General Histology: Epithelial Tissue
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Questions and Answers

What characteristic allows transitional epithelium to function without leakage during stretching?

  • Presence of multiple cell layers
  • Presence of tight junctions between cells (correct)
  • Absence of a basement membrane
  • Ability to change cell shape (correct)

Which of the following accurately describes pseudo-stratified epithelium?

  • Is exclusively ciliated
  • Lines the urinary bladder
  • Consists of multiple layers of cells
  • Has nuclei located at varying levels (correct)

What distinguishes exocrine glands from endocrine glands?

  • Endocrine glands are involved in digestion
  • Endocrine glands secrete into ducts
  • Only exocrine glands secrete hormones
  • Only exocrine glands have ducts (correct)

What type of secretion do mucous glands produce?

<p>Thick, viscid material (A)</p> Signup and view all the answers

Which is an example of pseudo-stratified columnar ciliated epithelium?

<p>Trachea (B)</p> Signup and view all the answers

How do transitional epithelium cells change shape when the urinary bladder is full?

<p>Become flat and irregular (C)</p> Signup and view all the answers

Which germ layer is responsible for the development of epithelial tissues such as the lining of the gastrointestinal tract?

<p>Endoderm (B)</p> Signup and view all the answers

What type of gland consists of a single secretory cell?

<p>Unicellular gland (C)</p> Signup and view all the answers

Which statement about epithelial tissue is incorrect regarding its structure?

<p>Epithelial tissues contain a significant amount of intercellular substance. (D)</p> Signup and view all the answers

What is the primary characteristic that distinguishes simple epithelium from stratified epithelium?

<p>Simple epithelium consists of only one layer of cells. (C)</p> Signup and view all the answers

Which structure serves as the lining for organs subjected to tension?

<p>Transitional epithelium (C)</p> Signup and view all the answers

Which type of epithelium consists of cells arranged in a single layer but may appear to have multiple layers?

<p>Pseudo-stratified epithelium (A)</p> Signup and view all the answers

What is the significance of the high turnover rate of epithelial tissue?

<p>It allows for rapid healing and regeneration. (D)</p> Signup and view all the answers

Which epithelial tissue would most likely develop from mesodermal origin?

<p>Endothelium of blood vessels (D)</p> Signup and view all the answers

Why are epithelial tissues more susceptible to mutations compared to other tissue types?

<p>They experience high turnover rates. (B)</p> Signup and view all the answers

Which classification of epithelium primarily consists of cells arranged in sheets for protection?

<p>Stratified epithelium (D)</p> Signup and view all the answers

Which characteristic is true about elastic cartilage compared to hyaline cartilage?

<p>It is more flexible and elastic. (D)</p> Signup and view all the answers

Where can fibrocartilage be typically found?

<p>In intervertebral discs. (B)</p> Signup and view all the answers

What is the primary structural feature of skeletal muscle tissue?

<p>It is striated and voluntary. (D)</p> Signup and view all the answers

What distinguishes smooth muscle tissue from other types of muscle tissue?

<p>It has tapering, elongated fibers. (A)</p> Signup and view all the answers

Which statement accurately describes the collagen fibers in fibrocartilage?

<p>They are arranged in parallel bundles along the direction of stress. (D)</p> Signup and view all the answers

How does the cytoplasm of muscle cells, known as sarcoplasm, differ from that of typical cells?

<p>It is rich in myofibrils and proteins. (C)</p> Signup and view all the answers

What is unique about the arrangement of chondrocytes in fibrocartilage?

<p>They are arranged in rows between collagen bundles. (B)</p> Signup and view all the answers

Which muscle type is classified as striated and involuntary?

<p>Cardiac muscle. (B)</p> Signup and view all the answers

What is the shape of the nuclei in skeletal muscle fibers?

<p>Oval and peripheral (C)</p> Signup and view all the answers

What distinguishes the A band in myofibrillar banding?

<p>Contains thick myofilaments of myosin (C)</p> Signup and view all the answers

Where is smooth muscle primarily distributed?

<p>In hollow viscerae and blood vessels (C)</p> Signup and view all the answers

Which of the following accurately describes the contraction of smooth muscle?

