Podcast
Questions and Answers
What is a key characteristic of epithelial tissue?
What is a key characteristic of epithelial tissue?
Metaplasia in epithelial tissue refers to what?
Metaplasia in epithelial tissue refers to what?
Which type of epithelium consists of multiple layers of cells?
Which type of epithelium consists of multiple layers of cells?
How is the nutritional support received by epithelial tissue?
How is the nutritional support received by epithelial tissue?
Signup and view all the answers
Which of the following does NOT apply to epithelial tissue?
Which of the following does NOT apply to epithelial tissue?
Signup and view all the answers
What characteristic primarily distinguishes simple squamous epithelium from other types?
What characteristic primarily distinguishes simple squamous epithelium from other types?
Signup and view all the answers
The basement membrane serves what purpose for the epithelium?
The basement membrane serves what purpose for the epithelium?
Signup and view all the answers
Where is simple cuboidal epithelium most likely found?
Where is simple cuboidal epithelium most likely found?
Signup and view all the answers
Which of the following best describes the apical surface of epithelial tissue?
Which of the following best describes the apical surface of epithelial tissue?
Signup and view all the answers
What is the primary function of simple columnar epithelium in the stomach?
What is the primary function of simple columnar epithelium in the stomach?
Signup and view all the answers
Which of the following cell shapes is NOT considered a classification of epithelial tissue?
Which of the following cell shapes is NOT considered a classification of epithelial tissue?
Signup and view all the answers
Which of the following describes pseudostratified columnar epithelium?
Which of the following describes pseudostratified columnar epithelium?
Signup and view all the answers
Which organ is most likely to contain simple squamous epithelium?
Which organ is most likely to contain simple squamous epithelium?
Signup and view all the answers
Ciliated columnar epithelium is typically found in which of the following locations?
Ciliated columnar epithelium is typically found in which of the following locations?
Signup and view all the answers
What is a key feature of simple columnar epithelium?
What is a key feature of simple columnar epithelium?
Signup and view all the answers
Which characteristic is NOT true of simple cuboidal epithelium?
Which characteristic is NOT true of simple cuboidal epithelium?
Signup and view all the answers
What characteristic distinguishes the stratum corneum?
What characteristic distinguishes the stratum corneum?
Signup and view all the answers
In which location is stratified squamous non-keratinized epithelium typically found?
In which location is stratified squamous non-keratinized epithelium typically found?
Signup and view all the answers
Which layer is present only in non-hairy thick skin?
Which layer is present only in non-hairy thick skin?
Signup and view all the answers
What is the primary function of transitional epithelium?
What is the primary function of transitional epithelium?
Signup and view all the answers
Which cell layer is primarily found between the stratum granulosum and stratum corneum?
Which cell layer is primarily found between the stratum granulosum and stratum corneum?
Signup and view all the answers
What defines stratified cuboidal epithelium?
What defines stratified cuboidal epithelium?
Signup and view all the answers
What type of epithelium is specifically referred to as urothelium?
What type of epithelium is specifically referred to as urothelium?
Signup and view all the answers
Which of the following layers contains cells rich in keratohyaline granules?
Which of the following layers contains cells rich in keratohyaline granules?
Signup and view all the answers
What type of gland is characterized by a branched duct and branched tubular secretory parts?
What type of gland is characterized by a branched duct and branched tubular secretory parts?
Signup and view all the answers
Which type of gland produces thin, watery secretions?
Which type of gland produces thin, watery secretions?
Signup and view all the answers
Which feature identifies mucous glands?
Which feature identifies mucous glands?
Signup and view all the answers
What is the morphology of a simple tubuloalveolar gland?
What is the morphology of a simple tubuloalveolar gland?
Signup and view all the answers
Which type of gland is NOT characterized by a branched duct?
Which type of gland is NOT characterized by a branched duct?
Signup and view all the answers
Which type of secretory unit contains nuclei that are spherical and near the center of the cells?
Which type of secretory unit contains nuclei that are spherical and near the center of the cells?
Signup and view all the answers
Where are myoepithelial cells situated in mucous glands?
Where are myoepithelial cells situated in mucous glands?
Signup and view all the answers
What type of secretions do compound alveolar glands produce?
What type of secretions do compound alveolar glands produce?
Signup and view all the answers
What distinguishes pseudostratified columnar ciliated epithelium from stratified epithelium?
What distinguishes pseudostratified columnar ciliated epithelium from stratified epithelium?
