Download 4-4 Connective Tissue

Chapter 4
The Tissue Level
of Organization
The original lecture presentation
by Lee Ann Frederick (University
of Texas at Arlington) has been
extensively modified for use in
MCB 244 & 246 by Drs. Kwast &
Brown, University of Illinois at
Champaign-Urbana (2016–2017)
© 2015 Pearson Education, Inc.
Chapter 4: Learning Objectives
• Understand the fundamental characteristics,
classifications, structure/functions and locations of the 4
basic types of tissue and membranes:
1.
2.
3.
4.
Epithelial tissue (8 types + glands)
Connective tissue (3 + many cell types)
Muscle tissue (3 types)
Neural or nervous tissue
Membranes = epithelial + connective tissue (4
types)
2
4-1 An Introduction to Tissues
• Tissues
• Collection of specialized cells (and their products) that
perform limited number of specific functions
• Have discrete structural and functional properties
• Tissues in combination form organs (e.g., heart, liver)
• Organs can be grouped into 11 organ systems
• Histology is the study of tissues
While there are some 200 types of cells, there are only
four types of tissues in the body.
3
4-1 Four Types of Tissue
1. Epithelial tissue: “covering ”
• Lines internal passages &
covers exposed surfaces
• Specialized for absorption
and secretion
• Forms glands
2. Connective tissue: “support ”
• Fills internal spaces
• Supports other tissues
• Transports materials
• Stores energy
3. Muscle tissue: “movement ”
• Specialized for contraction
• Skeletal muscle, heart
muscle, and smooth muscle
lining the walls of hollow
organs
4. Neural tissue: “control ”
• Carries electrical signals
from one part of the body to
another, excitable
membranes
4
4-1 Three Primary Germ Layers
• Embryonic germ layers give rise to all four tissue
types in adults:
• Ectoderm (outer): epithelial (epidermis) & nervous
• Mesoderm (middle): muscle, connective, epithelial
(endothelium - lines blood & lymph vessels + mesothelium
- lines pleural, pericardial & peritoneum cavities)
• Endoderm (inner): epithelial (mucosa - lines GI &
respiratory tracts)
5
4-2 Epithelial Tissue
• 2 Categories:
• Epithelia - layers of cells covering internal or external surfaces
• Glands - structures that produce fluid secretions
• Characteristics of Epithelia
• Cellularity – closely packed cell junctions w/little extracellular
material between adjacent cells; tight junctions between cells
• Polarity – apical (exposed) and basal (attached) ends, separate
functions
• Attachment – bound to basement membrane (basal lamina)
• Avascularity – lack blood vessels (no room) so obtain nutrients
from underlying connective tissue or through apical membrane
• Regeneration – high turnover; damaged or lost cells continually
replaced by epithelial stem cells
6
4-2 Epithelial Tissue Morphology & Specialization
1. Apical Surface: exposed to
environment, may have:
• Microvilli: absorption or secretion
• Cilia: fluid movement
2. Basolateral Surfaces:
attachment to neighboring cells via
intercellular connections; also
attachment to basement
membrane
• Specializations of Epithelial Cells
1. Move fluids over the epithelium (protection)
Figure 4-1
The Polarity of
Epithelial Cells
2. Move fluids through the epithelium (permeability)
3. Produce secretions (protection and messengers)
7
4-2 Epithelial Tissue Functions
• Functions of Epithelial Tissue
1. Provide physical protection of exposed and internal surfaces (abrasion,
dehydration, infection, etc.)
2. Control permeability – selective absorption or secretion (regulated)
3. Provide sensation – large sensory nerve supply (e.g., touch); includes
neuroepithelium for specific modalities (taste, smell, sight, equilibrium &
hearing)
4. Produce specialized secretions (glandular epithelium): chemical messengers
• Integrity of barrier maintained by:
1. Intercellular connections
2. Attachment to the basement membrane
3. Epithelial maintenance and repair
8
4-2 Epithelial Tissue Intracellular Connections
• For Both Support & Communication (2 types)
• A. General Adhesion: Large Connections
1. CAMs (cell adhesion molecules):
• Connect adjacent membranes or binds extracellular materials (e.g.
