the tissue level of - napa valley college 105/ess...move fluids over the epithelium (protection)...

C h a p t e r

The Tissue

Level of Organization

PowerPoint® Lecture Slides

prepared by Jason LaPres

Lone Star College - North Harris

publishing as Pearson Benjamin Cummings

Four Types of Tissues

Tissues are collections of cells and cell

products that perform specific, limited

functions

Types of tissue

Epithelial tissue

Covers exposed surfaces

Lines internal passageways

Forms glands

Four Types of Tissues

Types of Tissue (cont’d)

Connective tissue

Fills internal spaces

Supports other tissues

Transports materials

Stores energy

Muscle tissue

Specialized for contraction

Skeletal muscle, heart muscle, and walls of hollow organs

Neural tissue

Carries electrical signals from one part of the body to another

Epithelial Tissues

Epithelia

Layers of cells covering internal or external

surfaces

Glands

Structures that produce secretions

Epithelial Tissues

Characteristics of Epithelia

Cellularity (cell junctions)

Polarity (apical and basal surfaces)

Attachment (basal lamina)

Avascularity

Regeneration

Epithelial Tissues

Figure 4–1 The Polarity of Epithelial Cells.

Epithelial Tissues

Functions of Epithelial Tissue

Provide physical protection

Control permeability

Provide sensation

Produce specialized secretions (glandular

epithelium)

Epithelial Tissues

Specializations of Epithelial Cells

Move fluids over the epithelium (protection)

Move fluids through the epithelium (permeability)

Produce secretions (protection and messengers)

Free Surface and Attached Surface

Polarity

Apical surfaces:

– microvilli increase absorption or secretion

– cilia (ciliated epithelium) move fluid

Basolateral surfaces

Epithelial Tissues

Maintaining the Integrity of Epithelia

Intercellular connections

Attachment to basal lamina

Epithelial maintenance and repair

Epithelial Tissues

Intercellular Connections

Support and communication

CAMs (cell adhesion molecules):

– transmembrane proteins

Intercellular cement:

– proteoglycans

Hyaluronan (hyaluronic acid):

– glycosaminoglycans

Epithelial Tissues

Cell junctions

Form bonds with other cells or extracellular material:

– occluding (tight) junctions

– gap junctions

– macula adherens (desmosomes)

Epithelial Tissues

Cell Junctions

Occluding (Tight) junctions—between two plasma

membranes

Adhesion belt attaches to terminal web

Prevents passage of water and solutes

Isolates wastes in the lumen

Gap junctions—allow rapid communication

Held together by channel proteins (junctional proteins,

connexons)

Allow ions to pass

Coordinate contractions in heart muscle

Epithelial Tissues

Cell Junctions

Macula adherens (Desmosomes)

CAMs, dense areas, and intercellular

cement

Spot desmosomes

– tie cells together

– allow bending and twisting

Hemidesmosomes

– attach cells to the basal lamina

Epithelial Tissues

Attachment to the Basal Lamina

Clear layer (Lamina lucida)

Thin layer

Secreted by epithelia

Barrier to proteins

Dense layer (Lamina densa)

Thick fibers

Produced by connective tissue

Strength and filtration

Epithelial Tissues

Figure 4–2 Intercellular Connections

Epithelial Tissues

Epithelial Maintenance and Repair

Epithelia are replaced by division of

germinative cells (stem cells)

Near basal lamina

Classification of Epithelia

Singular epithelium; plural epithelia

Classes of Epithelia

Based on shape

Squamous epithelia: thin and flat

Cuboidal epithelia: square shaped

Columnar epithelia: tall, slender rectangles

Based on layers

Simple epithelium: single layer of cells

Stratified epithelium: several layers of cells

Squamous Epithelia

Simple squamous epithelium

Absorption and diffusion

Mesothelium

Lines body cavities

Endothelium

Lines heart and blood vessels

Figure 4–3 Squamous Epithelia.

Squamous Epithelia

Stratified squamous epithelium

Protects against attacks

Keratin protein adds strength and water resistance

Figure 4–3 Squamous Epithelia.

