Chapter 05
Lecture Outline
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Cells are Organized into Tissues
In complex organisms, cells are organized into tissues
Tissues: Groups of similar cells with a common function
The study of tissues is called histology.
There are 4 major types of tissues in the body:
1. Epithelial tissue
2. Connective tissue
3. Muscle tissue
4. Nervous tissue
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Table 5.2 - 4 Major Tissue Types
Type
Function
Location
Distinguishing
Characteristics
Epithelial
Protection, secretion,
absorption, excretion
Cover body surface,
cover and line internal
organs, compose glands
Lack blood vessels, cells
readily divide, cells are tightly
packed
Connective
Bind, support, protect, fill
spaces, store fat, produce
blood cells
Widely distributed
throughout the body
Mostly have good blood
supply, cells are farther apart
than epithelial cells, with
extracellular matrix in
between
Muscle
Movement
Attached to bones, in
the walls of hollow
internal organs, heart
Able to contract in response
to specific stimuli
Nervous
Conduct impulses for
coordination, regulation,
integration, and sensory
reception
Brain, spinal cord,
nerves
Cells communicate with each
other and other body parts
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Figure 5.1 Intercellular Junctions
Tight junctions:
• Membranes of adjacent cells merge and fuse.
• Located among cells that form linings, sheet-like layers.
• Blood-brain barrier.
Desmosomes:
• Form “spot welds” between cells.
• Structural reinforcement.
• Located among outer skin cells.
Gap junctions:
• Tubular channels between cells.
• Molecules can move between cells.
• Located in cardiac muscle cells.
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Table 5.1 Types of Intercellular Junctions
Type
Characteristics
Example
Tight junctions
Close space between cells by fusing
cell membranes
Cells that line the small intestine
Desmosomes
Bind cells by forming “spot welds”
between cell membranes
Cells of the outer skin layer
Gap junction
Form tubular channels between cells
that allow exchange of substances
Muscle cells of the heart and
digestive tract
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From Science to Technology 5.1
Nanotechnology Meets the Blood-Brain Barrier
Nanotechnology helps with drug delivery across the blood-brain barrier
Blood-brain barrier selects which chemicals are allowed to cross;
protects from toxins & chemical fluctuations
Nanotechnology uses structures smaller than 100 nm in at least 1
direction, to help medications cross the barrier
Example: Anesthetics or chemotherapeutics are combined with
liposomes (phospholipid bubbles) to mask portion of drug that cannot
cross the barrier
Example: Insulin can be inhaled in nanoparticles, instead of being
injected
©2019 McGraw-Hill Education.
Epithelial Tissue
General Characteristics:
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•
•
•
Covers organs and body surface.
Lines cavities and hollow organs.
Makes up glands.
Have a free surface on outside, and basement membrane on inside.
This tissue lacks blood vessels (avascular) and nutrients diffuse to epithelial
tissue from underlying connective tissue.
Cells readily divide; injuries heal rapidly.
Cells are tightly packed.
Classified according to cell shape and number of cell layers.
Shapes: squamous (flat), cuboidal (cube-shaped), columnar (tall).
Layers: simple (one layer of cells), stratified (2 or more layer of cells), or
pseudostratified (appears layered, but is not).
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Figures 5.3 and 5.4 Epithelial Tissue Types
Simple squamous:
• Single layer of thin, flat cells.
• Substances pass easily through air sacs
(alveoli) & capillaries.
• Thin & delicate, can be damaged.
• Found in diffusion & filtration sites.
• Lines air sacs (alveoli) & capillaries.
• Lines blood & lymphatic vessels.
Simple cuboidal:
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•
•
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•
Single layer of cube-shaped cells.
Secretion and absorption.
Lines kidney tubules, thyroid follicles.
Covers ovaries.
Lines ducts of some glands.
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Top: b-c: © McGraw-Hill Education/Al Telser, photographer.
Bottom: b: © Victor P. Eroschenko
Figures 5.5 and 5.7 Epithelial Tissue Types
Simple columnar:
• Single layer of elongated cells.
