HIstology Lecture 2-Epithelial Tissues and Glands Flashcards
What are the four basic/primary types of tissue?
1.) Epithelial tissue 2.) Connective tissue 3.) Muscular tissue 4.) Nervous tissue
Define “tissues”
group of cells and their extracellular matrix that work together to perform a function
____ or more tissues forms an organ
2 or more tissues forms and organ
Function of epithelial tissue
Covers/protects body surfaces, organs, ducts, and glands
Function of connective tissue
protects and supports the body. Multiple types with a lot of extracellular matrix.
Function of muscular tissue
made of contractile cells with moderate extracellular matrix in order to move the body
Function of nervous tissue
detects changes and conditions inside and outside of the body. It responds to stimuli by generating action potentials. It is made up of many differnt cells with long processes and no extracellular matrix.
Name the two main categories of Epithelial Tissue and describe them.
- ) Covering or Lining Epithelium-covering external body surfaces (skin), lines GI tract, respiratory tract, and internal body cavities (pleural cavity), as well as organs
- ) Glandular Epithelium-covers secretory and duct portions
What are 6 functions of Epithelial tissue?
- ) Secretion- thinking of the stomach, some of these cells produce secretions
- ) Absorption- thinking about intestinal epithelial (absorbs nutrients)
- ) Filtration- thinking about the kidney filtering the blood
- ) Excretion- although we filter the blood there is still stuff in the blood that we need to pull out and excrete
- ) Transport- some epithelium have cilia in order to transport (repiratory tract and mucus)
- ) Protection- multiple layers of cells for chemical, mechanical and bacterial protection (skin)
What are the (6) characteristics of Epithelial Tissues? (What makes epithelium, epithelium?)
1.) Cellularity-made up of lots of cells (almost entirely of cells, almost no ECM) 2.) Specialized Contacts between cells 3.) Polarity -free or apical surface/pole/domain -lateral surface/domain -basal surface/pole/domain 4.) Supported by Connective Tissue – lamina propria 5.) Avascular, but Innervated 6.) Regeneration
To define the subclasses of epithelium, look at the morphology. Naming epithelium is based on what two morphological features?
1.) number of cell layers 2.) cell height/shape
Epithelium which all cell layers sit on the basement membrane between the epithelial tissue and connective tissue
Simple
Epithelium which one the deepest layer of cells sits on the basement membrane between the epithelial tissue and connective tissue
Stratified
Epithelium which appears stratified, but in fact all cell layers sit on the basement membrane between the epithelial tissue and connective tissue
Pseudostratified
Epithelium which appears flat, the width is greater than the height, nuclei are flattened
Squamous
Epithelium which appears box shaped, tall as they are wide, and the nucleus is centered and round
Cuboidal
Epithelium which appears taller than they are wide, column shaped, the nucleus is associated with basal side of cell and is slightly elongated
Columnar
How would you classify the cells in the image?
Simple cuboidal
How would you classify the cells in the image?
Stratified squamous
How would you classify the cells in the image?
Ciliated Pseudostratified
How would you classify the cells in the image?
Simple squamous
How would you classify the cells in the image?
Simple Cuboidal
How would you classify the cells in the image?
Non-Ciliated Simple Columnar
How would you classify the cells in the image?
Ciliated Simple Columnar
Label A-D
A.) Nonkeratinized simple squamous epithelium
B.) Nonkeratinized simple squamous epithelium
C.) Keratinized simple squamous epithelium
D.) Keratinized simple squamous epithelium
Describe Transitional Epithelium (Urothelium)
1)its found lining urinary passageways (beginning of urethra, bladder, ureter), it can be stretches, sometiems multinucleated, look funny/umbrella like. Maybe 6-8 layers, as bladder stretches, the surface cells go flat and the shape changes (transitioning).
What type of epithelium is shown in the image?
Transitional Epithelium (Urothelium)
What type of epithelium is pictured? What is the function? Where might you find this type of epithelium?
Simple Squamous Epithelium
Function: allows passage of materilas by diffusion and filtration in sites where protection is not important; secretes lubricating substances in serosae.
Location: kidney glomeruli, air sacs of lumgs, lining of heart, blood vessels, lymphatic vessels, and lining of ventral body cavity (serosae).
