Transcript Chapter 4: Tissue The Fabric of Life

Chapter 4: Tissue
The Fabric of Life
Tissue
• Group of cells – similar in structure and
perform a common function
• 4 Basic Types –
1. Epithelial – covering
2. Connective – support
3. Muscle - movement
4. Nervous - control
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, binds
other tissues together
• Bones
• Tendons
• Fat and other soft padding tissue
Histology
• Study of tissues
• Preparing tissue:
• Specimen –
1. Must be fixed (preserved)
2. Cut into sections (slices)
3. Stained – enhance contrast
• Artifacts – minor distortions – tissue on slides,
not exactly like living tissue
Epithelial Tissue
• Epithelium
• Sheet of cells that cover a body surface or lines a body
cavity
• 2 main types:
1. Covering and lining
2. Glandular epithelium
• Boundaries between different environments
1.
2.
3.
4.
5.
6.
Protection
Absorption
Filtration
Excretion
Secretion
Sensory reception
Epithelial Tissue
• Special Characteristics
1. Polarity –
- Apical surface – upper free surface exposed to body
exterior
- Basal surface – lower attached surface
- Apical – basal polarity
- Apical Surfaces: Microvilli- fingerlike extensions of
plasma membrane or Cilia – tiny hair like projections
- Basal lamina – supporting sheet – adhesive sheet
Epithelial Tissue
2. Specialized Contacts – adjacent cells bound
together by tight junctions and desomosomes
Epithelial Tissue
3. Supported by Connective Tissue
- Reticular lamina – layer of extracellular
material
- Collagen protein fibers
- Basement membrane
Epithelial Tissue
4. Avascular but Innervated –
- Innervated – supported by nerve fibers
- Avascular – no blood vessels
- Nourished by nutrients diffusing from blood
vessels in underlying connective tissue
5. Regeneration – reproduces rapidly when
damaged
Epithelial Tissue
• Classification – based on number of layers
and type of cell
• 2 names
– 1st – number of cell layers present
– 2nd – shape of cell
• Simple epithelia – single cell layer
• Stratified epithelium – 2 or more cell layers
Simple
Stratified
(a) Classification based on number of cell layers.
Cell Shape
• Squamous cells – flattened and scale like
• Cubodial cells – boxlike, ~as tall as they are
wide
• Columnar cells – tall and column shaped
Squamous
Cuboidal
Columnar
(b) Classification based on cell shape.
Epithelial Tissue
• Simple Epithelia –
• Simple – single cell layer
• Most concerned with absorption, secretion,
and filtration
• Very thin
Epithelial Tissue- Simple
•
•
•
•
•
•
•
•
Simple Squamous Epithelium Simple – one cell layer
Flattened laterally
Cytoplasm sparse
Thin, permeable
Found everywhere
Filtration or exchange by rapid diffusion
Ex. Endothelium – slick, friction reducing lining of
lymphatic vessels and blood vessels
• Mesothelium – epithelium of serous membrane linign
ventral body cavity and organs
Description: Single layer of flattened
cells with disc-shaped central nuclei
and sparse cytoplasm; the simplest
of the epithelia.
Air sacs of
lung tissue
Function: Allows passage of
materials by diffusion and filtration
in sites where protection is not
important; secretes lubricating
substances in serosae.
Nuclei of
squamous
epithelial
cells
Location: Kidney glomeruli; air sacs
of lungs; lining of heart, blood
vessels, and lymphatic vessels; lining
of ventral body cavity (serosae).
Photomicrograph: Simple squamous epithelium
forming part of the alveolar (air sac) walls (125x).
Epithelial Tissue - Simple
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•
•
•
Simple Cubodial Epithelium –
Single layer of cube-like cells
Secretion and absorption
Found in walls of smallest ducts and glands
(b) Simple cuboidal epithelium
Description: Single layer of
cubelike cells with large,
spherical central nuclei.
Simple
cuboidal
epithelial
cells
Function: Secretion and
absorption.
Basement
membrane
Location: Kidney tubules;
ducts and secretory portions
of small glands; ovary surface.
Connective
tissue
Photomicrograph: Simple cuboidal
epithelium in kidney tubules (430x).
