Transcript Chapter 3 Cells and Tissues

Essentials of Human Anatomy & Physiology
Seventh Edition
Elaine N. Marieb
Chapter 3
Cells and Tissues
Slides 3.38 – 3.54
Lecture Slides in PowerPoint by Jerry L. Cook;
some slides adapted or added by Kerry C. Roy
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Tissue: The Living Fabric
Cells in multicellular organisms (i.e.
humans) do not operate independently
or in isolation.
Instead, cells are highly specialized to
perform specific functions.
– This cell specialization allows the body to
function in very sophisticated ways.
Behold, the cell…
Body Tissues
 Tissues--groups of closely associated cells with
similar structure and function
 Four primary tissue types
1.
2.
3.
4.
Epithelial—protection
Connective—support
Nervous tissue—control
Muscle—movement
Most organs contain several tissue types and
the arrangement of tissues determines the
structure and function of the organ.
Specialized Cells form Tissues 4.26.asf
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings; adapted by K. Roy
Slide 3.41
1. Epithelial Tissue
(epithelium)
 Found in different areas
1. Body coverings & linings
2. Glandular tissue
 Functions
1.
2.
3.
4.
Protection
Absorption
Filtration
Secretion
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 3.42
Areas where epithelium is found …
1. Covering & lining epithelium
– Found on free surfaces of body such as outer
layer of skin, dipping into and lining the open
cavities of the digestive and respiratory systems,
lines blood vessels and heart, and covers walls
and organs of closed ventral cavity
– Nearly all substances received or given off by the
body must pass thru the epithelium
2. Glandular epithelium
– Fashions (forms) the glands of the body
4 functions of the epithelium
1. protection—skin (protects mechanical/
chemical/ bacterial)
2. Absorption—digestive tract
3. Filtration—kidneys (also do protection and
absorption)
4. Secretion—specialty of glands
excretion, sensory reception (other functions,
but not primary functions)
5 Epithelium Characteristics
1. Cellularity—
• Composed almost entirely of cells
• Epithelial cells fit closely together
to form continuous sheets (in
contrast, muscle & connective
tissue cells are often widely
separated)
• Bound together by desmosomes &
tight junctions
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings: adapted by K. Roy
Slide 3.43
Epithelium Characteristics cont.
2. Polarity—
•
always has one free (apical) surface
–
•
portion of epithelium exposed to the body
exterior or the cavity of an internal organ
some exposed surfaces are smooth & slick,
others exhibit modifications such as microvilli
or cilia
–
microvilli—fingerlike extensions of the plasma
membrane; increase surface area & are common
in tissues that absorb & secrete substances
(intestine & kidney)
–
cilia—hairlike projections commonly found in
lining of trachea (& other internal tracts); propel
substances along the epithelial surface
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings: adapted by K. roy
Slide 3.43
Epithelium Characteristics cont.
3. Avascularity (have no blood supply)
• well supplied with nerve fibers, but
has no blood vessels
• all cells receive nutrients (food & O2)
by diffusion from underlying
connective tissue
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings: adapted by K. roy
Slide 3.43
Epithelium Characteristics cont.
4. Basement membrane—membrane that
reinforces epithelial tissues, helping it to
resist stretching & tearing forces
2 parts:
•
Basal lamina (epithelial)
•
Reticular lamina (connective)
5. Regeneration
•
As long as the cells receive adequate nutrition,
they can replace lost cells rapidly by cell
division (mitosis)
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings: adapted by K. roy
Slide 3.43
Classification of Epithelium
 The types of epithelia are identified by
 shape of cells
 arrangement of cells (number of
cell layers present)
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 3.44a
Classification of Epithelium
 All epithelial cells are irregularly
polyhedral (many-sided) in cross section,
but differ in cell height.