What type of epithelium is pictured in the image? What different name does it have?
Simple squamous epithelium. It is called Mesothelium.
Where is mesothelium located? What does it do?
Mesothelium lines the body cavities (the peritoneum). It produces serous fluid which is in the cavity to allow the organs to slide past one another.
What type of epithelium is pictured? What different name does it have?
Simple squamous epithelium. It is called endothelium.
Where is endothelium located? What does it do?
Endothelium lines blood vessels, the heart, lymphatic vessels. Long axis of cells run parallel to the vessels.the endothelium acts as a semi-selective barrier between the vessel lumen and surrounding tissue, controlling the passage of materials and the transit of white blood cells into and out of the bloodstream. Also vasoconstriction and vasodilation.
What type of epithelium is pictured? What is the function? Where might you find this type of epithelium?
Simple cuboidal epithelium. The function is secretion and absorption. It is located kidney tubules, ducts and secretory portions of small glands, ovary surface.
Label A-D. Where might this epithelium be located?
A.) Simple cuboidal epithelium
B.) Nucleus of simple cuboidal cell
C.) Lumen of duct
D.) Connective tissue
Covers surface of ovary, lines kidney tubules and smaller ducts, many glands such as the thyroid. This image is from the pancreas.
What type of epithelium is pictured? What is the function? Where might you find this type of epithelium?
Non-ciliated simple columnar epithelium. Its function is absorption, secrection of mucus, enzymes and other substances. It is located lining most of the digestive tract, gallbladder, and excretory ducts of some glands.
Label A-E. What type of epithelium is pictured? What is the function? Where might you find this type of epithelium?
Ciliated Simple Columnar Epithelium.
A.) Lumen of uterine tbe
B.) Cilia
C.) Nucleus
D.) Ciliated simple columnar epithelium
E.) Connective tissue
What type of epithelium is pictured? What is the function? Where might you find this type of epithelium?
Non-keratinized stratified squamous epithelium. Its function is to protect underlying tissues in areas subjected to abrasion. It is located in the moist linings of the esophagus, mouth, and vagina.
What type of epithelium is pictured? What is the function? Where might you find this type of epithelium?
Keratinized stratified squamous epithelium. Its function is to protect underlying tissues in areas subjected to abrasion. It is located in the epidermis of the skin.
What type of epithelium is pictured? What is the function? Where might you find this type of epithelium?
Stratified cuboidal epithelium. The function is protection and secretion. It lines part of the urethra, large excretory ducts of some glands
What type of epithelium is pictured? What is the function? Where might you find this type of epithelium?
Ciliated-Psedostratified columnar epithelium. Its function is secretion, particulary of mucus, propulsion of mucus by ciliary action. It is located lining the trachea and most of the upper respiratory tract. (Non-ciliated in sperm ducts and glands).
What type of epithelium is pictured? What is the function? Where might you find this type of epithelium?
It is transitional epithelium. Its function is it stretches readily and permits distention of urinary organ by contained urine. It is located lining the ureters, bladder, and part of the urethra.
What type of epithelium is pictured?
transitional epithelium
What type of epithelium is pictured?
Non-keratinized stratified squamous epithelium
What type of epithelium is pictured?
Non-ciliated Simple columnar epithelium
What type of epithelium is pictured?
Ciliated pseudostratified columnar epithelium
What type of epithelium is pictured?
Simple Cuboidal Epithelium
What are the three domains that Epithelial cells have?
oApical domain-directed at the environment
oLateral domain-cell to cell contact
oBasal domain- where ET meets CT
What are microvilli and where are they found? What is their function?
o Cytoplasmic extensions/processes with core of actin filaments
oCreating striated border (intestinal epithelium) or brush border (kidney tubule cells)
oFunction: increase surface area
What structures are shown?
Microvilli
What structures are pictured?
microvilli
What structures are pictured? Where are they found? What is their function?
Sterocilia. found in epididymis, sensory cells of inner ear. Their function is to facilitate absorption.
What structures are part of the apical domain?
Microvilli, stereocilia, cilia
What structures are part of the lateral domain?