Figure 4.3b
Epithelial Tissue - Simple
• Simple Columnar Epithelium –
• Single layer of tall, closely packed cells aligned
in a row
• Lines digestive tract
• Absorption and secretion
• Modifications in digestive tract
1. Dense microvilli on apical surface of absorptive
cells
2. Cells secrete protective mucus
(c) Simple columnar epithelium
Description: Single layer of tall cells
with round to oval nuclei; some cells
bear cilia; layer may contain mucussecreting unicellular glands (goblet cells).
Simple
columnar
epithelial
cell
Function: Absorption; secretion of
mucus, enzymes, and other substances;
ciliated type propels mucus (or
reproductive cells) by ciliary action.
Location: Nonciliated type lines most of
the digestive tract (stomach to anal canal),
gallbladder, and excretory ducts of some
glands; ciliated variety lines small
bronchi, uterine tubes, and some regions
of the uterus.
Basement
membrane
Photomicrograph: Simple columnar epithelium
of the stomach mucosa (860X).
Figure 4.3c
Epithelial Tissue - Simple
• Pseudostratified Columnar Epithelium –
• Vary in height
• False – pseudo – impression of many cell
layers
• Absorbs or secretes substances
• Ciliated version lines respiratory tract
(d) Pseudostratified columnar epithelium
Description: Single layer of cells of
differing heights, some not reaching
the free surface; nuclei seen at
different levels; may contain mucussecreting cells and bear cilia.
Cilia
Mucus of
mucous cell
Pseudostratified
epithelial
layer
Function: Secretion, particularly of
mucus; propulsion of mucus by
ciliary action.
Location: Nonciliated type in male’s
sperm-carrying ducts and ducts of
large glands; ciliated variety lines
the trachea, most of the upper
respiratory tract.
Trachea
Photomicrograph: Pseudostratified ciliated
columnar epithelium lining the human trachea (570x).
Basement
membrane
Figure 4.3d
Epithelial Tissue - Stratified
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•
•
•
•
Stratified Epithelium –
2 or more cell layers
Regenerate from below
More durable the simple
Protection – major role
Epithelial Tissue - Stratified
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•
•
•
Stratified Squamous Epithelium –
Several layers
Areas of wear and tare
Cell surface – epidermis – keratinized – cell
surface contains keratin – protective protein
(e) Stratified squamous epithelium
Description: Thick membrane
composed of several cell layers;
basal cells are cuboidal or columnar
and metabolically active; surface
cells are flattened (squamous); in the
keratinized type, the surface cells are
full of keratin and dead; basal cells
are active in mitosis and produce the
cells of the more superficial layers.
Stratified
squamous
epithelium
Function: Protects underlying
tissues in areas subjected to abrasion.
Nuclei
Location: Nonkeratinized type forms
the moist linings of the esophagus,
mouth, and vagina; keratinized variety
forms the epidermis of the skin, a dry
membrane.
Basement
membrane
Connective
tissue
Photomicrograph: Stratified squamous epithelium
lining the esophagus (285x).
Figure 4.3e
Epithelial Tissue - Stratified
• Stratified Cubodial epithelium
• Rare
• Found in ducts of larger glands: sweat,
mammary
• 2 layers of cubodial cells
Epithelial Tissue - Stratified
• Stratified columnar Epithelium –
• Small amounts in pharynx, male urethra, and
lining some glandular ducts
• Only apical layers of cells is columnar
Epithelial Tissue
• Transitional –
• Forms lining of hallow urinary organs which
stretch
• Basal layer – cubodial or columnar
• Apical – vary in appearance
• Ability to change shape
• Allows bladder to stretch
(f) Transitional epithelium
Description: Resembles both
stratified squamous and stratified
cuboidal; basal cells cuboidal or
columnar; surface cells dome
shaped or squamouslike, depending
on degree of organ stretch.
Transitional
epithelium
Function: Stretches readily and
permits distension of urinary organ
by contained urine.
Location: Lines the ureters, urinary
bladder, and part of the urethra.
Basement
membrane
Connective
tissue
Photomicrograph: Transitional epithelium lining the urinary
bladder, relaxed state (360X); note the bulbous, or rounded,
appearance of the cells at the surface; these cells flatten and
become elongated when the bladder is filled with urine.
