Epithelial tissue_PM_1
Reticular Function
Forms a soft internal skeleton, or stroma, that supports other cell types
Adherens
Found along wall of cell to anchor and adhere, closer to the apical surface.
Squames
Found in dry-keratinized epithelium. Non-living scale-like cells essential only contain keratin. Dog footpad slide.
Hyaline Cartilage Location
Found in embryonic skeleton, the end of long bones, nose, trachea, costal cartilage, and larynx
Fibrocartilage Location
Found in intervertebral discs, the pubic symphysis, and in discs of the knee joint
Reticular Location
Found in lymph nodes, bone marrow, and the spleen
Dense Regular Location
Found in tendons and ligaments
Stratified columnar epithelium
Found in the conguctiva of the eye, Columnar cells in apical layer only, basal layers has irregular shaped cells and functions in protection and secretion.
Dense Irregular Location
Found in the dermis, submucosa of the digestive tract, and fibrous organ capsules
Adipose Location
Found under skin, around kidneys, within abdomen, and in breasts
Transitional epithelium
Function: Allows flexibility. Location: Urinary bladder, ureters, urethra Description: Resembles both stratified squamous and stratified cuboidal; basal cells cuboidal or columnar; surface cells dome shaped or squamous like, depending on degree of organ stretch.
Blood
Functions in the transport of respiratory gases, nutrients, and wastes
Simple Cuboidal Location
Glands and kidney tubules
Simple cuboidal epithelium
Glands; ducts; portions of kidney tubules; thyroid gland; ovaries. Occurs where secretion or absorption takes place.
Goblet Cells
Interspersed among simple columnar and pseudostratified epithelial cells. Thinner at base and bulbous at apex. Appears to be empty on slide. Mucus-containing secretory cells.
Simple Squamous epithelium
Kidney (glomerulous), Lungs (alveoli), all blood vessels, capillaries and heart
Simple Columnar Location
Lining of digestive tract, gallbladder, uterus
Pseudostratified
Looks like stratified but it isn't
Simple Squamous Location
Lungs
Elastic Cartilage Function
Maintains shape and structure while allowing flexibility
parietal mesothelium
Mesothelium that lines the body walls.
Cilia contains what for movement?
Microtubule doublets AND dynein arms for movement (uses ATPase)
Where in the skin do you usually find the junctional complex?
Near the surface where the junctional complex is. There is no need to have these complexes any deeper
Basal Lamina
Produced by epithelial cells, First layer of basement membrane. Secreted by the overlying epithelial tissue. In epithelial tissues with more than one layer, the basal layer refers to the deepest layer of epithelial cells.
Stratified epithelium - primary purpose?
Protection
Stratified Squamous Function
Protection from external exposure
Epithelia (4 FUNCTIONS)
Protection, Absorption, Secretion, Sensory Perception.
Stratified Cuboidal Function
Protects larger ducts
Fibrocartilage Function
Provides tensile strength and absorbs compression shock
Adipose Function
Reserves food stores, insulates against heat loss, and supports and protects
Pseudostratified Location
Respiratory tract
Keratinized Stratified Squamous Function
Retards water loss and barrier to organisms
Gap junctions
Used for cytoplasmic communication, allow electrolytes to pass through. Found in all types of tissue.
Skeletal Muscle
Voluntary movement, multinucleate
Keratinization
Wet vs Dry. Wet- Most superficial cells, though still squamous in morphology, retain their nuclei and do not die. Dry- Most superficial cells die and lose nuclei, forming layers of SQUAMES.
lung
Where does this tissue come from?
small intestine
Where does this tissue come from?
trachea
Where does this tissue come from?
Areolar Location
Widely distributed
Dense Irregular Function
Withstands tension in many directions providing structural strength
Areolar Function
Wraps and cushions organs
Tight junction
"Zipper like" Prevent substances from going in between epithelial cells. They create impermeable or semi-permeable membranes between epithelial cells.
