Chapter 2: Epithelial And Glands Flashcards by Aeron Justine Aquino

groups of cells that are similar in structure and function.

Tissues

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A sheet of aggregated cells forming the body’s external and internal surfaces.

Epithelium

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Epithelium originates from all three germ layers:

ectoderm, endoderm, and mesoderm.

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Epithelium is separated from underlying connective tissue by a?

basement membrane

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Epithelium are ? receiving nutrients through diffusion from connective tissue.

Avascular

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Constantly renewed due to wear and tear

Epithelium

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Separates epithelium from connective tissue

Basement Membrane

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Basement Membrane may consist of two layers:

basal lamina and reticular lamina, or just the basal lamina

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This layer of basement membrane is present in all epithelia.

Basal Lamina

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This layer of basement membrane composition is poorly understood

Reticular Lamina

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Single layer of cells resting on the basement membrane

Simple Epithelium

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made up of two or more layers of cells with only basal cell layer resting on the basementmembrane

Stratified epitherlium

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wider than tall (plate or “scale” like)

Squamous cells

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are as wide as tall, as in cubes

Cuboidal cells

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are taller than they are wide, like columns

Columnar cells

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Thin, flat cells lining body cavities, heart, and blood vessels

Endothelium

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Lines closed body cavities (pleural, pericardial, peritoneal)

Mesothelium

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Lines heart, blood, and lymph vessels

Endothelium

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Lines subarachnoid and subdural spaces, anterior chamber of the eye, perilymphatic spaces of the ear

Mesenchymal

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Description
- consists of a single layer of cells with width and height approximately equal.
- cells appear as squares in cross-sections but are more hexagonal when viewed from the surface.

Function
- depending on their location, this cells may have absorptive or secretory functions.

Location
- lines the ducts of glands and covers the choroid plexus and ciliary body of the eye.

Simple cuboidal epithelium

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When the height is slightly less than the width, it is referred to as?

tall cuboidal epithelium

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Description
- Single layer of column-shaped (rectangular) cell oval nuclei
- Some bear cilia at their apical surface
- May contain goblet cells

Function
- Absorption; secretion of mucus, enzymes, and other substances

Location
- Respiratory and reproductive system

Simple Columnar Epithelium

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Description
- Composed of a single layer of cells with irregular shapes and sizes.
- Only tall cells reach the apical surface
- May contain goblet cells and bear cilia
- Nuclei lie at varying heights within cells

Function
secretion of mucus; propulsion of mucus by cilia

Locations
Non-ciliated type
- Ducts of male reproductive tubes
- Ducts of large glands

Ciliated variety
- Lines trachea and most of upper respiratory tract

Pseudostratified Columnar

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Several layers with squamous-shaped surface cells

Stratified Squamous Epithelium

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type of Stratified squamous epithelium found on wet surfaces subjected to wear and tear, without absorptive function (e.g., mouth, esophagus, vagina).

Non-keratinized

type of Stratified squamous epithelium found in skin, with surface cells filled with keratin, a water-resistant protein

Keratinized

The deepest layer, consisting of a single layer of cuboidal to columnar cells. It is rich in polyribosomes for tonofilament synthesis and mitotic figures.

Stratum Basale

A layer composed of multiple layers of polyhedral cells tightly adhered by desmosomes. The cells appear "spiny" due to cytoplasmic shrinkage.

Stratum Spinosum

A layer of granulated cells that accumulate keratohyaline granules. It is not present in all stratified squamous epithelia, particularly in non-keratinized forms or those producing hard keratin

Stratum Granulosum

A translucent layer found only in non-hairy skin regions, positioned between the Stratum Granulosum and Stratum Corneum. It contains eleidin, a protein similar to keratin.

Stratum Lucidum

Outermost layer of dead, keratinized cells providing environmental protection, with cells flaking off due to weakened junctions.

Stratum Corneum

Description: - Two or more layers with cuboidal surface cells Location: - lining excretory ducts of glands. Function: - Protection and secretion

Stratified Cuboidal

Description: - Several layers with columnar surface cells. Location: - Distal portion of the urethra, parotid and mandibular ducts, lacrimal sac and duct. Function: - Protection and secretion

Stratified Columnar

Description: - Basal cells usually cuboidal or columnar - Superficial cells dome-shaped or squamous - It is characterized by its ability to change shape depending on the distention of the organ it lines. - When the epithelium is relaxed, the surface cells are large and pillow-shaped, while deeper cells are smaller and irregularly shaped. Function: - stretches and permits distension of urinary bladder Location: - Lines ureters, urinary bladder and part of urethra

Transitional Epithelium

Cells with cilia on their luminal surface, found in respiratory and reproductive systems.

Ciliated

Modified epithelium to receive and transmit sensory information (e.g., olfactory cells, gustatory cells, hair cells).