basal lamina)
2. Intercellular cement:
• Thin layer of proteoglycans + glycosaminoglycans (GAGs) such as hyaluronan
– Attach adjacent membranes
• B. Specific Adhesion = Cell Junction
1. Tight Junctions
2. Gap Junctions
3. Desmosomes
Figure 4-2
Cell Junctions
9
4-2 Epithelial Tissue Cell Junctions: Tight Junctions
• Between two plasma membranes
• Interlocking junctional proteins
bind lipid portion of membrane
producing a water tight seal
Figure 4-2 Cell Junctions
• Prevents passage of water and
solutes
• Isolates wastes in lumen
• Just inferior (deep) to the tight
junction, an adhesion belt
consisting of CAMs bind to the
microfilaments of the terminal
web
10
4-2 Epithelial Tissue Cell Junctions: Gap Junctions
• Connexons form protein
channels between adjacent cells
that allow molecules (e.g., small
ions) to pass between
Figure 4-2 Cell Junctions
• Allows for rapid communication
• Cells can work in concert, for
example as in the beating of cilia
or contractions of the heart
11
4-2 Epithelial Tissue Cell Junctions: Desmosomes
Strong connections that use cell adhesion
molecules (CAMs) cemented to dense
areas, which attach to the cytoskeleton
Figure 4-2 Cell Junctions
• resist stretching and twisting
• responsible for sheet-like properties
1.
Spot Desmosomes:
• tie cells together; allow bend & twist
2.
Hemidesmosomes:
• Half spot desmosome at basal
surface, attaches cell to extra-cellular
filaments in basal lamina
Basal Lamina Attachment
Clear layer (Lamina lucida) - thin layer
secreted by epithelia; barrier to proteins
Dense layer (Lamina densa) - thick fibers
produced by connective tissue; provide
strength & a selective filtration barrier
12
4-2 Epithelial Tissue Maintenance & Repair
• Epithelial stem cells are anchored to lamina lucida
(clear layer)
• Epithelia are replaced by division of germinative
cells (stem cells)
• Stem cells divide and migrate toward apical region
13
4-3 Classification of Epithelia
• Based on shape and layers
1. Based on shape (all look
hexagonal from top)
•
Squamous — thin & flat;
disc-shaped nucleus
•
Cuboidal — cube or square;
round nucleus
Columnar — tall & slender;
oval nucleus
•
2. Based on layers
•
•
Simple (single layer)—fairly
weak; for absorption,
secretion or filtration
Stratified (> 1 layer)—strong;
for protection
• 8 types of Epithelial Tissues…
14
4-3 Classification of Epithelia – 1. Simple Squamous
• Thin & delicate
• Locations: found in protected regions
• Mesothelium (serosa-body cavity lining), endothelium (line blood
vessels & heart), kidney tubules, cornea, and alveoli of lungs
• Functions:
•
Absorption, diffusion, filtration, or secretion
Figure 4-3a
Squamous
Epithelium
15
4-3 Classification of Epithelia – 2. Stratified Squamous
• Basal cells look cuboidal; apical cells - squamous
• Locations: exposed surfaces (e.g., skin, mouth, throat, etc.)
• Functions: protection from abrasion, pathogens & chemicals
Two types:
Nonkeratinized = mucosa
- Must kept moist; all cells are nucleated (mouth, esophagus, anus & vagina)
Keratinized = epidermis (skin)
- Dry, apical cells dead; keratin resists dehydration and adds strength
Figure 4-3b
Squamous Epithelia
16
4-3 Classification of Epithelia – 3. Simple Cubiodal
• Locations:
Kidney tubules
Pancreas
Salivary glands
Thyroid gland
• Functions
Secretion
Absorption
Figure 4-4a Cuboidal Epithelia
Figure 4-4a Cuboidal Epithelia
17
4-3 Classification of Epithelia – 4. Stratified Cuboidal
• Rare
• Typically two layers
• Locations:
Some sweat glands
Some mammary glands
• Functions
Secretion
Absorption
Figure 4-4b Stratified Cuboidal Epithelium
18
4-3 Classification of Epithelia – 5. Transitional
•
Tolerates repeated cycles of stretching and recoiling and returns to its
previous shape without damage
•
Appearance changes as stretching occurs
• Relaxed: looks like stratified cuboidal; Stretched: stratified squamous
•
Location: Urinary bladder & ureters
•