Figure 4.3f
Epithelial Tissue
• Glandular Epithelium –
• Gland – one or more cells that make and secrete
(export) a particular product
• Secretion – the product, aqueous 9water-based) fluid
that usually contains proteins, but there is some
variation
• Active process
• Classified as –
–
–
–
–
Endocrine – internally secreting
Exocrine – externally secreting
Unicellular – one celled
Multicellular – many cells
Glandular Epithelium
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•
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Endocrine Glands –
Eventually loose their ducts
Ductless glands
Produce hormones – regulatory chemicals
Secrete – exocytosis – directly into
extracellular space
• Enter blood or lymph
• Travel to target organs
Glandular Epithelium
• Exocrine Gland –
• Secrete products onto body surfaces (skin) or
into body cavities
• Unicellular – exocytosis
• Multicellular – epithelium, walled ducts
• Include mucus, sweat, etc.
Glandular Epithelium
• Unicellular Exocrine Glands –
• Mucus cells and goblet cells
• Sprinkled in epithelial linings of intestinal and
respiratory tracts
• Humans – all produce mucin – glycoprotein that
dissolves in water when secreted , once dissolved
forms mucus
• Called goblet cells – b/c accumulation of mucus
distends the top of the cell
• Distortion does not occur in mucosal cells
Microvilli
Secretory
vesicles
containing
mucin
Rough ER
Golgi
apparatus
(a)
Nucleus
(b)
Figure 4.4
Glandular Epithelium
• Multicellular Exocrine Glands –
• 2 parts – duct and secretory unit (acinus)
• Supportive connective tissue surrounds
secretory unit and supplies it with blood
vessels
Multicellular Exocrine Glands
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•
•
•
Structural Classification –
Simple glands – unbranched duct
Compound glands – branched duct
Secretory units –
1.
2.
3.
Tubular – secretory cells form tubes
Alveolar – small, flask like sacs
Tubular alveolar - both
• Modes of secretion –
1. Merocrine glands – secrete products by exocytosis as they
are produced
– Ex. Sweat glands
2. Holorcrine glands – accumulate products within them until
the rupture
– Cells – die for their cause
– Sebaceous (oil) glands of skin
• Apocrine gland – present in other animals
– Controversy – as to if in humans
Tubular
secretory
structure
Simple duct structure
Compound duct structure
(duct does not branch)
(duct branches)
Simple tubular
Simple branched
tubular
Example
Example
Compound tubular
Intestinal glands
Stomach (gastric)
glands
Duodenal glands of small intestine
Example
Alveolar
secretory
structure
Simple
alveolar
Simple branched
alveolar
Compound alveolar
Example
Example
Example
No important
example in humans
Sebaceous (oil)
glands
Mammary glands
Surface epithelium
Duct
Compound
tubuloalveolar
Example
Salivary glands
Secretory epithelium
Figure 4.5
Connective Tissue
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•
•
•
Found everywhere in body
Most abundant
Widely distributed in primary tissues
4 main classes
1.
2.
3.
4.
Connective tissue proper – fat and fibrous tissue of ligaments
Cartilage
Bone tissue
Blood
• Major functions
1.
2.
3.
4.
Binding and support
Protection
Insulation
Transportation (blood)
Table 4.1
Connective Tissue
• Common Characteristics –
1. Common origin – all arise from mesenchyme (embryonic
tissue)
2. Degrees of Vascularity –
-
Cartilage – avascular
Dense – poorly vascularized
Others – highly vascularized
3. Extracellular Matrix –
-
Nonliving extracellular matrix
Able to bear weight
Withstand great tension
Endure abuses – physical trauma and abrasion
Connective Tissue
• Structural Elements –
• 3 main – ground substance, fiber, and cells
• Extracellular matrix – ground substance +
fibers
Connective Tissue – Structural
Elements
•
•
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•
Ground Substances –
Unstructured material that fill space between cells
Contain fibers
Composed of:
– Interstitial (tissue) fluid
– Cell adhesion proteins
– proteoglycans
• Cell adhesion proteins – fibronectin, laminin, and others
• Connective tissue “glue”
• Proteoglycans – protein core with glycoaminoglycans (GAGs)
attached
• Form gel-like matrix
– Interstitial (tissue) fluid
– Cell adhesion proteins
– proteoglycans
Connective Tissue – Structural
Elements
• Fibers – provide support
1. Collagen fibers – fibrous protein collagen
