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Tissue Level
Of Organization
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Introduction
Epithelial Tissue
Connective Tissue
Muscle Tissue
Nervous Tissue
Cells, Tissues, & Organ
Systems
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Learning Objectives
• Introduction:
 Identify the four major tissue types of
the body & their roles
• Epithelial Tissue:
 Discuss the types & functions of
epithelial cells
 Describe the relationship between form
& function for each epithelial type
• Connective Tissues:
 Compare the structures & functions of
the various types of connective tissues
Tissue Types &
Functions
• Epithelial Tissue
 Covers exposed surfaces
 Lines internal passages & chambers
 Forms glands
• Connective Tissue
 Fills internal spaces
 Provides structural support for other
tissues
 Transports materials w/in the body
 Stores energy reserves
Tissue Types &
Functions
• Muscle Tissue
 Contracts to perform specific
movements
 Generates heat to warm the body
•
Nervous Tissue
 Carries information from one part of the
body to another in the form of electrical
impulses
Epithelial Tissue
•
•
•
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Characteristics
Functions
Specializations
Epithelial Integrity
Characteristics
• Cellularity
 cell junctions
• Polarity
 apical surface
 basal surface
• Attachment
 basal membrane
• Avascularity
 No blood vessels
• Regeneration
 stem cell mitosis
Functions
• Provide physical protection
 Protect exposed & internal surfaces from
abrasion, dehydration, & destruction by
chemical or biological agents
• Control of permeability
 Substances enter & leave body across an
epithelium
 May be regulated by hormones
Functions
• Provide sensation
 Extensive innervation by sensory nerves
Detect: touch, temperature change
 Neuroepithelia provide: smell, taste,
sight, equilibrium, & hearing
• Produce specialized secretions
 Gland cells
Endocrine glands – secretions discharged
into interstitial fluid or blood (hormones)
Exocrine glands – secretions discharged
onto surface of skin or other internal
surface (sweat glands; digestive glands)
Specializations
• Production of secretions
– Glandular epithelia
• Movement of fluids over the epithelial
surface
– Ciliated epithelia
• Transport of substances through the
epithelium
– Microvilli – increase surface area for
absorption
Cell
Attachments
Maintenance
of
Epithelial Integrity
• Intercellular connections
 Tight junctions – belt-like connections
Partial fusion of lipid bilayer of adjacent cells
 Desmosomes – bands & rivets
Cytoskeletal elements link through cell
membrane
• Belt desmosomes – band that encircles cell
• Button desmosome – fibrous discs
 Gap junctions – channels
Interlocking membrane channel proteins
Maintenance of
Epithelial Integrity
• Basement membrane
 Basal lamina – secreted by
epithelial cells (closest to
epithelial cells)
Fine network of protein filaments &
glycoproteins
Provides protective barrier
 Reticular lamina – secreted by
underlying connective tissue cells
Course bundles of protein fibers
Provides strength
Maintenance of
Epithelial Integrity
• Maintenance & repair
 Epithelial cells exposed to mechanical
abrasion, toxic chemicals, disruptive
enzymes, pathogenic bacteria
 Germinative cells
A.k.a., stem cells
Located in deepest layers of an
epithelium
Undergo active mitosis throughout life to
replace damaged or dead cells in the
epithelium
Epithelial Tissue
Terminology: Layers
• Simple
 1 layer of cells
 all in contact w/ basement membrane