 By height, there are 3 common shapes
– Squamous – flattened like fish scales
– Cuboidal – cube-shaped (as tall as
they are wide), like dice
– Columnar – column-like (tall & column
shaped)
*In each, the shape of the nucleus
conforms to that of the cell. Thus, nuclear
shape can be very helpful when
attempting to distinguish epithelial types
Figure 3.16b
Slide 3.44b
Classification of Epithelium
 Cell arrangement (# of cell layers)
 2 major types of epithelium
1. Simple – one layer; usually very
thin, not good at protection;
typically found where absorption
& filtration occur
2. Stratified – more than one layer
stacked on top of the other;
more durable; typically found in
high abrasion areas where
protection is important (skin
surface & lining of mouth)
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 3.16a
Slide 3.44a
Classification of Epithelium
4 major classes of simple epithelial tissue
1. simple squamous
2. simple cuboidal
3. simple columnar (may or may not contain cilia)
4. pseudostratified columnar
(may or may not contain cilia)
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 3.44a
Classification of Epithelium
4 major classes of stratified epithelial tissue
1. stratified squamous
2. stratified cuboidal
3. stratified columnar
4. transitional epithelium
 FYI—classification of epithelia by cell type and
arrangement reveals nothing about the tissue’s
body location
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 3.44a
In your notes…
• Make a table that lists the 4 major simple &
stratified epithelial tissues. Include columns
for description, location, & function.
• Use textbook pgs. 79-81
Now, let’s review your table…
Simple Epithelium
 Simple squamous
 Single layer of flat cells (like
floor tiles)
 Usually forms membranes
where filtration or exchange
of substances by rapid
diffusion occurs
 Lines body cavities
 Lines air sacs of lungs
and walls of capillaries
 Forms serous membrane
(serosae)
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 3.17a
Slide 3.45
Simple Epithelium
 Simple cuboidal
 Single layer of cubelike cells
 Common in glands
and their ducts
(salivary glands &
pancreas)
 Forms walls
of kidney tubules
Figure 3.17b
 Covers the ovaries
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 3.46
Simple Epithelium
 Simple columnar
 Single layer of tall cells
 Often includes goblet
cells, which produce
mucous
Figure 3.17c
 Lines digestive tract
 Forms mucous
membranes
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 3.47
Simple Epithelium
 Pseudostratified
 Single layer, but some cells
are shorter than others
 Often looks like a double cell
layer
 Sometimes ciliated, such as in
the respiratory tract; mucous
traps dust/debris while cilia
propels mucous up & away
from lungs
Figure 3.17d
 May function in absorption or
secretion
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 3.48
Stratified Epithelium
 Stratified squamous
 Most common stratified epithelium
 Cells at the free edge are flattened
(squamous)
 Basement membrane cells are cuboidal
or columnar
Figure 3.17e
 Found as a protective covering where
friction is common
 Locations
 Skin (outer)
 Mouth
 Esophagus
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 3.49
Stratified Epithelium
 Stratified cuboidal
 Two layers of cuboidal cells
 Stratified columnar
 Surface cells are columnar, cells
underneath vary in size and shape
 Both:
 Rare in human body
 Found mainly in ducts of large glands—
function in protection
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 3.50
Stratified Epithelium
 Transitional epithelium
 Highly modified, stratified
squamous epithelium
 Shape of cells depends
upon the amount of
stretching
 Lines organs of the urinary
system
 Cells slide past one
another & change shape
allowing structures to
stretch
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 3.17f
Slide 3.51
Epithelial Tissue cont.
Epithelial membrane
– Continuous multicellular sheet composed
of at least 2 primary tissue types:
epithelium bound to an underlying layer of
connective tissue
– 3 common types of epithelial membranes
1.
2.
3.