molecules secreted into space- assemble
cross linking
- Cross linking – tough and provide tensile
strength
- White appearance – also called white fibers
Connective Tissue – Structural
Elements
2. Elastic fibers – long, thin form branching
networks
- Contain elastin-allows stretch and recoil
- Skin, lungs, blood vessel walls
- Yellow appearance – yellow fibers
Connective Tissue – Structural
Elements
3. Reticular fibers – short, fine collagenous
fibers
- Continuous with collagen fibers, branch
extensively
- Form delicate networks
- “fuzzy” nets
- Allow give
Connective Tissue – Cells
• Primary cell types –
1. Connective tissue proper – fibroblast
2. Cartilage – chondroblast
3. Bone – osteoblast
-
Hematopoietic stem cell – undifferentiated cell –
produces blood cells
Home to other cell types –
1. Fat cells – store nutrients
2. Mobile cells – WBCs –neutrophils, esinophils,
lymphocytes
3. Mast cells – cluster among blood vessels – detect foreign
organisms
4. Macrophages – phagotiyze board variety of foreign
materials
Types of Connective Tissue
• All arise from a common embryonic line –
mesenchyme derived from embryonic mesoderm
• Connective tissue proper – Loose connective
tissue
• 2 subclasses:
– loose connective tissue
• Areolar, Adipose, Reticular
– Dense connective tissue
• Dense regular, dense irregular, elastic
Loose Connective Tissue
1. Areolar Connective Tissue –
- Functions;
-
-
Support and binding to other structures
Holding body fluids
Defending against infection
Storing nutrients as fat
Loose arrangement of tissue
Loose nature – reservoir for water and salts for
surrounding body tissues
Hold approximately as much as entire blood stream
1. Areolar Connective Tissue
• High content of hyaluronic acid - makes it very
viscous
• WBC – secrete hyaluronidase – to liquefy
ground substances so they can maneuver
• Edema – in a body region, inflamed, soaks up
excess fluid, swells and puffy
• Most widely distributed
• Universal packing tissue
(a) Connective tissue proper: loose connective tissue, areolar
Description: Gel-like matrix with all
three fiber types; cells: fibroblasts,
macrophages, mast cells, and some
white blood cells.
Elastic
fibers
Function: Wraps and cushions
organs; its macrophages phagocytize
bacteria; plays important role in
inflammation; holds and conveys
tissue fluid.
Collagen
fibers
Location: Widely distributed under
epithelia of body, e.g., forms lamina
propria of mucous membranes;
packages organs; surrounds
capillaries.
Fibroblast
nuclei
Epithelium
Lamina
propria
Photomicrograph: Areolar connective tissue, a
soft packaging tissue of the body (300x).
Figure 4.8a
2. Adipose (Fat) Tissue
• Similar to areolar tissue in structure and function, but
can store nutrients
• Also called white fat or white adipose fat
• Adipocytes – adipose of fat cells
• 90 % of tissue mass
• Matrix – scanty
• Cells packed closely together
• Chicken wire appearance
• Oil droplet occupies most of cells volume, displaces
nucleus to one side
• Richly vascularized, high metabolic activity
2. Adipose (Fat) Tissue
• With out fat stores body can not survive for more than
a few days without eating
• 18 % of average person’s body weight
• Chubby – 50 % fat without being considered obese
• Can develop anywhere, usually accumulates in
subcutaneous tissue – acts as a shock absorber,
insulation, and energy storage
• Poor heat conductor – so prevents heat loss from body
• Also accumulates around kidneys, behind eyeballs,
abdomen and hips
2. Adipose (Fat) Tissue
• Brown fat – brown adipose tissue
• Abundant mitochondria
• Which use lipid fuels to heat bloodstream to
warm body rather than produce ATP
• Richly vascularized – only occurs in babies
who lack the ability to produce body heat by
shivering
(b) Connective tissue proper: loose connective tissue, adipose
Description: Matrix as in areolar,
but very sparse; closely packed
adipocytes, or fat cells, have
nucleus pushed to the side by large
fat droplet.
Function: Provides reserve food
fuel; insulates against heat loss;
supports and protects organs.
Nucleus of
fat cell
Location: Under skin in the
hypodermis; around kidneys and
eyeballs; within abdomen; in breasts.
Vacuole
containing
fat droplet
Adipose
tissue
Mammary
glands
Photomicrograph: Adipose tissue from the
subcutaneous layer under the skin (350x).