Intercellular junctions
Components of the Junctional Complex:
1) Zonula Occludens or Tight Junctions
2) Zonula Adherens
3) Macula Adherens or Desmosomes
Describe Zonula Occludens
Also know as tight junctions.
otype of occluding junction
ofound closest to apical surface
otransmembrane proteins (occludins and claudins) fuse outer surfaces of adjacent membranes together sealing off the intercellular space
oforms a continuous band around the cell which is impermeable, thus it limits the movement of substances between luminal space and tissue compartments via the intercellular space
odiffusion barrier between cells
ogives the “barrier” characteristic to epithelial tissue; for items to get across now they must be actively transported via the specialized membrane proteins of epithelial cells
oalso prevents integral membrane proteins movement between domains
oprovide only limited resistance to mechanical stresses
What structure is at A?
occludin (part of zonula occludens) also know at tight junctions
Describe Zonula Adherens
o a type of anchoring junction
o provide mechanical stability by linking cytoskeleton of one cell to the cytoskeleton of the next; great for resisting separation
o forms a continuous band around the cell
o microfilaments (actin) of the first cell attach to a plaque on the inside of its plasma membrane; this plaque is attached to transmembrane protein (cadherin) which crosses the plasma membrane of the first cell and attaches to the cadherin of an adjacent cell; this second cell’s cadherin crosses its plasma membrane where it attaches to a plaque just on the inside of the plasma membrane; this plaque is attached to the microfilaments (actin) of the second cell; thus connecting cytoskeleton of one cell to the next.
What structure is shown?
Zonula Adherens
Describe Macula Adherens
Also known as Desmosome
oa type of anchoring junction
oprovide mechanical stability by linking cytoskeleton of one cell to the cytoskeleton of the next; great for resisting separation
oforms spot welds; not continuous around cell; localized
ointermediate filaments of the first cell attach to a plaque on the inside of its plasma membrane; this plaque is attached to transmembrane protein (cadherin) which crosses the plasma membrane of the first cell and attaches to the cadherin of an adjacent cell; this second cell’s cadherin crosses its plasma membrane where it attaches to a plaque just on the inside of the plasma membrane; this plaque is attached to the intermediate filaments of the second cell; thus connecting cytoskeleton of one cell to the next.
•
What structure is shown?
Macula adherens or Desmosome
What are Gap juntions?
othese are communicating junctions
otransmembrane proteins are in the form of a protein tunnel called a connexon
othe connexon of one cell lines up with the connexon of the next cell allowing the cells to exchange ions and small molecules; these items can diffuse from the cytosol of one cell to the cytosol of the next.
oallows communication between cells; this is especially important in tissues were the activity of the cells need to be coordinated.
What structures are pictured?
gap juntions
Describe the difference between the basal lamina and the basement membrane.
Basement membrane is made up of 2 parts which include 1.) basal lamina and 2.) reticular lamina- from connective tissue.
What are the components of the basal lamina?
It used to be thought that there were two components:
- Lamina Lucida
- Lamina Densa
But lamina lucida does not exist.
What is a focal adhesion?
oa type of anchoring junction
olooks somewhat similar to a zonula adherens junction, but it doesn’t link adjacent cells
olinks the cell to the basal lamina; specifically it anchors microfilaments (actin) of the cytoskeleton of a cell to the basal lamina
oactin filaments are attached to extracellular matrix glycoproteins (ex. laminin and fibronectin) in the basal lamina via integrins (the transmembrane protein used here)
ofunctional role in signal detection and transmitting signals from the extracellular environment into the interior of the cell; mechanosensitivity
What is a hemidesmosome?
oa type of anchoring junction
olooks somewhat similar to a desmosome, but it doesn’t link adjacent cells
olinks the cell to the basal lamina; specifically it anchors intermediate filaments of the cytoskeleton to the basal lamina
ointermediate filaments are attached to laminin and type IV collagen in the basal lamina via integrins (the transmembrane protein used here)
ofound in epithelia subject to abrasion and mechanical shearing forces; useful for keeping the epithelium from separating from the underlying connective tissue
What are some of the components of the basal domain?
focal adhesion and hemidesmosomes
What are the two categories of epithelial tissue?
- Covering or Lining Epithelium
- Glandular Epithelium
Describe glandular epithelium
Profliferation of cells and their downgrowth into the subadjacent connective tissue.