Fibrous Lamina
2nd layer of basement membrane, underneath basil lamina. Fibrous layer secreted by fibroblasts. Visible with light microscope. FUNCTION: anchor basal lamina to underlying conn. tissue.
Basil Lamina
immediately subjacent to epithelial cells. Made up of type IV collagen. Not visible on light microscope. FUNCTION: establish polarity of epithelial cells, Macromolecule exchange
Gap Juncton (aka Nexus) - describe appearance and function
- 6 proteins arranged to create a circle channel. - membranes are close together between the two arrows. This is the junction. Many junctions exist between, and each junction has 6 proteins.
Locations of microvilli
- Found on most epithelial cells but are mot developed in absorptive cells such as kidney tubule cells and small bowel epithelium
Terminal Bar = ?
- Junctional Complex - Formed by adherent junctions towards the apex of adjacent columnar and cuboidal cells - appears as a dark line under the surface membrane
Identify this epithelium type
- Multiple cell types. - findbasement membrane - note all cells touch the basement membrane, but not all cells touch the surface. Therefore this is pseudostratified. - The cells at surface of lumen are columnar. - therefore this is pseudostratified columnar
what is involved in a Zonula Adherens?
- Not as tight as zonula occludens - associated with actin filaments
Desmosomes / Macula Adherens - what is involved?
- Strong spot attachment (macula = spot) - Due to interdigitating - Where the 'zips' overlap, are the dark areas
Where do you find cilia?
- Trachea - uterine tubules
List the different types of junctions in epithelial cells?
- Zonula occludens (tight junctions): diffusion barrier - Zonula Adherence / Macula Adherens (desosomes): Anchor via cytoskeleton - Gap Junctions (nexus): Communication sites between epithelial cells
Purpose of microvilli
- actually extensions of the membrane (and are covered with the layer of membrane) - This forms a brush border on the cell - increases surface area. - absorption
Hemidesmosomes - appearance and function?
- anchor base of epithelium to the basement junction and connective tissue - fibrils are the small dots beneath the arrow
Basal histological appearance/ function
- attachment to connective tissue - communication purposes
Identify this type of epithelium
- cell nuclei appear very flat - appears to be one layer - this would be a simple Squamous epithelium
Identify this type of epithelium
- contains Cuboidal epithelial cells in epithelium - contains columnar epithelial cells in epithelium - lateral gap junctions - Therefore this is a transitional epithelium (taken in the bladder)
Identify this epithelium type
- dark pink edges are basement membrane - each lumen has a single layer of nuclei - cells are roughly cuboidal in shape - therefore simple cuboidal
histological appearance of apical surface cells
- directed to lumen - suface modifications
Identify this epithelium type
- endothelium - simple squamous epithelium
Lateral walls - histological properties
- held together via junctions so nothing can get through between cells.
Basement membrane function
- influencing cell differentiation and proliferation - filtration barrier via ionic charges - attachment. - most epithelial cells would have the basement membrane.
Identify this type of epithelium
- look at the nuclei if unsure - the nuclei are long and flat along epithelial surface. This is squamous. - There is only one layer of these cells. This is simple. - Therefore this is simple squamous epithelial (this is taken from a kidney)
Identify this epithelium type
- multiple cell types - not all cells touch basal membrane - therefore transitional (stratified)
Identify this epithelium type
- single line of nuclei - spot the junctional complex - spot the microvilli of lumen - this is taken from small intestine - this is simple columnar
Simple single layers of epithelium - what cells are these related to?
- usually related to cells with transport - usually have receptors on the surface as well
Epithelia (5 general characteristics)
-Form sheets/tubes -Little intercellular space between cells -Attached to subjacent connective tissue by basement membrane -Cover body surfaces and separate internal tissue from cavity lumen -Do not contain blood vessels.