• Nuclei usually at same level, near
basement membrane.
• Sometimes have cilia.
• Sometimes have microvilli.
• Sometimes have goblet cells
(secrete mucus).
• Secretion and absorption.
• Lines uterus, stomach, intestines.
Pseudostratified columnar:
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•
•
•
•
•
Single layer, but appears layered.
Nuclei at 2 or more levels.
Cells vary in shape.
Often has cilia, goblet cells.
Protection from infection.
Lines respiratory passageways.
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Top: b: © Victor P. Eroschenko, Bottom: © McGraw-Hill Education/Dennis Strete
Figures 5.8 and 5.9 Epithelial Tissue Types
Stratified squamous:
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Many cell layers; thick.
Protective layer.
Outermost cells are flat.
Deeper cells are cuboidal.
New cells form, push older cell
toward free surface.
• Outer layer of skin (keratinized).
• Lines oral cavity, vagina, anal canal.
Stratified cuboidal:
• 2 to 3 layers of cube-shaped cells.
• More protection than 1 layer.
• Lines ducts of mammary, sweat,
& salivary glands, and pancreas.
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Top: © McGraw-Hill Education/Al Telser, photographer
Bottom: © McGraw-Hill Education/Al Telser, photographer
Figures 5.10 and 5.11 Epithelial Tissue Types
Stratified columnar:
• Top layer of elongated cells.
• Cube-shaped cells in
deeper layers.
• Lines part of male urethra,
ducts of exocrine glands.
Transitional (uroepithelium):
• Many cell layers.
• Cube-shaped and elongated cells.
• Changes shape with increased
tension; stretches.
• Line urinary bladder, ureters, and
part of urethra.
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Top: b: © McGraw-Hill Education/Al Telser, photographer
Bottom: b,d: © Ed Reschke
Glandular Epithelium
Glandular Epithelium: Composed of cells that produce and secrete
substances into ducts or body fluids
There are 2 types of glands:
• Endocrine glands secrete into tissue fluid or blood.
• Exocrine glands secrete into ducts that open onto surface.
2 structural types of exocrine glands:
Unicellular: Composed of one cell, such as a goblet cell (secretes mucus).
Multicellular:
• Composed of many cells.
• Sweat glands, salivary glands, etc.
• Simple or compound.
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Figure 5.12 Structural Types of Exocrine Glands
Simple: duct does not branch
Compound: duct branches before it reaches secretory portion
Tubular: consist of epithelial-lined tubes
Alveolar: terminal portions form sac-like dilations
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Table 5.3 Types of Exocrine Glands
Type
Characteristics
Example
Unicellular
A single secretory cell
Mucous-secreting cell (see
Figure 5.5)
Multicellular
Glands that consist of many cells
Simple glands
Glands that communicate with the surface by
means of ducts that do not branch before reaching
the secretory portion
1. Simple tubular gland
Straight tube-like gland that opens directly onto
surface
Intestinal glands of small
intestine (see Figure 17.3)
2. Simple branched tubular gland
Branched, tube-like gland; duct short or absent
Gastric glands (see Figure
17.19)
3. Simple coiled tubular gland
Long, coiled, tube-like gland; long duct
Merocrine (sweat) glands of
skin (see Figures 6.10 and
6.11)
4. Simple branched alveolar gland
Secretory portions of gland expand into saclike
compartments along duct
Sebaceous gland of skin (see
Figure 5.14)
Compound glands
Glands that communicate with surface by means
of ducts that branch repeatedly before reaching
the secretory portion
1. Compound tubular gland
Secretory portions are tubules extending from
branches of branches that combine into one duct
Bulbourethral glands of male
(see Figure 22.4)
2. Compound alveolar gland
Secretory portions are irregularly branched tubules
with numerous saclike outgrowths
Mammary glands (see Figure
23.28)
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Figure 5.13 Types of Glandular Secretion
(a) Merocrine gland
(b) Apocrine gland
(c) Holocrine gland
Merocrine glands: Secrete fluid products by exocytosis; salivary & sweat glands, pancreas
Apocrine glands: Lose small part of cell during secretion; mammary & ceruminous glands
Holocrine glands: Release entire cells filled with product; sebaceous glands
©2019 McGraw-Hill Education.