Cuboidal Epithelia

Simple cuboidal epithelium

Secretion and absorption

Stratified cuboidal epithelia

Sweat ducts and mammary ducts

Figure 4–4 Cuboidal Epithelia.

Transitional Epithelium

Tolerates repeated cycles of stretching and recoiling

and returns to its previous shape without damage

Appearance changes as stretching occurs

Situated in regions of the urinary system (e.g. urinary

bladder)

Columnar Epithelia

Simple columnar epithelium

Absorption and secretion

Pseudostratified columnar epithelium

Cilia movement

Stratified columnar epithelium

Protection

Figure 4–5 Columnar Epithelia.

Glandular Epithelia

Endocrine glands

Release hormones:

– into interstitial fluid

– no ducts

Exocrine glands

Produce secretions:

– onto epithelial surfaces

– through ducts

Mechanisms of Glandular Secretion

Modes of Secretion in Glandular Epithelia

Merocrine secretion

Is produced in Golgi apparatus

Is released by vesicles (exocytosis)

For example, sweat glands

Apocrine secretion

Is produced in Golgi apparatus

Is released by shedding cytoplasm

For example, mammary gland

Holocrine secretion

Is released by cells bursting, killing gland cells

Gland cells replaced by stem cells

For example, sebaceous gland

Figure 4–6 Modes of Glandular Secretion.

Glandular Epithelia

Types of secretions

Serous glands:

– watery secretions

Mucous glands:

– secrete mucins

Mixed exocrine glands:

– both serous and mucous

Glandular Epithelia

Gland structure

Unicellular glands

– Mucous (goblet) cells are the only unicellular

exocrine glands:

» scattered among epithelia

» for example, in intestinal lining

Glandular Epithelia

Gland structure

Multicellular glands:

– structure of the duct:

» simple (undivided)

» compound (divided)

– shape of secretory portion of the gland:

» tubular (tube shaped)

» alveolar or acinar (blind pockets)

– relationship between ducts and glandular areas:

» branched (several secretory areas sharing one duct)

Figure 4–7 A Structural Classification of Exocrine Glands.

Connective Tissues

Connect epithelium to the rest of the body

(basal lamina)

Provide structure (bone)

Store energy (fat)

Transport materials (blood)

Have no contact with environment

Connective Tissues

Characteristics of Connective Tissues

Specialized cells

Solid extracellular protein fibers

Fluid extracellular ground substance

The extracellular components of connective

tissues (fibers and ground substance) make up

the matrix

Majority of tissue volume

Determines specialized function

Connective Tissues

Classification of Connective Tissues

Connective tissue proper

Connect and protect

Fluid connective tissues

Transport

Supportive connective tissues

Structural strength

Connective Tissues

Categories of Connective Tissue Proper

Loose connective tissue

More ground substance, less fibers

For example, fat (adipose tissue)

Dense connective tissue

More fibers, less ground substance

For example, tendons

Connective Tissues

Fibroblasts

Fibrocytes

Macrophages

Adipocytes

Mesenchymal cells

Melanocytes

Mast cells

Lymphocytes

Microphages

Nine Cell Types of Connective Tissue Proper

Connective Tissues

Connective Tissue Proper Cells

Fibroblasts

The most abundant cell type:

– found in all connective tissue proper

– secrete proteins and hyaluronan (cellular cement)

Fibrocytes

The second most abundant cell type:

– found in all connective tissue proper

– maintain the fibers of connective tissue proper

Connective Tissues

Macrophages

Large, amoeba-like cells of the immune system:

– eat pathogens and damaged cells

– fixed macrophages stay in tissue

– free macrophages migrate

Adipocytes

Fat cells:

– each cell stores a single, large fat droplet

Mesenchymal Cells

Stem cells that respond to injury or infection:

– differentiate into fibroblasts, macrophages, etc.