Endothelium
A special type of epithelium which is found only in blood vessels. Endothelium type is simple squamous
Simple Columnar Function
Absorption (cillia)
Simple Cuboidal Function
Absorption, secretion, and movement of mucous
Simple columnar epithelium
Absorption; Secretion of mucus, enzymes, and other substances. Non-ciliated line most of the digestive tract and gallbladder. Ciliated line uterine tubes, and some regions of the uterus. MAINLY INTESTINES
Desmosomes
Anchoring junctions that hold one cell to another and help prevent lateral tearing of tissue. ie: in the heart
Surface exposed to the lumen is known as?
Apical surface
Dense Regular Function
Attaches muscles to bone or to other muscles, and bone to bone
Lamina Reticularis
Basement membrane. Produced by underlying connective tissue.
Transitional Epithelium Location
Bladder, ureters, urethra
Transitional
Cells are changing within the epithelium
Basement Membrane
Composed of: Basil Lamina- immediately subjacent to epithelial cells. Made up of type IV collagen. Not visible on light microscope. FUNCTION: establish polarity of epithelial cells, Macromolecule exchange Fibrous Lamina- 2nd layer, underneath basil lamina. Fibrous layer secreted by fibroblasts. Visible with light microscope. FUNCTION: anchor basal lamina to underlying conn. tissue.
Stratified Cuboidal Epithelium
Ducts of glands, 2-3 layers of cells
Keratinized Stratified Squamous Location
Epidermal layer of feet and palms
Pseudostratified epithelium
Every cell still makes contact with basement membrane. Respiratory tract where they have cilia and produce mucus; nasal cavity; male reproductive (vasdeferens, urethra, epididemus)
Stratified squamous epithelium
STRUCTURE: SEVERAL LAYERS OF CELLS THAT ARE CUBOIDAL IN THE BASAL LAYER AND PROGRESSIVELY FLATTENED TOWARD THE SURFACE, THE EPITHELIUM CAN BE NONKERATINIZED-esophagus,mouth, anus,vagina,nasal OR KERATINIZED- skin, IN NONKERITINIZED STRATIFIED SQUAMOUS EPITHELIUM, THE SURFACE CELLS RETAIN A NUCLEUS AND CYTOPLASM. IN KERITINIZED THE SYTOPLASM OF CELLS AT THE SURFACE IS REPLACED BY A PROTEIN CALLED KERATIN, AND THE CELLS ARE DEAD.
Pseudostratified Function
Secretion and propulsion of mucus (goblet cells)
What type of epithelium lines the Abdominal cavity / Peritoneum ?
Simple Squamous (mesothelium)
What type of epithelium lines the Pericardial / Heart sac?
Simple Squamous (mesothelium)
What type of epithelium lines the Thoracic cavity / aka Pleura?
Simple Squamous (mesothelium)
What type of epithelium lines the organs?
Simple Squamous (visceral mesothelium)
Endothelium
Specialized simple squamous epithelium that lines heart, blood and lymphatic vessels.
Mesothelium
Specialized simple squamous that covers internal organs, lines major serous cavities of body.
Transitional Epithelium Function
Stretches to permit distension
Hyaline Cartilage Location
Supports external ear (pinna) and the epiglottis
Bone Function
Supports, protects, and provides levers for muscular action. Stores calcium, minerals, and fat. Marrow is site of hematopoesis.
Hyaline Cartilage Function
Supports, reinforces, cushions, and resists compression
Stratified Cuboidal Location
Sweat glands, mammary glands, salivary glands
Lateral walls?
These are the walls of the cells.
Stratified Squamous Location
Tongue, esophagus, vagina
Which cells divide slowly, rapidly and never?
skeleta/cardiac - usually replaced with non-functional tissue
Apical surface
surface exposed to the lumen
What is involved in a Zonula Occludens area?ac
the cells appear to be touching, but the gap is very small (3nm)
Height of the cell usually reflects which aspect of the cell?
the function of the cell
People with asthma and exposed to high levels of oxygen will thicken the basal membrane (true/false)
true
