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Basic Histology > Histology Ch. 4 > Flashcards

Histology Ch. 4 Flashcards

Epithelial Tissue (100 cards)

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1
Q

What are the four basic tissue types in animals?

A

Epithelial, connective, muscular, and nervous tissues

Each type is specialized to perform specific functions.

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2
Q

What does parenchyma refer to in the context of organs?

A

The cells responsible for the organ’s specialized functions

In contrast, the stroma consists of supportive cells.

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3
Q

What is the primary function of epithelial tissues?

A

Covering, lining, and protecting surfaces, absorption, and secretion

Examples include the epidermis and intestinal lining.

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4
Q

Epithelial cells are characterized by their shape. Name the three primary shapes.

A

Columnar, cuboidal, and squamous

Cell shape generally corresponds to its function.

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5
Q

What is the role of the basement membrane in epithelial tissue?

A

Acts as a semipermeable filter and provides structural support

It consists of the basal lamina and reticular lamina.

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6
Q

What types of junctions are found in epithelial cells?

A

Tight junctions, adherent junctions, desmosomes, and gap junctions

These junctions facilitate adhesion and communication between cells.

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7
Q

What is the main characteristic of tight junctions?

A

Form a seal between adjacent cells

Also known as zonulae occludens.

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8
Q

What do adherens junctions do in epithelial cells?

A

Create sites of strong cell adhesion

They often anchor cells to their neighbors.

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9
Q

What is the function of gap junctions?

A

Act as channels for communication between adjacent cells

They allow the passage of ions and small molecules.

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10
Q

Fill in the blank: The _______ is a thin extracellular layer that lies at the interface of epithelial cells and connective tissue.

A

basement membrane

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11
Q

What is the function of the lamina propria?

A

Connective tissue layer that underlies the epithelia lining the organs of the digestive, respiratory, and urinary systems

It contains blood vessels that supply nutrients to epithelial cells.

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12
Q

What type of proteins are involved in the formation of tight junctions?

A

Claudin and occludin

These transmembrane proteins create the seal between cells.

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13
Q

What are myoepithelial cells?

A

Specialized contractile cells found in certain epithelia

They assist in the secretion of glandular products.

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14
Q

True or False: Epithelia contain blood vessels.

A

False

Epithelial tissues receive nutrients via diffusion from underlying connective tissue.

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15
Q

What do papillae do in epithelial tissues?

A

Increase the area of contact between connective tissue and epithelium

They are particularly found in areas subject to friction.

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16
Q

What is the primary role of the basal lamina?

A

Support and organize epithelial cells and maintain cell polarity

It plays a role in various cell activities such as endocytosis and signal transduction.

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17
Q

Fill in the blank: The _______ lamina is a more diffuse meshwork that contains type III collagen.

A

reticular

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18
Q

What is the role of hemidesmosomes?

A

Bind epithelial cells to the underlying basal lamina

They provide stability to the epithelial layer.

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19
Q

What are the two poles of epithelial cells called?

A

Basal pole and apical pole

These regions differ in structure and function.

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20
Q

Describe the function of basement membrane proteins.

A

Mediates cell-to-cell interactions and marks routes for cell migrations

They also assist in epithelial repair and regeneration.

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21
Q

What is the significance of the extracellular matrix (ECM) in connective tissue?

A

Provides structural and biochemical support to surrounding cells

It consists of various proteins and molecules that influence cell behavior.

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22
Q

What bacterium is an important factor in the etiology of gastric ulcers?

A

Helicobacter pylori

Helicobacter pylori binds tight-junction proteins and disrupts signaling.

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23
Q

What type of junction encircles epithelial cells immediately below the tight junction?

A

Adherens junction or zonula adherens

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24
Q

What proteins are responsible for cell adhesion in adherens junctions?

