What are tissues?
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Tissues are aggregates or groups of cells and extracellular matrix organized to perform one or more specific functions.
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What are tissues?
Tissues are aggregates or groups of cells and extracellular matrix organized to perform one or more specific functions.
What is found at the apical surface of certain epithelial cells?
Striated border.
What are the two types of glands based on duct appearance?
Simple (ducts not branched) and compound (ducts with two or more branches).
What structure is located at the base of epithelial cells?
Basement membrane.
What are myoepithelial cells?
Epithelial cells that acquire the characteristics of smooth muscle cells.
What defines multicellular glands?
They are composed of more than one cell.
What are intermediate filaments in epithelial cells made of?
Proteins called cytokeratins.
How can multicellular glands be subclassified?
According to the arrangement of the secretory cells in the secretory portions (acini) and the presence or absence of branching of the duct elements.
In which locations can myoepithelial cells be found?
Sweat glands, mammary glands, salivary glands, and the iris of the eye.
What characteristic do epithelial cells exhibit?
Epithelial cells exhibit functional and morphological polarity.
Where is the basement membrane located?
At the basal surface.
What are the three distinct surface domains of epithelial cells?
The three distinct surface domains are the free surface or apical part, the lateral part, and the basal part.
What is a key morphological characteristic of epithelium related to its ability to renew itself?
Regeneration.
What staining method is used to identify the basement membrane?
PAS+ (Periodic Acid-Schiff positive).
What determines the properties of each domain in epithelial cells?
The properties of each domain are mostly determined by specific membrane proteins and glycoproteins.
Do epithelia have a direct blood and lymphatic supply?
No, epithelia lack a direct blood and lymphatic supply and are therefore avascular.
Why is regeneration an important characteristic of epithelial tissue?
It allows the epithelium to repair and renew itself, maintaining its protective and functional roles.
What is the apical surface in relation to epithelial cells?
The surface facing the intestinal lumen.
What are the three types of secretory portions based on their appearance?
Tubular, alveolar, and mixed (tubuloalveolar).
What is the primary function of glandular epithelium?
To produce and secrete various macromolecules.
How do epithelia receive nutrients?
Nutrients are delivered by diffusion from subepithelial connective tissue blood vessels.
Where do exocrine glands secrete their products?
Onto a surface directly or through epithelial ducts that are connected to a surface.
What does the intestinal lumen refer to?
The inside space of the intestine.
What is the shape of tubular secretory portions?
Either short or long sac-like structures, and coiled.
What are intermediate filaments?
Intermediate filaments are a component of the cytoskeleton that provide structural support to cells.
What are glands?
Specialized organs comprised of epithelial cells that produce and secrete macromolecules.
What is the stria vascularis and where is it found?
The stria vascularis is found in the stratified cuboidal epithelium and is responsible for the production and maintenance of the fluid endolymph in the ductus cochlearis of the inner ear.
What is neuroepithelium?
Neuroepithelium is a type of epithelium involved in sensory functions.
What is the extracellular matrix (ECM)?
The ECM is the material that underlies or surrounds cells in tissues.
Where is pseudostratified ciliated epithelium found in the respiratory system?
In the trachea and bronchial tree.
What is the clinical significance of intermediate filaments?
Intermediate filaments, such as cytokeratins, are used as markers in the diagnosis of certain cancers and other diseases.
What is the shape of alveolar secretory portions?
Rounded.
What is a key characteristic of endocrine glands?
They lack a duct system.
What are the two types of neuroepithelium mentioned?
Taste and olfactory neuroepithelium.
What are unicellular glands?
The simplest in structure, consisting of single cells distributed among other nonsecretory cells.
What types of substances can secretory cells synthesize, store, and release?
Proteins (in the pancreas), lipids (adrenal, sebaceous glands), or complexes of carbohydrates and proteins (salivary glands).
In which type of tissue is the ECM particularly abundant?
Connective tissue.
What are the four basic types of tissue?
Epithelial tissue, Connective tissue, Muscle tissue, and Nervous tissue.
Which part of the male reproductive system contains pseudostratified ciliated epithelium with stereocilia?
The ductus deferens.
What is simple epithelium?