Mucous membranes
Cutaneous membrane
Serous membrane
3 Epithelial membrane types
1. Mucous membranes (mucosae)
–
–
–
–
Epithelial membranes that line the body
cavities that are open to the exterior (digestive,
respiratory, & urogenital tracts)
In all cases, they are “wet,” or moist,
membranes bathed by secretions
Often adapted for absorption and secretion
Often made of simple columnar cells
3 Epithelial membrane types
2. Cutaneous membrane
–
–
–
Your SKIN
An organ made of keratinized stratified
squamous epithelium (epidermis) firmly
attached to a thick connective tissue layer
(dermis)
Uniquely different b/c it is exposed to air and is
a dry membrane
3 Epithelial membrane types
3. Serous membrane (serosae)
–
Moist membranes found in closed ventral body
cavities
Typically made of simple squamous
Remember that each serosa consists of parietal
and visceral layers
Serosae are named according to site & specific
organ association
–
–
–
•
Ex. Pleura—lining of thoracic wall & covering the lungs
Pericardium—encloses the heart
Peritoneum—abdominopelvic cavity
Glandular Epithelium
 Gland – one or more cells that make &
secrete an aqueous (water-based) fluid that
typically contains proteins = secretion.
 Glandular cells obtain needed substances
from the blood and use them to make their
secretion.
 Glands are classified as:
1. endocrine
2. exocrine
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 3.52
Endocrine gland
 Ductless
 Produce hormones (regulatory chemicals) Ex.
Thyroid, adrenals, pituitary, ovaries, testes
Exocrine gland
 Empty through ducts to the epithelial surface
 Include sweat and oil glands, salivary glands,
liver, pancreas, mammary glands, mucous
glands, etc.
2. Connective Tissue
(2nd primary tissue type)
 Connects body parts
 Found everywhere in the body; but the
amount varies greatly
 Includes the most abundant and widely
distributed of the tissue types
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 3.53
Connective Tissue cont.
 Major functions are
1. Binding—connective tissue
2. Support—bone & cartilage
3. Protection—bone, cartilage, & fat
4. Insulation—fat
5. Transportation—blood
6. Serve as a water reservoir
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 3.53
3 Connective Tissue Characteristics
1. Common origin
– all connective tissue forms from mesenchyme
(embryonic tissue derived from the mesoderm
germ layer)
2. Degrees of Vascularity
– Variations in blood supply
– Most connective tissues are well vascularized
(good blood supply), but there are exceptions
• Cartilage is avascular (thus heal very slowly when
injured)
• Tendons & ligaments—poor blood supply
3 Connective Tissue Characteristics
3. Extracellular matrix
– What is matrix?
• Nonliving substance found outside the cells;
typically includes ground substance (fluid to
hard) & fibers (collagen, elastic, or reticular)
which separates the living cells of tissue
– Why is matrix important?
• Matrix is what enables connective tissue to
bear weight, withstand great tension, &
endure abuses such as physical trauma or
abrasion
3 Structural Elements of Connective Tissue
 3 main components of connective tissue
1. Ground substance
matrix
2. Fibers
White fibers—collagen
Yellow fibers—elastic
3. Cells
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Fine collagen—reticular
Slide 3.55
Primary Cell Types of Connective Tissue
1. Connective tissue proper (loose & dense) 
fibroblast
2. Cartilage  chondroblast
3. Bone  osteoblast
4. Blood  hemocytoblast (always actively
mitotic)
• Each cell type exists in immature & mature forms
– These cells are actively mitotic when immature
& less active when mature
“—blast” = immature cell “—cyte” = mature cell
Connective Tissue cont.
Classes of Connective Tissue
• All classes consist of living cells surrounded by a
matrix
• Major differences reflect cell type, fiber type, & #
fibers in matrix
• Major connective tissue classes (from softest to
most rigid)
1. Loose connective
2. Dense connective
3. Cartilage
4. Bone
FYI—Blood is also
a connective tissue
class that will be
discussed.
