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Chapter 04

Lecture Outline

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2

Chapter 4-Tissues

• What is a tissue?

group of cells with similar structure and

function plus extracellular substance (matrix)

• Histology:

study of tissues

3

Types of Tissues

1. Epithelial

2. Connective

3. Muscular

4. Nervous

4

Epithelial Tissues

• Location:

- cover body (internal and external)

- Ex. Skin, kidney, trachea, glands, etc.

5

• Characteristics:

- cells close together (very little extracellular

matrix)

- form most glands

- have free surface

- Basal surface:

attaches epithelial cells to underlying tissues

7

Functions of Epithelial Tissues

1. Protect:

Ex. Skin

2. Act as a barrier:

Ex. Skin keeps bacteria out

3. Diffusion and Filtration:

Ex. Lungs and kidneys

4. Secretion:

Ex. Sweat glands

5. Absorption:

Ex. Small intestine

8

Classification of Epithelial Tissue

• Classified according to number of cell layers

and cell shape

• Simple and stratified = number of cell layers

• Squamous, cuboidal, columnar, transitional= cell

shape

10

Types of Epithelial Tissues

• Simple Epithelium

Structure: 1 layer of cells

• Stratified Epithelium

Structure: many layers of cells

11

• Simple Squamous

Structure: 1 layer of flat, tile-like cells

Function: diffusion and filtration

Location: blood vessels, lungs, heart, kidneys

• Simple Cuboidal

Structure: 1 layer of square-shaped cells

Function: secretion

Location: glands, ovaries, kidneys

12

Lung alveoli

TABLE 4.2 Simple Epithelium

(a) Simple Squamous Epithelium

Structure: Function: Location:

Single layer of flat, often hexagonal

cells; the nuclei appear as bumps

when viewed in cross section because

the cells are so flat

Diffusion, filtration, some secretion,

and some protection against friction

Lining of blood vessels and the

heart, lymphatic vessels, alveoli

of the lungs, portions of the

kidney tubules, lining of serous

membranes of body cavities

(pleural, pericardial, peritoneal)

Free surface

Nucleus

Basement

membrane

Simple

squamous

epithelial

cell

LM 640x


a(2): © McGraw-Hill Higher Education, Inc./Dennis Strete, photographer

13

Kidney

Structure:

(b) Simple Cuboidal Epithelium

Function: Location:

Single layer of cube-shaped cells;

some cells have microvilli (kidney

tubules) or cilia (terminal bronchioles

of the lungs)

Active transport and facilitated

diffusion result in secretion and

absorption by cells of the kidney

tubules; secretion by cells of glands

and choroid plexuses; movement of

particles embedded in mucus out of

the terminal bronchioles by ciliated cells

Kidney tubules, glands and their ducts,

choroid plexuses of the brain, lining

of terminal bronchioles of the lungs,

and surfaces of the ovaries

Basement

membrane

Simple

cuboidal

epithelial

cell

Nucleus

Free surface

LM 640x

b(2): © Victor Eroschenko

TABLE 4.2 continued


14

• Simple Columnar

Structure: 1 layer of tall, narrow cells

Function: secrete mucus and absorption

Location: stomach, intestines, resp. tract

• Pseudostratified Columnar

Structure: 1 layer of tall, narrow cells

appears stratified but isn’t

Function: secrete mucus and propel debris out of

resp. tract (cilia)

Location: nasal cavity and trachea

15

TABLE 4.2 continued

(c) Simple Columnar Epithelium

Structure:

Single layer of tall, narrow cells; some

cells have cilia (bronchioles of lungs,

auditory tubes, uterine tubes, and

uterus) or microvilli (intestines)

Function:

Movement of particles out of the

bronchioles of the lungs by ciliated

cells; partially responsible for the

movement of oocytes through

the uterine tubes by ciliated cells;

secretion by cells of the glands,

the stomach, and the intestine;

absorption by cells of the intestine

Location:

Glands and some ducts,

bronchioles of lungs,

auditory tubes, uterus,

uterine tubes, stomach,

intestines, gallbladder, bile

ducts, and ventricles of

the brain

Lining of

stomach and

intestines

Free surface

Goblet cell

containing mucus

Nucleus

Simple

columnar

epithelial

cell

Basement

membraneLM 640x


c(2): © Victor Eroschenko

TABLE 4.2 continued

16

(d) Pseudostratified Columnar Epithelium


Single layer of cells; some

cells are tall and thin and reach the

free surface, and others do not; the

nuclei of these cells are at different

levels and appear stratified; the cells

are almost always ciliated and are

associated with goblet cells that

secrete mucus on to the free surface

Synthesize and secrete mucus on to

the free surface and move mucus

(or fluid) that contains foreign

particles over the surface of the

free surface and from passages

Lining of nasal cavity, nasal

sinuses, auditory tubes, pharynx,

trachea, and bronchi of lungs Trachea

Bronchus

Cilia

Basement

membrane

Nucleus

Pseudostratified

columnar

epithelial cell

LM 413x

Goblet cell

containing mucus

Free surface

d(2): © Victor Eroschenko


17

• Stratified Squamous

Structure: many layers of flat, tile-like cells

Function: protect and acts as a barrier

Location: skin, mouth, throat, esophagus

• Transitional

Structure: special type of stratified epi. changes

shape (stretched squamous, not stretched

cuboidal)

Function: hold fluids

Location: urinary bladder

18


Esophagus

Mouth

Cornea

Skin

LM 286x

Basement

membrane

Nuclei

Nonkeratinized

stratified

squamous

epithelial cell

Free surface

TABLE 4.3 Simple Epithelium

(a) Stratified Squamous Epithelium


Several layers of cells that are cuboidal

in the basal layer and progressively

flattened toward the surface; the

epithelium can be nonkeratinized (moist)

or keratinized; in nonkeratinized stratified

squamous epithelium, the surface cells

retain a nucleus and cytoplasm; in keratinized

stratified epithelium, the cytoplasm of cells

at the surface is replaced by a protein called

keratin, and the cells are dead

Protects against abrasion, forms

a barrier against infection, and

reduces loss of water from the body

Keratinized—outer layer of the skin;

nonkeratinized—mouth, throat,

larynx, esophagus, anus, vagina,

inferior urethra, and corneas

a(2): © Victor Eroschenko

19

(b) Transitional Epithelium

Structure:

Stratified cells that appear cuboidal

when the organ or tube is not stretched

and squamous when the organ or tube

is stretched by fluid

Function:

Accommodates fluctuations in the

volume of fluid in an organ or a tube;

protects against the caustic effects

of urine

Location:

Lining of urinary bladder,

ureters, and superior urethra

Ureter

Urinary bladder

Urethra

LM 413x

Free surface

Transitional

epithelial cell

Nucleus

Basement

membrane

Tissue stretched

Basement

membrane

Nucleus

Transitional

epithelial

cell

Free surface

Tissue not stretched

LM 413x

b(2, 3): © Victor Eroschenko

TABLE 4.3 continued


20

Free Cell Surfaces

• Surface not in contact with other cells

• Smooth to reduce friction, Ex. Blood vessels

• Microvilli:

- increase cell’s surface area

- Ex. Small intestine

21

• Cilia:

- move materials across cell’s surface

- Ex. Trachea

• Goblet cells:

- produce mucus

- Ex. Stomach

22

Cell Connections

• Tight junctions:

- bind adjacent cells together

- Ex. Intestines

• Desmosomes:

mechanical links that bind cells

• Hemidesmosomes:

bind cells to basement membrane

• Gap junctions:

- small channels that allow molecules to pass

between cells

- allow cells to communicate

- most common

23

Figure 4.2

25

Glands• What are they?

structures that secrete substances onto a surface, into

a cavity, or into blood

• Exocrine glands:

- glands with ducts

- Ex. Sweat or oil glands

• Endocrine glands:

– no ducts (directly into bloodstream)

– Ex. Thyroid, thymus, pituitary glands, etc.