Simple epithelium is built from one layer of cells that are all connected to the basement membrane (BM).
What is histology?
Histology is the study of cells, tissues, and organs of the body, focusing on their development, structure (including ultrastructure), and functions under normal conditions.
How are the cells in epithelial tissue arranged?
The cells in epithelial tissue are tightly packed together with very little intercellular matrix.
What is the shape of mixed (tubuloalveolar) secretory portions?
A combination of tubular and alveolar shapes.
How are cytokeratins used in clinical diagnostics?
Cytokeratins are used as biomarkers to identify the origin of metastatic tumors and to diagnose epithelial cell-derived cancers.
What is surface epithelium?
Surface epithelium is a type of epithelial tissue that covers the outer surface of the body and lines internal organs and structures.
Where can olfactory neuroepithelium be found?
In the nasal cavity, responsible for the sense of smell.
Can glandular epithelial cells occur as single cells?
Yes, they can occur as single cells in epithelia with other major functions.
How do endocrine glands deliver their products to target cells?
They secrete their products into the bloodstream.
What are the main types of glands based on their mode of secretion evacuation?
Exocrine glands and endocrine glands.
What proportion of the body's proteins can the ECM comprise?
Up to half the proteins in the body.
Where can pseudostratified ciliated epithelium be found in the epididymis?
In the efferent ductules.
What is the secretory component of unicellular glands?
Single cells distributed among other nonsecretory cells.
What defines squamous cells in surface epithelium?
Squamous cells are defined by their width being greater than their height.
What does the term 'histology' derive from?
The term 'histology' derives from the Greek words 'histos' meaning tissue and 'logos' meaning study.
What are tight (occluding) junctions and where are they located?
Tight (occluding) junctions are localized apically and display certain proteins such as occludins and claudins.
Where can simple squamous epithelium be found?
Endothelium, mesothelium, cornea, alveoli, and kidney.
What is the function of epithelial tissue?
Epithelial tissue covers body surfaces, lines body cavities, and forms glands.
Why are intermediate filaments important in cancer diagnosis?
They help in identifying the tissue of origin of cancer cells, which is crucial for determining the appropriate treatment.
What is the role of the retina in the context of neuroepithelium?
The retina is a type of neuroepithelium involved in the sense of vision.
What is simple epithelium?
Simple epithelium is built from one layer of cells that are all connected to the basement membrane (BM).
How do exocrine glands evacuate their secretions?
They release their secretions through ducts to an epithelial surface.
What are the products of endocrine glands called?
Hormones.
Which ducts in the salivary glands contain non-ciliated pseudostratified epithelium?
The interlobular ducts.
What is the basal surface in epithelial tissue?
The basal surface is the part of the epithelial cell that rests on the basement membrane.
How does the abundance of ECM in connective tissue compare to the cells it surrounds?
The ECM in connective tissue is frequently more plentiful than the cells it surrounds.
What defines cuboidal cells in surface epithelium?
Cuboidal cells have approximately the same width, depth, and height.
What are the main focuses of histology?
The main focuses of histology are the development, structure (including ultrastructure), and functions of cells, tissues, and organs under normal conditions.
Where can simple cuboidal epithelium be found?
Ovary, kidney, and bronchioles (ciliated).
What are adherent or anchoring junctions and what is their function?
Adherent or anchoring junctions (adhesion belts and desmosomes) are sites of strong cell adhesion, typically 20-30 nm apart.
Where are Goblet cells found?
In pseudostratified ciliated (respiratory) epithelium and intestines.
Where is transitional epithelium commonly found?
In the urinary bladder.
What is the role of connective tissue?
Connective tissue underlies or supports the other three basic tissues, both structurally and functionally.
From which germ layers does epithelium develop?
Epithelium develops from all three germ layers: ectoderm, mesoderm, and entoderm.
Where can you find simple squamous epithelium?
In the endothelium, mesothelium, cornea, alveoli, and kidney.
How is the classification of surface epithelium described?
By describing the number of cell layers (simple or stratified) and the cell shape.
What types of tissue are shown in a section through the tongue?
Nerve fibers, muscle, connective tissue, and blood vessels.