1. Loose Connective Tissue
--softer & has more cells, fewer fibers than any
other conn. tissue type (except blood)
Loose Conn. Tissue Types
1. Areolar—packages organs & surrounds capillaries
2. Adipose—reserve E, insulation, support, &
protection
3. Reticular—soft internal skeleton to support other
cell types
Loose Connective Tissue Types
 Areolar
 Most widely distributed in body
 Soft, pliable tissue “cobwebby”
 Wraps, cushions & protects organs
 Functions as universal packing
tissue/glue b/c it helps hold internal
organs together & in place
Figure 3.18e
 Provides a reservoir of water & salts
for surrounding tissues
*all body cells obtain their
nutrients from & release their
wastes into this “tissue fluid”
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 3.60
Loose Connective Tissue Types
 Adipose (fat)
 an areolar tissue in which fat
cells predominate
 Functions
 Insulates
 Protects from heat/cold
Figure 3.18f
 Serves as a site of
fuel storage (source of E)—ex.
hips and breasts serve as fat
“depots”
 Protects some organs individually
(surrounds them with fat)
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 3.61
Loose Connective Tissue Types
 Reticular
connective tissue
 Delicate network of
interwoven fibers
 Forms stroma
(supporting
framework) of
lymphoid organs
 Lymph nodes
 Spleen
 Bone marrow
Figure 3.18g
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 3.62
2. Dense Connective Tissue
Slide 3.59
 aka dense fibrous tissue
 Main matrix element is collagen
fibers
 Makes up lower layers of skin
(dermis) where it is arranged in
sheets
 Forms strong, ropelike structures
such as tendons & ligaments
 Tendon – attach muscle to bone
(BMT)
 Ligaments – connect bones to
bones at joints (more stretchy &
contains more elastic fibers than
tendons)
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 3.18d
Connective Tissue Classes
3. Cartilage
• Less hard & more flexible than bone
• Found in only a few places in body
• Avascular and lacks nerve fibers
3 Varieties of Cartilage
1. Hyaline cartilage
 Most common/abundant
cartilage
 Forms the supporting structures
of larynx (voice box), attaches
ribs to sternum (breast bone),
covers ends of bones at joints
Figure 3.18b
 Fetal skeleton begins as hyaline
cartilage
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Slide 3.57
3 varieties of cartilage cont.
2. Elastic cartilage
 Found where structure with elasticity is desired
 Maintains shape of a structure while allowing
great flexibility
 Example: supports the external ear & found in
epiglottis
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Slide 3.57
3 varieties of cartilage cont.
3. Fibrocartilage
 Highly compressible
 forms cushion-like discs
between vertebrae &
spongy cartilage of knees
Figure 3.18c
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 3.58b
Connective Tissue Classes—
4. Bone (osseous)
Figure 3.18a
 Used to support & protect the body
 Exceptional ability to protect &
support other body organs
 Provides cavities for fat storage &
synthesis of blood cells
 Composed of:
 Bone cells in lacunae (cavities)
 Hard matrix of calcium salts (bone
salts)
 Large numbers of collagen fibers
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
b/c of these 2, bone
matrix is harder &
more rigid than
cartilage matrix
Slide 3.56
Bone cont.
Osteoblasts— immature bone cells
Osteocytes—mature bone cells;
*unlike cartilage, bone is very well
supplied by blood vessels
Other Connective Tissue Classes
5. Blood (vascular tissue)
 Most atypical connective tissue
 Does NOT connect things or
give mechanical support
 Classified as connective tissue
b/c it develops from
mesenchyme & consists of
blood cells surrounded by a
nonliving fluid matrix called
blood plasma
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 3.18h
Slide 3.63
5. Blood cont.
 Functions --transport vehicle for
materials for CV system, carries
nutrients, wastes, respiratory
gases, & other substances
Magic School Bus Blood Cells &
Throat Tissue.asf
Figure 3.18h
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 3.63
3. Nervous Tissue
(3rd primary tissue type)
 Found in brain, spinal cord, & nerves
 Functions in regulation & control of
body functions
 Neuron—primary cell type
 All neurons receive & conduct
electrochemical impulses from 1 part of
body to another
Figure 3.20
 2 major functional characteristics:
1. Irritability
2. Conductivity
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Slide 3.68
Nervous Tissue cont.
