Microanatomy Final Exam

What are the four main types of basic tissues in the body?

Epithelial tissue, connective tissue, muscle tissue, and neural tissue.

According to cell theory, what are four statements about cells?

1. Cells are the building blocks of all plants and animals.

2. Cells are the smallest functioning unit of life.

3. Cells are produced by the division of preexisting cells.

4. Each cell maintains homeostasis.

How many different types of cells are there in the human body?

Approximately 200 different types.

How do cells form tissues?

Cells of similar morphology and function combine with extracellular matrix to form tissues.

What is histology (or microanatomy)?

The study of normal cells and tissues.

What is pathology (or histopathology)?

The study of the changes to normal cells and tissues that occurs in various disease processes.

What are the two main categories of epithelial tissue?

1. Epithelia (layers of cells that cover internal or external surfaces)

2. Glands (specialized epithelia that excrete substances).

List four characteristics of epithelia.

1. Cells are bound close together.

2. A free surface exposed to the environment or internal chamber.

3. Attached to underlying connective tissue aka basement membrane.

4. Avascular.

Name four functions of epithelial tissue.

1. Provide physical protection (abrasion, dessication)

2. Control permeability (any substance that enters/exits the body must pass through epithelium)

3. Provide sensation (specialized cells detect changes in the environment)

4. Produce specialized secretions (glands)

What are the three morphological characteristics used to classify epithelia?

1. Number of cell layers, 2. Cell shape, 3. The presence of surface specializations.

What is a simple epithelium and where is it found?

A single layer of cells covering the basement membrane;

found in protected areas where diffusion, secretion, or absorption occurs.

What is a stratified epithelium and where is it found?

Several layers of cells above the basement membrane;

found in areas subject to mechanical or chemical stress.

What are the three basic cell shapes in epithelial tissue?

Squamous, cuboidal, and columnar.

Describe squamous epithelial cells.

thin and flat, with the nucleus in the thickest middle part of the cell

Describe cuboidal epithelial cells.

cells that look like boxes, with the nuclei in the center of the cells in a neat row

Describe columnar epithelial cells.

Ttall and slender cells with elongated nuclei closer to the basement membrane (polarity)

What are two surface specializations found in epithelial tissue?

Cilia and keratin.

What are cilia?

motile, hair-like structures that beat in waves to push mucous and debris in a constant direction

What is the function of cilia on epithelial cells?

To beat in a wave-like rhythm, propelling surface films, mucus, particles, or fluid in a consistent direction over the epithelial surface.

What is the length of cilia and how many can a single epithelial cell have?

About 7 to 10 μm in length; up to 300 per cell.

What is keratin?

A fibrous protein that is durable, flexible, and water resistant; coats the skin surface and forms hair, calluses, and nails.

What are microvilli and how are they seen under the microscope?

Finger-like projections of the plasma membrane found in epithelia specialized for absorption.

Seen as a brush border

How much can microvilli increase surface area?

Up to 30-fold.

What is the length of microvilli and how many can each cell have?

0.5-1.0 μm; 3000

What are stereocilia?

Extremely long microvilli found in the epididymis.

What is the function of simple squamous epithelium?

Lines surfaces involved in diffusion of gases (lungs) or fluids (capillaries).

What is the lining of blood vessels called?

Endothelium.

What is the function and location of simple cuboidal epithelium?

Lines small ducts and tubules with excretory, secretory, or absorptive functions; found in kidney tubules, salivary glands, and pancreas.

What is the function and location of simple columnar epithelium?

Found on absorptive surfaces (small intestine) and secretory surfaces (stomach)

Where is simple columnar ciliated epithelium found?

Fallopian tubes

What is the function of simple columnar ciliated epithelium in the female reproductive tract?

Cilia generate a current that propels the ovum from ovary to uterus.

What is pseudostratified columnar ciliated epithelium?

A variant of simple columnar epithelium where all cells rest on the basement membrane but nuclei are at different levels, creating a false appearance of stratification.

Where is pseudostratified columnar ciliated epithelium found?

Almost exclusively in the largest airways of the respiratory system (respiratory epithelium).

