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113 Cards in this Set

  • Front
  • Back

What is histology?

Microscopic study of tissues.

Define "biopsy."

Removal of tissues for diagnostic purposes.

Define "autopsy."

Examination of organs of a dead body to determine cause of death.

How is tissue classified? (3)

1. Structure of cells

2. Composition of non-cellular extracellular matrix

3. Cell function

What are the four classifications of tissues?

1. Epithelial

2. Connective

3. Muscle

4. Nervous

What are the three germ layers of embryonic tissue?

1. Endoderm

2. Mesoderm

3. Ectoderm

What layer does the endoderm form? What structures does it form?

1. Inner layer

2. Forms lining of digestive tract and derivatives

What layer does the mesoderm form? What structures does it form?

1. Middle layer

2. Forms tissues such as muscle, bone, and blood vessels.

What layer does the ectoderm form? What structures does it form?

1. Outer layer

2. Forms skin and neuroectoderm.

What is the basement membrane formed by? Is it cellular or acellular?

Secretions of both epithelium and connective tissue. It is an acellular layer.

What are some functions of the basement membrane? (3)

1. Attachment to C.T.

2. Guides cell migration during tissue repair

3. Acts as a filter in the nephron of the kidney.

Does every epithelium have a basement membrane associated with it?


What is the primary composition of epithelial tissue?


What are the basic functions of epithelial tissue?

Covers the body surface (lining) and forms glands.

Where can epithelial tissue be found? (4)

1. Outside the surface of the body

2. Lining of digestive, respiratory, and urogenital systems

3. Heart and blood vessels

4. Linings of many body cavities

What are the three surfaces of epithelial tissue?

1. Free surface

2. Basal surface (basement membrane)

3. Lateral surface

What are the three classifications of epithelium?

1. Simple

2. Stratified

3. Specialized

Define "simple epithelium."

One layer of cells. Each extends from basement membrane to the free surface.

Define "stratified epithelium."

More than one layer. Shape of cells of the apical layer used to name the tissue.

Define "squamous."

Flat, scale-like.

Define "cuboidal."

About equal in height and width.

Define "columnar."

Taller than wide.

Define "pseudostratified."

Tissue appears to be stratified, but all cells contact basement membrane so it is in fact simple. Associated with cilia and goblet cells.

Define "transitional epithelium."

Cells transition between cuboidal and squamous (urinary system.)

What are the functional characteristics of simple epithelium?

1. Diffusion of gases

2. Filtration of blood

3. Secretion

4. Absorption

What is the function characteristic of stratified epithelium?

Protection, particularly against abrasion.

What is the functional characteristic of squamous epithelium?

Allows diffusion, or acts as a filter.

What are the functional characteristics of cuboidal and columnar epithelium?

1. Secretion

2. Absorption

3. May include goblet cells that produce and secrete mucus.

What are the five structures of the free surfaces of epithelium?

1. Smooth

2. Microvilli

3. Cilia

4. Sterocilia

5. Folds

What is the purpose of a smooth surface?

It reduces friction.

What is the function of microvilli?

Increase surface area for absorption or secretion.

What is the function of cilia?

Move materials across the surface.

What are stereocilia? What is their function?

They are elongated microvilli. They are used for sensation and absorption.

Where are folds found?

In transitional epithelium where an organ must be able to change shape.

Simple squamous epithelium:


1. Structure

2. Location

3. Function

1. Structure: Single layer of flat cells

2. Location: 

  • Lining of blood and lymphatic vessels (endothelium) and small ducts
  • Alveoli of the lungs
  • Loop of Henle in kidney tubules
  • Lining of serous membranes (mesothelium)
  • Inner surface of the eardrum


3. Functions:

  • Diffusion
  • FIltration
  • Some protection against friction, secretion, absorption

Simple cuboidal epithelium:


1. Structure

2. Location

3. Function

1. Structure: Single layer of cube-shaped cells; some types have microvilli (kidney tubules) or cilia (terminal bronchioles of the lungs)

2. Location:

  • Kidney tubules
  • Glands and their ducts
  • Choroid plexus of the brain
  • Lining terminal bronchioles of the lungs
  • Surface of the ovaries

3. Functions:

  • Secretion and absorption in the kidney
  • Secretion in glands and choroid plexus
  • Movement of mucus out of the terminal bronchioles by ciliated cells

Simple columnar epithelium:


1. Structure

2. Location

3. Function

1. Structure: Single layer of tall narrow cells. Some have cilia (bronchioles of lungs, auditory tubes, uterine tubes, and uterus) or microvilli (intestine)

2. Location:

  • Glands and some ducts
  • Aids in the movement of oocytes through the uterine tubes by ciliated cells
  • Secretion by glands of the stomach and the intestine
  • Absorption by cells of the intestine

Stratified squamous epithelium:


1. Structure

2. Location

3. Function

1. Structure: Multiple layers of cells that are cuboidal in the basal layer and progressively flatten toward the surface. In moist surfaces, surface cells retain a nucleus and cytoplasm. In keratinized, surface cells are dead.