• Stratified
 2 or > layers of cells
 bottom layer in contact w/ basement
membrane
• Pseudostratified
 1 layer of cells
 arrangement of nuclei gives
appearance of several layers
 all in contact w/ basement membrane
Epithelial Tissue
Terminology: Cell Shapes
• Squamous cells
 thin; flattened; irregular
 appear spindle-like in sectional view;
appear like “fried eggs” in surface view
• Cuboidal cells
 hexagonal; box-like
 appear square in sectional view
• Columnar cells
 hexagonal; tall & slender
 appear rectangular in sectional view
Epithelial Tissue
Classification
• Classification of Epithelia:
 Squamous epithelia
Simple
Stratified
 Cuboidal epithelia
Simple
Stratified
Transitional (type of stratified)
 Columnar epithelia
Simple
Stratified
Pseudostratified
General Epithelia
cell layer
basement membrane
underlying
connective tissue
Simple Squamous
Epithelium
• Locations
 mesothelial linings of body cavities
 endothelial lining of heart & blood
vessels
 kidney tubules (loop of Henle)
 inner lining of cornea
 alveoli of lungs
• Functions
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protection
reduce friction
control vessel permeability
absorption & secretion
Stratified Squamous
Epithelium
• Locations
 surface of skin
 lining of mouth, pharynx,
esophagus, rectum, anus
 lining of vagina
• Functions
 physical protection against
abrasion
 protection from pathogen &
chemical attack
Simple Cuboidal
Epithelium
• Locations
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Basement
exocrine
glands
Membrane
ducts
kidney tubules
thyroid (endocrine) gland
• Functions
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limited protection Lumen
Nuclei of
secretion &/or absorption
Cells in 1
Layer
Stratified Cuboidal
Epithelium
Basement
Membrane
• Locations
Connective
Tissue
 lining of some ducts (rare)
• Functions
 protection
 secretion
 absorption
Lumen
Nuclei of
Cells in 2
Layers
Transitional
Epithelium
relaxed
• Locations
 urinary bladder
stretched
 renal pelvis
 ureters
• Functions
Basement
Membrane
 protection
 permit expansion & recoil after
stretching
Connective
Tissue
Simple Columnar
Epithelium
• Locations
 lining of stomach, intestine, & gall
bladder
 lining of uterine tubes
 collecting ducts of kidney
• Functions
 protection
 secretion & absorption
 surface movement
Stratified Columnar
Epithelium
• Locations
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Superficial
Columnar Cells
small areas of pharynx Deeper Columnar
Cells
epiglottis
salivary gland ducts & anus
mammary glands
urethra
• Function
 protection
Pseudostratified
Columnar Epithelium
• Locations
 lining of nasal cavity
 lining of bronchi
• Functions
 protection
 secretion
 surface movement
Glandular
Epithelial Tissue
• Glandular Epithelia:
 Endocrine glands – no ducts
 Exocrine glands – w/ ducts
Modes of secretion
Types of secretions
 Gland structure
Unicellular – goblet cell only
Multicellular – all other glands
• Simple
• Compound
Modes of Secretion
• Merocrine secretion
 secretory vesicles released from intact
cell by exocytosis; whole cell left intact
• Apocrine secretion
 apical portion of cytoplasm packed w/
secretory vesicles is shed; part of cell
destroyed
• Holocrine secretion
 entire cell packed w/ secretory vesicles
disintegrates; whole cell destroyed
Types of Secretions
• Mucus glands
 mucin – glycoprotein: becomes
slippery lubricant
• Serous glands
 watery solution w/ enzymes
• Mixed mucus & serous
 more than 1 type of gland cell;
secretes both mucus & watery
solution
Exocrine Gland
Structure
