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Chapter 4
Tissues, Glands,
& Membranes
1
General Definitions:
•
Tissue - group of cells similar structure
and function along with similar
extracellular substances between the
cells
• Histology – microscopic study of tissue
structure
• Histo- = tissue, -ology = study
2
Causes of Tissue Change
Development
 Growth
 Aging
 Trauma
 Disease

3
Four Basic Types of Tissues

Epithelial tissues

Epi = on + thele = covering or lining
Connective tissues
 Muscle tissues
 Nervous tissues

4
Epithelial Tissue, General Characteristics
• Covers internal and external body
surfaces
• Skin, digestive tract, respiratory
passages, and blood vessels
• Comprises major tissue of glands
5
Epithelial Tissue, Unique characteristics


Consists mostly of cells
with very little
extracellular material
(matrix or ECM)
Lacks blood vessels

Gases, nutrients, &
waste diffuse across
basement membrane


Cells attached to
underlying tissue
Free membrane is not
touching any other cells
6
Functions of Epithelial Tissue
• Protect underlying structures
•
Skin & oral cavity
• Barrier
•
Skin keeps water in/out, prevents entrance of toxins
& microorganisms
• Exchange of substances
•
O2 & CO2 diffused through lung epithelia between air
and blood
• Secretion
•
Sweat glands, mucous glands, pancreas
• Absorption
•
Carrier molecules in intestine absorb nutrients
(vitamins, ions, food molecules)
7
Classification of Epithelia
• Classified based on number of cell layers
and cell shape
• Simple epithelium – 1 layer of cells
• Stratified epithelium - >1 layer of cells
• Squamous (flat and scale-like)
• Cuboidal (cube shaped)
• Columnar (tall and thin)
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Layers or “Arrangement”
9
Shapes
10
11
Types of Epithelia
1) Simple squamous epithelia (lungs)
2) Simple cuboidal epithelia
3) Simple columnar epithelia
4) Pseudostratified columnar epithelia (w/cilia)
(trachea)
5) Stratified squamous epithelia
6) Transitional epithelium (bladder)
12
Simple Squamous Epithelium
• Single layer of thin, flat
cells
• Line blood vessels,
lymphatic vessels,
heart, alveoli, kidney
tubules, serous
membranes
• Diffusion, filtration,
anti-friction, secretion,
absorption
13
Simple Cuboidal Epithelium

Single layer of cubeshaped cells, some
with microvilli or cilia
 Kidney tubules,
glands/ducts, brain,
bronchioles, ovary
surface
 Secretion,
absorption,
movement of
particles
14
Simple Columnar Epithelium

Single layer of tall,
narrow cells, some with
cilia/microvilli
 Lining of stomach,
intestines, glands,
ducts, bronchioles,
auditory tubes, uterus,
uterine tubes
 Secretion, absorption,
movement of
particles/oocytes
15
Pseudostratified Columnar
Epithelium

Single layer of cells,
some tall and thin,
others not, nuclei at
different levels,
appear stratified,
almost always
ciliated
 Lining of nasal
cavity, nasal
sinuses, auditory
tubes, pharynx,
trachea, bronchi
 Synthesis/secretion/
movement of mucus
16
Transitional Epithelium

Stratified cells
appear cuboidal
when not stretched
and squamous when
stretched
 Lining of bladder,
ureters, superior
urethra
 Deals with changing
volume of fluid in an
organ, protects from
urine contact
17
Simple Columnar Epithelium
18
Simple Squamous Epithelium
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Stratified Squamous Epithelium
20
Simple Cuboidal Epithelium
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Stratified Columnar Epithelium
22
Pseudostratified Columnar Epithelium
23
Transitional Epithelium
[bladder]
24
Stratified Cuboidal Epithelium
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Structural & Functional
Relationships

Cell Layers & Cell Shapes

Single layers – control passage of materials
through epithelium
Gas diffusion across lung alveoli
 Fluid filtration across kidney membranes
 Gland secretion
 Nutrient absorption in intestines


Multiple layers – protect underlying tissues
Damaged cells replaced by underlying cells
 Protect from abrasion (ex: skin, anal canal,
vagina)

