tissues. 10/6/20152 what is histology? study of tissues

Tissues

04/19/23 2

What is Histology?

Study of Tissues

Tissues

• Groups of cells similar in structure and function

• Types of tissues– Epithelial tissue– Connective tissue– Muscle tissue– Nerve tissue

Tissues

Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Four Types of Tissues

• 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

Figure 4.1

Nervous tissue: Internal communication• Brain, spinal cord, and nerves

Muscle tissue: Contracts to cause movement• Muscles attached to bones (skeletal)• Muscles of heart (cardiac)• Muscles of walls of hollow organs (smooth)

Epithelial tissue: Forms boundaries between different environments, protects, secretes, absorbs, filters• Skin surface (epidermis)• Lining of GI tract organs and other hollow organs

Connective tissue: Supports, protects, bindsother tissues together• Bones• Tendons• Fat and other soft padding tissue

Epithelial Tissue

04/19/23 copyright (your organization) 2003 9

• Forms the coverings of all of the body’s surfaces

• Lines body cavities • Functions:

– Protection– Secretion– Absorption– Excretion– Filtration– Diffusion– Sensory Reception


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

Figure 4.2a

Stratified

Simple

Apical surface

Basal surface

Apical surface

Basal surface

(a) Classification based on number of cell layers.

Figure 4.2b

Squamous

Cuboidal

Columnar(b) Classification based on cell shape.


Types of Epithelial Tissue


Simple Squamous

• Allows for diffusion, filtration, and osmosis

• Examples:– Lines heart– Lines Blood

vessels– Lines Alveoli

Epithelia: Simple Squamous

Figure 4.2a


Stratified Squamous

• Lining of smooth muscles• Superficial layer of skin• Esophagus, mouth, vagina• Aides in protection

Figure 4.3e

(e) Stratified squamous epithelium

Description: Thick membranecomposed of several cell layers;basal cells are cuboidal or columnarand metabolically active; surfacecells are flattened (squamous); in thekeratinized type, the surface cells arefull of keratin and dead; basal cellsare active in mitosis and produce thecells of the more superficial layers.

Function: Protects underlyingtissues in areas subjected to abrasion.

Location: Nonkeratinized type formsthe moist linings of the esophagus,mouth, and vagina; keratinized varietyforms the epidermis of the skin, a drymembrane.

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

Stratifiedsquamousepithelium

Nuclei

Basementmembrane

Connectivetissue


Simple Cuboidal

• Aides in secretion and absorption• Examples

– Surface of ovaries– Kidney tubules

Epithelia: Simple Cuboidal

Figure 4.2b

• Single layer of cubelike cells with large, spherical central nuclei

• Function in secretion and absorption

• Present in kidney tubules, ducts and secretory portions of small glands, and ovary surface


Stratified Cuboidal• Aides in protection• Examples:

– Sweat gland ducts– Male urethra



Figure 4–4 Cuboidal Epithelia.


Simple Columnar (NON-CILIATED)

• Lines: – GI tract– Gall bladder

• Aides in:– Secretion – Absorption


Ciliated Simple Columnar• Located in:

– Respiratory tract– Fallopian tubes– Uterus– Sinuses

Epithelia: Simple Columnar

Figure 4.2c


Transitional

• Located in:– Urinary bladder– Uterus– Urethra

Epithelia: Transitional

Figure 4.2f

• Several cell layers, basal cells are cuboidal, surface cells are dome shaped

• Stretches to permit the distension of the urinary bladder

• Lines the urinary bladder, ureters, and part of the urethra


Pseudostratified Columnar

• Aides in the movement of material• CiliatedUpper Respiratory tract

• Non-ciliatedEpididymus and male urethra

Figure 4.3d

(d) Pseudostratified columnar epithelium

Description: Single layer of cells ofdiffering heights, some not reachingthe free surface; nuclei seen atdifferent levels; may contain mucus-secreting cells and bear cilia.

Function: Secretion, particularly ofmucus; propulsion of mucus byciliary action.

Location: Nonciliated type in male’ssperm-carrying ducts and ducts oflarge glands; ciliated variety linesthe trachea, most of the upperrespiratory tract.

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

Trachea

Cilia

Pseudo-stratifiedepitheliallayer

Basementmembrane

Mucus ofmucous cell



Figure 4–5 Columnar Epithelia.