Connective Tissues

Melanocytes

Synthesize and store the brown pigment melanin

Mast Cells

Stimulate inflammation after injury or infection:

– release histamine and heparin

Basophils are leukocytes (white blood cells) that

also contain histamine and heparin

Connective Tissues

Lymphocytes

Specialized immune cells in lymphoid (lymphatic) system:

– For example, lymphocytes may develop into plasma cells

(plasmocytes) that produce antibodies

Microphages

Phagocytic blood cells:

– respond to signals from macrophages and mast cells

– For example, neutrophils and eosinophils

Connective Tissues

Connective Tissue Fibers

Collagen fibers

Most common fibers in connective tissue proper

Long, straight, and unbranched

Strong and flexible

Resist force in one direction

For example, tendons and ligaments

Connective Tissues

Reticular fibers

Network of interwoven fibers (stroma)

Strong and flexible

Resist force in many directions

Stabilize functional cells (parenchyma) and

structures

For example, sheaths around organs

Connective Tissues

Elastic fibers

Contain elastin

Branched and wavy

Return to original length after stretching

For example, elastic ligaments of vertebrae

Connective Tissues

Ground Substance

Is clear, colorless, and viscous

Fills spaces between cells and slows

pathogen movement

Connective Tissues

Figure 4–8 The Cells and Fibers of Connective Tissue Proper.

Connective Tissues

Figure 4–8 The Cells and Fibers of Connective Tissue Proper.

Connective Tissues

Embryonic Connective Tissues

Are not found in adults

Mesenchyme (embryonic stem cells)

The first connective tissue in embryos

Mucous connective tissue

Loose embryonic connective tissue

Connective Tissues

Figure 4–9 Connective Tissues in Embryos.

Connective Tissues

[INSERT FIG. 4.9b]

Figure 4–9 Connective Tissues in Embryos.

Connective Tissues

Loose Connective Tissues

The packing materials of the body

Three types in adults

Areolar

Adipose

Reticular

Connective Tissues

Areolar Tissue

Least specialized

Open framework

Viscous ground substance

Elastic fibers

Holds blood vessels and capillary beds

For example, under skin (subcutaneous layer)

Connective Tissues

Adipose Tissue

Contains many adipocytes (fat cells)

Types of adipose tissue White fat:

– most common

– stores fat

– absorbs shocks

– slows heat loss (insulation)

Brown fat:

– more vascularized

– adipocytes have many mitochondria

– when stimulated by nervous system, fat break down accelerates, releasing energy

– absorbs energy from surrounding tissues

Connective Tissues

Adipose Tissue

Adipose cells

Adipocytes in adults do not divide:

– expand to store fat

– shrink as fats are released

Mesenchymal cells divide and

differentiate:

– to produce more fat cells

– when more storage is needed

Connective Tissues

Reticular Tissue

Provides support

Complex, three-dimensional network

Supportive fibers (stroma)

Support functional cells (parenchyma)

Reticular organs

Spleen, liver, lymph nodes, and bone marrow

Connective Tissues

Figure 4–10 Adipose and Reticular Tissues.

Connective Tissues

Figure 4–10 Adipose and Reticular Tissues.

Connective Tissues

Dense Connective Tissues

Connective tissues proper, tightly packed with

high numbers of collagen or elastic fibers

Dense regular connective tissue

Dense irregular connective tissue

Elastic tissue

Connective Tissues

Dense Regular Connective Tissue

Tightly packed, parallel collagen fibers

Tendons attach muscles to bones

Ligaments connect bone to bone and stabilize

organs

Aponeuroses attach in sheets to large, flat

muscles

Connective Tissues

Figure 4–11 Dense Connective Tissues.

Connective Tissues

Dense Irregular Connective Tissue

Interwoven networks of collagen fibers

Layered in skin

Around cartilages (perichondrium)

Around bones (periosteum)

Form capsules around some organs (e.g., liver,

kidneys)

Connective Tissues

Elastic Tissue

Made of elastic fibers

For example, elastic ligaments of spinal vertebrae

Connective Tissues

Fluid Connective Tissues

Blood and lymph

Watery matrix of dissolved proteins

Carry specific cell types (formed elements)

Formed elements of blood

– red blood cells (erythrocytes)

– white blood cells (leukocytes)

– platelets

Connective Tissues

Fluid Elements of Fluid Connective

Tissues

Extracellular

Plasma

Interstitial fluid

Connective Tissues

Figure 4–12 Formed Elements of the Blood.