Signup and view all the answers
Where is non-ciliated pseudostratified columnar epithelium typically found?
Where is non-ciliated pseudostratified columnar epithelium typically found?
Signup and view all the answers
Which statement about keratinized stratified squamous epithelium is correct?
Which statement about keratinized stratified squamous epithelium is correct?
Signup and view all the answers
What is the function of the stratum basale in stratified squamous epithelium?
What is the function of the stratum basale in stratified squamous epithelium?
Signup and view all the answers
In which location would you expect to find stratified squamous non-keratinized epithelium?
In which location would you expect to find stratified squamous non-keratinized epithelium?
Signup and view all the answers
Which cell layer is associated with desmosomes in stratified squamous epithelium?
Which cell layer is associated with desmosomes in stratified squamous epithelium?
Signup and view all the answers
What is a main characteristic of ciliated pseudostratified columnar epithelium?
What is a main characteristic of ciliated pseudostratified columnar epithelium?
Signup and view all the answers
What process occurs in the stratum spinosum layer of stratified squamous epithelium?
What process occurs in the stratum spinosum layer of stratified squamous epithelium?
Signup and view all the answers
Which zone of the cytoplasm is characterized by the presence of rough endoplasmic reticulum (rER)?
Which zone of the cytoplasm is characterized by the presence of rough endoplasmic reticulum (rER)?
Signup and view all the answers
What type of secretion involves the loss of the entire cell during the process?
What type of secretion involves the loss of the entire cell during the process?
Signup and view all the answers
Which glands have serous cells that form crescent-shaped clusters at the periphery of mucous units?
Which glands have serous cells that form crescent-shaped clusters at the periphery of mucous units?
Signup and view all the answers
What is the role of myoepithelial cells?
What is the role of myoepithelial cells?
Signup and view all the answers
Which type of glands release their secretions without loss of cell material?
Which type of glands release their secretions without loss of cell material?
Signup and view all the answers
Where can neuroepithelium typically be found?
Where can neuroepithelium typically be found?
Signup and view all the answers
Which type of gland involves secretion with apical loss?
Which type of gland involves secretion with apical loss?
Signup and view all the answers
What feature distinguishes the basal zone of the cytoplasm?
What feature distinguishes the basal zone of the cytoplasm?
Signup and view all the answers
Study Notes
Epithelial Tissue
- Epithelial tissue is one of the four basic tissues in the body, the others being connective, muscular, and nervous tissues.
- It forms a sheet of aggregated, similar cells.
- It covers body surfaces, lines hollow organs, and forms glands.
- It originates from one of the three embryonic germ layers (ectoderm, mesoderm, and endoderm).
- It is composed of many similar cells close together, with little intercellular substance.
- Cells adhere to one another via specialized cell junctions.
- All epithelia have an apical surface, which faces the body surface or the lumen of a hollow organ.
- Epithelia are separated from underlying connective tissue by a basement membrane.
- Epithelial tissue is avascular; blood and lymph vessels do not penetrate it.
- Nutrients are delivered via diffusion.
- While not highly vascular, it is highly innervated.
- Epithelial cells have a high capacity for regeneration.
- Epithelial tissue can change from one form to another in a process called metaplasia.
- Functions include protection, secretion, excretion, absorption, sensory reception, and contraction.
Classification
- Epithelial tissue is classified into four types: epithelial membranes, glandular epithelium, myoepithelium, and neuroepithelium.
- Epithelial membranes are further classified based on cell layers (Simple vs. Stratified) and cell shape (Squamous, Cuboidal, Columnar).
- Simple Epithelium: a single layer of cells.
- Stratified Epithelium: two or more layers of cells.
- Shapes of epithelial cells include:
- Squamous: scale-like.
- Cuboidal: cube-like
- Columnar: pillar-like.
Simple Epithelium
-
Simple Squamous Epithelium
- One layer of thin, flat, scale-like cells.
- Cells have an irregular shape with a slightly serrated border.
- Nuclei are centrally located (spherical or oval).
- Found in lung alveoli, glomerular capsule, linings of blood and lymph vessels (endothelium), serous membranes (mesothelium), subarachnoid and subdural spaces (mesenchymal epithelium), anterior chamber of the eye, and perilymphatic spaces of the ear.
-
Simple Cuboidal Epithelium
- One layer of cube-like cells (width and height are nearly equal).