Identify the tissues

Connective Tissues

Connective Tissue

• Most abundant and widely distributed tissue type

• Four classes– Connective tissue proper– Cartilage– Bone tissue– Blood

Table 4.1


Functions

• Bind structures together• Supports the organs and the

body (Framework)• Stores fat (Insulation)• Transports substances

(blood)• Protects from disease• Helps repair tissue damage

Figure 4.7

Macrophage

Fibroblast

Lymphocyte

Fat cell

Mast cell

Neutrophil

Capillary

Cell types Extracellularmatrix

Fibers• Collagen fiber• Elastic fiber• Reticular fiber

Ground substance

Connective Tissue Proper

• Types:– Loose

connective tissue• Areolar• Adipose• Reticular

– Dense connective tissue• Dense regular• Dense irregular• Elastic


Types1. Areolar (loose)

• Stretchable, superficial, soft tissue

• Examples:• Surrounds blood vessels and

nerves• Attaches skin to muscles

(Fascia)

Connective Tissue Proper: Loose

Figure 4.8b


2. Adipose:• Functions

– Stores Fats– Protects and supports– Insulates – Food reservoir

• Located anywhere fat is in excess


Figure 4.8c


3. Reticular:• Functions

– Forms network of spleen, lymph nodes, and bone marrow

– Provides defense against microorganisms


Figure 4.8d


4. Dense (fibrous):• Provide flexible but strong

connections• Examples:

– Tendons (Bone-Muscle)– Ligaments (Bone-Bone)– Aponeuroses (Muscle-

Muscle)

Fibrous Connective Tissue

Tendons = muscles to bones Ligaments = bones to bones

Connective Tissue Proper: Dense Regular

Figure 4.8e

Figure 4.8e

(e) Connective tissue proper: dense connective tissue, dense irregular

Description: Primarilyirregularly arranged collagenfibers; some elastic fibers;major cell type is the fibroblast.

Function: Able to withstandtension exerted in manydirections; provides structuralstrength.

Location: Fibrous capsules oforgans and of joints; dermis ofthe skin; submucosa ofdigestive tract.

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

Collagenfibers

Nuclei offibroblasts

Fibrousjointcapsule

Figure 4.8f

(f) Connective tissue proper: dense connective tissue, elastic

Description: Dense regularconnective tissue containing a highproportion of elastic fibers.

Function: Allows recoil of tissuefollowing stretching; maintainspulsatile flow of blood througharteries; aids passive recoil of lungsfollowing inspiration.

Location: Walls of large arteries;within certain ligaments associatedwith the vertebral column; within thewalls of the bronchial tubes.

Elastic fibers

Aorta

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


• Bone->Compact and spongy

• Blood->55% liquid/plasma

45% formed elements

Specialized Types

Connective Tissue: Bone (Osseous Tissue)

Figure 4.8j

Connective Tissue: Blood

Figure 4.8k


• Cartilage->Hyaline

Fibrous

Elastic


Supportive Connective Tissues

Figure 4–14 The Types of Cartilage.

Figure 4.8g

(g) Cartilage: hyaline

Description: Amorphous but firmmatrix; collagen fibers form animperceptible network; chondroblastsproduce the matrix and when mature(chondrocytes) lie in lacunae.

Function: Supports and reinforces;has resilient cushioning properties;resists compressive stress.

Location: Forms most of theembryonic skeleton; covers the endsof long bones in joint cavities; formscostal cartilages of the ribs; cartilagesof the nose, trachea, and larynx.

Photomicrograph: Hyaline cartilage from thetrachea (750x).

Costalcartilages

Chondrocytein lacuna

Matrix

Figure 4.8h

(h) Cartilage: elastic

Description: Similar to hyalinecartilage, but more elastic fibersin matrix.

Function: Maintains the shapeof a structure while allowinggreat flexibility.

Location: Supports the externalear (pinna); epiglottis.

Photomicrograph: Elastic cartilage fromthe human ear pinna; forms the flexibleskeleton of the ear (800x).

Chondrocytein lacuna

Matrix

Figure 4.8i

(i) Cartilage: fibrocartilage

Description: Matrix similar tobut less firm than that in hyalinecartilage; thick collagen fiberspredominate.