32
Structural & Functional
Relationships

Cell Layers & Cell Shapes, continued

Flat/thin (squamous) – diffusion, filtration
Diffusion in lung alveoli
 Fluid filtration in kidney tubules


Cuboidal/columnar – secretion, absorption;
contain more organelles

Secretory vesicles (mucus) in stomach lining


Mucus protects against digestive enzymes and acid
Secretion/absorption in kidney tubules made
possible by ATP production by multiple
mitochondria

Active transport of molecules into/out of kidney
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Structural & Functional
Relationships

Free Cell Surfaces

Smooth – reduces friction


Microvilli – increase cell surface area; cells
involved in absorption or secretion


blood vessel lining – smooth blood flow
Small intestine lining
Cilia – propel materials along cell’s surface
Nasal cavity/trachea – moves dust and other
materials to back of throat (swallowed/cough up)
 Goblet cells secrete mucus to entrap the “junk”

34
Structural & Functional
Relationships

Cell Connections



Tight junctions – bind adjacent cells together
 Permeability layers – prevent passage of materials
 Intestinal lining and most simple epithelia
Desmosomes – anchor cells to one another
 Hemidesmosomes – anchor cells to basement
membrane
 Epithelia subject to stress (skin stratified squamous)
Gap Junctions – allow passage of molecules/ions
between adjacent calls (communication)
 Most epithelia
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Cell Connections
36
Glands

Gland – multicellular structure secreting
substance onto a surface, into a cavity, or into
the blood

Exocrine gland (exo-outside + krino-to separate): glands
with ducts; secretions pass through ducts onto a
surface or into an organ





Simple – ducts w/o branches
Compound – ducts w/ branches
Tubular – tubes
Acinus/alveolus – saclike
Endocrine gland (endo-within): glands w/o ducts

Hormones are secreted into blood
37
Exocrine Gland Structures
38
Exocrine Gland Structures
39
Connective Tissue
• The most abundant and widely distributed
tissue in the body
• Multiple types, appearances and
functions
• Relatively few cells in extracellular
matrix (think: fruit “cells” floating or
suspended in Jell-O)
• Protein fibers
• Ground substance
• Fluid
40
Structure of Connective Tissue
Three types of protein fibers:
 Collagen fibers:


Reticular fibers:


Rope-like; resist stretching
Fine, short collagen fibers; branched for
support
Elastic fibers:

Coiled; stretch and recoil to original shape
41
Structure of Connective Tissue,
continued…

Ground substance – combination of
proteins and other molecules


Varies from fluid to semisolid to solid
Proteoglycans – protein/polysaccharide
complex that traps water
42
Naming of Connective Tissue Cells

Based on function:



Blast (germ) – produce matrix
Cyte (cell) – cells maintain it
Clast (break) – cells break down for remodeling





Osteoblast (osteo-bone) – form bone
Osteocyte – maintain bone
Osteoclast – break down bone
Macrophage (makros-large + phago-to eat) – large,
mobile cells that ingest foreign substances found in
connective tissue
Mast Cells – nonmotile cells that release chemicals
that promote inflammation
43
Functions of Connective Tissue
1. Enclose organs and separate organs
and tissues from one another
• Liver, kidney; muscles, blood vessels,
nerves
2. Connect tissue to each other
• Tendons – muscles to bone
• Ligaments – bone to bone
3. Support and movement
• Bones, cartilage, joints
44
Functions of Connective Tissue,
continued…
4. Storage
• Fat stores energy; bone stores calcium
5. Cushion and insulation
• Fat cushions/protects/insulates (heat)
6. Transportation
• Blood transports gases, nutrients,
enzymes, hormones, immune cells
7. Protection
• Immune & blood cells protect against
toxins/tissue injury; bones protect
underlying structures
45
Classification of Connective Tissues
46
Loose connective tissue



Composition: ECM has
fibroblasts, other cells,
collagen, fluid-filled
spaces
Functions: forms thin
membranes between
organs and binds them
(loose packing material)
Locations: widely
distributed, between
glands, muscles, nerves,
attaches skin to tissues,
superficial layer of
dermis
47
Adipose Connective Tissue