Table 5.5 Epithelial Tissues
Type
Description
Function
Location
Simple squamous
epithelium
Single layer, flattened cells
Filtration, diffusion, osmosis,
covers surface
Air sacs of lungs, walls of capillaries, linings
of blood and lymph vessels, part of the
membranes lining body cavities and
covering viscera
Simple cuboidal
epithelium
Single layer, cube-shaped
cells
Protection, secretion,
absorption
Surface of ovaries, linings of kidney tubules,
and linings of ducts of certain glands
Simple columnar
epithelium
Single layer, elongated cells
Protection, secretion,
absorption
Linings of uterus, stomach, and intestines
Pseudostratified
columnar epithelium
Single layer, elongated cells
Protection, secretion,
movement of mucus and
substances
Linings of respiratory passages
Stratified squamous
epithelium
Many layers, top cells
flattened
Protection
Superficial layer of skin and linings of oral
cavity, vagina, and anal canal
Stratified cuboidal
epithelium
2 or 3 layers, cube-shaped
cells
Protection
Linings of ducts of mammary glands, sweat
glands, salivary glands, and pancreas
Stratified columnar
epithelium
Top layer of elongated
cells, lower layers of cubeshaped cells
Protection, secretion
Part of the male urethra and lining of larger
ducts of excretory glands
Transitional epithelium
Many layers of cubeshaped and elongated cells
Stretchability, protection
Inner lining of urinary bladder and linings of
ureters and part of urethra
Glandular epithelium
Unicellular or multicellular
Secretion
Salivary glands, sweat glands, endocrine
glands
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Connective Tissues
General characteristics:
Most abundant tissue type Cells are farther apart than epithelial cells; contain matrix
between cells
Many functions:
• Bind structures together.
• Provide support and protection.
• Serve as frameworks.
• Fill spaces.
• Store fat.
• Produce blood cells.
• Protect against infections.
• Help repair tissue damage.
Extrcellular matrix consists of protein fibers and ground substance; consistency varies from fluid to
semisolid to solid
Most have good blood supply, and are well-nourished, but vascularity varies among tissue types
Most cells can divide
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Clinical Application 5.1
The Body’s Glue: The Extracellular Matrix
Functions of normal extracellular matrix (ECM):
• scaffolding that organizes & anchors cells into tissues.
• relays chemical signals that control cell division and differentiation, tissue
repair, cell migration.
Cancer: Can convert fibroblasts into myofibroblasts, which take on
characteristics of cancer cells; also loosens fibroblast connections, allowing
migration of converted fibroblasts and spreading cancer
Liver Fibrosis: Collagen deposition increases, and ECM now exceeds its
normal 3% of organ. Damaging agents evoke normal inflammatory response,
but if it continues too long, it can block connection between liver cells and
blood, perhaps leading to cirrhosis.
Heart Failure and Atherosclerosis: Some forms involve excess collagen
deposition, which can stiffen the heart or block blood flow
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Figures 5.15 and 5.16 Major Cell Types of Connective Tissue
Fibroblasts:
• Most common fixed cell.
• Large star-shaped cell.
• Secrete fibers into extracellular matrix.
Macrophages (Histiocytes):
• Usually attached to fibers, but can
detach and wander
• Conduct phagocytosis.
• Defend against infection.
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Top: © Juergen Berger/Science Source, Bottom: © Biology Pics/Science Source
Figures 5.17 Major Cell Types of Connective Tissue
Mast Cells:
• Large cells.
• Release heparin to prevent
blood clotting.
• Release histamine, which.
• causes inflammatory response.
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© Steve Gschmeissner/Science Source
Figure 5.18 Connective Tissue Fibers
Fibroblasts produce 3 types of fibers in connective tissue:
1. Collagen Fibers:
• Thick threads of collagen, the body’s main structural protein.