- Cells are squares in cross-section with centrally located spherical nuclei.
- Located in glands and organs with secretory or absorptive functions: e.g. thyroid follicles, glands' ducts, kidney tubules.
-
Simple Columnar Epithelium
- One layer of tall, narrow cells with height greater than width.
- Nuclei are oval and located near the base of the cells.
- Found in stomach lining, oviducts, bronchioles, small intestine, and gall bladder (absorptive function).
-
Pseudostratified Columnar Epithelium
- Composed of single layer of irregular cells.
- All cells rest on the basement membrane, but not all reach the luminal surface.
- Nuclei located at different levels, creating a false impression of stratification.
- Cells reaching the surface are either ciliated or goblet cells, with short cells acting as progenitors for tall cells.
- Located in trachea, auditory tube, male urethra, and epididymis.
Stratified Epithelium
-
Stratified Squamous Epithelium
- Several layers of cells; with only superficial cells having squamous shape.
- Types: non-keratinized and keratinized.
- Non-keratinized: surface cells are living with nuclei, and kept moist by local glandular secretions. Found in oral cavity, pharynx, esophagus, anal canal, and vagina.
- Keratinized: surface cells are dead and lose their nuclei. They contain keratin, a water-resistant protein forming a non-living covering. Found in skin, epidermis of thick skin (palm and sole), hooves, horns, and feathers.
-
Stratified Cuboidal Epithelium
- Two or more layers of cells, with superficial cells being cuboidal, usually seen as two-layered epithelium.
- Found in large ducts of sweat and salivary glands.
-
Stratified Columnar Epithelium
- Several layers of cells, with only superficial cells being columnar.
- Found in distal portion of the urethra, ducts of parotid and mandibular glands, lacrimal sac, and parts of the lacrimal duct.
-
Transitional Epithelium
- A stratified epithelium found only in the urinary tract (lines the ureter and urinary bladder = urothelium).
- Highly specialized to stretch and withstand urine toxicity.
- 4 to 6 cells thick.
- Differences (compared to other stratified squamous epithelium): Cells at the surface are not squamous; deepest cells are columnar or cuboidal; middle layers are made of polyhedral or pear-shaped cells; surface cells are large and often shaped like an umbrella.
Glandular Epithelium
-
Classification of Glandular Epithelium: based on the presence or absence of ducts (exocrine vs. endocrine) and the microscopic structure of the glands (e.g. tubules or alveoli).
- Exocrine: have duct systems that convey secretions to sites of utilization (eg. salivary glands).
- Endocrine: secrete products into the blood stream with no duct system (eg. thyroid glands).
- Paracrine: secrete products into the local extracellular space, affecting surrounding cells (eg.enteroendocrine cells of GIT)
- Unicellular: a single secretory cell (e.g. goblet cell)
- Multicellular: clusters of cells (e.g. salivary glands and pancreas)
- Types Based Morphology: Simple tubular, Simple acinar/alveolar, Simple tubuloalveolar, Simple branched tubular, Simple branched alveolar, Simple branched tubuloalveolar, Compound tubular, Compound alveolar, Compound tubuloalveolar
-
Types of Glands Based on Secretion:
- Merocrine: cells remain intact during secretion
- Apocrine: apical parts of the cells are lost during secretion
- Holocrine: products are secreted with whole cell destruction secretion with the whole cell disintegrating in glands such as sebaceous glands
-
Serous glands: Produce thin, watery secretions.
- Pyramidal shaped secretion cells.
- Nuclei are spherical and centrally located
- Cytoplasm has two zones: basophilic (rER) and eosinophilic (zymogen granules.
-
Mixed glands: Such as seromucous.
- Primarily mucous secretory units with crescent-shaped clusters of serous cells (serous demilunes) located on the periphery of the mucous units.
- Serous secretion reaches the lumen through intercellular canaliculi located between the mucous cells.
Myoepithelial Cells
- Myoepithelial cells are specialized flattened cells with cytoplasmic processes.
- Lie between secretory cells and the basement membrane.
- Processes form a basket-like network (basket cells) around the secretory units of certain glands.
- Cytoplasm is rich in actin and myosin filaments.
- Contraction forces secretory products into the duct system.
- Found in salivary, sweat, and mammary glands
Neuroepithelium
- A special type of epithelium designed to receive sensory stimuli.
- Examples: taste buds and olfactory epithelium.
- Related to digestive and respiratory systems.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