<p>Slow, sustained, and resistant to fatigue (C)</p> Signup and view all the answers

What primarily composes the light band (I band) in muscle fibers?

<p>Thin myofilaments (actin) only (C)</p> Signup and view all the answers

What happens to the size of skeletal muscle fibers during periods of disuse?

<p>Decreases in diameter and length (A)</p> Signup and view all the answers

What structural unit is formed between successive Z lines in muscle fibers?

<p>Sarcomere (D)</p> Signup and view all the answers

Which of the following statements about myofibrils is accurate?

<p>They contain fundamental units called myofilaments. (C)</p> Signup and view all the answers

What type of cells primarily line the lumen of arteries in the tunica intima?

<p>Polygonal endothelial cells (C)</p> Signup and view all the answers

Which artery type contains 40-60 bands of elastic tissue in its tunica media?

<p>Elastic arteries (C)</p> Signup and view all the answers

What is a key characteristic of the internal elastic lamina in muscular arteries?

<p>It is prominent and appears as a wavy band (B)</p> Signup and view all the answers

Which component primarily makes up the tunica adventitia of elastic arteries?

<p>Bundles of collagen fibres (C)</p> Signup and view all the answers

In terms of thickness, how does the tunica media of muscular arteries compare to their lumen?

<p>Significantly thicker than the lumen (D)</p> Signup and view all the answers

Which layer of elastic arteries comprises up to 80% of the total thickness of the aortic wall?

<p>Tunica Media (D)</p> Signup and view all the answers

What characterizes the tunica adventitia in muscular arteries compared to elastic arteries?

<p>It is thinner than the media (B)</p> Signup and view all the answers

What role do vasa vasorum play in blood vessels?

<p>They supply blood to the outer layers of larger arteries (B)</p> Signup and view all the answers

What is characteristic of the cytoplasm of mucous-secreting cells?

<p>It appears vacuolated and basophilic. (D)</p> Signup and view all the answers

Which gland type is characterized by the total disintegration of secretory cells to release their contents?

<p>Holocrine gland (B)</p> Signup and view all the answers

What distinguishes the histological appearance of serous secreting cells?

<p>Triangular shape with basophilic apical cytoplasm. (B)</p> Signup and view all the answers

Which gland primarily produces a clear, watery fluid containing enzymes?

<p>Parotid gland (D)</p> Signup and view all the answers

What feature identifies mixed glands in terms of secretory structure?

<p>Distinct crescent-shaped serous units. (D)</p> Signup and view all the answers

Which type of gland secretes material by discharging part of the cell?

<p>Apocrine gland (A)</p> Signup and view all the answers

What is a defining characteristic of merocrine glands?

<p>Discharge of secretory material without loss of cell parts. (A)</p> Signup and view all the answers

What defines the shape of tubular exocrine glands?

<p>Hollow cylinder shape. (A)</p> Signup and view all the answers

Flashcards

What are the four primary tissues of the human body?

The four main types of tissue found in the human body: epithelial, connective, muscular, and nervous.

What is epithelial tissue?

A continuous layer of cells with minimal intercellular substance, arranged in sheets or masses. Epithelial cells rest on a basement membrane and lack blood vessels and lymph vessels.

Where does ectoderm-derived epithelial tissue develop?

Epithelial tissue that forms the outer layer of skin, lining of the mouth and anus.

Where does endoderm-derived epithelial tissue develop?

Epithelial tissue that forms the lining of the digestive and respiratory tracts, as well as glands.

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Where does mesoderm-derived epithelial tissue develop?

Epithelial tissue that forms the lining of blood vessels and lymphatic vessels, as well as the mesothelium of body cavities like the pleura.

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How is epithelium classified?

Epithelial tissue classified based on its function, either providing a covering or lining (like skin) or producing secretions (like glands).

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What is the turnover rate of epithelial tissue?

Epithelial tissue has a rapid turnover rate, meaning cells are constantly being replaced. This rate varies depending on location and function.

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What is simple epithelium?

Simple epithelium is characterized by a single layer of cells, all of which touch the basement membrane.