• Shape of secretory portion of gland
 tubular – tube-like arrangement
 alveolar (acinar) – pocket-like
arrangement
 tubuloalveolar – combination of above
• Branching pattern of ducts
 simple – undivided duct leading to gland
cells
 compound – ducts divide leading to
gland cells
Exocrine Gland
Structure
• Relationship btw/ ducts & glandular
areas
 branched – several secretory areas
share a common duct
 Always refers to glandular areas not to
duct
Connective Tissues
• Basic Structure
• Functions
• Classification Categories:
 connective tissue proper
 fluid connective tissues
 supporting connective tissues
Basic
Tissue Components
• Specialized cell types
– widely separated
• Extracellular protein fibers
• Ground substance (extracellular
fluid)
 Viscosity
Syrupy in most connective tissues
• proteoglycans
• glycoproteins
Watery in fluid connective tissues
Note: extracellular fibers & ground substance
constitute the extracellular matrix
Extracellular Matrix
fluid ground
substance
protein fibers
Functions
Note examples of common connective
tissues
• Structural framework
• Transport of fluids & dissolved
materials
• Protection/insulation of delicate
organs
• Support & interconnection of other
tissue types
• Storage of energy reserves
• Defense against microorganisms
Examples of Common
Connective Tissues
Note functions
• Adipose (fat) tissue – protection;
insulation, & energy storage
• Tendons & ligaments –
support & anatomical
interconnection
• Fascia – framework & anatomical
interconnection
Examples of Common
Connective Tissues
• Blood & lymph – transport
(physiological interconnection)
& defense
• Cartilage & bone – support,
anatomical interconnection &
protection
Connective Tissue
Categories
• Connective tissue proper
 Loose connective tissue
 Dense connective tissue
• Fluid connective tissues
 Blood
 Lymph
• Supporting connective tissue
 Cartilage
 Bone
Connective Tissue
Proper: Classification
• Connective Tissue Proper
cell populations
fibers types
ground substance
Connective Tissue
Proper: Cell Types
• Fibroblasts – make fibers
• Macrophages – engulf pathogens &
dead cells
• Adipocytes – store lipid triglycerides
• Mesenchymal cells – stem cells:
differentiate into different cell types when
needed
Connective Tissue
Proper: Cell Types
• Melanocytes – pigment cells
• Mast cells – wound-healing response
• Lymphocytes – killer cells &
antibodies
• Microphages
(eosinophils &
neutrophils from plasma) – engulf
pathogens; produce chemicals important
in responses to wounds
Connective Tissue
Proper: Fiber Types
• Collagen fibers
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protein: collagen
long; thick; straight; unbranched
skin; bone; tendons & ligaments
most common fiber in body
• Reticular fibers
 collagen-like protein
 short; thin; branched
 stabilize organs
Connective Tissue
Proper: Fiber Types
• Elastic fibers
 protein: elastin
 long; thin; wavy; branched
 elastic ligaments of vertebrae
Connective Tissue Proper:
Ground Substance
• Characteristics
 Clear
 Colorless
 Viscous
Syrupy in most connective tissues
• proteoglycans
• glycoproteins
Connective Tissue
Proper: Characteristics
• Loose Connective Tissues
 Areolar tissue
 Specialized loose connective
tissues
Adipose tissue
Reticular tissue
Loose Connective
Tissue: Areolar
• Locations
 Wide-spread “packing material” of the
body
 Fills spaces btw/ organs
 Supports epithelia
 Surrounds blood vessels & nerves
• Functions
 Provides cushioning
 Provides routes for diffusion of
nutrients btw/ other tissues
 Specialized varieties: adipose tiss. & reticular
tiss.