2. Location:

  • Moist (nonkeratinized) - mouth, throat, larynx, esophagus, anus, vagina, inferior urethra, and cornea
  • Keratinized - skin

3. Functions: Protection against abrasion, caustic chemicals, water loss, and infection.

Stratified cuboidal epithelium:


1. Structure

2. Location

3. Function

1. Structure: Multiple layers of somewhat cube-shaped cells

2. Location:

  • Sweat gland ducts
  • Ovarian follicular cells
  • Salivary gland ducts

3. Functions:

  • Secretion
  • Absorption
  • Protection against infections

Stratified columnar epithelium:


1. Structure

2. Location

3. Function

1. Structure: Multiple layers of cells with tall thin cells resting on layers of more cuboidal cells. Cells ciliated in the larynx.

2. Locations:

  • Mammary gland duct
  • Larynx
  • Portion of male urethra

3. Function: 

  • Protection
  • Secretion

Pseudostratified Columnar Epithelium:


1. Structure

2. Location

3. Function

1. Structure: All cells reach basement membrane. Appears stratified because nuclei are at various levels. Almost always ciliated and associated with goblet (mucus-producing) cells

2. Location:

  • Lining of nasal cavity
  • Nasal sinuses
  • Auditory tubes
  • Pharynx
  • Trachea
  • Bronchi of lungs

3. Functions:

  • Synthesize and secrete mucus onto the free surface
  • Move mucus (or fluid) that contains foregin particles over the free surface and from passages

Transitional Epithelium:


1. Structure

2. Location

3. Function

1. Structure: Stratified; cells change shape depending upon amount of distention in the organ

2. Location: Lining of urinary bladder, ureters and superior urethra

3. Functions: Accomodates fluctuations in the volume of fluid in an organ or tube; protection against the caustic effects of urine.

Where are cell connections found?

On lateral and basal surfaces of cells.

What are some functions of cell connections?

1. Form permeability layer

2. Bind cells together

3. Provide mechanism for intercellular (between) communication.

What are some types of cell connections?

1. Desmosomes

2. Tight junctions

3. Gap junctions

Define "desmosomes." What substances make up the desmosome?

Disk-shaped regions of cell membrane; often found in areas that are subjected to stress.


Desmosomes contain especially adhesive glycoproteins. They also contain intermediate protein filaments that extend into the cytoplasm of cells.

Define "hemidesmosomes." What do they do?

Half of a desmosome; attach epithelial cells to basement membrane.

What are the two types of tight junctions? And what is their function.

Zonula adherens are found between adjacent cells. They function as a weak glue that holds cells together. Found in simple epithelium.


Zonula occludens function as a permeability barrier (carrier proteins), e.g. stomach and urinary bladder, chemicals cannot pass between cells.

What are gap junctions? Their functions?

They are protein channels that aid intercellular communication.


1. Allows ions and small molecules to pass through.

2. Coordinate function of cardiac and smooth muscle.

3. May help coordinate movement of cilia in ciliated types of epithelium.

How are exocrine and endocrine glands formed?

By infolding of the epithelium.

Define "exocrine."

Open contact maintained with exterior; ducts.

Define "endocrine."

No open contact with exterior; no ducts; produce hormones (secrete into bloodstream).

What are the three methods of secretion?

1. Merocrine

2. Apocrine

3. Holocrine

Merocrine gland

Cells of the gland produce secretion by active transport or produce vesicles that contain secretory products, and the vesicles empty their contents into the duct through exocytosis.

Apocrine gland

Secretory products are stored in the cell near the lumen of the duct. A portion of the cell near the lumen containing secretory products is pinched off the cell and joins secretions produced by a merocrine process.

Holocrine gland

Secretory prducts are stored in the cells of the gland. Entire cells are shed by the gland and become part of the secretion. The lost cells are replaced by other cells deeper in the gland.

How are multicellular exocrine glands classified?

On the basis of types of ducts or mode of secretion.

What are the two types of multicellular exocrine gland ducts?

1. Simple

2. Compound

Define a simple duct in a multicellular exocrine gland.

Ducts with few branches.

Define a compound duct in a multicellular exocrine gland. What are the two types?

Ducts with many branches.


Acini: ducts ending in tubules or sac-like structures.

Alveoli: ducts ending in simple sacs

What are four characteristics of connective tissue?