Do all cells in pseudostratified columnar epithelium reach the free surface?
No, all cells rest on the basement membrane but not all reach the free surface.
What are the four classifications of epithelial tissue?
How do endocrine glands evacuate their secretions?
They release their secretions (hormones) directly into the bloodstream.
Where can simple columnar epithelium be found?
Kidney, small intestine, and gall bladder.
What does LM stand for in histology?
LM stands for Light Microscopy.
What staining technique is used to observe transitional epithelium?
Hematoxylin and Eosin (H&E) staining.
What defines columnar cells in surface epithelium?
Columnar cells have a height that appreciably exceeds their width.
What are hemidesmosomes and where are they found?
Hemidesmosomes are found on the basal surface of epithelial cells and are involved in cell adhesion.
Which tissue type is responsible for movement?
Muscle tissue, which is made up of contractile elements.
Which type of epithelium develops from the ectoderm?
Skin epithelium (epidermis) and corneal epithelium.
What is simple epithelium?
Simple epithelium is built from one layer of cells that are all connected to the basement membrane (BM).
What is the function of Goblet cells?
They secrete mucus.
What are the two main types of surface epithelia based on the number of cell layers?
Simple epithelia and stratified epithelia.
What is the primary function of epithelial tissue?
To line all external and internal surfaces of the body.
Where can you find simple cuboidal epithelium?
In the ovary, kidney, and bronchioles (ciliated).
What is the primary difference between exocrine and endocrine glands?
Exocrine glands use ducts to release secretions to an epithelial surface, while endocrine glands release hormones directly into the bloodstream.
Which type of tissue in the tongue is responsible for transmitting signals?
Nerve fibers.
Where can pseudostratified columnar epithelium with cilia be found?
In the trachea.
Where can pseudostratified epithelium be found?
Trachea (ciliated) and ducts of salivary glands (non-ciliated).
Which type of epithelium develops from the mesoderm?
Kidneys.
What type of gland is a Goblet cell?
A unicellular gland.
What are communicating junctions and what proteins do they involve?
Communicating junctions, also known as gap junctions, involve transmembrane channels formed by connexin family proteins.
What is the basic unit of life?
The cell.
What is a key characteristic of transitional epithelium?
It has several layers of cells with surface cells that bulge into the lumen.
What does TEM stand for in histology?
TEM stands for Transmission Electron Microscopy.
What is the function of nervous tissue?
Nervous tissue receives, transmits, and integrates information from both outside and inside the body to control bodily activities.
What are microvilli?
Fingerlike, non-motile processes that protrude from the cell's apical surface.
Where can you find simple columnar epithelium?
In the kidney, small intestine, and gall bladder.
Where can you find simple squamous epithelium?
In the endothelium, mesothelium, cornea, alveoli, and kidney.
What is the function of cilia on the apical surface of pseudostratified columnar epithelium?
Cilia help to move mucus and trapped particles out of the respiratory tract.
How many cell layers does simple epithelium have?
One cell layer.
Which type of tissue in the tongue is responsible for movement?
Muscle tissue.
What is the origin of the term 'epithelial'?
It comes from Greek 'epi' meaning 'upon' and 'thele' meaning 'tissue'.
Which type of epithelium develops from the entoderm?
Respiratory and gastrointestinal system epithelium.
What is a group of similar cells that perform a common function called?
A tissue.
What is stratified epithelium built from?
Several cell layers, with only the cells of the 1st layer connected to the basement membrane (BM) and named as basal cells.
What is the function of microvilli in the intestinal epithelium?
To increase the surface area for absorption.
What is stratified epithelium built from?
Several cell layers, with only the cells of the 1st layer connected to the basement membrane (BM) and named as basal cells.
What type of cells are found at the base of transitional epithelium?
Basal cells.
What is the basement membrane?
A noncellular, protein-polysaccharide-rich layer to which the epithelial cell basal surface is attached.
Where can you find simple cuboidal epithelium?
In the ovary, kidney, and bronchioles (ciliated).
What is the basement membrane (BM) in epithelial tissue?
The basement membrane is a thin, fibrous, extracellular matrix that separates the epithelium from underlying connective tissue.
What is pseudostratified epithelium and where can it be found?