Connective Tissues

Extracellular fluid

Collected from interstitial space

Monitored by immune system

Transported by lymphoid (lymphatic) system

Returned to venous system

Connective Tissues

Fluid Tissue Transport Systems

Cardiovascular system (blood)

Arteries

Capillaries

Lymphoid (lymphatic) system (lymph)

Lymphatic vessels

Supportive Connective Tissues

Support soft tissues and body weight

Cartilage

Gel-type ground substance

For shock absorption and protection

Calcified (made rigid by calcium salts, minerals)

For weight support

Cartilage Matrix

Proteoglycans derived from chondroitin sulfates

Ground substance proteins

Chondrocytes (cartilage cells) surrounded by

lacunae (chambers)

Cartilage Structure

No blood vessels:

Chondrocytes produce antiangiogenesis factor

Perichondrium:

Outer, fibrous layer (for strength)

Inner, cellular layer (for growth and maintenance)

Figure 4–13 The Growth of Cartilage.

Types of Cartilage

Hyaline cartilage

Stiff, flexible support

Reduces friction between bones

Found in synovial joints, rib tips, sternum, and trachea

Elastic cartilage

Supportive but bends easily

Found in external ear and epiglottis

Fibrous cartilage (fibrocartilage)

Limits movement

Prevents bone-to-bone contact

Pads knee joints

Found between pubic bones and intervertebral discs

Figure 4–14 The Types of Cartilage.

Bone or osseous tissue Strong (calcified: calcium salt deposits)

Resists shattering (flexible collagen fibers)

Bone cells or osteocytes Arranged around central canals within matrix

Small channels through matrix (canaliculi) access blood supply

Periosteum Covers bone surfaces

Fibrous layer

Cellular layer

Figure 4–15 Bone.

Membranes

Are physical barriers

That line or cover portions of the body

Consist of

An epithelium

Supported by connective tissues

Membranes

Four Types of Membranes

Mucous membranes

Serous membranes

Cutaneous membrane

Synovial membranes

Membranes

Mucous membranes (mucosae)

Line passageways that have external connections

In digestive, respiratory, urinary, and reproductive

tracts

Epithelial surfaces must be moist

To reduce friction

To facilitate absorption and excretion

Lamina propria

Is areolar tissue

Membranes

Serous Membranes

Line cavities not open to the outside

Are thin but strong

Have fluid transudate to reduce friction

Have a parietal portion covering the cavity

Have a visceral portion (serosa) covering the

organs

Membranes

Three Serous Membranes

Pleura:

Lines pleural cavities

Covers lungs

Peritoneum:

Lines peritoneal cavity

Covers abdominal organs

Pericardium:

Lines pericardial cavity

Covers heart

Membranes

Figure 4–16 Membranes.

Membranes

Cutaneous membrane

Is skin, surface of the body

Thick, waterproof, and dry

Synovial membranes

Line moving, articulating joint cavities

Produce synovial fluid (lubricant)

Protect the ends of bones

Lack a true epithelium

Membranes

Figure 4–16 Membranes.

Internal Framework of the Body

Connective tissues

Provide strength and stability

Maintain positions of internal organs

Provide routes for blood vessels, lymphatic vessels,

and nerves

Fasciae

Singular form is fascia

The body’s framework of connective tissue

Layers and wrappings that support or surround

organs

Three Types of Fasciae

Superficial fascia

Deep fascia

Subserous fascia

Figure 4–17 The Fasciae.