Function: stretch tolerance
Figure 4-4c Transitional Epithelia
19
4-3 Classification of Epithelia – 6. Simple Columnar
•
Nuclei line up near basal lamina
•
Apical surface typically has microvilli = “brush border” (in intestine)
•
Goblet cells, which secrete mucus, often present
•
Location: Stomach, intestine, gall bladder, uterine tubes, and collecting
ducts of kidney
•
Function: Absorption and secretion
Figure 4-5a Columnar Epithelia
20
4-3 Classification of Epithelia – 7. Pseudostratified
Ciliated Columnar
•
•
•
•
•
•
Several cell types: varying shapes and functions
All cells contact basal lamina but some too short to reach apical surface
Nuclei scattered so it appears stratified (hence “pseudostratified”)
Tall cells have cilia on apical surface
Goblet cells (mucus) often present
Location:
• Function:
Nasal cavity, trachea, bronchi,
Move materials
Male reproductive tract,
across surface
Female uterine tubes
Figure 4-5b Columnar Epithelia
21
4-3 Classification of Epithelia – 8. Stratified Columnar
•
•
•
•
Rare
Two or more layers with only apical layer columnar
Locations (tiny parts of):
Pharynx, epiglottis, anus, mammary glands, salivary glands, and
urethra
Functions:
Minor protection
Figure 4-5c Columnar Epithelia
22
4-3 Classification of Epithelia: Glandular
• Glandular Epithelia
1. Endocrine glands: “internally secreting”
• secrete into interstitial fluid (ductless)à blood
• secretions = hormones
• regulate and coordinate activities
• e.g., pancreas, thyroid, thymus, pituitary
2. Exocrine glands: “externally secreting”
• secrete into duct à epithelial surface
• e.g., digestive enzymes, perspiration, tears, milk, and mucus
• Classified in three ways:
1. Mode of Secretion (3)
2. Type of Secretion (3)
23
3. Structure (8)
4-3 Modes of Secretion in Exocrine Glandular Epithelia
• Merocrine (mero = part) secretion
• Produced in Golgi apparatus
• Released by secretory vesicles
(exocytosis)
• e.g., mucin, sweat
• Apocrine (apo = off) secretion
• Produced in Golgi apparatus
• Released by shedding cytoplasm
(apical)
• e.g., mammary gland - milk
• Holocrine (holo = entire) secretion
• Released by cells bursting, killing gland cells
• Gland cells replaced by stem cells
• e.g., sebaceous gland - oils
24
4-3 B. Types of Secretion in Exocrine Glandular Epithelia
1.
Serous Glands: water + enzymes
• e.g., parotid salivary gland
2.
Mucus Glands: mucin
(mucin + water = mucus)
• e.g., goblet cell, sublingual salivary gland
3.
Mixed exocrine glands:
serous + mucin secretion
• e.g., submandibular salivary gland
25
4-3 C. Gland Structure of Glandular Epithelia
• Two Classifications of Exocrine Glands based on
Structure:
• Unicellular glands (= 1 cell)
• Mucous (goblet) cells are the only unicellular exocrine glands
• Scattered among epithelia
• For example, in intestinal lining
• Multicellular glands
• groups of cells named for their
• structure (simple or compound),
• shape (tubular or aveolar) and
• relationship between ducts and glandular areas (e.g.,
branched)
26
4-3 Multicellular Exocrine Gland Structure
Structure of the duct:
a. simple (undivided)
b. compound (divided)
Shape of secretory
portion of the gland:
a. tubular (tube shaped)
b. alveolar or acinar or
acinous or sacculus
(blind pockets or sacs)
Relationship between ducts
and glandular areas:
a. branched (several
secretory areas sharing
one duct)
27
4-4 Structure/Function of Connective Tissue
Diverse Functions:
• Connect epithelium to the rest of the body (basal lamina)
• Provide structure (bone), store energy (fat), transport materials (blood)
Features:
• Never exposed to the environment
• Usually vascularized
• Consists of cells in a matrix (extracellular fibers + ground substance [a fluid]),
which makes up the majority of tissue volume & determines function
Basic Components:
1.
Specialized cells:
Produce matrix, provide protection
2.
Extracellular protein fibers:
Support, strength
3.