Pseudostratified epithelium appears to be stratified but all cells are connected to the BM. It can be found in the trachea (ciliated) and ducts of salivary glands (non-ciliated).
What is the appearance of epithelium cells that develop from all three germ layers?
They consist of simply structured undifferentiated cells, exhibiting a primitive appearance.
How many cell layers does stratified epithelium have?
Two or more layers.
What is another name for transitional epithelium?
Urothelium.
What are the characteristics of epithelial tissue?
Close cell apposition, presence at a free surface, and little amount of ECM.
Which type of tissue in the tongue provides structural support?
Connective tissue.
What type of secretion do serous cells produce?
Watery fluid.
What forms specialized cell junctions in epithelial tissue?
Cell-to-cell adhesion molecules and cell membranes.
What are the protective functions of epithelial tissue?
Protection from UV, physical force, chemical harm, and antigens, as seen in the stratified squamous epithelium of the skin (epidermis) and the transitional epithelium of the urinary bladder.
What is formed by a group of tissues working together to perform a specific function?
An organ.
What is the cytoskeleton of microvilli composed of?
Actin microfilaments (6 nm).
What are the types of stratified squamous epithelium?
Nonkeratinized, keratinized, and parakeratinized.
What is the shape of the cells in the middle layer of transitional epithelium?
Pear-shaped cells.
What are the types of stratified squamous epithelium?
Nonkeratinized, keratinized, and parakeratinized.
What structures attach the epithelial cell basal surface to the basement membrane?
Hemidesmosomes.
Where can transitional epithelium be found in the body?
Renal calyces, ureters, bladder, and urethra.
Which type of tissue in the tongue is involved in nutrient and oxygen transport?
Blood vessels.
Where can you find simple columnar epithelium?
In the kidney, small intestine, and gall bladder.
What are the characteristics of serous cells?
Cuboidal cells with spherical to elliptical nuclei.
What type of epithelial tissue forms glands?
Glandular epithelium.
How does epithelial tissue function as a selective barrier?
It acts as a selective barrier in the CNS, kidneys, lungs, and testis.
What supports epithelial cells?
The underlying basement membrane (BM).
How is glandular epithelium classified based on the number of cells?
Unicellular or multicellular.
What are the four basic types of tissues in the human body?
Epithelial, connective, muscle, and nervous tissues.
What is the length range of microvilli?
0.5 – 2 μm.
Where can you find nonkeratinized stratified squamous epithelium?
In the cornea and esophagus.
Where can you find nonkeratinized stratified squamous epithelium?
In the cornea and esophagus.
What is the apical surface in epithelial cells?
The apical surface in epithelial cells exhibits special structural surface modifications to carry out specific functions.
What is simple epithelium?
Simple epithelium is built from one layer of cells that are all connected to the basement membrane (BM).
What is epithelial tissue?
Epithelial tissue is a type of tissue that covers the surfaces of the body, lines internal cavities, and forms glands.
What are the characteristics of basal cells in transitional epithelium?
They are roughly cuboidal.
What type of cells are found on the surface of transitional epithelium?
Superficial cells.
What role does epithelial tissue play in transportation?
It transports materials along the surface of an epithelium by motile cilia (e.g., in the trachea) and transports molecules and ions across an epithelium to and from the underlying connective tissue.
Where can serous cells be found?
Salivary glands, sweat glands, pancreatic exocrine part.
What are the two main layers of the basement membrane visible under an electron microscope?
Basal lamina and lamina reticularis.
What is pseudostratified epithelium and where can it be found?
Pseudostratified epithelium appears to be stratified but all cells are connected to the BM. It can be found in the trachea (ciliated) and ducts of salivary glands (non-ciliated).
What does polarity in epithelial cells refer to?
The polarization of organelles within cells.
Which type of epithelial tissue is involved in sensory functions?
Sense epithelium (neuroepithelium).
What is the impact of microvilli in renal proximal tubuli?
They aid in reabsorption.
Where can you find keratinized stratified squamous epithelium?
In the epidermis.
What are the types of ducts in glandular epithelium?
Simple or compound.
What are cilia in epithelial cells?