• Great tensile strength and flexible, slightly elastic.
• Found in ligaments and tendons.
2. Elastic (Yellow) Fibers:
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Composed of elastin protein; branching.
Can stretch and return to original shape.
Not as strong as collagen fibers.
Found in vocal cords, respiratory air passages.
3. Reticular Fibers:
• Thin, branching fibers of collagen.
• Form delicate, supporting networks.
• Found in spleen, liver.
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© Prof. P. Motta/Univ. “La Sapienza”/Science Source
Table 5.6 Components of Connective Tissue
Component
Characteristics
Function
Cellular
Blank
Blank
Fibroblasts
Widely distributed, large, star-shaped
cells
Secrete proteins that become
fibers
Macrophages
Motile cells sometimes attached to fibers
Clear foreign particles from tissues
by phagocytosis
Mast cells
Large cells, usually located near blood
vessels
Release substances that may help
prevent blood clotting (heparin)
and promote inflammation
(histamine)
Extracellular Matrix
Blank
Blank
Collagen fibers (white fibers)
Thick, threadlike fibers of collagen with
great tensile strength
Hold structures together
Elastic fibers (yellow fibers)
Bundles of microfibrils embedded in
elastin
Provide elastic quality to parts that
stretch
Reticular fibers
Thin fibers of collagen
Form delicate supportive networks
within tissues
Ground substance
Nonfibrous protein and other molecules,
and varying amounts of fluid
Fills in spaces around cells and
fibers
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Clinical Application 5.2
Abnormalities of Collagen
Collagen makes up > 60% of the protein in bone and cartilage,
and a large percentage of dry weight of skin, tendons, ligaments
Has a very precise structure, and is vulnerable to disruption
Examples:
• Chondrodysplasia: Collagen chains are asymmetric and too
wide, causing stunted growth and deformed joints.
• Marfan syndrome: Deficiency of the protein fibrillin; leads to
long limbs, spindly fingers, sunken chest, weak aorta,
dislocation of the lens of the eye.
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Categories of Connective Tissue
Connective tissues can be classified in 2 major categories:
Connective Tissue Proper:
Loose connective tissues:
• Areolar.
• Adipose.
• Reticular.
Dense connective tissues:
• Dense Regular.
• Dense Irregular.
• Elastic.
Specialized connective tissues:
Cartilage
Bone
Blood
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Figures 5.19 and 5.20 Connective Tissue Types
Areolar Connective Tissue:
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Forms thin, delicate membranes.
Cells are mainly fibroblasts.
Gel-like ground substance.
Collagenous & elastic fibers.
In subcutaneous layer.
Beneath most epithelia, where it
nourishes nearby epithelial cells.
Adipose Tissue:
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Adipocytes store fat.
Push their nuclei to one side.
Crowd out other cell types.
Cushions and insulates.
Beneath skin (subcutaneous layer).
Behind eyeballs.
Around kidneys and heart.
Spaces between muscles.
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Top: b: © McGraw-Hill Education/Al Telser, photographer
Bottom: b: © McGraw-Hill Education/Al Telser, photographer
Figures 5.21 and 5.22 Connective Tissue Types
Reticular Connective Tissue:
• Composed of thin reticular fibers.
• Supports walls of internal organs.
• Walls of liver, spleen.
Dense Regular Connective Tissue:
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Closely packed collagenous fibers.
Fine network of elastic fibers.
Most cells are fibroblasts.
Very strong, withstands pulling.
Binds body parts together.
Tendons, ligaments, dermis.
Poor blood supply; slow to heal.
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Top: b: © McGraw-Hill Education/Al Telser, photographer
Bottom: b: © McGraw-Hill Education/Dennis Strete
Figures 5.23 and 5.24 Connective Tissue Types
Dense Irregular Connective Tissue:
• Randomly organized, thick,
interwoven collagenous fibers.
• Can withstand tension exerted from
different directions.
• Dermis of skin.
• Around skeletal muscles.
Elastic Connective Tissue:
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Abundant yellow elastic fibers.
Some collagenous fibers.
