Questions and Answers
What are the 4 basic types of tissues in the body?
What are the 4 major characteristics of epithelial tissues?
Covers and lines body surfaces, cells are densely packed together, cells are firmly attached by intercellular junctions, cells rest on a basement membrane.
What are the 2 functions of a basement membrane?
Anchors epithelium to underlying connective tissue, acts as a selective barrier for diffusion.
How does epithelial tissue derive its nutrients?
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Describe the nerve supply of epithelial tissue.
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Describe the vascularity of epithelial tissue.
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The epithelium develops from what 3 germ layers?
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What specific parts of the body does each germ layer form?
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What are the classifications of epithelial tissue?
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What is the covering of epithelial tissue classified by?
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What are the specific classifications for the number of layers of cells?
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What are the specific classifications for the shape of surface cells?
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What are simple epithelial tissues?
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What are the functions of simple epithelial tissues?
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What are the 4 types of simple epithelial tissues?
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What is the function of simple squamous epithelium and where is it found in the body?
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What is the function of simple cuboidal epithelium and where is it located in the body?
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What is the function of simple columnar epithelium and where is it located?
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What is meant by 'pseudostratified'?
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How do nuclei appear in pseudostratified epithelium?
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What are the 2 subtypes of pseudostratified columnar epithelium and where is each found in the body?
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What are stereocilia?
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What is the main function of stratified epithelial tissues?
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What are the 4 types of stratified epithelial tissues?
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What are the 2 types of stratified squamous epithelium and in what tissues are they found?
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Where is stratified cuboidal epithelium found?
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Where is stratified columnar epithelium found?
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What is transitional epithelium and where is it found?
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How does transitional epithelium appear in its relaxed and stretched state?
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Name and describe the 5 types of cell junctions in epithelial tissues.
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How do desmosomes connect adjacent cells?
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What are the 3 types of surface specialization of epithelial tissues?
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What types of epithelium contain cilia?
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What are some important characteristics of cilia and where are they found?
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What is a brush border and where is it found?
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Describe the appearance and function of microvilli.
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Describe the appearance of stereocilia and comment on its location.
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What is the function of stereocilia?
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What are goblet cells and where are they found?
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What type of gland is a goblet cell?
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What are myoepithelial cells and where are they found?
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What is glandular epithelium and its function?
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Is glandular epithelium vascular or avascular?
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What are the 2 major classifications of glandular epithelium?
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How are glands formed?
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What are exocrine glands?
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What are the 4 criteria for classification of exocrine glands?
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What are the 2 types of branching of exocrine glands? Define each.
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What are the 2 shapes of secretory units? Define each.
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What are the 3 types of secretions? Define and give an example of each.
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What are the 3 modes of secretion of exocrine glands? Define and give examples of each.
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How are endocrine glands classified?
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What are the 2 classifications of endocrine glands? Describe and give examples of each.
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What are the 7 functions of epithelial tissue? Cite locations in the body with each function.
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Study Notes
Basic Types of Tissues
- Four primary types of tissues: epithelial, connective, muscular, nervous.
Characteristics of Epithelial Tissue
- Covers and lines body surfaces.
- Cells are closely packed with little intercellular substance.
- Firm attachment through intercellular junctions.
- Rest on a basement membrane from underlying connective tissue.
Basement Membrane Functions
- Anchors epithelial tissue to connective tissue.
- Serves as a selective barrier for nutrient diffusion.
Nutrient Supply
- Epithelial tissue receives nutrients through diffusion from underlying connective tissue.
Nerve Supply and Vascularity
- Richly supplied with nerve fibers.
- Avascular, meaning it lacks its own blood supply.
Germ Layers and Epithelial Development
- Derived from ectoderm, mesoderm, and endoderm.
- Ectoderm forms the epidermis; endoderm forms the digestive tract epithelium; mesoderm forms the serous lining of cavities.
Classifications of Epithelial Tissue
- Covering/lining epithelium.
- Glandular epithelium (endocrine and exocrine).
- Neuroepithelium (taste buds).
Epithelial Classification Criteria
- Classified by the number of layers (simple or stratified) and shape of surface cells (squamous, cuboidal, columnar).
Simple Epithelial Tissues
- Composed of one cell layer.
- Functions include absorption, diffusion, secretion, and excretion.
- Types include simple squamous, cuboidal, columnar, and pseudostratified columnar.
Specific Functions and Locations
- Simple squamous: major function is diffusion; found in Bowman's capsule, blood vessels, alveoli.
- Simple cuboidal: involved in absorption, secretion; located in kidney tubules, thyroid gland.
- Simple columnar: aids in absorption, secretion; ciliated form found in uterine tubes; non-ciliated in stomach and intestines.
- Pseudostratified: appears layered but is one cell layer; varies in respiratory and male reproductive systems.
Stratified Epithelial Tissues
- Main function is protection against wear and tear.
- Types include stratified squamous, cuboidal, columnar, and transitional.
Stratified Epithelial Locations
- Stratified squamous: keratinized in skin, non-keratinized in oral cavity, vagina.
- Stratified cuboidal: rare, found in small ducts of sweat glands.
- Stratified columnar: rare, found in salivary glands and penile urethra.
- Transitional: changes shape, found in urinary system structures such as bladder.
Cell Junctions
- Types include tight junctions (prevent leakage), adherent junctions (strong adhesion), gap junctions (ion and small molecule transport), desmosomes (connect cells), and hemidesmosomes (attach to connective tissue).
Surface Specializations
- Cilia: propel substances; found in respiratory tract and fallopian tubes.
- Microvilli (brush border): increase surface area for absorption; found in small intestine.
- Stereocilia: long microvilli; located in male reproductive passages, absorb testicular fluid.
Goblet Cells and Myoepithelial Cells
- Goblet cells: modified cells that secrete mucus; found in GI tract and respiratory tract.
- Myoepithelial cells: contractile cells around glandular secretory units; found in lacrimal, salivary, mammary, and sweat glands.
Glandular Epithelium
- Organized collections from covering epithelial cells that synthesize and secrete substances.
- Vascularized.
- Classifications: exocrine (ducts) and endocrine (no ducts).
Exocrine Glands
- Release secretions into ducts.
- Classified based on duct branching (simple or compound), secretory unit shape (tubular or acinar), secretion type (serous, mucous, mixed), and mode (eccrine, apocrine, holocrine).
Endocrine Glands
- Classified by arrangement; include follicular (e.g., thyroid gland) and anastomosing cords (e.g., parathyroid gland).
Functions of Epithelial Tissue
- Protection: covers surfaces and lines organs.
- Absorption: occurs in intestines and kidneys.
- Secretion: performed by glandular epithelium.
- Excretion: conducted by kidneys.
- Sensation: neuroepithelium role in taste.
- Contractility: myoepithelial cells in glands.
- Reproduction: germinal epithelium in ovaries and testes.
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Test your knowledge on the fundamental characteristics and types of epithelial tissues. This quiz will cover the basic types of tissues in the body and the major traits that define epithelial tissue. Ideal for students studying anatomy and physiology.