Ground Substance:
Gel fluid, consisting of interstitial fluid, cell adhesion molecules &
GAGs (glycosaminoglycans = proteoglycans that form a gel)
28
4-4 Connective Tissue
• Specific Functions of Connective Tissue
• Establishing a structural framework for the body
• Transporting fluids and dissolved materials
• Protecting delicate organs
• Supporting, surrounding, and interconnecting other
types of tissue
• Storing energy reserves, especially in the form of
triglycerides
• Defending the body from invading microorganisms
29
4-4 Connective Tissue: Classifications
1. Connective tissue proper
• Connect and protect (e.g., adipose tissue and tendons)
A. Loose connective tissue = More ground substance,
less fibers (e.g., adipose tissue)
B. Dense connective tissue = More fibers, less ground
substance (e.g., tendons)
2. Fluid connective tissues
• Transport (e.g., blood and lymph)
3. Supporting connective tissues
• Structural strength (e.g., cartilage and bone)
30
4-4 Connective Tissue Proper: Cells and Fibers
• Connective Tissue Proper contains:
1. Extracellular fibers
2. Ground Substance (a clear, colorless, and viscous fluid that fills
spaces between cells and slows pathogen movement)
3. A Varied Cell Population (9 different types)
Figure 4-8 The Cells and
Fibers of Connective Tissue
Proper
31
4-4 Connective Tissue Proper: 9 Cell Types
1. Fibroblasts
3. Macrophages cont.
• The most abundant cell type:
• eat pathogens & damaged cells
- found in all connective tissue proper
- fixed macrophages stay in
- secrete proteins and hyaluronan
tissue
(cellular cement), which makes
- free macrophages migrate
ground substance viscous; also
4. Adipocytes
secrete protein subunits that make
• Fat cells:
up the extracellular fibers
- each cell stores a single, large
fat droplet
2. Fibrocytes
• The second most abundant cell type: 5. Mesenchymal Cells
- found in all connective tissue proper
• Stem cells that respond to injury or
- maintain the fibers of connective
infection:
tissue proper
- differentiate into fibroblasts,
macrophages, etc.
3. Macrophages
• Large, amoeba-like cells of the immune 6.
system:
Melanocytes
32
• Synthesize and store melanin
4-4 Connective Tissue Proper: 9 Cell Types
7. Mast Cells
• Stimulate inflammation after injury or
infection:
– release histamine and heparin
– (Basophils, a type of leukocytes or
white blood cells, also contains
histamine and heparin that aids in
the inflammatory response and
tissue repair)
9. Microphages
• Phagocytic white blood cells:
– respond to signals from
macrophages and mast cells
– e.g., neutrophils and
eosinophils
8. Lymphocytes
• Specialized immune cells in lymphoid
(lymphatic) system:
– e.g., lymphocytes may develop into
plasma cells (plasmocytes) that
produce antibodies
33
4-4 Connective Tissue Fiber Types
1. Collagen fibers: collagen protein (most common)
• rope like, long, straight, unbranched
• resists force in 1 direction; strong & flexible
• e.g., tendons and ligaments
2. Reticular fibers: collagen protein
• network of interwoven fibers (stroma)
• resist force in many directions
• strong & flexible
• stabilize functional cells (parenchyma)
and structures
• e.g., sheaths around organs
3. Elastic fibers: elastin protein
• branched and wavy, flexible
• return to original length after stretching
• e.g., elastic ligaments of vertebrae
Collagen
fibers
Reticular
fibers
Elastic
fibers
34
4-4 Embryonic Connective Tissue
• Embryonic connective tissue first appears in the developing embryo as
star-shaped cells in a gelatinous matrix
• Mesenchyme (embryonic stem cells)
• The first connective tissue in embryos
• Mucous connective tissue
• Loose embryonic connective tissue not found in adults
35
4-4 – 1. Connective Tissue Proper (2 types)
A. Loose Connective Tissues (3 subtypes)
• The “packing materials” of the body
• Highly vascularized; Varied cell types
• Functions:
• Fill space
• Cushion & support tissues
• Store fat
• Feed epithelial layers
• Three types in adults:
I. Areolar (“little space”)
• Least specialized
• Open framework
• Viscous ground substance
• All fiber types, especially elastic fibers
• Holds blood vessels and capillary beds
• Separates skin from muscle
36
4-4 – 1. Connective Tissue Proper
A. Loose Connective Tissues
II. Adipose Tissue
• 90% adipocytes (+ mesenchymal cells for replacement)
• Adult adipocytes do NOT divide, can only expand/retract
Locations: deep to skin, surrounding eyeballs, kidneys, heart
Functions: padding, insulation, and energy storage
Two subtypes:
A. White fat: triglyceride storage, insulation, shock absorber
B. Brown fat: more abundant in infants, high mitochondria content for
heat generation, highly vascularized for heat dissipation
37
4-4 – 1. Connective Tissue Proper
A. Loose Connective Tissues
III. Reticular Tissue
• Provides support
• Complex, three-dimensional network
• Supportive fibers (stroma) of organs
Location: some organs --lymph nodes, bone marrow,
liver, spleen
Function: Support functional cells (parenchyma)
Reticular Tissue
Figure 4-10b Adipose and Reticular Tissues
LOCATIONS: Liver, kidney, spleen,
lymph nodes, and bone marrow
FUNCTIONS: Provides supporting
framework
Reticular
fibers
Reticular tissue
from liver
Reticular Tissue
LM ´ 375
38
4-4 - 1. Connective Tissue Proper
B. Dense Connective Tissues
•
•
•
Tightly packed tissue with high numbers of collagen or
elastic fibers and little ground substance
Poorly vascularized
Cells are primarily fibroblasts
Two Types according to current book edition:
I.