1. Abundant; found in every oran

2. Consists of cells separated by extracellular matrix

3. Many diverse types (solid, semi-solid, fluid)

4. Performs variety of important functions

What are seven functions of connective tissue?

1. Enclose organs as a capsule and separate organs into layers

2. Connect tissues to one another (tendons and ligaments)

3. Support and movement (bones)

4. Storage (fat)

5. Cushion and insulate (fat)

6. Transport (blood)

7. Protect (cells of the immune system)


Create the matrix, example osteoblast (bone-forming cells)


Maintain the matrix, example chondrocyte (mature cartilage cells)


Break the matrix down for remodeling, example osteoclasts

What are the three protein fibers of the matrix?

1. Collagen

2. Reticular

3. Elastic


Most common protein in body; strong, flexible, inelastic (made by fibroblasts)


Fill spaces between tissues and organs. Fine collagenous, form branching networks.


Returns to its original shape after distension or compression. Contains molecules of protein elastin that resemble coiled springs; molecules are cross-linked.

Name three ground substance molecules.

1. Hyaluronic acid

2. Proteoglycans

3. Adhesive molecules

Hyaluronic acid

Polysaccharide. Good lubricant. Vitreous humor of eye.


Protein and polysaccharide. Protein part attaches to hyaluronic acid. Trap large amounts of water.

Adhesive molecules

Hold proteoglycan aggregates together.


1. Chondronectin

2. Osteonectin

3. Fibronectin

Define loose (areolar) connective tissue.

Loose packing material of most organs and tissues, also known as stroma.

Name the locations of loose (areolar) connective tissue.

1. Packing between glands, muscles, and nerves.

2. Attaches the skin to underlying tissues.

3. Often seen in association with other types of C.T., like reticular tissue and fat.

What does loose (areolar) connective tissue contain?

1. Collagen

2. Reticular

3. Elastic

4. All five types of cells

Yellow (white) adipose

Most abundant type, has a wide distribution. White at birth and yellows 
with age. 

1. Carotenes come from plants and can be metabolized into vitamin A. 
2. Scant ring of cytoplasm surrounding single large lipid droplet. Nuclei flattened and eccentric. 


Brown adipose

Found only in specific areas of body: axillae, neck and near kidneys

– Cells are polygonal in shape, have a considerable volume of cytoplasm and contain multiple lipid 
droplets of varying size. Nuclei are round and almost centrally located. 


Reticular tissue

1. Forms superstructure of lymphatic and hemopoietic tissues 
2. Network of fine reticular fibers and reticular cells. 
3. Spaces between cells contain white cells and dendritic cells

4. Found within the lymph nodes, spleen, and bone marrow

Dense regular connective tissue

• Has abundant collagen fibers that resist stretching 
– Tendons: Connect muscles to bones; fibers are not necessarily 
– Ligaments: Connect bones to bones. Collagen often less 
compact, usually flattened, form sheets or bands

Dense Irregular Connective Tissue

  • Protein fibers arranged in a randomly oriented network 
  • Forms innermost layer of the dermis of the skin, scars, capsules of kidney and spleen
  • Tensile strength capable of withstanding stretching in all directions

Dense Regular Elastic Connective Tissue

  • Ligaments in vocal folds 
  • Collagen fibers give strength (for when you shout), but elastic fibers are more prevalent
  • Able to stretch and recoil like a rubber band, with strength in the direction of fiber orientation

Dense Irregular Elastic Connective Tissue

  • Bundles and sheets of collagenous and elastic fibers oriented in 
  • multiple directions 
  • In walls of elastic arteries (aorta) 
  • Strong, yet elastic


  • Composed of chondrocytes located in matrix-surrounded spaces called 
  • lacunae. 
  • Type of cartilage determined by components of the matrix.
  •  Avascular and no nerve supply 
  • Heals slowly 


  • Dense irregular connective tissue that surrounds cartilage. 
  • Fibroblasts of perichondrium can differentiate into chondroblasts.

Types of cartilage

1. Hyaline (articulating cartilage) 
2. Fibrocartilage (IVD) 
3. Elastic (external ear)

Hyaline cartilage


1. Structure

2. Locations

• Structure: 
– large amount of collagen fibers evenly distributed in proteoglycan matrix 
– Smooth surface in articulations 

• Locations: 
– Found in areas for strong support and some flexibility: rib cage, trachea, and bronchi 
– In embryo forms most of skeleton 
– Involved in growth that increases bone length



1. Structure

2. Locations

• Structure: 
– thick collagen fibers distributed in proteoglycan matrix; slightly compressible 
and very tough

• Locations: 
– found in areas of body where a great deal of pressure is applied to joints 
– Knee, jaw, between vertebrae (intervertebral disc)

Elastic Cartilage


1. Structure

2. Location

• Structure: 
– Elastic and collagen fibers embedded in proteoglycans. 
– Rigid but elastic properties 

• Locations: 
– External ears and epiglottis


Hard connective tissue composed of living cells (osteocytes) and mineralized matrix. 