Figure 4.8b
3. Reticular Connective Tissue
•
•
•
•
•
Resembles areolar tissue
Only fibers – reticular fibers
Reticular cells – fibroblasts – scattered
Labyrinth – like stroma or internal framework
Support many free body cells in lymph nodes,
spleen, and bone marrow
(c) Connective tissue proper: loose connective tissue, reticular
Description: Network of reticular
fibers in a typical loose ground
substance; reticular cells lie on the
network.
Function: Fibers form a soft internal
skeleton (stroma) that supports other
cell types including white blood cells,
mast cells, and macrophages.
Location: Lymphoid organs (lymph
nodes, bone marrow, and spleen).
White blood
cell
(lymphocyte)
Reticular
fibers
Spleen
Photomicrograph: Dark-staining network of reticular
connective tissue fibers forming the internal skeleton
of the spleen (350x).
Figure 4.8c
Connective Tissue Proper – Dense
Connective Tissue
• Also called fibrous connective tissue
1. Dense regular connective tissue –
• Closely packed bundles of collagen fibers running
in the same direction
• Parallel to the direction of pull
• White, flexible structures with great resistance to
tension (pulling forces) where tension is exerted
in a single direction
• Crowded in – rows of fibroblasts
1. Dense Regular Connective Tissue
•
•
•
•
•
•
Slightly wavy
Allow tissue to stretch
Once straightened – no further give
Few cells – other than fibroblasts
Poorly vascularized
Forms
– Tendons
– Fascia – fibrous membranes – wrap around muscles,
blood vessels, and nerves
– Ligaments – slightly more stretchy
(d) Connective tissue proper: dense connective tissue, dense regular
Description: Primarily parallel
collagen fibers; a few elastic fibers;
major cell type is the fibroblast.
Collagen
fibers
Function: Attaches muscles to
bones or to muscles; attaches bones
to bones; withstands great tensile
stress when pulling force is applied
in one direction.
Location: Tendons, most
ligaments, aponeuroses.
Nuclei of
fibroblasts
Shoulder
joint
Ligament
Photomicrograph: Dense regular connective
tissue from a tendon (500x).
Tendon
Figure 4.8d
2. Dense Irregular Connective Tissue
• Same structural elements
• Bundles of collagen fibers – thicker and arranged
irregularly
• Runs in more than one plane
• Forms sheets in body areas where tension is
exerted in many directions
• Skin – leathery dermis
• Fibrous joint capsules
• Fibrous coverings that surround organs – kidneys,
bones, cartilages, muscles, and nerves
(e) Connective tissue proper: dense connective tissue, dense irregular
Description: Primarily
irregularly arranged collagen
fibers; some elastic fibers;
major cell type is the fibroblast.
Nuclei of
fibroblasts
Function: Able to withstand
tension exerted in many
directions; provides structural
strength.
Location: Fibrous capsules of
organs and of joints; dermis of
the skin; submucosa of
digestive tract.
Fibrous
joint
capsule
Collagen
fibers
Photomicrograph: Dense irregular
connective tissue from the dermis of the
skin (400x).
Figure 4.8e
3. Elastic Connective Tissue
• Very elastic
• Few ligaments – ligamenta nuchea and flara
(f) Connective tissue proper: dense connective tissue, elastic
Description: Dense regular
connective tissue containing a high
proportion of elastic fibers.
Function: Allows recoil of tissue
following stretching; maintains
pulsatile flow of blood through
arteries; aids passive recoil of lungs
following inspiration.
Elastic fibers
Location: Walls of large arteries;
within certain ligaments associated
with the vertebral column; within the
walls of the bronchial tubes.
Aorta
Heart
Photomicrograph: Elastic connective tissue in
the wall of the aorta (250x).
Figure 4.8f
Cartilage
• Intermediate between dense connective tissue
and bone
• Stands up to both tension and compression
• Tough but flexible
• Provides rigidity
• Lacks nerve fibers
• Avascular
• Receives nutrients by diffusion from blood vessels
localized in connective tissue membrane
(perichondrium)
Cartilage
•
•
•
•
Exceptional amount of tissue fluid
Approx. 80 % water
Chondroblasts – predominant cell type
Produce new matrix until skeleton stops
growing at end of adolescence
• Chondrocytes – mature cartilage cells
• Typically found in small groups with in cavities
- lacunae
3 Varieties of Cartilage
1.