Dense regular connective tissue
(which includes the subtype “elastic tissue”)
II. Dense irregular connective tissue
39
4-4 – 1. Connective Tissue
B. Dense Connective Tissue
I. Dense Regular Connective Tissue
Tightly packed bundles of parallel collagen fibers, aligned with force direction
Location:
• Tendons attach muscles to bones
• Ligaments connect bone to bone and stabilize organs
• Aponeuroses attach broad flat muscles to bones or other muscles
Function:
• High strength attachment; stabilizes position
Figure 4-11 Dense
Connective Tissues
40
4-4 – 1. Connective Tissue Proper
B. Dense Regular Connective Tissue
Elastic Connective Tissue
• Made mostly of elastic fibers with some collagen
Location:
• Vertebral ligaments and artery walls
Function:
• Strength with stretch and flexibility (elasticity)
Figure 4-11 Dense Connective Tissues
41
4-4 – 1. Connective Tissue Proper
B. Dense Connective Tissue
II. Dense Irregular Connective Tissue
Interwoven networks of collagen fibers
Location:
•
•
•
•
forms capsules around some organs (e.g., liver, kidneys)
periosteum (sheath around bone)
perichondrium (around cartilage)
dermis (deep skin)
Function:
• resist tension from many directions; forms attachments
Figure 4-11 Dense
Connective Tissues
42
4-4 – 2. Fluid Connective Tissue
• Watery matrix of dissolved proteins
• Carry specific cell types (formed elements)
• Two Types: Blood & Lymph
A. Blood
Matrix = Plasma = serum (fluid) + plasma proteins (produced by liver)
fibers are soluble until clot forms
Cells = Formed elements
originate from hemocytoblast (stem cells) in bone marrow
Location:
contained in blood vessels
Function:
transport nutrients, wastes and defense cells throughout the body
(cardiovascular system – arteries, capillaries & veins)
Plasma à Interstitial Fluid à Lymph à Plasma
43
4-4 – 2. Fluid Connective Tissue
A. Blood
• Formed elements:
Erythrocytes (red blood cells)
Leukocytes (white blood cells): Neutrophils, Eosinophils,
Basophils, Lymphocytes (B and T cells), Monocytes
(Macrophages)
Figure 4-12 Formed Elements of the Blood
Platelets (carry clotting factors)
44
4-4 – 2. Fluid Connective Tissue
B. Lymph
• Matrix: Lymph = recollected plasma fluid from the
interstitial space
• Cells: Lymphocytes (immune defense)
• Location: Lymphatic vessels
• Function: Purify and return fluid to venous
(cardiovascular) system
45
4-5 – 3. Supporting Connective Tissues
• Support Soft Tissues and Body Weight (against
gravity)
• Strong framework, few cells (chondrocytes only),
fibrous matrix
A. Cartilage
• Gel-type ground substance
• For shock absorption and protection
B. Bone
• Calcified (made rigid by calcium salts, minerals)
• For weight support
46
4-5 - 3. Supporting Connective Tissues
A. Cartilage
Composition:
• Matrix: 80% water, firm gel of glycoaminoglycans made of chondroitin
sulfate and hyaluronic acid, + fibers
• Cells: chondrocytes in lacunae (chambers)
• Only cells in the cartilage matrix
Structure:
• No innervation
• Avascular (no blood vessels)
• chondrocytes produce antiangiogenesis factor
• Surrounded by Perichondrium:
• Outer fibrous layer = dense irregular connective tissue
– Function: strength, protection, attachment
• Inner cellular layer (fibroblasts)
– Function: growth and maintenance
47
4-5 - 3. Supporting Connective Tissues
A. Cartilage Growth – 2 Mechanisms:
I. Interstitial Growth (embryos)
Chondroblasts in matrix divide
Daughters produce more matrix
Mature cells = chondrocytes
Important during development
Figure 4-13a The Growth of Cartilage
Matrix
New
matrix
Chondrocyte
Lacuna
Chondrocyte undergoes division
within a lacuna surrounded by
cartilage matrix.
