle
To perform specific body functions, tissues are organized into ___ such as the heart, kidneys, and lungs.
Organs
The study of tissues
Histology
What is the other name for epithelial tissues?
Epithelium
A sheet of cells that covers a body surface or lines a body cavity.
Epithelial Tissue
Characterized by closely joined cells with tight junctions. Being tightly packed, tight junctions serve as barriers to pathogens, mechanical injuries, and fluid loss.
Epithelial Tissue
Epithelial tissues can occur in the body as:
Covering and Lining Epithelium
Glandular
Functions of Epithelial Tissues
Protection
Absorption
Filtration
Excretion
Secretion
Sensory Reception
The epithelial tissue covers the body and ___.
protects it from bacterial invasion and chemical damage.
Epithelial Tissues Distinguishing Characteristics
Polarized
Specialized Contacts
Supported by Connective Tissue (Basement Membrane)
Avascular
Regeneration
The membranes always have one free surface, called the apical surface, and typically that surface is significantly different from the basal surface.
Polarity
Cells fit closely together to form membranes, or sheets of cells, and are bound together by specialized junctions.
Specialized contacts
The cells are attached to and supported by an adhesive basement membrane, which is an acellular material secreted partly by the epithelial cells (basal lamina) and connective tissue cells (reticular lamina) that lie next to each other.
Supported by connective tissue.
Epithelial tissues are supplied by nerves but have no blood supply of their own (are avascular). Instead they depend on diffusion of nutrients from the underlying connective tissue.
Avascular but innervated.
If well nourished, epithelial cells can easily divide to regenerate the tissue. This is an important characteristic because many epithelia are subjected to a good deal of abrasion.
Regeneration
Why do epithelial cells important to have regeneration?
They are subjected to a fair amount of abrasion.
Epithelial Tissues on Arrangement
Simple (One)
Stratified (Multiple)
Pseudostratified (One, illusion of Many)
How are stratified epithelia named?
By the cells present on the apical surface.
Epithelial Tissues based on Cell Shape
Squamous (Scale, Flat)
Cuboidal (Cube)
Columnar (Hollow Columns)
Transitional (Rounded, Plump)
Glands lose their surface connection (duct) as they develop; thus they are referred to as ductless glands. They secrete hormones into the extracellular fluid, and from there the hormones enter the blood or the lymphatic vessels that weave through the glands.
Endocrine Glands
Retain their ducts, and their secretions empty through these ducts either to the body surface or into body cavities. The exocrine glands include the sweat and oil glands, liver, and pancreas.
Exocrine Glands
Plate-like flattened cells; for exchange of material through diffusion where protections is not important.
Simple Squamous
The simplest of the epithelia, commonly found in air sacs of lungs; heart; lining of ventral body cavity (serosae).
Simple Squamous
Single layer of cube-like cells with large, spherical central nuclei; secretion and absorption.
Simple Cuboidal
Mostly found in kidney tubules; ducts and secretory portions of small glands; ovary surface.
Simple Cuboidal
Brick-shaped cells; for secretion of mucus, enzymes, and active absorption.
Simple Columnar
Commonly found in the stomach to rectum, gallbladder, and excretory ducts of some glands.
Simple Columnar
A single layer of cells; may just look stacked because of varying height; for the lining of the respiratory tract; usually lined with cilia (i.e., a type of cell modification that sweeps the mucus by ciliary action).
Pseudostratified Columnar
Commonly found in Nonciliated type in male’s sperm-carrying ducts and ducts of large glands; ciliated variety lines the trachea, most of the upper respiratory tract.
Pseudostratified Columnar
Multilayered and regenerates quickly; for protection.
Stratified Squamous
Why do stratified squamous epithelial cells need to regenerate quickly?
It protects underlying tissues in areas commonly subjected to abrasion like the skin.
Two layers; Functions as protection commonly found in the largest ducts of sweat glands, mammary glands, and salivary glands.
Stratified Cuboidal