Cilia are fingerlike extensions that can be motile or non-motile, present in cells specialized for the transport of fluid or mucus over the surface of the epithelium.
What is stratified epithelium built from?
Several cell layers, with only the cells of the 1st layer connected to the basement membrane (BM) and named as basal cells.
Which tissue type covers body surfaces and lines body cavities?
Epithelial tissue.
What shape are the intermediate cells in transitional epithelium?
Polygonal (pear-shaped).
What are the main functions of epithelial tissue?
The main functions of epithelial tissue include protection, absorption, secretion, and sensation.
Where does absorption and reabsorption occur in epithelial tissue?
In the columnar epithelium of the intestines and the proximal convoluted tubules in the kidney.
Where can you find keratinized stratified squamous epithelium?
In the epidermis.
What structure supports the transitional epithelium?
The basement membrane.
What are cytokeratins?
Cytokeratins are an important component of intermediate filaments (10 nm) in epithelial tissue.
What type of secretion do mucous cells produce?
Viscous secretion.
Where can you find simple squamous epithelium?
In the endothelium, mesothelium, cornea, alveoli, and kidney.
What components are found in the lamina lucida of the basal lamina?
Integrins and laminins.
What are some examples of apical surface specializations in epithelial cells?
Microvilli and cilia.
Which type of epithelial tissue has contractile properties?
Myoepithelium.
How are microvilli observed under a light microscope (LM)?
As a brush border.
What is the secretion function of epithelial tissue?
Epithelial tissue forms glands and is involved in secretion, as seen in the salivary, gastric glands, and skin (sebaceous, sweat) glands.
What are the types of stratified squamous epithelium?
Nonkeratinized, keratinized, and parakeratinized.
Where can you find parakeratinized stratified squamous epithelium?
In the oral cavity.
What are the types of secretory units in glandular epithelium?
Alveolar, tubular, or mixed.
How is epithelial tissue classified?
Epithelial tissue is classified based on the number of cell layers (simple or stratified) and the shape of the cells (squamous, cuboidal, or columnar).
Where can you find parakeratinized stratified squamous epithelium?
In the oral cavity.
What is the length of cilia in epithelial cells?
Cilia can be up to 10 μm in length.
What is the main function of connective tissue?
To support and bind other tissues.
Where can you find simple cuboidal epithelium?
In the ovary, kidney, and bronchioles (ciliated).
What components are found in the lamina densa of the basal lamina?
Fibronectin, collagen IV, entactin/nidogen, perlecan, and heparin sulfate-proteoglycans.
What are lateral surface specializations in epithelial cells?
Cell junctions.
What are the characteristics of mucous cells?
Cuboidal cells with flat, elongate nuclei.
Where is Cytokeratin 1 (CK-1) found?
In the epidermis (skin).
What are the characteristics of surface cells (umbrella cells) in transitional epithelium?
They are large and rounded.
How are microvilli observed under an electron microscope (EM)?
As fingerlike processes protruding from the cell's apical surface.
What is the receptor function of neuroepithelium?
Neuroepithelium receives and transduces external stimuli, as seen in the taste buds of the tongue, olfactory epithelium of the nasal mucosa, and the retina of the eye.
Where can you find nonkeratinized stratified squamous epithelium?
In the cornea and esophagus.
What are the types of secretion in glandular epithelium?
Merocrine, apocrine, or holocrine.
What is the basement membrane?
The basement membrane is a thin, fibrous layer that separates the epithelial tissue from the underlying connective tissue.
What structural components make up cilia?
Cilia consist of microtubules (25 nm, cytoskeleton) that comprise the axoneme, which includes tubulin and dynein.
Where is stratified cuboidal epithelium typically found?
In the ducts of sweat glands.
Which tissue type is responsible for movement?
Muscle tissue.
What type of section is used to study the mucosa that lines the underside of the tongue?
Paraffin section.
Where can you find simple columnar epithelium?
In the kidney, small intestine, and gall bladder.
What components are found in the lamina reticularis?
Collagen I, III (reticular) fibers, anchoring fibrils of type VII collagen, proteoglycans, and glycosaminoglycans.
Where can you find stratified cuboidal epithelium?
In the ducts of sweat glands.