Neuroepithelium

Contains intracytoplasmic pigments (e.g., melanin in the retinal pigment epithelium)

Pigmented

Specialized epithelial cells associated with exocrine glands, containing myofibrils and contractile elements for expressing secretory products.

Myoepithelium

Carbohydrate-rich surface coat.

Glycocalyx

Structures that connect cells.

Junctional Complexes

Fusion of outer layers of cell membranes.

Zonula Occludens (Tight Junction)

Slight separation of cell membranes.

Zonula Adherens (Intermediate Junction)

Spot-weld like attachment between cells.

Macula Adherens (Desmosomes)

Passageways for ions and small molecules

Gap Junctions

Structureless membrane upon which all epithelia rest.

Basal Lamina

Bulb-like,invaginations of the cell membrane.

Caveolae

Half of a desmosome found along the basal cell membrane

Hemidesmosomes

Finger-like projections increasing surface area for absorption.

Microvilli

are apoptotic extracellular vesicles that form around the nucleus of an apoptotic cell

Pyknotic vesicles

They are released when the cell dies

Caveolae and Pyknotic Vesicles

Whip-like structures capable of movement

Cilia

Long, slender cilia for moving materials along epithelium.

Kinocilia

Extremely long, branched microvilli for facilitating secretory activity

Stereocilia

are structures derived from the epithelium of varying complexities and highly specialized to perform secretory functions.

Glands

consist of a single secretory cell in a nonsecretory epithelium. The goblet cell is an example of this type of gland scattered throughout the respiratory and digestive systems. It is a specialized epithelial cell that produces mucinogen, which is released onto the epithelial surface.

Unicellular glands

are composed of more than one secretory cell that is grouped to form secretory units called adenomeres.

Multicellular glands

occur as a cluster of only few secretory cells within a surface epithelium.

Intraepithelial glands

are large accumulations of cells that have proliferated into the underlying connective tissue.

Extraepithelial glands

are multicellular glands without a system of ducts to convey their secretory products to the site of utilization. The secretory products (hormones) are released directly into the intercellular fluid, from which it is transported to the site of action by the blood and lymph.

Endocrine glands

are multicellular glands with a system of ducts through which their secretory products are transported to the site of utilization.

Exocrine glands

consist of single or several secretory units connected to the surface through the unbranched duct.

Simple glands

- hollow cylinder simple gland

Tubular (straight, coiled, branched)

-globular or pear-shaped simple gland

Acinar/Alveolar (single, branched)

-combination of both simple gland

Tubuloacinar/Tubuloalveolar

have large number of secretory units emptying into a branched duct system.

Compound glands

is the portion that connects to the surface upon which the glands empties its secretions.

Excretory main duct

drain the lobes and are connected to excretory ducts.

Interlobar or lobar ducts

are large continuation of lobar ducts within the gland.

Intralobar ducts

drain the lobules.

Interlobular ducts

are continuation of lobular duct within the lobule.

Intralobular or striated ducts

are continuation of striated ducts

Intercalated ducts

secrete clear watery product, secretory units have spherical nuclei near the center of the cells, and the apical cytoplasm is filled with small secretory granules

Serous glands

Serous glands- secrete clear watery product, secretory units have spherical nuclei near the center of the cells, and the apical cytoplasm is filled with small secretory granules. These granules are precursors of enzymes produced by many of the serous glands and are called?

zymogen granules

produce a thick, viscous secretion forming a protective coat over the lining of hollow organs that communicate outside of the body. The nuclei are displaced toward the basal part of the cell and are usually flattened against the cell membrane. The cells of mucus-secreting units are filled with mucinogen, the precursor of mucus.

Mucous glands

are combination of both containing serous and mucous cells. The serous cells are located at the periphery of the mucus-secreting unit and are half-moon or crescent-shaped clusters of cells called serous demilune

Seromucous glands (mixed)

Seromucous glands (mixed) are combination of both containing serous and mucous cells. The serous cells are located at the periphery of the mucus-secreting unit and are half-moon or crescent-shaped clusters of cells called?

serous demilune

mode of secretion is one which releases product as secretory granules enclosed within the membrane referred to as granulated vesicles. The secretory product is discharged from the cell without any disruption of the plasmalemma or any loss of its cytoplasmic components. This is an example of exocytosis. Typical of salivary glands

Merocrine (eccrine)

mode of secretion, one in which the apical part of the cytoplasm of the cell is discharged together with the,secretion. The intracellular secretory droplet is surrounded by a unit membrane. The membrane-bound droplet together with a rim of cytoplasm and plasmalemma is released from the cell leaving the cell membrane intact. Typical of most sweat glands of domestic animals

Apocrine

mode of secretion is one in which the whole cell is secreted together with its secretion. Typical of sebaceous glands

Holocrine

mode of secretion is an unusual transfer of secretory material from one cell to the cytoplasm of another cell. This occurs when the melanocyte of the epidermis transfers the brown melanin pigment into the cytoplasm of the keratinocyte

Cytocrine