Function: Tensile strengthwith the ability to absorbcompressive shock.

Location: Intervertebral discs;pubic symphysis; discs of kneejoint.

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

Intervertebraldiscs

Chondrocytesin lacunae

Collagenfiber


• All have nerve supply (Except Cartilage)

• Very Vascular (Except Cartilage)

• All consist of cells and matrix– Matrix=fibers between the

cells

Muscle Tissue


Components

• Made up of cells that can shorten or contract in order to produce movement in body parts

• Well supplied with blood vessels• Cells are long and slender

(muscle fibers)• Actin and myosin are contractile

proteins.– http://www.sci.sdsu.edu/movies/acti

n_myosin.html

http://www.sci.sdsu.edu/movies/actin_myosin.html

http://www.sci.sdsu.edu/movies/actin_myosin.html


3 Types of Muscle Tissues

1. Skeletal->regular (voluntary)• Aka. Striated (striped)• Many nuclei per cell b/c extremely long

2. Smooth->intestines (involuntary)• Non-striated

1. Cardiac->heart (involuntary)• Striated

Figure 4.10a

(a) Skeletal muscle

Description: Long, cylindrical,multinucleate cells; obviousstriations.

Function: Voluntary movement;locomotion; manipulation of theenvironment; facial expression;voluntary control.

Location: In skeletal musclesattached to bones oroccasionally to skin.

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

Nuclei

Striations

Part ofmuscle fiber (cell)

Figure 4.10b

(b) Cardiac muscle

Description: Branching, striated, generally uninucleate cells that interdigitate atspecialized junctions (intercalated discs).

Function: As it contracts, it propels blood into the circulation; involuntary control.Location: The walls of the heart.

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

Intercalateddiscs

Striations

Nucleus


Muscle Tissue

Figure 4–18 Muscle Tissue.

Figure 4.10c

(c) Smooth muscle

Description: Spindle-shapedcells with central nuclei; nostriations; cells arranged closely to form sheets.

Function: Propels substancesor objects (foodstuffs, urine,a baby) along internal passage-ways; involuntary control.Location: Mostly in the wallsof hollow organs.

Photomicrograph: Sheet of smooth muscle (200x).

Smoothmusclecell

Nuclei


Muscle Tissue

Figure 4–18 Muscle Tissue.

Nervous Tissue


• Located in the brain, spinal cord, and nerves

• Coordinates and controls many of the bodies activities

• Stimulates muscle contractions

• Creates awareness• Has a role in emotions,

memory, and reasoning.

Figure 4.9

Photomicrograph: Neurons (350x)

Function: Transmit electricalsignals from sensory receptorsand to effectors (muscles andglands) which control their activity.

Location: Brain, spinalcord, and nerves.

Description: Neurons arebranching cells; cell processesthat may be quite long extend fromthe nucleus-containing cell body;also contributing to nervous tissueare nonirritable supporting cells(not illustrated).

Dendrites

Neuron processes Cell body

Axon

Nuclei ofsupportingcells

Cell bodyof a neuron

Neuronprocesses

Nervous 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

– Heat

– Pain



• Inflammatory Response

– Can be triggered by

• Trauma (physical injury)

• Infection (the presence of harmful

pathogens)

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



• Regeneration

– When the injury or infection is

cleaned up

• Healing (regeneration) begins


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

Cell Differentiation

• All cells carry complete DNA instructions for all body functions

• Cells specialize or differentiate– To form tissues (liver cells, fat cells, and

neurons)

– By turning off all genes not needed by that cell

• All body cells, except sex cells, contain the same 46 chromosomes

• Differentiation depends on which genes are active and which are inactive

- CancerWhat Is Cancer?

• Cancer is a disease in which cells grow and divide uncontrollably, damaging the parts of the body around them.

Tumors and Cancer

• Cancer develops in steps

– Abnormal cell

– Primary tumor

– Metastasis

– Secondary tumor

Tumors and Cancer• Tumor (neoplasm)

– Enlarged mass of cells

– Abnormal cell growth and division

– Benign tumor • Contained

• Not life threatening

– Malignant tumor • Spreads into surrounding tissues (invasion)

• Starts new tumors (metastasis)

tissues. 10/6/20152 what is histology? study of tissues

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