A

Cadherins

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25
What cytoskeletal elements are linked to cadherins in adherens junctions?
Actin filaments
26
What is the function of desmosomes?
Provide firm cellular adhesion and tensile strength
27
Which proteins do desmosomes contain that are larger members of the cadherin family?
Desmogleins and desmocollins
28
What do desmoplakins bind to in desmosomes?
Intermediate filament proteins
29
What type of diseases are associated with abnormal desmosome function?
Blistering (bullous) diseases
30
What is the primary function of gap junctions?
Mediating intercellular communication
31
What are the protein complexes that form gap junctions called?
Connexons
32
What is the diameter of the central pore formed by connexons in gap junctions?
About 1.5 nm
33
What types of molecules can pass through gap junctions?
Molecules with diameters smaller than 1.5 nm
34
What is the term for the anchoring junctions that attach epithelial cells to the basal lamina?
Hemidesmosomes
35
What proteins do hemidesmosomes use to bind to the basal lamina?
Integrins
36
What are focal adhesions linked to in migrating cells?
Bundled actin filaments
37
What signaling protein is associated with focal adhesions?
Focal adhesion kinase
38
What is the primary function of microvilli?
Increase apical surface area for absorption
39
What are the cytoplasmic projections on epithelial cells that reflect the movements of actin filaments?
Microvilli
40
What is the brush border in epithelial cells?
An array of densely packed microvilli
41
What condition is characterized by loss of the microvilli brush border?
Celiac disease
42
What are stereocilia and where are they commonly found?
Long apical processes found in the male reproductive system
43
What is the primary structural difference between cilia and microvilli?
Cilia contain microtubules, while microvilli contain microfilaments
44
What is the arrangement of microtubules in cilia known as?
9 + 2 array
45
What is the role of dynein in ciliary movement?
Facilitates sliding of microtubules
46
What is the function of the basal body in cilia?
Anchors the axoneme to the apical cytoplasm
47
What activates dynein arms in ciliary motion?
ATP ## Footnote Dynein arms bind neighboring microtubules, allowing doublets to slide past each other.
48
What is the role of nexin cross-links in ciliary motion?
They restrict sliding motion between doublets, causing bending of the axoneme.
49
What is the structure that anchors cilia to the cytoskeleton?
Basal bodies ## Footnote Basal bodies have triplets of microtubules and dynamic tubulin protofilaments.
50
What are the two main types of epithelia?
* Covering (lining) epithelia * Secretory (glandular) epithelia
51
How are simple epithelia classified?
According to the number of cell layers and cell morphology.
52
What are the three classifications of simple epithelial cells based on shape?
* Squamous * Cuboidal * Columnar
53
What is the function of simple squamous epithelium?
Regulates passage of substances into underlying tissue ## Footnote Examples include lining of vessels and cavities.
54
What is the difference between keratinized and nonkeratinized stratified squamous epithelium?
* Keratinized: packed with keratin, protects against dehydration * Nonkeratinized: retains nuclei, found in moist internal cavities
55
What type of epithelium lines the urinary tract?
Transitional epithelium (urothelium) ## Footnote Characterized by dome-like superficial cells.
56
What is pseudostratified columnar epithelium?
Epithelial cells that appear stratified but all rest on the basement membrane.
57
What is the role of goblet cells?
Secrete lubricating mucus ## Footnote Common in the lining of the small intestine and respiratory tract.
58
What distinguishes exocrine glands from endocrine glands?
* Exocrine: maintain connection with surface epithelium, have ducts * Endocrine: lose connection, lack ducts
59
What is the function of endocrine glands?
Produce hormones for transport in blood to target cells.
60
Fill in the blank: Transitional epithelium is characterized by _______ cells.
dome-like
61
True or False: Stratified cuboidal and columnar epithelia are common.
False ## Footnote They are relatively rare.
62
What happens to epithelial tissues in chronic vitamin A deficiency?
They may be replaced by stratified squamous epithelium.
63
What is the primary function of stratified squamous epithelia?
Protection against invasion by microorganisms and water loss.
64
What is the primary function of exocrine glands?
Exocrine glands secrete products through ducts to another organ or the body surface.
65
How can exocrine glands be classified based on their duct structure?
Exocrine glands can be classified as simple (not branched) or compound (branched).
66
What are the two types of secretory portions in exocrine glands?
Secretory portions can be tubular (short or long) or acinar (rounded and saclike).
67
What are the three basic mechanisms for secretion in exocrine glands?
* Merocrine secretion * Holocrine secretion * Apocrine secretion
68
What characterizes merocrine secretion?
Merocrine secretion involves typical exocytosis from membrane-bound vesicles.
69
Describe holocrine secretion.
Holocrine secretion involves the complete disintegration of secretory cells, releasing product and cell debris.
70
What is apocrine secretion?