Fibroblasts.
Attachments between bones of spinal
column.
• Walls of hollow organs, such as large
arteries, airways.
• Parts of heart.
• Elastic quality, stretches.
©2019 McGraw-Hill Education.
Top: © Victor P. Eroschenko
Bottom: © McGraw-Hill Education/Al Telser, photographer
Connective Tissue Types
1
Cartilage:
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A rigid, specialized connective tissue.
Support, framework, attachments.
Protection of underlying tissue.
Models for developing bone.
Matrix contains collagen in gel-like ground substance.
Chondrocytes (cartilage cells) in lacunae (chambers), surrounded by
matrix.
• Lacks blood supply; heals slowly.
• Covered by perichondrium (connective tissue), which provides some
nutrients to the cartilage.
• 3 types of cartilage: Hyaline, Elastic, and Fibrocartilage.
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Figures 5.25 and 5.26 Connective Tissue Types
Hyaline cartilage:
• Most common type.
• Fine collagen fibers.
• Ends of bones in joints Nose,
respiratory passages.
• Embryonic skeleton.
Elastic cartilage:
• Flexible, due to elastic
fibers in matrix.
• External ear, larynx.
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Top: b: © McGraw-Hill Education/Al Telser, photographer
Bottom: b: © McGraw-Hill Education/Al Telser, photographer
Figure 5.27 Connective Tissue Types
Fibrocartilage:
• Very tough, due to many collagenous fibers.
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Shock absorber.
Intervertebral discs.
Pads of knee and pelvic girdle.
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b: © Victor P. Eroschenko
Connective Tissue Types
Bone (Osseous Tissue):
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Most rigid connective tissue.
Solid matrix, composed of mineral (Ca) salts & collagen.
Supports structures.
Protects vital structures.
Produces blood cells.
Stores & releases Ca, P.
Attachment sites for muscles.
Forms skeleton.
Contain osteocytes (bone cells) in lacunae.
2 types: compact and spongy.
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2
Figure 5.28 Connective Tissue Types
Compact Bone:
• Osteoblasts deposit matrix in lamellae (layers).
• Lamellae occur in rings around central canals.
• Osteocytes + matrix + central canal form cylindrical units called.
Osteons:
• Osteons are cemented together to form compact bone.
• Central canals contain blood vessels; bone is well-nourished, heals more quickly than
cartilage.
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b: © McGraw-Hill Education/Sennis Strete, phototgrapher. c: © Prof. P. Motta/Univ. “La Sapienza”/Science Source
Figure 5.29 Connective Tissue Types
Blood:
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•
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Cells suspended in fluid matrix called plasma.
Red blood cells transport gases.
White blood cells defend again infection.
Platelets help in blood clotting.
Transports substances around body.
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b: © McGraw-Hill Education/Dennis Strete, photographer
Table 5.7 Connective Tissues
Type
Description
Function
Location
Areolar connective
tissue
Cells in fluid-gel matrix
Binds organs
Beneath the skin, between muscles, beneath
epithelial tissues
Adipose tissue
Cells in fluid-gel matrix
Protects, insulates, stores fat
Beneath the skin, around the kidneys,
behind the eyeballs, on the surface of the
heart
Reticular
connective tissue
Cells in fluid-gel matrix
Supports
Walls of liver and spleen
Dense regular
connective tissue
Cells in fluid-gel matrix
Binds body parts
Tendons, ligaments
Dense irregular
connective tissue
Cells in fluid-gel matrix
Sustains tissue tension
In the deep layer of skin
Elastic connective
tissue
Cells in fluid-gel matrix
Provides elastic quality
Connecting parts of the spinal column, in
walls of arteries and airways
Hyaline cartilage
Cells in solid-gel matrix
Supports, protects, provides
framework
Ends of bones, nose, and rings in walls of
respiratory passages
Elastic cartilage
Cells in solid-gel matrix
Supports, protects, provides
flexible framework
Framework of external ear and part of larynx
Fibrocartilage
Cells in solid-gel matrix
Supports, protects, absorbs
shock
Between bony parts of spinal column, parts
of pelvic girdle, and knee
Bone
Cells in solid matrix
Supports, protects, provides
framework
Bones of skeleton, middle ear
Blood
Cells and platelets in
fluid matrix
Transports gases, defends
against disease, clotting
Throughout the body in a closed system of
blood vessels and heart chambers
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Types of Membranes
1
Membranes are sheets of cells
Epithelial membranes are composed of epithelial and connective tissue; cover
body surfaces and line cavities
3 types of epithelial membranes:
1. Serous membranes:
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•
•
•
Line body cavities that do not open to outside of body.