Loose Connective
Tissue: Adipose Tissue
• Locations
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Under skin
Breasts, buttocks, groin
Eye sockets
Surrounds kidneys & heart
Fat “apron” covers abdominal cavity
• Functions
 Body contouring associated w/ sexual
attraction
 Padding against mechanical shock
 Insulation – preventing heat loss
 Packing around delicate structures
Loose Connective
Tissue: Reticular Tissue
 Spleen, liver
 Lymph nodes, bone marrow
• Functions
 Structural framework of body
organs
Reticular Fibers
• Locations
Connective Tissue
Proper: Characteristics
• Dense Connective Tissues
 Regular dense connective
tissue
Elastic tissue
 Irregular dense connective
tissue
• Locations
collagen fibers
Dense Connective
Tissue: Regular
• Functions
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provide firm attachment
conducts pull of muscles
reduce friction betw/ muscles
stabilizes position of bones
fibroblast
nuclei
 tendons - betw/ skeletal muscles &
skeleton
 ligaments – betw/ bones
 covering skeletal muscles (deep fascia)
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vertebral ligaments
under transitional epithelium
walls of blood vessels
walls of respiratory passages
• Functions
 stabilizes position of vertebrae
 allows cycles of expansion &
contraction
fibroblast
nuclei
• Locations
elastin fibers
Dense Regular Connective
Tissue: Elastic
Dense Connective
Tissue: Irregular
• Locations
collagen
 capsules of visceral organs
fiber
 periostea & perichondria (membranes
bundles
around bones & cartilage)
 nerve & muscle sheaths
 dermis
• Functions
 provide strength to resist
multidirectional forces
 prevents over-expansion of organs (e.g.,
urinary bladder)
Fluid
Connective Tissue
• Blood
 formed elements
 plasma proteins
 plasma
• Lymph
 white blood cells
 lymph
 interstitial fluid
Fluid
Connective Tissue
• Blood
 Cell Types: formed elements
red blood cells (RBCs)
white blood cells (WBCs)
platelets (cell fragments)
 Extracellular Proteins – plasma
proteins
 Ground Substance – plasma
Blood:
Formed Elements
Transport
O2 & CO2
Defense against disease
Blood
clotting
Fluid
Connective Tissue
• Lymph
 Cell Types:
lymphocytes – WBCs (99%)
macrophages
microphages
 Ground Substance:
interstitial fluid
lymph
Supporting
Connective Tissue
• Types of Cartilage
 hyaline cartilage
 elastic cartilage
 fibrocartilage
• Bone
 osseus tissue
Supporting
Connective Tissue
• Cartilage
 Cell Types – chondrocytes
 Matrix – collagen & elastin fibers
embedded in chondroitin sulfates
• Bone
 Cell Types – osteocytes
 Matrix – collagen fibers embedded
in calcium salts
 btw/ tips of ribs & sternum
 covering bone surfaces of synovial
joints
 supporting larynx, trachea, & bronchi
 nasal septum
• Functions
 stiff – flexible support
 reduces friction
matrix
• Locations
chondrocytes
Hyaline Cartilage
• Locations
 tip of nose
 pinna of external ear
 epiglottis
• Functions
chondrocytes
in lacunae
Elastic Cartilage
matrix
 support
elastic
 tolerates distortion w/out damage fibers
 pads w/in knee joint
 btw/ pubic bones of pelvis
 intervertebral discs
• Functions
 resists compression
 prevents bone-to-bone contact
 limits relative movement
chondrocyte in
lacunae
• Locations
collagen
fibers
Fibrocartilage
Bone
canaliculi
• Locations
central canal of
osteon
 organs of the skeletal system
• Functions
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support of the body
protection of other organs
movement
mineral storage
blood formation
matrix
osteocyte in lacuna
Differences btw
Cartilage & Bone
Cartilage
Vol of ground subst –
greater
Ground subst – firm
gel
Avascular – no blood
Bone
vessels w/in tissue
Vol of ground subst –
very little
Ground subst –
mineralized
Vascular ized – blood
vessels w/in tissue
Learning Objectives
• Membranes:
 Explain how epithelial membranes &
connective tissues combine to form four
different types of membranes
 Specify the functions of the various
types of membranes in the body
• Connective Tissue Framework:
 Describe how connective tissue
establishes the framework of the body
Membranes
• Functions
• Classification:
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Mucous membranes
Serous membranes
Cutaneous membrane
Synovial membranes
Membrane
Structure & Functions
• General Structure:
derived from –
 epithelia
 loose connective tissue
• General Functions:
 cover & protect organ surfaces &
body cavities
 reduce friction due to organ & body
movements
 absorption & secretion
Mucus Membranes
 Structure – simple epithelium
underlain by loose c.t. (lamina propria)
 Characteristics – thin to thick; moist;
often ciliated or w/ microvilli
 Locus – line digestive, respiratory,
urinary, & reproductive tracts
 Functions – protection from
microorganisms, etc;
absorption/secretion; surface
transport
Serous Membranes
 Structure – simple squamous
mesothelium supported by loose c.t.