Apocrine secretion involves the pinching off of apical portions of cells, releasing product surrounded by cytoplasm and membrane.
71
True or False: All exocrine glands use merocrine secretion.
False. Exocrine glands can use merocrine, holocrine, or apocrine secretion.
72
What distinguishes serous cells from mucous cells?
Serous cells synthesize proteins that are mostly not glycosylated, while mucous cells produce heavily glycosylated proteins called mucins.
73
What role do myoepithelial cells play in exocrine glands?
Myoepithelial cells help propel secretory products from acini into the duct system.
74
How do endocrine glands differ from exocrine glands in terms of structure?
Endocrine glands lack ducts and secrete hormones directly into the bloodstream.
75
What is the function of the Na+/K+-ATPase pump?
The Na+/K+-ATPase pump extrudes Na+ from cells to maintain low intracellular sodium concentration.
76
Define transcellular transport.
Transcellular transport involves the movement of ions and water through epithelial cells.
77
Fill in the blank: Apical tight junctions prevent _______ diffusion between epithelial cells.
paracellular
78
What is the primary role of epithelial cells in kidney tubules?
Epithelial cells in kidney tubules are specialized for transcellular transport of ions and water.
79
What are mixed seromucous glands?
Mixed seromucous glands contain both serous acini and mucous tubules.
80
What is the significance of the term 'holocrine' in relation to acne vulgaris?
Holocrine glands, such as sebaceous glands, are involved in acne vulgaris due to excessive secretion leading to blocked ducts.
81
What is the effect of contraction in myoepithelial cells?
Contraction of myoepithelial cells compresses the acinus and aids in expulsion of secretory products.
82
True or False: Endocrine glands release their products via ducts.
False. Endocrine glands release hormones directly into the bloodstream.
83
What is the role of capillaries in epithelial tissue?
Capillaries remove water and other substances absorbed across the epithelium. ## Footnote Capillaries are crucial for maintaining fluid balance and nutrient transport.
84
What separates the apical and basolateral compartments in epithelial cells?
Junctional complexes between individual cells. ## Footnote These complexes are essential for maintaining the integrity of epithelial tissues.
85
What process allows cells to internalize extracellular molecules and fluid?
Endocytosis and formation of cytoplasmic, membrane-bound vesicles. ## Footnote This process is critical for nutrient absorption and cellular signaling.
86
What is transcytosis?
The process where pinocytotic vesicles cross thin cells and release their contents on the opposite side by exocytosis. ## Footnote Transcytosis is important for transport across barriers in epithelial tissues.
87
How often does the intestinal epithelium renew itself?
Every week. ## Footnote This rapid turnover is essential for maintaining gut health.
88
Where do stem cells and mitosis occur in stratified epithelial tissues?
Only within the basal layer in contact with the basal lamina. ## Footnote This localization is vital for the regeneration of epithelial tissues.
89
What are carcinomas?
Malignant tumors of epithelial origin. ## Footnote Carcinomas are among the most common cancers.
90
What are adenocarcinomas?
Malignant tumors derived from glandular epithelial tissue. ## Footnote Adenocarcinomas are prevalent in adults after age 45.
91
What is metaplasia?
The transformation of one type of epithelial tissue into another type under abnormal conditions. ## Footnote This process can be reversible and is often seen in smokers.
92
What is the structure of the basement membrane?
A thin extracellular layer consisting of a basal lamina and a more fibrous reticular lamina. ## Footnote The basement membrane supports epithelial cells and regulates substance passage.
93
What are the three major types of intercellular junctions in epithelia?
Tight junctions, adherent junctions, and gap junctions. ## Footnote Each type serves different functions in cellular adhesion and communication.
94
What do tight or occluding junctions prevent?
Paracellular passage of substances between the cells. ## Footnote These junctions are crucial for maintaining the barrier function of epithelia.
95
What are microvilli?
Small membrane projections that increase the apical surface area for absorption. ## Footnote Microvilli are essential for enhancing nutrient uptake in epithelial cells.
96
What is the primary function of exocrine glands?
Synthesis and secretion of specialized products. ## Footnote Exocrine glands play a key role in digestion and other bodily functions.
97
What mechanism do endocrine glands use to secrete hormones?
Hormones are secreted into the interstitial fluid and blood without ducts. ## Footnote This allows hormones to target specific cells throughout the body.
98
What are the three basic secretory mechanisms of glands?
Merocrine, holocrine, and apocrine. ## Footnote Each mechanism describes a different process of secretion.
99
What type of glands produce mucus?
Mucous glands. ## Footnote Goblet cells are examples of mucous-producing cells.
100
What type of glands produce enzymes and are darkly stained with H&E?
Serous glands. ## Footnote These glands are rich in rough endoplasmic reticulum and secretory granules.

Basic Histology (5 decks)

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