26


Secretion in duct

Vesicle releasing

contents into duct

Pinched-off portion

of cell in the secretion

Dying cell releases

secretory products

Cell shed into

the duct

Replacement

cell

Secretory products

stored in the cell

Vesicle containing

secretory products

(a) Merocrine gland

Cells of the gland produce

secretions by active transport or

produce vesicles that contain

secretory products, and the

vesicles empty their contents into

the duct through exocytosis.

(b) 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 merocine

process.

(c) Holocrine gland

Secretory products 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.

Types of Exocrine Glands

• Simple:

no branches

• Compound:

many branches

• Tubular:

end of duct

• Alveolus:

sac-like structure

27

29

Connective Tissues Characteristics

• Cells far apart

• Contain large amounts of extracellular matrix

• Classified based on type of extracellular matrix

and function

• Ex. Blast cells build, clast cells carve

• Extracellular matrix contains 3 components (in

varying amounts): protein fibers, ground

substance, fluid

• Ground substance: proteins and sugars

30

Types of Protein Fibers

• Collagen fibers:

look like ropes and are flexible but resist

stretching

• Reticular fibers:

supporting network that fills spaces between

organs and tissues

• Elastic fibers:

recoil after being stretched

31

Functions of Connective Tissue

1. Enclose and separate:

Ex. around organs and muscles

2. Connect tissues:

Ex. Tendons: connect bone to muscle

Ex. Ligaments: connect bone to bone

3. Support and Movement:

Ex. bones

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4. Storage:

Ex. bones store calcium and adipose tissue

stores fat

5. Cushion and insulate:

Ex. adipose tissue protects organs and helps

conserve heat

6. Transport:

Ex. Blood

7. Protect:

Ex. Immune cells

34

Types of Ordinary Connective Tissue

• Loose

Location: between organs, muscles, glands, skin

Structure: collagen fibers far apart

Function: support and protect

35


TABLE 4.5 Connective Tissue Proper: Loose Connective Tissue

(a) Areolar Connective Tissue


A fine network of fibers (mostly collagen

fibers with a few elastic fibers) with spaces

between the fibers; fibroblasts, macrophages,

and lymphocytes are located in the spaces

Loose packing, support, and nourishment for

the structures with which it is associatedWidely distributed throughout the body;

substance on which epithelial basement

membranes rest; packing between glands,

muscles, and nerves; attaches the skin to

underlying tissues

Elastic

fiber

Nucleus

Collagen

fiber

Epidermis

Dermis

Loose connective tissue

with fat

Muscle

Skin

LM 400X

(a): © Ed Reschke

36

• Dense

Location: tendons, ligaments, skin

Structure: collagen fibers packed close together

Function: connect and can withstand pulling

forces

• Adipose

Location: under skin and around organs

Structure: collagen and elastic fibers, cells filled

with lipids

Function: storage, insulate, cushion

37


TABLE 4.6 Connective Tissue Proper: Dense Connective Tissue

(a) Dense Collagenous Connective Tissue


Matrix composed of collagen fibers

running in somewhat the same direction

in tendons and ligaments; collagen fibers

run in several directions in the dermis of

the skin and in organ capsules

Withstand great pulling forces exerted in

the direction of fiber orientation due to

great tensile strength and stretch

resistance

Tendons (attach muscle to bone) and

ligaments (attach bones to each other);

also found in the dermis of the skin, organ

capsules, and the outer layer of many

blood vessels

Ligament

Tendon

Nucleus of

fibroblast

Collagen

fibers

LM 165x

(a): © Victor Eroschenko

38

(b) Dense Elastic Connective Tissue

Structure:

Matrix composed of collagen fibers and

elastin fibers running in somewhat the

same direction in elastic ligaments;

elastic fibers run in connective tissue of

blood vessel walls

Function:

Capable of stretching and recoiling like a

rubber band with strength in the direction

of fiber orientation

Location:

Elastic ligaments between the vertebrae

and along the dorsal aspect of the neck

(nucha) and in the vocal cords; also found

in elastic connective tissue of blood

vessel walls

Base of tongue

Vocal folds

(true vocal cords)

Vestibular fold

(false vocal cord)