Glands can be classified based on connection to surface (where do they secrete their secretions?) Name and describe the two classifications?
- Endocrine Glands – ductless glands; secrete into interstitial fluid.
- Exocrine Glands – secrete their products onto a surface either directly or via an epithelial duct.
Endocrine glands release 3 types of hormones:
- Circulatory Hormones
- Paracrine Hormones
- Autocrine Hormones
Exocrine glands are classified based on 4 things:
- Cellularity- how many cells make up
a. ) Unicellular Exocrine Glands – one cell that’s right at the surface
b. ) Multicellular Exocrine Glands – more than one cell; consists of a cluster of cells. Some part of duct, some part of secretory - Structure/Morphology
- Type of Secretion-serous, protein, mucous
- Mode/Mechanism of Secretion
Give an example of a unicellular exocrine gland.
Intestinal epithelium-goblet cells–produce and secrete mucin; also found within epithelial lining of respiratory tract
What structure is pictured?
Exocrine gland
Exocrine glands can be classified based on structure:
A.Structure of Duct
- Simple – unbranched
- Compound – two or more branches
B.Structure of Secretory Units*
- Tubular – tube shaped; either short or long and coiled
- Alveolar or Acinar – round or globular
- Tubuloalveolar and Tubuloacinar – combination
Classify the gland
simple tubular
classify the gland
Simple branched tubular
Classify the gland
simple acinar
Classify the gland
Simple coiled tubular
Classify the gland
compound acinar
Exocrine glands can also be classified based on the type of secretion. What are the three types?
A.Mucous Glands
B.Serous Glands
C.Mixed Glands
What are the two major types of secretory cells associated with glands? Describe them.
1.Serous Cells
- Polarized, protein-secreting cells
- Typically produce digestive enzymes and other proteins
- Pyramidal in shape – broad base on basal lamina and narrow apical surface facing lumen
- Contain secretory granules called zymogen granules – spherical in shape; found in apical cytoplasm
- Basophilic cytoplasm due to RER and free ribosomes
- Nuclei are rounded
2.Mucous Cells
- Produce hydrophilic glycoprotein mucins
- Cuboidal or columnar in shape
- Flattened nuclei at base of cells
- Contain secretory granules called mucinogen granules – found in apical cytoplasm; PAS positive
There is a third type of cell that is associated with glands. What is it and describe it.
1.Myoepithelial Cells- Epi cells that have a contractitle ability
- Found within the basal lamina of secretory units and the initial part of duct system
- Can contract; accelerates secretion of the product
- Also prevent distention of area when lumen fills
What is the basic unit of a salivary gland?
salivon
What is a salivon composed of?
The acinus and all related ducts.
What is an acinus?
A blind sac composed of secretory cells and is the secretory portion of the savlivon.
What are the three secretory acini found in salivary glands? Describe them.
- Serous Acini – serous cells only; generally spherical shaped- producing proteins
- Mucous Acini – mucous cells only; generally tubular shaped-producing mucus
- Mixed Acini – contain both serous and mucous cells; in traditional fixation methods it appears the mucous acini have a cap of serous cells; these caps are called serous demilunes; found in the sublingual and submandibular glands. If do convectional fixation, see
Label A-E
A.) Serious acini
B.) Mucous acini
C.) Mixed acini
D.) excretory ducts
E.) striated duct
Exocrine glands can be classified based on the mode of secretion. There are three classes:
A.Merocrine Glands
B. Holocrine Glands
C. Apocrine Glands
How do merocrine glands secrete their products?
Merocrine glands sercrete products via exocytosis, most common form of secretion in body
How do holocrine glands secrete their products?
Apocrine glands secrete products via cell death. They accumulate their product then undergo apoptosis. They rupture. It is the cytoplasm, dead cell parts, and secretion.
How do Apocrine glands secrete their products?
Apocrine glands secrete products via accumulate in apical part of cell, then cell pinches off. So you get some cytoplasm. There is a debate whether or not this occurs in the human body. Mammary gland is closest thing to it.
What type of exocrine gland is pictured?
Merocrine gland
What type of exocrine gland is shown?
Holocrine Gland
What type of exocrine gland is pictured?
Apocrine gland