2 major cell types
1. Neuron
•
•
•
Highly specialized nerve cells that generate & conduct
nerve impulses
Branching cells
The presence of cytoplasmic extensions, or processes, allow
them to transmit electrical impulses over substantial
distances w/n the body
2. Supporting cells
•
•
Nonconducting cells that support, insulate, and protect the
delicate neurons.
Ex. Myelin sheath
4. Muscle Tissue
(4th primary tissue type)
 Highly cellular, well-vascularized tissues
 Highly specialized to contract (short) to
produce body mvmts
 Called muscle fibers since cells are
elongated to provide a long axis for
contraction
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 3.64
3 Types Muscle Tissue
Figure 3.19b
1. Skeletal muscle
 Packaged by connective tissue sheets into
organs called skeletal muscle
 Form the flesh of the body
 As they contract , they pull on bones or skin
causing body mvmts
 Can be controlled voluntarily
 Cells are long, cylindrical, and
striated/banded which shows precise
alignment of myofilaments (actin & myosin)
 Cells have many nuclei (multinucleate)
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 3.65
3 Types Muscle Tissue
Figure 3.19a
2. Smooth muscle (visceral)
 No visible striations
 Involuntary muscle
 Individual cells are spindle shaped &
contain one centrally located nucleus
 Found in walls of hollow organs (except
heart); stomach, bladder, uterus, & blood
vessels
 Functions to squeeze substances thru
organs by alternately contracting &
relaxing (peristalsis)
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 3.67
3 Types Muscle Tissue
3. Cardiac muscle
 Found only in the wall of the heart
 Function is to pump blood
(involuntary) thru vessels to
all parts of body
 Cells are striated, like skeletal, but
there are structural differences:
Figure 3.19c
 Branching cells that fit together
tightly at unique junctions called
intercalated disks
 One nucleus per cell (uninucleate)
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Slide 3.66
Muscle Tissue cont.
*b/c skeletal muscle is under our control, it is
often called voluntary muscle
* Cardiac and smooth are called involuntary
muscle
Tissue Repair (aka wound healing)
Body has many ways to protect itself:
1. Mechanical barriers—skin & mucosae and
ciliary action
2. Chemical barriers—strong acid produced by
stomach glands
3. Ciliary activity of epithelial cells
*when tissue injury does occur, stimulates
the body’s inflammatory & immune
responses
Tissue Repair cont.
Inflammatory Response
– Generalized (nonspecific) body response
that attempts to prevent further injury
– Fast acting
Tissue Repair cont.
Immune Response
– Extremely specific response, takes longer to
activate
– Mounts a vigorous attack against
recognized invaders (bacteria, viruses,
toxins)
What is required for Tissue Repair?
• Required that cells divide & crawl (migrate).
• This is initiated by growth factors (wound hormones)
released by injured cells
How does Tissue Repair Occur?
1. regeneration—replacement of destroyed tissue
with same kind of tissue
2.fibrosis— repair by dense (fibrous) connective tissue,
formation of scar tissue
Which will occur? Depends on…
1.Type of injury (severity)
2.Type of tissue damaged
4 Steps to Repair
1. Inflammation
2. Capillaries become very permeable
– Allows fluid rich in clotting proteins & other
substances to seep into injured area
3. Granulation tissue forms
– Delicate pink tissue composed largely of new
capillaries that grow into the damaged area from
undamaged blood vessels
4. Surface epithelium regenerates
Regeneration of Tissues
 Regeneration varies widely among types of tissues
 Tissues that regenerate easily (GOOD)
 Epithelial tissue
 Fibrous connective tissue and bone
 Tissues that regenerate poorly (POOR)
 Skeletal muscle
 Tissues that are replaced largely with scar tissue (NONE)
 Cardiac muscle
 Nervous tissue within the brain and spinal cord
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Slide 3.71