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Elastic Cartilage

This type of cartilage offers flexibility and elasticity, found in the ear and epiglottis.

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Transitional Epithelium

A type of epithelium that can stretch and change shape, found in organs that need to expand and contract, like the urinary bladder. It has multiple layers of cells that can flatten and become thinner when stretched.

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Pseudostratified Epithelium

A type of epithelium that appears to have multiple layers, but actually only has one layer of cells. The nuclei of the cells are at different levels, giving the illusion of multiple layers.

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Fibrocartilage

A strong, supportive cartilage with bundles of collagen fibers, found in intervertebral discs and pubic symphysis.

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Muscle Tissue Classification

Muscle types can be categorized by their structure and function.

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Pseudostratified Columnar Ciliated Epithelium

A type of pseudostratified epithelium that has cilia, hair-like structures that help move fluids or particles.

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Pseudostratified Columnar Non-ciliated Epithelium

A type of pseudostratified epithelium that lacks cilia and has a columnar shape.

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Muscle Fiber Structure

Muscle cells are elongated and called fibers.

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Exocrine Glands

Glands that secrete their products into ducts, which then carry the secretions to their target organ.

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Myofibrils and Contractile Proteins

Myofibrils within muscle fibers contain two types of protein filaments: actin and myosin.

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Endocrine Glands

Glands that release their products directly into the bloodstream, without any ducts.

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Sarcoplasm and Sarcolemma

Muscle cells have specialized cytoplasm called sarcoplasm and a cell membrane called sarcolemma.

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Functional Classification of Muscle

Muscle can be divided into voluntary (conscious control) and involuntary (automatic).

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Mucous Glands

A type of exocrine gland that secretes a thick, sticky substance called mucin. These glands are often found in the digestive and respiratory systems.

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Structural Classification of Muscle

Muscle can also be classified based on its appearance: striated (striped) or non-striated (smooth).

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Serous Glands

A type of exocrine gland that secretes a watery, protein-rich fluid. These glands are often found in the digestive and salivary systems.

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Mucous Gland Structure

Characterized by the presence of large, rounded lumena in their acini and cuboidal or low columnar cells that secrete mucin.

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Serous Gland Structure

Characterized by small, rounded lumena in their acini and triangular cells with a deeply basophilic cytoplasm.

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Mixed Glands

These glands contain both serous and mucous secretory units.

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Serous Demilunes

Serous demilunes are crescent-shaped structures that cap over the mucous acini in mixed glands.

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Smooth Muscle

Muscle tissue responsible for involuntary, slow, sustained contractions. It is found in the walls of hollow organs like the stomach, bladder, and blood vessels.

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Smooth Muscle Cell Structure

A type of muscle tissue characterized by elongated, spindle-shaped cells with a single centrally located nucleus.

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Sarcolemma (Smooth Muscle)

The plasma membrane of a smooth muscle cell, responsible for transmitting signals and maintaining cell integrity.

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Sarcoplasm (Smooth Muscle)

The cytoplasm of a smooth muscle cell, containing myofilaments responsible for contraction.

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Sarcomere

The functional unit of a skeletal muscle fiber, extending between two Z-lines.

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A Band

A dark band in a skeletal muscle fiber, containing thick myosin filaments.

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I Band

A light band in a skeletal muscle fiber, containing thin actin filaments.

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M Line

A dark line in the center of the A band, representing the attachment point for myosin filaments.

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What are elastic arteries?

Large arteries with elastic fibers that conduct blood from the heart to muscular arteries.

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Name three examples of elastic arteries.

Aorta, common carotid artery, and pulmonary artery are examples of elastic arteries.

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What is the Tunica Intima?

This is the innermost layer of arteries, made up of endothelial lining, subendothelial layer, and internal elastic lamina.

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What is the Endothelial Lining?

It's a thin layer of polygonal cells that line the lumen of arteries.

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What is the Subendothelial Layer?

This layer is thick and contains elastic fibers, collagen fibers, and smooth muscle cells.

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What is the Tunica Media?

This layer is thick and made up of concentric layers of elastic laminae, collagen fibers, fibrocytes, and muscle cells.

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What is the Tunica Adventitia?