Inner linings of thorax and abdomen; covers organs.
Simple squamous epithelium + areolar connective tissue.
Secrete serous fluid for lubrication, reducing friction.
2. Mucous membranes:
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•
•
•
Line cavities and tubes that open to the outside of body.
Lining of digestive, respiratory, urinary, and reproductive tracts.
Epithelium + areolar connective tissue.
Goblet cells secrete mucus.
©2019 McGraw-Hill Education.
Types of Membranes
3. Cutaneous membranes:
• Covers body surface.
• Commonly called skin.
• Part of integumentary system.
4. Synovial membranes:
• Different from epithelial membranes.
• Composed entirely of connective tissue.
• Line joint cavities.
©2019 McGraw-Hill Education.
2
Figure 5.30 Muscle Tissues
General Characteristics:
• Muscle cells are also called muscle fibers.
• Contractile; can shorten and thicken.
• 3 types of muscle tissue: skeletal, cardiac, and smooth.
Skeletal muscle tissue:
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Attached to bones.
Striated.
Voluntary.
Multinucleated cells.
Long cylindrical cells.
Stimulated by nerve cells.
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b: © McGraw-Hill Education/Al Telser
Figures 5.31 and 5.32 Muscle Tissues
Smooth muscle tissue:
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Non-striated.
Spindle-shaped fibers.
Walls of hollow organs.
Walls of blood vessels.
Involuntary.
Cardiac muscle tissue:
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Only in wall of heart.
Branching cells.
Involuntary.
Striated.
Intercalated discs.
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Top: b: © McGraw-Hill Education/Al Telser, photographer
Bottom: b: © McGraw-Hill Education/Al Telser, photographer
Figure 5.33 Nervous Tissue
Nervous tissues:
• Found in brain, spinal cord, peripheral nerves.
• Main cells are neurons, which are specialized for communication, via
conduction of nerve impulses (sensory reception, motor control).
• Neurons coordinate, integrate, and regulate body functions.
• Neuroglia support and nourish neurons.
©2019 McGraw-Hill Education.
b: © McGraw-Hill Education/Al Telser, photographer
From Science to Technology 5.2
Tissue Engineering: Building a Replacement Bladder
Donor organs are in short supply
Tissue Engineering is showing promise for organ replacement, by growing cells or
extracellular matrix from a person’s own cells or matrix, on a synthetic scaffold.
No rejection by immune system
Has already been used to provide skin, cartilage, bone, blood vessels
Urinary bladders are being replaced by growing tissue donated by the patient
Patient’s bladder tissue contains progenitor cells for smooth muscle and
uroepithelium, which are used to grow a new bladder on a synthetic dome
After implant, synthetic scaffold degenerates over time, leaving new bladder in
place
©2019 McGraw-Hill Education.
Table 5.8 Muscle and Nervous Tissues
Type
Description
Function
Location
Skeletal muscle tissue
Long, thread-like cells,
striated, many nuclei
Voluntary movements of
skeletal parts
Muscles usually
attached to bones
Smooth muscle tissue
Shorter cells, single,
central nucleus
Involuntary movements
of internal organs
Walls of hollow
internal organs
Cardiac muscle tissue
Branched cells, striated,
single nucleus
Heart movements
Heart muscle
Nervous tissue
Cells with cytoplasmic
extensions
Sensory reception,
release of
neurotransmitter, and
conduction of electrical
impulses
Brain, spinal cord,
and peripheral
nerves
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