Muscle Tissue

Specialized for contraction

Produces all body movement

Three types of muscle tissue

Skeletal muscle

Large body muscles responsible for movement

Cardiac muscle

Found only in the heart

Smooth muscle

Found in walls of hollow, contracting organs (blood vessels;

urinary bladder; respiratory, digestive, and reproductive

tracts)

Muscle Tissue

Classification of Muscle Cells

Striated (muscle cells with a banded appearance)

Nonstriated (not banded; smooth)

Muscle cells can have a single nucleus

Muscle cells can be multinucleate

Muscle cells can be controlled voluntarily

(consciously)

Muscle cells can be controlled involuntarily

(automatically)

Muscle Tissue

Skeletal Muscle Cells

Are long and thin

Are usually called muscle fibers

Do not divide

New fibers are produced by stem cells

(myosatellite cells)

Muscle Tissue

Figure 4–18 Muscle Tissue.

Muscle Tissue

Cardiac muscle cells

Are called cardiocytes

Form branching networks connected at

intercalated discs

Are regulated by pacemaker cells

Smooth muscle cells

Are small and tapered

Can divide and regenerate

Muscle Tissue

Neural Tissue

Also called nervous or nerve tissue

Specialized for conducting electrical impulses

Rapidly senses internal or external

environment

Processes information and controls

responses

Neural Tissue

Neural tissue is concentrated in the

central nervous system

Spinal cord

Neural Tissue

Two Kinds of Neural Cells

Neurons

Nerve cells

Perform electrical communication

Neuroglia

Supporting cells

Repair and supply nutrients to neurons

Neural Tissue

Cell Parts of a Neuron

Cell body

Contains the nucleus and nucleolus

Dendrites

Short branches extending from the cell body

Receive incoming signals

Axon (nerve fiber)

Long, thin extension of the cell body

Carries outgoing electrical signals to their destination

Neural Tissue

Figure 4–19 Neural Tissue.

Tissue Injuries and Repair

Tissues respond to injuries to maintain

homeostasis

Cells restore homeostasis with two processes

Inflammation

Regeneration

Inflammation = inflammatory response

The tissue’s first response to injury

Signs and symptoms of the inflammatory

response include

Swelling

Redness

Inflammatory Response

Can be triggered by

Trauma (physical injury)

Infection (the presence of harmful pathogens)

The Process of Inflammation

Damaged cells release chemical signals into the

surrounding interstitial fluid

Prostaglandins

Proteins

Potassium ions

As cells break down

Lysosomes release enzymes

That destroy the injured cell

And attack surrounding tissues

Tissue destruction is called necrosis

Necrotic tissues and cellular debris (pus) accumulate

in the wound

Abscess:

– pus trapped in an enclosed area

Injury stimulates mast cells to release

Histamine

Heparin

Prostaglandins

Dilation of blood vessels

Increases blood circulation in the area

Causes warmth and redness

Brings more nutrients and oxygen to the area

Removes wastes

Plasma diffuses into the area

Causing swelling and pain

Phagocytic white blood cells

Clean up the area

Figure 4–20 An Introduction to Inflammation.

Regeneration

When the injury or infection is cleaned up

Healing (regeneration) begins

The Process of Regeneration

Fibrocytes move into necrotic area

Lay down collagen fibers

To bind the area together (scar tissue)

New cells migrate into area

Or are produced by mesenchymal stem cells

Not all tissues can regenerate

Epithelia and connective tissues regenerate well

Cardiac cells and neurons do not regenerate (or regenerate

poorly)

Aging and Tissue

Aging and Tissue Structure

Speed and efficiency of tissue repair

decreases with age, due to

Slower rate of energy consumption (metabolism)

Hormonal alterations

Reduced physical activity

Aging and Tissue

Effects of Aging

Chemical and structural tissue changes

Thinning epithelia and connective tissues

Increased bruising and bone brittleness

Joint pain and broken bones

Cardiovascular disease

Mental deterioration

Aging and Tissue

Aging and Cancer Incidence

Cancer rates increase with age

1 in 4 people in the United States develops cancer

Cancer is the #2 cause of death in the United

States

Environmental chemicals and cigarette smoke

cause cancer

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