Composition: very little
ECM (has collagen and
elastic fibers); large
adipocytes filled with lipid
Functions: Stores fat,
energy source, thermal
insulator, protection/
packing material
Locations: Beneath the
skin, in breasts, within
bones, in loose
connective tissues,
around organs (kidneys
and heart)
48
Dense Fibrous/Collagenous
Connective Tissue



Composition: ECM
mostly collagen (made
by fibroblasts),
orientation varies
Functions: withstands
pulling forces, resists
stretching in direction of
fibers orientation
Locations: tendons,
ligaments, dermis of
skin, organ capsules
49
50
Dense Elastic Connective Tissue



Composition: ECM
collagen and elastic
fibers; orientation
varies
Functions: stretches
and recoils; strength
in direction of fiber
orientation
Locations: arterial
walls, vertebral
ligaments, dorsal
neck, vocal cords
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Cartilage

Chondrocytes (cartilage cells) inside lacunae
(small spaces)
 Matrix composition (ECM):




Collagen – flexibility & strength
Water (trapped by proteoglycans) – rigidity and
flexibility
No blood vessels – slow healing, can’t bring
cells/nutrients
Three types:



Hyaline cartilage
Elastic cartilage
Fibrocartilage
52
Types & Locations of Cartilage
53
Examples of Cartilage
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Hyaline Cartilage



Composition: solid
matrix, small evenly
distributed collagen
fibers, transparent matrix,
chondrocytes in lacunae
Functions: supports
structures, some
flexibility, forms smooth
joint surfaces
Locations: costal
cartilages of ribs,
respiratory cartilage rings,
nasal cartilages, bone
ends, epiphyseal (growth)
plates, embryonic
skeleton
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Fibrocartilage



Composition: similar to
hyaline, numerous
collagen fibrous
arranged in thick
bundles
Functions: somewhat
flexible, withstands
great pressure,
connects structures
under great pressure
Locations:
intervertebral disks,
pubic symphysis,
articulating cartilage of
some joints (knee, TMJ)
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Elastic Cartilage

Composition: similar
to hyaline cartilage,
abundant elastic fibers
 Functions: rigidity,
more flexibility than
hyaline (elastic fibers
recoil to original
shape)
 Locations: external
ears, epiglottis,
auditory tubes
58
Bone



Composition: hard,
mineralized matrix,
osteocytes inside
lacunae, lamellae
layers
Functions: strength,
support, protects
organs,
muscle/ligament
attachments,
movement (joints)
Locations: all bones
of body
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60
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Blood



Composition: blood cells
in a fluid matrix (plasma)
Functions: transportation
(O2, CO2, hormones,
nutrients, waste, etc.),
protect from infection,
temperature regulation
Locations: in blood
vessels and heart,
produced by red bone
marrow, WBCs leave
blood vessels and enter
tissues
62
63
Muscle Tissue

General features:

Can contract




Contractile proteins
Enables movement of
the structures that are
attached to them
Muscle fibers = cells
Three (3) types of muscle
tissue:



skeletal
smooth
cardiac
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Skeletal Muscle

Composition:
striated muscle
fibers, large,
cylindrical cells that
have many nuclei
near periphery
 Functions: body
movement,
voluntary control
 Locations:
attached to bone
65
Cardiac Muscle

Composition:
cylindrical cells,
striated, single
nucleus, branched
and connected with
intercalated disks
 Functions: pump
blood, involuntary
control
 Locations: heart
66
Smooth Muscle



Composition: cells
tapered at each end, not
striated, single nucleus
Functions: regulates
organ size, forces fluid
through tubes, regulates
amount of light entering
eye, “goose bumps”,
involuntary control
Locations: walls of hollow
organs and tubes
(stomach, intestine, blood
vessels), eye
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Nervous Tissue

Forms brain, spinal cord, peripheral nerves
 Functions:







Conscious control of skeletal muscles
Unconscious control of cardiac muscles
Self and environmental awareness
Emotions
Reasoning skills
Memory
Action potentials = electrical signals responsible
for communication between neurons and other
cells
68
Nervous Tissue Structure

Neurons = conducts
action potentials (a.p.’s)