-
Hyaline Cartilage –
Most abundant in body
Matrix – amorphous and glassy
Chondrocytes – 1-10% of cartilage
Firm support with some pliability
Articulate cartilage = ends of bones
Springy pads – absorb compression
Tip of nose
Connect ribs to sternum
Embryonic skeleton until bond formed
(g) Cartilage: hyaline
Description: Amorphous but firm
matrix; collagen fibers form an
imperceptible network; chondroblasts
produce the matrix and when mature
(chondrocytes) lie in lacunae.
Function: Supports and reinforces;
has resilient cushioning properties;
resists compressive stress.
Location: Forms most of the
embryonic skeleton; covers the ends
of long bones in joint cavities; forms
costal cartilages of the ribs; cartilages
of the nose, trachea, and larynx.
Chondrocyte
in lacuna
Matrix
Costal
cartilages
Photomicrograph: Hyaline cartilage from the
trachea (750x).
Figure 4.8g
3 Varieties of Cartilage
2. Elastic Cartilage –
- Nearly identical to hyaline
- More elastic fibers
- Strength and exceptional stretch ability
required
- “skeletons” of external ear and epiglottis
(h) Cartilage: elastic
Description: Similar to hyaline
cartilage, but more elastic fibers
in matrix.
Function: Maintains the shape
of a structure while allowing
great flexibility.
Chondrocyte
in lacuna
Location: Supports the external
ear (pinna); epiglottis.
Matrix
Photomicrograph: Elastic cartilage from
the human ear pinna; forms the flexible
skeleton of the ear (800x).
Figure 4.8h
3 Varieties of Cartilage
3. Fibrocartilage –
- Structural intermediate between hyaline and
dense regular
- Rows of chondrocytes – alternated with thick
collagen fibers
- Resists tension well
- Strong support and ability to withstand heavy
pressure
- Intervertebral discs
- Spongy cartilage of knee
(i) Cartilage: fibrocartilage
Description: Matrix similar to
but less firm than that in hyaline
cartilage; thick collagen fibers
predominate.
Function: Tensile strength
with the ability to absorb
compressive shock.
Location: Intervertebral discs;
pubic symphysis; discs of knee
joint.
Chondrocytes
in lacunae
Intervertebral
discs
Collagen
fiber
Photomicrograph: Fibrocartilage of an
intervertebral disc (125x). Special staining
produced the blue color seen.
Figure 4.8i
Bone
•
•
•
•
•
•
Osseous tissue
Support and protect body structures
Provide cavities for fat,
Storage and synthesis of blood cells
Similar to cartilage
Added to matrix elements – inorganic calcium
salts
Bone
• Osteoblasts – produce organic portion of bone
matrix and bone salts are deposited on and
between fibers
• Mature bone cells – osteocytes
(j) Others: bone (osseous tissue)
Description: Hard, calcified
matrix containing many collagen
fibers; osteocytes lie in lacunae.
Very well vascularized.
Function: Bone supports and
protects (by enclosing);
provides levers for the muscles
to act on; stores calcium and
other minerals and fat; marrow
inside bones is the site for blood
cell formation (hematopoiesis).
Location: Bones
Central
canal
Lacunae
Lamella
Photomicrograph: Cross-sectional view
of bone (125x).
Figure 4.8j
Blood
• Fluid within blood vessels
• Atypical connective tissue
• Classified as connective tissue because it
comes from mesenchyme
• Blood cells surrounded by nonliving fluid
matrix called blood plasma
• RBS or erythrocytes
• Scattered WBCs
(k) Others: blood
Description: Red and white
blood cells in a fluid matrix
(plasma).
Plasma
Function: Transport of
respiratory gases, nutrients,
wastes, and other substances.
Location: Contained within
blood vessels.
Neutrophil
Red blood
cells
Lymphocyte
Photomicrograph: Smear of human blood (1860x); two
white blood cells (neutrophil in upper left and lymphocyte
in lower right) are seen surrounded by red blood cells.
Figure 4.8k
Nervous Tissue
• Brain, spinal cord, and nerves
• Regulate and control body function
• 2 major cell types
– Neurons
– Supporting cells
Nervous Tissue
1.