What is the function of pseudostratified columnar ciliated epithelium?

To propel a surface layer of mucus containing entrapped particles toward the pharynx.

Describe the appearance of the layers of stratified squamous epithelium

basal layer looks cuboidal, but cells at the free surface as squamous (flat)

Where is stratified squamous epithelium (non-keratinized) found?

Linings of the oral cavity, pharynx, esophagus, anal canal, uterine cervix, and vagina.

Where is keratinized stratified squamous epithelium found?

surface of the skin

What process occurs in stratified squamous keratinizing epithelium?

Keratinization, where cells accumulate cross-linked cytoskeletal proteins to form a tough, non-living surface layer of keratin.

Where is stratified cuboidal epithelium found and how many layers does it consist of?

Lining the larger excretory ducts of exocrine glands such as salivary glands; consists of 2-3 layers.

What is transitional epithelium and where is it found? What is its function?

A stratified epithelium exclusively in the urinary tract; specialized to accommodate stretch and withstand urine toxicity.

Describe transitional epithelium in the relaxed (contracted) state.

Appears 4-5 cell layers thick; basal cells cuboidal, intermediate cells polygonal, surface cells large and rounded (may have two nuclei).

Describe transitional epithelium in the stretched state.

Appears only 2-3 cells thick; intermediate and surface layers become extremely flattened.

What are the two main types of glandular epithelia?

Endocrine glands and exocrine glands.

What are endocrine glands?

Ductless glands that produce hormones released into blood or tissue fluid; hormones act on cells far from the site of secretion.

What are exocrine glands?

Glands that discharge their secretory product via a duct onto an epithelial surface.

What are the three basic components of all connective tissues?

1. Specialized cells, 2. Protein fibers, 3. Ground substance.

What is the extracellular matrix of connective tissue composed of?

protein fibers and ground substance.

List five functions of connective tissue.

1. Supporting and protecting

2. transporting materials

3. storing energy reserves

4. defending the body

5. and providing sensation (pain, pressure, temperature).

What are the two main cell populations in connective tissue proper?

Fixed cells (permanent residents for maintenance, repair, energy storage) and wandering cells (involved in defense and repair, not always present).

What is the most abundant cell in connective tissue proper and what is its function?

Fibroblasts; they produce and maintain connective tissue fibers and ground substance.

What is the function of macrophages in connective tissue?

To phagocytize damaged cells or pathogens and release chemicals that mobilize the immune system.

What are adipocytes and what is their function?

Fat cells that contain a large lipid droplet; function in energy storage, cushioning, and insulation.

What are mast cells and what is their function?

Small wandering cells near blood vessels that release chemicals to begin the body's defensive activities after injury or infection.

What are the three main types of connective tissue fibers?

Collagen fibers, elastic fibers, and reticular fibers.

What is the most abundant protein in the body?

Collagen.

Name 5 types of collagen and where they are found.

Type I: fibrous supporting tissue; dermis, tendons, ligaments, bone

Type II: fine fibrils in ground substance; hyaline cartilage

Type III (reticulin): delicate meshwork; liver, bone marrow, lymphoid tissue

Type IV: mesh-like; basement membranes

Type VII: anchoring fibrils; link to basement membrane

What is the function of elastic fibers (elastin) and where are they found?

Confer properties of stretching and elastic recoil; found in skin, lung, and blood vessels.

What stain is used to visualize elastic fibers?

Verhoeff's elastic stain (stains them black).

What stain is used to visualize reticular fibers?

Gomori's silver stain (stains them black).

What are the two main categories of connective tissue proper based on fiber density?

Loose connective tissue and dense connective tissue.

What is the function of loose connective tissues?

Packing material (fills spaces)

provides cushioning

supports epithelia

anchors blood vessels and nerves

stores lipids

provides a route for diffusion.

What cells and fibers are found in loose areolar connective tissue?

fibroblasts, macrophages, mast cells, adipocytes, collagen fibers, elastic fibers

Where is loose areolar connective tissue located?

Forms a layer separating skin from underlying muscle (padding and independent movement)

What is adipose connective tissue?

Loose connective tissue dominated by adipocytes (fat cells).