Bone matrix

Gives strength and rigidity; allows bone to support and protect other tissues 
and organs

– Organic: Collagen fibers 
– Inorganic: Hydroxyapatite (Ca2+ plus PO4) 


Blood plasma

– Liquid and lacks fibers. 
– Matrix formed by other tissues, unlike other types of connective tissue. 
– Moves through vessels, but both fluid and cells can move in/out of the vessels.

Formed elements of blood.

– Red cells (erythrocyte) 
– White cells (leukocyte) 
– Platelets (thrombocyte)

Hemopoietic tissues: 


– Forms blood cells 
– Yolk, Liver, Spleen, Bone 
– Two types of bone marrow 
• Yellow (fat) 
• Red

Types of bone marrow

– Red: 
• Hemopoietic tissue surrounded by a framework of reticular fibers. 
• Produces red, white cells, & PLT 
– Yellow: yellow adipose tissue 
• As children grow, yellow marrow replaces much of red marrow.

Characteristics of muscle tissue.

– Contracts or shortens with force 
– Moves entire body (skeletal muscle) and pumps blood 
(cardiac muscle) 

Skeletal muscle

Most attached to skeleton, but some attached to other types of connective tissue. Striated and voluntary. 


Cardiac muscle.

Muscle of the heart. Striated and involuntary. 


Smooth muscle

Muscle associated with tubular structures and with the skin. Nonstriated and involuntary.

Parts of a neuron.

• Cell body: contains nucleus 
• Axon: cell process; conducts impulses 
away from cell body; usually only one per 
• Dendrite: cell process; receive impulses 
from other neurons; can be many per 


Three types of neurons.

1. Multipolar

2. Bipolar

3. Unipolar

Mucous membranes

– Line cavities that open to the outside of 
– Secrete mucus 
– Contains epithelium with goblet cells, 
basement membrane, lamina propria 
(sometimes with smooth muscle) 
– Found in respiratory, digestive, urinary 
and reproductive systems.


Serous membranes

– Simple squamous epithelium called 
mesothelium, basement membrane, thin 
layer of loose C.T. 
– Line cavities not open to exterior 
– Pericardial, pleural, peritoneal 


Synovial membranes

– Line freely movable joints 
– Produce fluid rich in hyaluronic acid

Manifestations (cardinal signs) of tissue damage.

– Redness “Rubor” 
– Heat “Calor” 
– Swelling “Tumor” 
– Pain “Dolar” 
– Disturbed function “Functio laesa”

Chemical mediators of tissue damage.

– Stimulate pain receptor and 
increase blood vessel permeability 
as well movement of WBCs to 
affected area.

• Histamine: degranulation 
• Kinins: vasodilation, increase 
vascular permeability, & pain 
• Prostaglandins: vasodilation, 
fever, & pain. 
• Leukotrienes: leukocyte 
adhesion & activation

Tissue repair

Substitution of dead/damaged cells by viable/functional cells


• Capable of mitosis through life. 
• ie) skin, mucous membranes, hemopoietic tissue, lymphatic tissue


• No mitosis after growth ends, but can divide after injury. 
• ie) Liver, pancreas, endocrine cells 



• If killed, replaced by a different type of cell. 
• Limited regenerative ability. 
• ie) nervous, skeletal and cardiac muscle

Primary union

– Edges of wound are close together 
– Wound fills with blood 
– Clot forms: fibrin threads start to contract; pull 
edges together 
– Scab 
– Inflammatory response; pus forms as white 
cells die 
– Granulation tissue. Replaces clot, delicate C.T. 
composed of fibroblasts, collagen fibers, 
– Scar. Formed from granulation tissue. Tissue turns from red to white as capillaries are forced 


Secondary union

Edges of wound are not closed; greater chance of infection 
– Clot may not close gap 
– Inflammatory response greater 
– Wound contraction occurs leading to greater 

Effects of Aging on Tissues

• Cells divide more slowly 
• Collagen fibers become more irregular in structure, though they may increase in 
– Tendons and ligaments become less flexible and more fragile 
• Elastic fibers fragment, bind to calcium ions (calcification), and become less 
elastic – Arterial walls and elastic ligaments become less elastic 
• Changes in collagen and elastin result in 
– Atherosclerosis and reduced blood supply to tissues 
– Wrinkling of the skin 
– Increased tendency for bones to break 
• Rate of blood cell synthesis declines in the elderly 
• Injuries don’t heal as readily