Tissue

TissueChapter 4

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Tissues

• Tissue:

• 4 Primary Tissue Types1. Epithelial2. Connective3. Muscle4. Nervous

http://www.stegen.k12.mo.us/tchrpges/sghs/ksulkowski/images/20_Simple_Columnar_Epithelial_Tissue.jpg

Match Tissue Type to Function

1. Epithelial

2. Connective

3. Nervous

4. Muscle

A. Supports, protects, binds other tissues together

B. Internal communication

C. Contracts to cause movement

D. Forms boundaries between different environments, protects, secretes, absorbs, filters

Epithelial Tissue (Epithelium)

• Two main types (by location):1. Covering and lining epithelium2. Glandular epithelium

http://www.bio.davidson.edu/people/kabernd/BerndCV/Lab/EpithelialInfoWeb/goblet%20cells%20.jpg

Forms boundaries b/w different environments

Functions of Epithelial Tissue

• Protection• Absorption• Filtration• Excretion• Secretion• Sensory reception

Characteristics of Epithelial Tissue

1. Cells have polarity2. Are composed of closely packed cells3. Supported by a connective tissue reticular

lamina (under the basal lamina)4. Avascular but innervated 5. High rate of regeneration

Classification of Epithelia

• Ask two questions:

1. How many layers? 1 = simple epithelium>1 = stratified epithelium

Classification of Epithelia

2. What type of cell?• Squamous• Cuboidal• Columnar

Note: if stratified, name according to apical layer of cells!

Overview of Epithelial Tissues

• For each of the following types of epithelia, note:– Description– Function– Location

Simple Epithelia

• Single cell layer (usually very thin)• Concerned with:

– Absorption– Secretion– Filtration

• NOT concerned with: protection• Simple squamous, simple cuboidal, simple

columnar, pseudo stratified columnar

Simple Squamous Epithelium• Description

• Function

• Location

Photomicrograph: Simple squamous epitheliumforming part of the alveolar (air sac) walls (125x).Note: ENDOTHELIUM AND MESOTHELIUM

• Description

• Function

• Location

(b) Simple cuboidal epithelium

Photomicrograph: Simple cuboidalepithelium in kidney tubules (430x).

Simple Cuboidal Epithelium

(c) Simple columnar epithelium

Photomicrograph: Simple columnar epitheliumof the stomach mucosa (860X).

Simple Columnar Epithelium• Description

• Function

• Location

(c) Simple columnar epitheliumPseudostratified Columnar Epithelium• Description

• Function

• Location

Photomicrograph: Pseudostratified ciliatedcolumnar epithelium lining the human trachea (570x).

Stratified Epithelium

• 2+ cell layers• Regenerate from below• More durable than simple epithelia• Major role: Protection

Stratified Squamous Epithelium• Description

• Function

• Location

Photomicrograph: Stratified squamous epitheliumlining the esophagus (285x).

Stratified Cuboidal Epithelium• Description

• Function

• Location

Stratified Columnar Epithelium

http://www.sciencephoto.com/image/115414/large/C0051252-Stratified_columnar_epithelium,_urethra-SPL.jpg

• Description

• Function

• Location

Transitional Epithelium

• Description

• Function

• Location

Photomicrograph: Transitional epithelium lining the urinary bladder, relaxed state (360X); note the bulbous, or rounded, appearance of the cells at the surface; these cells flatten and become elongated when the bladder is filled with urine.

Glandular Epithelia

• Gland: one or more cells that secretes and aqueous fluid

• Classified by:– Site of product release

• Endocrine• Exocrine

– Relative number of cells forming the gland• Unicellular• Multicellular

GlandsEndocrine

• Ductless glands • Secrete hormones that

travel through lymph or blood to target organs

• Examples: Thyroid Gland, Pituitary Gland

• Covered in Ch. 16

Exocrine• Secrete products into

ducts• Secretions released

onto body surfaces (skin) or into body cavities

• Examples: mucous, sweat, oil, and salivary glands

More numerous!