The outermost layer of arteries, composed mainly of collagen fibers and vasa vasorum.

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What are muscular arteries?

Muscular arteries are smaller distributing arteries with thicker walls in relation to their lumen, like the brachial, radial, ulnar, femoral, and popliteal arteries.

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Study Notes

General Histology Contents

  • General Histology: page 1
  • Histology of Epithelial Tissue: page 1
  • Histology of Connective Tissue: page 15
  • Histology of Bone and Cartilage: page 23
  • Histology of Muscular Tissue: page 30
  • Histology of Blood Vessel: page 35
  • Histology of Nervous Tissue: page 43

Histology of Epithelial Tissue

  • Body is composed of cells, intercellular substances and tissue fluid
  • Body develops from 3 germ layers: Ectoderm, Mesoderm, and Endoderm
  • These 3 germ layers formed the 4 primary tissues: epithelial, connective, muscular, and nervous tissue
  • Epithelial tissue is continuous layer(s) of cells with little to no intercellular substance
  • Epithelial cells are arranged in sheets or masses
  • Epithelial cells rest on basement membrane which is avascular and alymphatic
  • Epithelial tissue develops from ectoderm, endoderm, or mesoderm
  • Epithelium develops from ectoderm: skin, mouth, anus
  • Epithelium develops from endoderm: lining of gastrointestinal tract, respiratory tract, glands
  • Epithelium develops from mesoderm: lining of blood vessels, lymphatic vessels, coelomic cavity (e.g., pleura)
  • Epithelia have the highest turnover rate of the four basic tissue types
  • Turnover rate varies depending on location and function
  • Skin epithelium turns over every 30 days
  • Colonic mucosal epithelium turns over every week

Simple Epithelium

  • Consists of only one layer of cells, with all cells touching the basement membrane
  • Divided in three types based on cell shape
  • Simple squamous
  • Simple cuboidal
  • Simple columnar

Simple Squamous Epithelium

  • Composed of one layer of flat or squamous cells resting on the basement membrane
  • Cells are irregular in outline, similar to platform plates
  • Nucleus is single, round, and centrally positioned

Simple Cuboidal Epithelium

  • Composed of a single layer of cubic or square shaped cells resting on the basement membrane
  • Cells appear hexagonal
  • Nucleus is single, round, and centrally positioned
  • Function includes protection, secretion, and absorption

Simple Columnar Epithelium

  • Composed of a single layer of tall cells resting on the basement membrane
  • Cells appear hexagonal
  • Nucleus is single, oval, and basally positioned
  • Functions include protection, lining, and secretion
  • It lines gastrointestinal tract (stomach to upper half of anal canal), excretory ducts of kidney, and uterine tube

Stratified Epithelium

  • More than one cell layer
  • Only the basal layer touches the basement membrane
  • Classified into 4 types
  • Stratified squamous
  • Stratified cuboidal
  • Stratified columnar
  • Transitional epithelium

Stratified Squamous Epithelium

  • Consists of multiple layers of cells, resulting in the exposed surface of the epithelium being squamous
  • Divided into keratinized and nonkeratinized based on presence or absence of keratin
  • Keratinized examples: skin
  • Nonkeratinized examples: tongue, esophagus, vagina, and palatine tonsil.

Stratified Cuboidal Epithelium

  • Superficial layer of cells is cuboidal in shape
  • Function includes protection and secretion
  • Found in ducts of sweat glands, multilayered primary ovarian follicles

Stratified Columnar Epithelium

  • Superficial layer of cells is columnar
  • Function is protection
  • Found in conjunctiva and cavernous portion of male urethra

Transitional Epithelium

  • The cells change shape depending on the degree of distension of the organ
  • Lines hollow organs (e.g., urinary bladder) that are prone to stretching
  • No obvious basement membrane
  • There is a superficial cell layer appearing as umbrella shaped, with nuclei that are single and central
  • In relaxed state, there are multiple layers of pear-shaped cells
  • In stretched state, shapes flatten and layers decrease to 2 or 3
  • Lines organs subjected to tension, such as urinary bladder, ureter, urethra near bladder, covering calyces, and pelvis of the kidney