Cell body = contains
nucleus, site of general
cell functions
Dendrite = conduct a.p.’s
toward cell body
Axon = conducts a.p.’s
away from cell body
Neuroglia = support cells:
nourish, protect, insulate
neurons
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Membranes
Thin sheet/layer of tissue covering a
structure or lining a cavity
 Made of epithelium & connective tissue
 Types:

Mucous membranes
 Serous membranes
 Skin/cutaneous membranes
 Synovial membranes
 Periosteum

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Membranes
Mucous
Serous
Synovial
72
Mucous Membranes

Structure: various types of epithelia resting on a
thick layer of connective tissue
 Locations: line cavities that opening to outside of
body (digestive, respiratory, excretory,
reproductive tracts)
 Mucous glands secrete mucus
 Functions:



Protection – oral cavity (stratified squamous epithelium)
Absorption – intestine (simple columnar epithelium)
Secretion – mucus and digestive enzymes in intestine
73
Serous Membranes
Structure: simple squamous epithelium
resting on delicate layer of loose
connective tissue
 Locations: line trunk cavities, cover
organs
 Mucous glands secrete serous fluid onto
membrane surface
 Function: prevent damage from abrasion
between organs in thoracic and
abdominopelvic cavities

74
Types of Serous Membranes

Pleural membranes – lungs


Pericardial membranes – heart


Pleurisy – inflammation of pleural
membranes
Pericarditis – inflammation of pericardium
Peritoneal membranes – abdominopelvic

Peritonitis – inflammation of peritoneum
75
More Serous Membranes

Skin/cutaneous
membranes



Synovial membranes



Stratified squamous
epithelium & dense
connective tissue
Skin
Connective tissue
Line joint cavities
Periosteum


Connective tissue
Surrounds bone
76
Inflammation

In response to tissue damage
Viral/bacterial infections
 Trauma


Functions:
Mobilize body’s defenses
 Destroy microorganisms, foreign materials,
damaged cells
 “Pave way” for tissue repair

77
Symptoms of Inflammation
Redness
 Heat
 Swelling
 Pain
 Disturbance of function

* Inflammation is beneficial, though painful!
78
Inflammatory Response

Mediators of inflammation cause dilation 
permeability of blood vessels (redness/heat)






Bring blood and important substances to site
Edema = swelling (water, proteins, etc.) of
tissues
Fibrin = protein that “walls off” site; keeps
infection from spreading
Neutrophils ingest bacteria (phagocytic WBC)
Macrophage ingest tissue debris
Pus = mixture of dead neutrophils, cells, fluid
79
Inflammation is
adaptive:

Inflammation warns
person from further injury:



Pain
Limitation of movement
(edema)
Tissue destruction
 Fibroclast migrate to
damaged tissue and
digest
80
Tissue Repair

Substitution of viable cells for dead cells
Regeneration = same type of cells takes
place of previous cells; same function
 Replacement = different type of tissue
develops; forms scars; loss of some
function
 Fibroclast lays down fibrin and forms scar
tissue
 Type of tissue repair is determined by:

Wound severity
 Tissue types involved

81
Not all cells divide alike…

Labile cells (not fixed)



Stable cells



Divide continuously through life
Skin, mucous membranes
Don’t actively divide, but can after injury
Connective tissue, glands (liver, pancreas)
Permanent cells


Little to no ability to divide
Neurons, skeletal muscle


If killed, replaced by connective tissue
Recover from limited damage (axon of neuron)
82
Review steps of tissue repair:
1.
2.
3.
4.
5.
6.
7.
8.
Clot (fibrin)
Scab (seal)
Blood vessel
dilation
Fibroclast-clean
up
Fibrin “walls off”
Epithelium
replaced
Scab sloughs
Fibroblasts form
granulation
tissue
Wound
contracture
83
It’s tough getting old…

Tissue changes with age:







 neurons and  muscle cells
 visual acuity, smell, taste, touch
 in functional capacities of respiratory and
cardiovascular systems
Slower cell division means slower healing
 flexibility (irregular collagen fibers in tendons &
ligaments)
 elasticity (elastic fibers bind to Ca2+, becoming
brittle) – makes skin wrinkled too 
Atherosclerosis – plaques in blood vessels
84