2. Ectoderm - skin, hair, hooves, nails, antlers and the entire nervous system
3. Mesoderm - skeletal, smooth and cardiac muscle, kidneys and connective tissue.
What surface faces the lumen or cavity of the epithelia?
What surface faces the connective tissue of the epithelia?
Basal membrane or basement
List 4 common epithelial characteristics
1. They are polar with apical surface facing the lumen/body cavity and basal membrane facing the underlying connective tissue.
2. Lateral surfaces are connected by tight junctions, gap junctions and spot desmosomes called junctional complexes.
3. They are avascular - lack blood vessels or capillaries. They rely on the connective tissue to provide oxygen and nutrients.
4. They are innervated to provide sensory input. Those that lack nerves = stomach, intestine and cervix.
Cells generally have 1 or 2 junctional complexes. What contains all 3 junctions?
What is the function of the tight junction and where are they found?
Barrier that prevents passage of substances from apical to basal membrane and vise versa. Must pass through the body of the cell in order to pass through the epithelial layer.
Found in Urinary bladder and digestive tracts.
What is the function of the gap junction and where are they found?
Allow passage of amino acids (ions) and sugars (nutrients) and transport electrical signals from one cell to another (muscle cells)
Found in intestinal cells, heart and smooth muscle cells.
What is the function of the spot desmosomes and where are they found?
Primarily act like velcro & anchors to make sure the walls don't separate. Seals and holds the area together.
Found in skin, heart and uterus (tension & stretch areas)
What is the purpose of the basal membrane?
It adheres the epithelial tissue to the connective tissue with a meshwork of fibers.
Surface area of the epithelial cells varies describe the characteristics of blood vessels
What is the purpose of microvilli and where is it found?
It increases surface area and is found in the intestines and urinary tract.
What is the purpose of brush borders and where would you find them?
To catch foreign bodies. Trachea
What are the epithelial surface area characteristics of skin?
It is smooth and has keratin for waterproofing.
Simple Squamous Epithelia
B) Appearance - single layer of hexagon shaped cells
Function - line surfaces involved in the passage of gas or blood.
Location - inner lining of the lungs, filtration membranes of kidneys, and lining of blood vessels.
Name of simple squamous epithelium in pleural, pericardial, peritoneal cells are called _____________?
Name of simple squamous epithelium that lines the heart, blood vessels and lymphatic vessels is called _______________?
Name of simple squamous epithelium that lines the brain, eye and discreet areas is called _______________?
What are two cells that can go through or between simple squamous epithelial cells and why?
Oxygen and carbon dioxide because they are lipophilic.
All blood vessels are lined by a layer of simple squamous epithelium cells called _____________?
Shock is ____?
Vasodilitation and reduced cardiac output. During vasodilitation, the cells pull apart allowing plasma and tissue to go out into the tissues which reduces the cardiac output resulting in shock.
Name 3 tissues that have the same simple squamous epithelium appearance but are derived from mesoderm?
Define mucosa and where you find it?
Lines cavities that open to the outside.
Found in rectum, esphogus
Define serosa and where you find it?
Lines cavities that do not open to the outside.
Found in abdominal cavity and body cavity.
Describe Feline Panleukopenia and Canine Parvoviral
Enteritis are caused by parvo “cousins” that attack the endothelium. Mortality is high in the young and disabled, as epithelial tissues have trouble renewing themselves. Squamous epithelial cells die and slough in sheets. Therefore animals develop diarrhea, vomit, and can become severely dehydrated in a short time.
Simple Cuboidal Epithelia
A) Appearance - tightly packed cube like cells
Function - lines ducts that carry enzymes and hormones. Carries hormones and sweat to the surface.
Location - surface of ovaries, ducts of liver, pancreas, kidney and salivary glands.
Simple Columnar Epithelia
C) Appearance - elongated and closely packed
Function - associated with absorption and secretion.
Location - line the gastrointestinal tract,
Ciliated cells found in uterine tubes, uterus, and small bronchi of lungs.
Stratified Squamous Epithelia
B) Appearance - Cubodial cells from the base and consists of various layers. As they push to the surface/mature loose their nuclei and cytoplasm and become squamous shaped.
Function - Protects underlying tissue in areas that are prone to friction and chemical stresses.
Location - mouth, esophagus, vagina and rectum.
Stratified Cuboidal Epithelia
A) Appearance - 2 layers of cuboidal
Function - Secretion, absorption and protection
Location - Ducts of mammary glands and sweat glands.
In what epithelial structure are goblet cells found. What are their function and provide examples of cells that contain goblet cells
Found: Simple columnar (most common) Never seen in simple squamous epithelium, or stratified squamous eputhelium.
Function: responsible secretion of enzymes for lubrication and digestion
Examples: lung and digestive system.
Pseudostratified Columnar Epithelia
C) Appearance - Appear to be stratified because the nuclei are at different levels
Function - Surface area of mucus traps particles.
Location - respiratory track and vas deferens (cilia help to push sperm out)
C) Appearance - contains a hog-pog of epithelium types
Function - allows for expanding and contracting - ability to stretch
Location - Urinary bladder, urethra, ureters
What is a gland?
A cell or group of cells that can manufacture and discharge secretions.
Describe the production and discharge of secretions?
Secretions are specialized protein molecules that are produced in the rough endoplasmic reticulum, packaged into granules by the Golgi apparatus, and then discharged from the cell.