-
Neurons – highly specialized nerve cells
Generate and conduct nerve impulses
Branching cells with cytoplasmic processes
Processes allow cell to:
-
Respond to stimuli
Transmit electrical impulses
Nervous Tissue
2. Supporting cells – non-conducting sells that
support, insulate, and protect neurons
Nervous tissue
Description: Neurons are
branching cells; cell processes
that may be quite long extend from
the nucleus-containing cell body;
also contributing to nervous tissue
are nonirritable supporting cells
(not illustrated).
Nuclei of
supporting
cells
Neuron processes Cell body
Axon
Dendrites
Cell body
of a neuron
Function: Transmit electrical
signals from sensory receptors
and to effectors (muscles and
glands) which control their activity.
Location: Brain, spinal
cord, and nerves.
Neuron
processes
Photomicrograph: Neurons (350x)
Figure 4.9
Muscle Tissue
• Highly cellular, well vascularized tissues
• Muscle cell process – myofilaments – actin
and myosin – bring about movement and
contraction
• 3 kinds of cells
– Muscle
– Cardiac
– Skeletal
Muscle Tissue
•
•
•
•
Skeletal Muscle –
Forms flesh of body
Contracts – pulls on bones or skin
Muscle cells – muscle fibers –
– Long cylindrical cells
– striated or branded in appearance
– Many nuclei
(a) Skeletal muscle
Description: Long, cylindrical,
multinucleate cells; obvious
striations.
Striations
Function: Voluntary movement;
locomotion; manipulation of the
environment; facial expression;
voluntary control.
Location: In skeletal muscles
attached to bones or
occasionally to skin.
Nuclei
Part of
muscle
fiber (cell)
Photomicrograph: Skeletal muscle (approx. 460x).
Notice the obvious banding pattern and the
fact that these large cells are multinucleate.
Figure 4.10a
Muscle Tissue
• Cardiac Muscle –
• Found in walls of the heart
• Contractions propel blood through blood vessels
to all parts of the body
• Striated
• Generally uninucleate
• Branching cells fit tightly together at unique
junctions, intercalated discs
• involuntary
(b) Cardiac muscle
Description: Branching,
striated, generally uninucleate
cells that interdigitate at
specialized junctions
(intercalated discs).
Striations
Intercalated
discs
Function: As it contracts, it
propels blood into the
circulation; involuntary control.
Location: The walls of the
heart.
Nucleus
Photomicrograph: Cardiac muscle (500X);
notice the striations, branching of cells, and
the intercalated discs.
Figure 4.10b
Muscle Tissue
• Smooth Muscle –
• No visible striations
• Spindle shaped with one centrally located
nucleus
• Found in walls of hallow organs: digestive and
respiratory tracts, uterus, blood vessels, etc.
• Squeezes substances through the organs by
contracting and relaxing
• Voluntary – under consious control
(c) Smooth muscle
Description: Spindle-shaped
cells with central nuclei; no
striations; cells arranged
closely to form sheets.
Function: Propels substances
or objects (foodstuffs, urine,
a baby) along internal passageways; involuntary control.
Location: Mostly in the walls
of hollow organs.
Smooth
muscle
cell
Nuclei
Photomicrograph: Sheet of smooth muscle (200x).
Figure 4.10c
Covering and Lining Membrane
• 3 types –
– cutaneous
– Mucous
– Serous
• Continuous multicellular sheets composed of
2 – primary tissues
• epithelium bound to underlying connective
tissue
Cutaneous Membranes
• Skin
• Organ system consisting of keratinized
stratified squamous epithelium (epidermis)
• Attached to a thick layer of dense irregular
connective tissue
• Exposed to air
• Dry membrane
Cutaneous
membrane
(skin)
(a) Cutaneous membrane (the skin)
covers the body surface.
Figure 4.11a
Mucous Membrane
•
•
•
•
•
Mucosae
Line body cavities open to the exterior
Digestives, respiratory, and urogenital tracts
Wet ‘moist” membranes bathed by body secretions
Either stratified squamous or simple columnar
epithelia
• Directly underlined by loose connective tissue – lamina
propria
• 3rd deeper layer of smooth muscle
• Doesn't always secrete mucus – urinary tract
Mucosa of
nasal cavity
Mucosa of
mouth
Esophagus
lining
Mucosa of
lung bronchi
(b) Mucous membranes line body cavities
open to the exterior.