Unicellular Exocrine Glands

• Goblet cell and Mucous cell– Mucin -> mucous

Multicellular Exocrine Glands

• Composed of a duct and a secretory unit• Classified according to:

1. Duct type • Simple• Compound

2. Structure of secretory units• tubular• alveolar• tubuloalveolar

Figure 4.5

Compound duct structure(duct branches)

Simple tubular

ExampleIntestinal glands

Simple branchedtubular

ExampleStomach (gastric)glands

Compound tubularExampleDuodenal glands of small intestine

Compound alveolarExampleMammary glands

SimplealveolarExampleNo importantexample in humans

Simple branchedalveolar

ExampleSebaceous (oil)glands

Compoundtubuloalveolar

ExampleSalivary glands

Tubularsecretorystructure

Alveolarsecretorystructure

Surface epithelium Duct Secretory epithelium

Simple duct structure(duct does not branch)

Modes of Secretion

Merocrine• Products are secreted

by exocytosis • pancreas, sweat and

salivary glands

Holocrine• Products are secreted

by rupture of gland cells • sebaceous (oil) glands

Connective Tissue

• Most abundant and widely distributed tissue type

• Four main classes1) Connective Tissue Proper2) Cartilage3) Bone Tissue4) Blood

See Table 4.1

Major Functions of Connective Tissue

1) Binding and Support2) Protection3) Insulation4) Stores reserve fuel5) Transports

Characteristics of Connective Tissue

• Connective tissues have:– Mesenchyme as their common tissue of origin– Varying degrees of vascularity– Cells separated by nonliving extracellular matrix

(ground substance and fibers) • 3 Structural Elements

– Ground substance– Fibers– Cells

Structural Elements of Connective Tissue

• Ground substance– Medium through which solutes diffuse between

blood capillaries and cells– Components:

• Interstitial fluid• Adhesion proteins (“glue”) • Proteoglycans

–Protein core + large polysaccharides–Trap water -> viscosity

Structural Elements of Connective Tissue

• Connective Tissue Fibers– Collagen (white fibers)

• Strongest and most abundant type• Provides high tensile strength

– Elastic (yellow fibers)• Networks of long, thin, elastin fibers that allow

for stretch/recoil– Reticular

• Short, fine, highly branched collagenous fibers

Structural Elements of Connective Tissue

• Cells (see table 4.1)– Mitotically active and secretory cells = “blasts”

• Fibroblasts, chondroblasts, osteoblasts, hematopoietic stem cells

– Mature cells = “cytes”• Chondrocytes, osteocytes

– Other cell types• Fat cells, white blood cells, mast cells, and

macrophages

Figure 4.7

Macrophage

Fibroblast

Lymphocyte

Fat cellMast cell

Neutrophil

Capillary

Cell types Extracellularmatrix

Fibers• Collagen fiber• Elastic fiber• Reticular fiber

Ground substance

Connective Tissue: Embryonic

• Mesenchyme—embryonic connective tissue– Gives rise to all other connective tissues – Gel-like ground substance with fibers and star-

shaped mesenchymal cells

Connective Tissue Proper

• Types:– Loose connective tissue

• Areolar• Adipose• Reticular

– Dense connective tissue

• Dense regular• Dense irregular• Elastic

Loose Connective: Areolar

• Description

• Function

• Location

Photomicrograph: Areolar connective tissue, asoft packaging tissue of the body (300x).

CONNECTIVE TISSUE PROPER

Loose Connective: Adipose

• Description

• Function

• Location

Photomicrograph: Adipose tissue from thesubcutaneous layer under the skin (350x).

CONNECTIVE TISSUE PROPER

Loose Connective: Reticular• Description

• Function

• Location

Photomicrograph: Dark-staining network of reticularconnective tissue fibers forming the internal skeletonof the spleen (350x).

CONNECTIVE TISSUE PROPER

Dense Connective: Dense Regular

• Description

• Function

• Location

Photomicrograph: Dense regular connectivetissue from a tendon (500x).

CONNECTIVE TISSUE PROPER

Dense Connective: Dense Irregular

• Description

• Function

• Location

Photomicrograph: Dense irregularconnective tissue from the dermis of theskin (400x).

CONNECTIVE TISSUE PROPER

Dense Connective: Elastic

• Description

• Function

• Location

Photomicrograph: Elastic connective tissue inthe wall of the aorta (250x).