LM 100x

Nucleus of

fibroblast

Elastin

fibers

(b): © Victor Eroschenko


TABLE 4.6 continued

39

(b) Adipose Tissue


Little extracellular matrix surrounding cells;

the adipocytes, or fat cells, are so full of lipid

that the cytoplasm is pushed to the periphery

of the cell

Packing material, thermal insulator, energy

storage, and protection of organs against

injury from being bumped or jarred

Predominantly in subcutaneous areas,

mesenteries, renal pelves, around kidneys,

attached to the surface of the colon,

mammary glands, and in loose connective

tissue that penetrates into spaces and

crevices

Adipose

tissue

Mammary

gland

Nucleus

Adipocytes

or fat cells

LM 100x

(b): © Ed Reschke

TABLE 4.5 continued


Cartilage

• Type of connective tissue

• Composed of chondrocytes

• Contains collagen

• Withstands compressions

• Provides support, flexibility, strength

40

41

Types of Cartilage

• Hyaline cartilage

Location: covers ends of bones

Structure: some collagen fibers

Function: reduces friction (cushion)

• Fibrocartilage

Location: between vertebra

Structure: lots of collagen fibers

Function: can withstand compression


TABLE 4.7 Supporting Connective Tissue: Cartilage

(a) Hyaline Cartilage

Structure:

Collagen fibers are small and evenly

dispersed in the matrix, making the matrix

appear transparent; the cartilage cells, or

chondrocytes, are found in spaces, or

lacunae, within the firm but flexible matrix

Function:

Allows growth of long bones; provides

rigidity with some flexibility in the trachea,

bronchi, ribs, and nose; forms strong,

smooth, yet somewhat flexible articulating

surfaces; forms the embryonic skeleton

Location:

Growing long bones, cartilage rings of the

respiratory system, costal cartilage of ribs,

nasal cartilages, articulating surface of

bones, and the embryonic skeleton

Bone

Hyaline

cartilage

Chondrocyte

in a lacuna

Nucleus

Matrix

LM 240x

(a): © Carolina Biological Supply/PhototakeUSA.com

43

• Elastic cartilage

Location: ear and tip of nose

Structure: elastic fibers

Function: can recoil


TABLE 4.7 continued

(b) Fibrocartilage

Structure:

Collagen fibers similar to those in hyaline

cartilage; the fibers are more numerous than

in other cartilages and are arranged in

thick bundles

Function:

Somewhat flexible and capable of

withstanding considerable pressure;

connects structures subjected to great

pressure

Location:

Intervertebral disks, pubic symphysis,

and articular disks (e.g., knees and

temporomandibular [jaw] joints)

Intervertebral

disk

Collagen fibers

in matrix

Nucleus

Chondrocyte

in lacuna

LM 240x

(b); © Victor Eroschenko; (c): © Victor Eroschenko

(c) Elastic Cartilage

Structure:

Similar to hyaline cartilage, but

matrix also contains elastin fibers

Function:

Provides rigidity with even more flexibility than

hyaline cartilage because elastic fibers return to

their original shape after being stretched

Location:

External ears, epiglottis, and

auditory tubes

Elastic fibers

in matrix

Chondrocytes

in lacunae

Nucleus

LM 240x

Bone

• Hard connective tissue

• 2 types: compact and spongy

• Composed of osteocytes

45


TABLE 4.8 Supporting Connective Tissue: Bone

Structure:

Hard, bony matrix predominates; many

osteocytes (not seen in this bone preparation)

are located within lacunae; the matrix is

organized into layers called lamellae

Function:

Provides great strength and support and

protects internal organs, such as the brain;

bone also provides attachment sites for

muscles and ligaments; the joints of bones

allow movements

Lacuna

Central

canal

LM 240x

Matrix

organized

into lamellae

Location:

All bones of the body

Spongy bone

Compact bone

© Trent Stephens

Blood

• Liquid connective tissue

• Erythrocytes, leukocytes, platelets

• Transport food, oxygen, waste, hormones

47


TABLE 4.9 Fluid Connective Tissue: Blood

Structure:

Blood cells and a fluid matrix

Function:

Transports oxygen, carbon dioxide, hormones,

nutrients, waste products, and other substances;

protects the body from infections and is

involved in temperature regulation

Location:

Within the blood vessels; white blood cells

frequently leave the blood vessels and enter

the interstitial spaces

Red

blood

cells

LM 400x

White

blood

cells

© Ed Reschke

49

Muscular TissueMuscle type Nucleus/i Nucleus/i location Striated

Skeletal many peripheral Y

(most muscle)

Cardiac 1 centrally Y

(heart)

Smooth 1 centrally N

(organs)


TABLE 4.10 Muscle Tissue

(a) Skeletal Muscle

Structure:

Skeletal muscle cells or fibers appear

striated (banded); cells are large, long,

and cylindrical, with many nuclei

Function:

Movement of the body; under

voluntary control

Location:

Attached to bone or other

connective tissue

Muscle

Nucleus (near

periphery of cell)

Skeletal

muscle

fiber

Striations

LM 800x

a(2): © Ed Reschke

(b) Cardiac Muscle

Structure: Location:

Cardiac muscle cells are cylindrical and

striated and have a single nucleus; they

are branched and connected to one

another by intercalated disks, which

contain gap junctions

Function:

Pumps the blood; under

involuntary (unconscious)

control

In the heart

Nucleus

Cardiac

muscle cell

Striations

Intercalated disks

(special junctions

between

cells)

LM 800x

b(2): © Ed Reschke

TABLE 4.10 continued



TABLE 4.10 continued

(c) Smooth Muscle

Structure:

Smooth muscle cells are tapered at

each end, are not striated, and have

a single nucleus

Function:

Regulates the size of organs, forces

fluid through tube, controls the

amount of light entering the eye,

and produces ″goose bumps″ in the skin;

under involuntary (unconscious) control

Location:

In hollow organs, such

as the stomach and intestine;

skin and eyes

Wall of stomach

Wall of colon

Wall of small

intestine

Nucleus

LM 800x

Smooth

muscle cell

c(2): © Victor Eroschenko

54

Nervous Tissue

• Consist of neurons or nerve cells

• Found in brain, spinal cord, and peripheral nerves

• Controls and coordinates body movements

• Includes axons, dendrites, cell bodies

55


TABLE 4.11 Nervous Tissue

Structure:

A neuron consists of dendrites, a cell

body, and a long axon; neuroglia,

or support cells, surround the neurons

Function:

Neurons transmit information in

the form of action potentials, store

information, and integrate and evaluate

data; neuroglia support, protect, and

form specialized sheaths around axons

Location:

In the brain, spinal cord,

and ganglia

Brain

Spinal

cord

Spinal

nerves

Dendrite

Cell body

of neuron

Nucleus

of neuron

Nuclei of

neuroglia

Axon

Neuroglia

LM 240x

© Trent Stephens

56

Tissue Repair

• What is it?

substitution of dead cells for viable

cells

• Regeneration:

cells of same type develop (no scar)

• Replacement:

cells of a different type develop (scar)

57

Inflammation

• Occurs when tissues are damaged

• Signals the body’s defenses (white blood cells)

to destroy foreign materials and damaged cells

so repair can occur.

• Chemical mediators:

- released after injury

- cause dilation of blood vessels

58

Symptoms of Inflammation

1. Redness: blood vessels dilate

2. Heat: due to increased blood flow

3. Swelling: from water and proteins

4. Pain: nerve endings are stimulated by

damage and swelling

3

1

2

1

2

3

A splinter in the skin causes damage and

introduces bacteria. Chemical mediators of

inflammation are released or activated in injured

tissues and adjacent blood vessels. Some blood

vessels rupture, causing bleeding.

Chemical mediators cause capillaries to dilate

and the skin to become red. Chemical

mediators also increase capillary permeability,

and fluid leaves the capillaries, producing

swelling (arrows).

White blood cells (e.g., neutrophils) leave the

dilated blood vessels and move to the site of

bacterial infection, where they begin to

phagocytize bacteria and other debris.

Splinter

Bacteria

introduced

Epidermis

Dermis

Blood

vessel

Bacteria

proliferating

Neutrophil

phagocytizing

bacteria Neutrophil

migrating through

blood vessel wall


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