 Characteristics – thin; moist;
permeable to fluids
 Locus – line ventral body cavity
(peritoneum) & pleural & pericardial
cavities
 Function – minimize friction btw/
internal organs
Cutaneous Membrane
 Structure – stratified squamous
epithelium underlain by loose c.t. &
supported by dense c.t.
 Characteristics – thick, waterproof,
dry
 Locus – outer surface of the skin
 Functions – protection; secretion of
waste; temperature regulation, etc
Synovial Membranes
 Structure – incomplete simple
squamous or cuboidal layer
supported by loose c.t.
 Characteristics – medium thick;
highly fibrous; synovial fluid
 Locus – joint cavities of freely
moveable joints
 Functions – minimize friction; prevent
direct bone-bone contact
Membrane Structure
Connective Tissue
Framework
• Functions
• Classification:
 superficial fascia
 deep fascia
 subserous fascia
Fascia
Structure & Functions
• General Structure:
 membranes
• General Functions:
 provide strength & stability
 maintain relative positions of
internal organs
 provide route for distribution of
blood vessels, lymphatics, &
nerves
Superficial Fascia
 Hypodermis or subcutaneous layer
 Locus – betw/ skin & underlying
organs
 Structure – loose connective tissue
 Functions – insulation & padding;
allows skin to move independently of
underlying organs
Deep Fascia
 Locus – surrounds internal organs
(liver, kidneys, etc), bones (including
ligaments), muscles (including
tendons)
 Structure – dense connective tissue
 Functions – binding structural
elements together (i.e., muscles to
bones, bones to each other)
Subserous Fascia
 Locus – betw/ deep fascia & serous
membranes of the body cavities
 Structure – loose connective tissue
 Functions – prevents distortion of
body cavity by movements of
skeletal muscles or internal organs
Learning Objectives
• Muscle Tissue:
 Describe the three types of
muscle tissue & the special
structural features of each type
 Discuss the functions of the three
types of muscle tissue
• Neural Tissue:
 Discuss the basic structure & role
of neural tissue
Muscle Tissue
• Functions
• Classification:
 skeletal muscle tissue
 cardiac muscle tissue
 smooth muscle tissue
Skeletal Muscle
Structure & Functions
• Cellular Structure:
 multinucleate cells
 long, thin “fibers”
 striated – due to overlapping
arrangement of contractile,
microfilament proteins
• Functions:
 gross movement of the body
 voluntary control
Skeletal Muscle
Cell Structure
Cardiac Muscle
Structure & Functions
• Cellular Structure:
 single nucleate cells
 branched w/ intercalated discs
joining cells
 striated – overlap arrangement of
contractile, microfilament proteins
• Functions:
 pumping blood through the
cardiovascular system
 involuntary control
Cardiac Muscle
Tissue
Smooth Muscle
Structure & Functions
• Cellular Structure:
 single nucleate cells
 spindle-shaped
 unstriated – due to more random
arrangement of contractile proteins
• Functions:
 regulation of blood flow through vessels;
movement of food through digestive
system; regulation of respiratory
passage diameter, etc
 involuntary control
Smooth Muscle
Cells
Neural Tissue
• Functions
• Classification:
 neurons
 neuroglia
Neurons
• Cellular Structure:
 variable
 typical: tree like dendrites; soma w/
nucleus & most organelles; long, thin
axon (nerve fiber)
• Functions:
 conscious & unconscious
communication by propagation of
electrical impulses
Neuron Structure
Impulse Transmission:
dendrites  soma  axon
soma
axon
dendrites
Neuroglia
• Cellular Structure:
 several types of neuroglia cells:
4 major types in CNS; 2 major types in
PNS
• Functions: support
 maintain physical structure of nervous
tissue
 repair tissue framework after injury
 perform phagocytosis of dead cells &
microorganisms
 provide nutrition to neurons
Neuron
& Neuroglial Cells
neuron
neuroglial
cells