Figure 4.11b
Serosa Membranes
•
•
•
•
Serosae
Moist membranes in ventral body cavity
Consists of simple squamous epithelium (mesothelium)
Resting on a thin layer of loose connective tissue
(areolar)
• Thin, clear serosa fluid lubrication
• Named according to function
– Pleura – lungs
– Pericardium – heart
– Peritoneums – abdominopelvic and viscera
Parietal
peritoneum
Parietal
pleura
Visceral
pleura
Visceral
peritoneum
Parietal
pericardium
Visceral
pericardium
(c) Serous membranes line body cavities
closed to the exterior.
Figure 4.11c
Tissue Repair
• Inflammatory response – nonspecific
• Immune response – specific
• Steps
1. Regeneration
2. Fibrosis
- Depends on
1. Type of issue injured
2. Severity of injury
Tissue Repair
1. Inflammation sets stage
- Tissue trauma – injured cells
- Macrophages, mast cells, and others –
release inflammatory chemicals
- Capillaries dilate and become permeable
- Allows WBC to seep into area
- Construct clot
Scab
Epidermis
Blood clot in
incised wound
Inflammatory
chemicals
Vein
Migrating white
blood cell
Artery
1 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 proteins
to seep into the injured area.
• Clotting occurs; surface dries and forms a scab.
Figure 4.12, step 1
Tissue Repair
2. Organization restores blood Suppy –
- Organization – blot clot replaced by
granulation tissue – delicate pink tissue
- Cappillaries lay down new bed
- Granulation tissue  scar tissue
Regenerating
epithelium
Area of
granulation
tissue
ingrowth
Fibroblast
Macrophage
2 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.
Figure 4.12, step 2
Tissue Repair
• Regeneration and fibrosis
– The scab detaches
– Fibrous tissue matures; epithelium thickens and
begins to resemble adjacent tissue
– Results in a fully regenerated epithelium with
underlying scar tissue
Regenerated
epithelium
Fibrosed
area
3
Regeneration and fibrosis effect permanent repair:
• The fibrosed area matures and contracts; the epithelium
thickens.
• A fully regenerated epithelium with an underlying area of
scar tissue results.
Figure 4.12, step 3
Regenerative Capacity
•
•
•
•
•
Epithelial
Bond
Areolar connective
Dense irregular
Blood forming
• Smooth muscle
• Dense irregular
• Skeletal
• Cartilage
• Caridac
• Nervous
Developmental Aspects
• Primary germ layers: ectoderm, mesoderm,
and endoderm
– Formed early in embryonic development
– Specialize to form the four primary tissues
• Nerve tissue arises from ectoderm
• Muscle and connective tissues arise from mesoderm
• Epithelial tissues arise from all three germ layers
16-day-old embryo
(dorsal surface view)
Ectoderm
Mesoderm
Endoderm
Epithelium
Muscle and connective
tissue (mostly from
mesoderm)
Nervous tissue
(from ectoderm)
Figure 4.13
Cancer
•
•
•
•
•
•
•
Cells fail to follow normal controls of cell division
Multiply excessively
Neoplasm – mass of proliferating cells
Classified as benign ‘kindly” or malignant “bad”
Benign – concentrated – 1 area, grows slowly
Malignant – grows restlessly, become killers
Metastasis – ability to travel to other parts of the
body
Carcinogens
• Cancer causers
• Physical factors – radiation, viral infections, chemicals,
etc.
– All cause mutations – changes in DNA  alter gene
expression
• Oncogenes – cancer causing genes
• Protooncogenes – benign forms of oncogenes
• Fragile sites – when exposed to carcinogens – convert
to oncogenes
• Loss of enzymatic controls
• Cells become evasive and metastasize
Tumor Suppressor Genes
•
•
•
•
•
Anti-oncogenes
Suppress cancer by inactivating carcinogens
Aid in DNA repair
Enhance immune response
2 important ones:
– p53 –
– p16 – cancer results in loss or malfunction of
these 2 genes
Cancer Treatments
Diagnosis –
1. Screening procedures
2. Biopsy
3. Tests to determine extent of cancer
- Designated stage 1- 4
- 1 – best probability of cure
- 4 – worst probability
New Therapies
• Old – cut, burn, poison
• New –
– Targeted drugs – interrupt signaling pathway of cancer
growth
– Drugs/radiation precisely to cancer sparing normal
tissue
– Genetically modified immune cells to target cancer
cells
– Drugs – that target cancer cells biogenetics
– Others – starve cancer cells
– Also – cancer vaccines