Pseudostratified Epithelium

  • One layer of cells but appears multilayered because nuclei are at different levels
  • All cells touch the basement membrane but not all reach the surface
  • Two types
  • Pseudostratified columnar ciliated
  • In respiratory tract
  • Pseudostratified columnar nonciliated
  • Lining the penile urethra

Histology of Glandular Epithelium

  • Glandular tissue is specialized for secretory functions
  • Two types of glands
  • Exocrine
  • Endocrine

Classification of Exocrine Glands

  • Based on Cell Number/Nature of Secretion
    • Unicellular*: One cell (e.g., goblet cell)
    • Multicellular*: More than one cell
  • Mucous—secrete thick, viscid material called mucin (e.g., sublingual salivary gland)
  • Serous—secrete clear, watery fluid with enzymes (e.g., parotid gland)
  • Mixed—both mucous and serous secretions (e.g., submandibular salivary gland)

According to Mode of Secretion

    • Merocrine (eccrine)*: Secrete through exocytosis, no loss of cellular components (e.g., sweat glands)
    • Apocrine*: Secretion and part of the cell are discharged. (e.g., apocrine sweat glands)
    • Holocrine*: Entire secretory cell disintegrates to release secretion. (e.g., sebaceous glands)

Classification of Glands by Duct System

    • Simple glands*: Single, unbranched duct. (e.g., intestinal glands, gastric glands)
    • Compound glands*: Branched duct. (e.g., salivary, mammary glands, pancreas)
        • Tubular*: hollow structure
        • Alveolar (acinar)*: rounded structure
        • Tubuloalveolar*: combination of both

Histology of Endocrine Glands

  • Secretion is released into the bloodstream
  • No ducts
  • Cells are arranged in cords or plates
  • e.g. Suprarenal, parathyroid gland
  • Some glands form sacs (follicles)
  • e.g., Thyroid follicles, ovarian follicles

Histology of Connective Tissue

  • Supporting and connecting tissue
  • Derived from embryonic mesenchyme
  • Types
  • Embryonic
  • Mesenchyme: gives rise to other connective tissues (except neuroglia)
  • Mucous: found in the umbilical cord
  • Adult
  • Areolar (loose): widespread throughout body
  • Fibrous (dense): tendons, ligaments
  • Adipose (fat): storage, insulation (adipocytes)
  • Cartilage: support, flexibility
  • Bone: support, structure, strength
  • Blood (specialized): transport, immunity
  • Reticular: stroma (e.g. lymphatic organs)

Cells of Connective Tissue

  • Fibroblasts: secrete fibers and ground substance
  • Macrophages: phagocytose foreign materials
  • Plasma cells: produce antibodies
  • Mast cells: release histamine and heparin (involved in allergic reactions)
  • Fat cells (adipocytes): store fat for energy
  • Leukocytes: immune cell types

Intercellular Substance

  • Solid ground substance (amorphous): hyaluronic acid, proteoglycans
  • Fibers: collagen (strength), elastic (stretch), reticular (support)

Histology of Bone and Cartilage

  • Bone:
  • Specialized type of connective tissue
  • Composed of cells, fibers, and matrix
  • Bone cells (osteoblasts, osteocytes, osteoclasts)
  • Matrix (35% organic, 65% inorganic) organic component is collagenous fibrils
  • Types (e.g., compact, spongy/cancellous)
  • Cartilage:
  • Specialized type of connective tissue providing support and flexibility
  • Composed of cells (chondrocytes) and matrix
  • Types (e.g., hyaline, elastic, fibrocartilage)

Histology of Muscular Tissue

  • Three types based on structure and function
  • Smooth: nonstriated, involuntary, found in internal organs
  • Cardiac: striated, involuntary, found in the heart
  • Skeletal: striated, voluntary, found attached to bones
  • Detailed notes:* further breakdowns of each topic are found within the pages of text.

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Explore the key concepts and structures of epithelial tissue in the context of general histology. This quiz covers the development, types, and characteristics of epithelial cells as part of the four primary tissue types in the body. Test your knowledge on how these tissues are formed from the three germ layers.

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