Where is adipose tissue commonly found?

Under skin of sides, buttocks, breasts; behind eyes; surrounding kidneys; in pericardial and peritoneal cavities.

Name three functions of adipose tissue.

• Padding and shock absorption • Insulation • Energy storage

What happens to adipocytes in routine H&E staining?

Lipid content is extracted during processing, leaving a large empty space within each cell.

What special stain is used to visualize fat?

Oil red O on frozen sections (stains fat red).

What are dense connective tissues?

Strong, durable tissues consisting mostly of collagen fibers; resist distortion and tension.

What are the two types of dense connective tissue?

Dense regular connective tissue and dense irregular connective tissue.

Describe dense regular connective tissue.

Collagen fibers bundled in a parallel fashion

mainly Type I collagen

fibroblasts in rows between fibers in lacunae

forms tendons and ligaments.

Tendons attach:

skeletal muscle to bone

Ligaments attach

bone to bone; also have some elastic fibers for some stretching

Describe dense irregular connective tissue.

Collagen fibers oriented in different directions (not parallel)

makes up dermis (skin), submucosa of digestive tract, and fibrous capsules.

What type of epithelium is found lining the trachea?

Pseudostratified ciliated columnar epithelium (respiratory epithelium).

What is the function of the pseudostratified ciliated columnar epithelium in the trachea?

To propel a surface layer of mucus containing entrapped particles toward the pharynx.

What type of epithelium lines the gall bladder?

Simple columnar epithelium; function is absorbing water to concentrate bile.

What type of epithelium lines the kidney collecting tubules?

Simple cuboidal epithelium; function is excretion, secretion, or absorption.

What type of epithelium lines the bladder and ureter?

Transitional epithelium; function is to accommodate stretch and withstand urine toxicity.

What type of epithelium lines the uterine cervix?

Stratified squamous epithelium (non-keratinized); function is to withstand abrasion.

What type of epithelium covers the skin?

Stratified squamous keratinizing epithelium; function is to withstand constant abrasion and desiccation.

What type of tissue makes up the majority of the pancreas?

Exocrine gland tissue (99%) producing pancreatic juice.

What is the endocrine function of the pancreas?

Clusters of cells called Islets of Langerhans produce insulin and glucagon.

What type of gland is the submandibular gland and what does it produce?

A salivary gland that produces saliva (hypotonic watery secretion with mucus, enzymes, antibodies, inorganic ions).

What are the two types of secretory units in the submandibular gland?

Serous acini (stained purple) and mucous acini (poorly stained).

What are the two types of supporting connective tissue?

Cartilage and bone.

What are the three types of cartilage?

Hyaline cartilage, elastic cartilage, and fibrocartilage.

What are chondrocytes and where are they found?

The only cells found in cartilage matrix; they live in small pockets called lacunae.

Is cartilage vascular or avascular?

Avascular.

How do chondrocytes obtain nutrients and eliminate waste?

By diffusion through the matrix.

What is the perichondrium?

A covering that separates cartilage from other tissues.

What is the most common type of cartilage?

Hyaline cartilage.

Where is hyaline cartilage found?

Connects ribs to sternum, supports respiratory passageways, covers bone surfaces within joints, and in the nasal septum.

What are the functions of hyaline cartilage?

Provides stiff but somewhat flexible support, reduces friction between bony surfaces, and serves as a precursor to bone in the developing skeleton.

What type of collagen fibers are found in hyaline cartilage?

Type II collagen.

Where is elastic cartilage found?

External ear, external auditory canal, epiglottis, parts of laryngeal cartilages, and walls of the Eustachian tubes.

What distinguishes elastic cartilage from hyaline cartilage?

Numerous bundles of branching elastic fibers in the matrix, especially dense near chondrocytes.

What property does elastic cartilage provide?

Extreme resilience and flexibility.

What is the structure of fibrocartilage?

Alternating layers of hyaline cartilage and thick layers of dense collagen fibers oriented in the direction of functional stresses.

Where is fibrocartilage found?

Intervertebral discs, some articular cartilages, pubic symphysis, joint capsules, ligaments, and connections of tendons to bone.