CONNECTIVE TISSUE PROPER

Connective Tissue: Cartilage

• Stands up to both compression and tension• No nerve fibers, avascular• 80% water• Chondroblasts – produce new matrix• Chondrocytes – mature cartilage cells

– Found in small groups in lacunae

Hyaline Cartilage• Description

• Function

• Location

Photomicrograph: Hyaline cartilage from the trachea (750x).

CARTILAGE

Elastic Cartilage• Description

• Function

• Location

Photomicrograph: Elastic cartilage from the human ear pinna; forms the flexible skeleton of the ear (800x).

CARTILAGE

Fibrocartilage• Description

• Function

• Location

Photomicrograph: Fibrocartilage of anintervertebral disc (125x). Special stainingproduced the blue color seen.

CARTILAGE

Connective Tissue: Bone• Description

• Function

• Location

Photomicrograph: Cross-sectional view of bone (125x).

Connective Tissue: Blood• Description

• Function

• LocationPhotomicrograph: Smear of human blood (1860x); two white blood cells (neutrophil in upper left and lymphocyte in lower right) are seen surrounded by red blood cells.

Nervous Tissue• Description

• Function

• Location

Photomicrograph: Neurons (350x)

Muscle Tissue

• Highly cellular, well vascularized• Movement• Types

1. Skeletal2. Cardiac3. Smooth

Skeletal Muscle• Description

• Function

• Location

Photomicrograph: Skeletal muscle (approx. 460x).Notice the obvious banding pattern and thefact that these large cells are multinucleate.

MUSCLE TISSUE

Cardiac Muscle• Description

• Function

• Location

Photomicrograph: Cardiac muscle (500X); notice the striations, branching of cells, and the intercalated discs.

MUSCLE TISSUE

Smooth Muscle• Description

• Function

• Location

Photomicrograph: Sheet of smooth muscle (200x).

MUSCLE TISSUE

Epithelial Membranes

• Cutaneous membrane (skin)• Mucous membranes

– Mucosae• Line body cavities open to the exterior (e.g., digestive

and respiratory tracts)

• Serous Membranes– Serosae—membranes (mesothelium + areolar

tissue) in a closed ventral body cavity• Parietal serosae line internal body walls• Visceral serosae cover internal organs

Figure 4.11b

Mucosa ofnasal cavity

Mucosa oflung bronchi

Mucosa ofmouth

Esophaguslining

(b) Mucous membranes line body cavitiesopen to the exterior.

Figure 4.11c

Parietalpericardium

Visceralpericardium

(c) Serous membranes line body cavitiesclosed to the exterior.

Parietalperitoneum

Visceralperitoneum

ParietalpleuraVisceralpleura

Steps in Tissue Repair

• Inflammation• Organization and Restored Blood Supply• Regeneration and Fibrosis

Figure 4.12, step 1

Scab

Blood clot inincised wound

Epidermis

Vein

Inflammatorychemicals

Inflammation sets the stage:• Severed blood vessels bleed and inflammatory chemicals are

released.• Local blood vessels become more permeable, allowing white

blood cells, fluid, clotting proteins and other plasma proteinsto seep into the injured area.

• Clotting occurs; surface dries and forms a scab.

Migrating whiteblood cell

Artery

1

Figure 4.12, step 2

Regeneratingepithelium

Area ofgranulationtissueingrowth FibroblastMacrophage

Organization restores the blood supply:• The clot is replaced by granulation tissue, which restores

the vascular supply.• Fibroblasts produce collagen fibers that bridge the gap.• Macrophages phagocytize cell debris.• Surface epithelial cells multiply and migrate over the

granulation tissue.

2

Figure 4.12, step 3

Regeneratedepithelium

Fibrosedarea

Regeneration and fibrosis effect permanent repair:• The fibrosed area matures and contracts; the epitheliumthickens.• A fully regenerated epithelium with an underlying area ofscar tissue results.

3

Developmental Aspects• Primary germ layers: ectoderm, mesoderm,

and endoderm– Formed early in embryonic development– Specialize to form the four primary tissues

• Nerve tissue arises from ectoderm• Muscle and connective tissues arise from mesoderm• Epithelial tissues arise from all three germ layers