Chapter 4: Histology - The Study Of Tissues

Front 1

What is histology?

Back 1

Microscopic study of tissues.

Front 2

Define "biopsy."

Back 2

Removal of tissues for diagnostic purposes.

Front 3

Define "autopsy."

Back 3

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

Front 4

How is tissue classified? (3)

Back 4

1. Structure of cells

2. Composition of non-cellular extracellular matrix

3. Cell function

Front 5

What are the four classifications of tissues?

Back 5

1. Epithelial

2. Connective

3. Muscle

4. Nervous

Front 6

What are the three germ layers of embryonic tissue?

Back 6

1. Endoderm

2. Mesoderm

3. Ectoderm

Front 7

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

Back 7

1. Inner layer

2. Forms lining of digestive tract and derivatives

Front 8

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

Back 8

1. Middle layer

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

Front 9

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

Back 9

1. Outer layer

2. Forms skin and neuroectoderm.

Front 10

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

Back 10

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

Front 11

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

Back 11

1. Attachment to C.T.

2. Guides cell migration during tissue repair

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

Front 12

Does every epithelium have a basement membrane associated with it?

Back 12

No.

Front 13

What is the primary composition of epithelial tissue?

Back 13

Cells.

Front 14

What are the basic functions of epithelial tissue?

Back 14

Covers the body surface (lining) and forms glands.

Front 15

Where can epithelial tissue be found? (4)

Back 15

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

Front 16

What are the three surfaces of epithelial tissue?

Back 16

1. Free surface

2. Basal surface (basement membrane)

3. Lateral surface

Front 17

What are the three classifications of epithelium?

Back 17

1. Simple

2. Stratified

3. Specialized

Front 18

Define "simple epithelium."

Back 18

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

Front 19

Define "stratified epithelium."

Back 19

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

Front 20

Define "squamous."

Back 20

Flat, scale-like.

Front 21

Define "cuboidal."

Back 21

About equal in height and width.

Front 22

Define "columnar."

Back 22

Taller than wide.

Front 23

Define "pseudostratified."

Back 23

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

Front 24

Define "transitional epithelium."

Back 24

Cells transition between cuboidal and squamous (urinary system.)

Front 25

What are the functional characteristics of simple epithelium?

Back 25

1. Diffusion of gases

2. Filtration of blood

3. Secretion

4. Absorption

Front 26

What is the function characteristic of stratified epithelium?

Back 26

Protection, particularly against abrasion.

Front 27

What is the functional characteristic of squamous epithelium?

Back 27

Allows diffusion, or acts as a filter.

Front 28

What are the functional characteristics of cuboidal and columnar epithelium?

Back 28

1. Secretion

2. Absorption

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

Front 29

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

Back 29

1. Smooth

2. Microvilli

3. Cilia

4. Sterocilia

5. Folds

Front 30

What is the purpose of a smooth surface?

Back 30

It reduces friction.

Front 31

What is the function of microvilli?

Back 31

Increase surface area for absorption or secretion.

Front 32

What is the function of cilia?

Back 32

Move materials across the surface.

Front 33

What are stereocilia? What is their function?

Back 33

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

Front 34

Where are folds found?

Back 34

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

Front 35

Simple squamous epithelium:

 

1. Structure

2. Location

3. Function

Back 35

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

Front 36

Simple cuboidal epithelium:

 

1. Structure

2. Location

3. Function

Back 36

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

Front 37

Simple columnar epithelium:

 

1. Structure

2. Location

3. Function

Back 37

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

Front 38

Stratified squamous epithelium:

 

1. Structure

2. Location

3. Function

Back 38

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.

Front 39

Stratified cuboidal epithelium:

 

1. Structure

2. Location

3. Function

Back 39

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

Front 40

Stratified columnar epithelium:

 

1. Structure

2. Location

3. Function

Back 40

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

Front 41

Pseudostratified Columnar Epithelium:

 

1. Structure

2. Location

3. Function

Back 41

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

Front 42

Transitional Epithelium:

 

1. Structure

2. Location

3. Function

Back 42

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.

Front 43

Where are cell connections found?

Back 43

On lateral and basal surfaces of cells.

Front 44

What are some functions of cell connections?

Back 44

1. Form permeability layer

2. Bind cells together

3. Provide mechanism for intercellular (between) communication.

Front 45

What are some types of cell connections?

Back 45

1. Desmosomes

2. Tight junctions

3. Gap junctions

Front 46

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

Back 46

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.

Front 47

Define "hemidesmosomes." What do they do?

Back 47

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

Front 48

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

Back 48

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.

Front 49

What are gap junctions? Their functions?

Back 49

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.

Front 50

How are exocrine and endocrine glands formed?

Back 50

By infolding of the epithelium.

Front 51

Define "exocrine."

Back 51

Open contact maintained with exterior; ducts.

Front 52

Define "endocrine."

Back 52

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

Front 53

What are the three methods of secretion?

Back 53

1. Merocrine

2. Apocrine

3. Holocrine

Front 54

Merocrine gland

Back 54

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.

Front 55

Apocrine gland

Back 55

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.

Front 56

Holocrine gland

Back 56

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.

Front 57

How are multicellular exocrine glands classified?

Back 57

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

Front 58

What are the two types of multicellular exocrine gland ducts?

Back 58

1. Simple

2. Compound

Front 59

Define a simple duct in a multicellular exocrine gland.

Back 59

Ducts with few branches.

Front 60

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

Back 60

Ducts with many branches.

 

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

Alveoli: ducts ending in simple sacs

Front 61

What are four characteristics of connective tissue?

Back 61

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

Front 62

What are seven functions of connective tissue?

Back 62

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)

Front 63

Blasts

Back 63

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

Front 64

Cytes

Back 64

Maintain the matrix, example chondrocyte (mature cartilage cells)

Front 65

Clasts

Back 65

Break the matrix down for remodeling, example osteoclasts

Front 66

What are the three protein fibers of the matrix?

Back 66

1. Collagen

2. Reticular

3. Elastic

Front 67

Collagen

Back 67

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

Front 68

Reticular

Back 68

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

Front 69

Elastic

Back 69

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

Front 70

Name three ground substance molecules.

Back 70

1. Hyaluronic acid

2. Proteoglycans

3. Adhesive molecules

Front 71

Hyaluronic acid

Back 71

Polysaccharide. Good lubricant. Vitreous humor of eye.

Front 72

Proteoglycans

Back 72

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

Front 73

Adhesive molecules

Back 73

Hold proteoglycan aggregates together.

 

1. Chondronectin

2. Osteonectin

3. Fibronectin

Front 74

Define loose (areolar) connective tissue.

Back 74

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

Front 75

Name the locations of loose (areolar) connective tissue.

Back 75

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.

Front 76

What does loose (areolar) connective tissue contain?

Back 76

1. Collagen

2. Reticular

3. Elastic

4. All five types of cells

Front 77

Yellow (white) adipose

Back 77

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. 

 

Front 78

Brown adipose

Back 78

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. 

 

Front 79

Reticular tissue

Back 79

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

Front 80

Dense regular connective tissue

Back 80

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

Front 81

Dense Irregular Connective Tissue

Back 81

• 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

Front 82

Dense Regular Elastic Connective Tissue

Back 82

• 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

Front 83

Dense Irregular Elastic Connective Tissue

Back 83

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

Front 84

Cartilage

Back 84

• 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 

Front 85

Perichondrium

Back 85

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

Front 86

Types of cartilage

Back 86

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

Front 87

Hyaline cartilage

 

1. Structure

2. Locations

Back 87

• 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

Front 88

Fibrocartilage

 

1. Structure

2. Locations

Back 88

• 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)

Front 89

Elastic Cartilage

 

1. Structure

2. Location

Back 89

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

• Locations: 
– External ears and epiglottis

Front 90

Bone

Back 90

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

 

Front 91

Bone matrix

Back 91

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

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

 

Front 92

Blood plasma

Back 92

– 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.

Front 93

Formed elements of blood.

Back 93

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

Front 94

Hemopoietic tissues: 

 

Back 94

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

Front 95

Types of bone marrow

Back 95

– 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.

Front 96

Characteristics of muscle tissue.

Back 96

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

Front 97

Skeletal muscle

Back 97

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

 

Front 98

Cardiac muscle.

Back 98

Muscle of the heart. Striated and involuntary. 

 

Front 99

Smooth muscle

Back 99

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

Front 100

Parts of a neuron.

Back 100

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

 

Front 101

Three types of neurons.

Back 101

1. Multipolar

2. Bipolar

3. Unipolar

Front 102

Mucous membranes

Back 102

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

 

Front 103

Serous membranes

Back 103

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

 

Front 104

Synovial membranes

Back 104

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

Front 105

Manifestations (cardinal signs) of tissue damage.

Back 105

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

Front 106

Chemical mediators of tissue damage.

Back 106

– 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

Front 107

Tissue repair

Back 107

Substitution of dead/damaged cells by viable/functional cells

Front 108

Labile

Back 108

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

Front 109

Stable

Back 109

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

 

Front 110

Permanent

Back 110

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

Front 111

Primary union

Back 111

– 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, 
capillaries 
– Scar. Formed from granulation tissue. Tissue turns from red to white as capillaries are forced 
out.

 

Front 112

Secondary union

Back 112

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

Front 113

Effects of Aging on Tissues

Back 113

• Cells divide more slowly 
• Collagen fibers become more irregular in structure, though they may increase in 
number 
– 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