As daughter cells secrete additional matrix, they
move apart, expanding the cartilage from within.
48
4-5 - 3. Supporting Connective Tissues
A. Cartilage Growth
II. Appositional Growth (children, minor repair in adult)
New layers added by cells of inner perichondrium
Serious Injury = scar; cartilage replaced by fibrous
collagen
Figure 4-13b The Growth of Cartilage
Dividing stem cell
Fibroblast
Perichondrium
New matrix
Chondroblasts
Cells in the cellular layer
of the perichondrium
differentiate into
chondroblasts.
These immature
chondroblasts secrete
new matrix.
Immature
chondrocyte
Older matrix
Mature
chondrocyte
As the matrix enlarges, more
chondroblasts are incorporated;
they are replaced by divisions of
stem cells in the perichondrium.
49
4-5 – 3. Supporting Connective Tissues
A. Cartilage Types (3)
I. Hyaline cartilage:
•
•
Contains fine, closely packed collagen fibers
Tough, springy
Location:
• Synovial joints, rib tips - sternum and trachea
• Articular surfaces have no perichondrium
Function:
• Provide stiff flexible support
• Reduce friction between bones
Figure 4-14a Types of Cartilage
50
4-5 – 3. Supporting Connective Tissues
A. Cartilage Types (3)
II. Elastic cartilage:
•
•
Matrix contains tightly packed elastic fibers
Flexible support
Location:
• Auricle (external) of ear, epiglottis
Function:
• Support but resilient, flexible and shape holding support
Figure 4-14b Types of Cartilage
Elastic Cartilage
LOCATIONS: Auricle of external
ear; epiglottis; auditory canal;
cuneiform cartilages of larynx
FUNCTIONS: Provides support,
but tolerates distortion without
damage and
returns to
original
shape
Chondrocyte
in lacuna
Elastic fibers
in matrix
Elastic cartilage
LM ´ 358
51
4-5 – 3. Supporting Connective Tissues
A. Cartilage Types (3)
III. Fibrocartilage:
•
•
Matrix contains dense interwoven collagen fibers with little ground substance
Tough, durable
Location:
Function:
•
Knee (meniscus)
• Limits movement
•
Pubic symphysis, knee joint • Absorbs Shock: Pads
•
Intervertebral discs
• Prevents bone-to-bone contact
Figure 4-14c Types of Cartilage
52
4-5 – 3. Supporting Connective Tissues
B. Bone or Osseous Tissue
• Strong (calcified calcium salt deposits)
• Resists shattering (flexible collagen fibers)
• Highly vascularized with little ground substance
Matrix:
• 2/3 calcified: calcium salts deposits for strength
• Calcium phosphate + calcium carbonate
• 1/3 collagen for flexibility to resist shatter
• Bone Cells or Osteocytes
• Located in lacunae arranged around central canals within matrix
• Small channels through matrix (canaliculi) access blood supply
• Canaliculi necessary for nutrient and waste exchange, no
diffusion through calcium
53
4-5 – 3. Supporting Connective Tissues
B. Bone or Osseous Tissue
• Periosteum (dense, irregular connective tissue)
• Covers bone surfaces
• Outer Fibrous layer for attachment (surrounding tissue as
well as tendons & ligaments)
• Inner cellular layer for growth (appositional) and repair
Location: Bones
Function: Support & Protection; Levers for movement
Storage of minerals
Figure 4-15
Bone
54
4-5 – 3. Supporting Connective Tissues
Comparison of (A) Cartilage & (B) Bone
55
4-6 Membranes
• Membranes
• Are physical barriers
• Line or cover portions of the body
• Consist of an epithelium supported by connective tissues
Four Types of Membranes
1. Mucous membranes
2. Serous membranes
3. Cutaneous membrane
4. Synovial membranes
56
4-6 Membranes
1. Mucous Membranes (Mucosae)
• Consist of epithelium + areolar connective tissue called lamina
propria
• Line passageways that have external connections
• In digestive, respiratory, urinary, and reproductive tracts
• Epithelial surfaces must be moist
• To reduce friction
• To facilitate absorption and excretion
Figure 4-16a
Membranes
57
4-6 Membranes
2. Serous Membranes
• Consist of Mesothelium + areolar
connective tissue
• Line cavities not open to the outside
Figure 4-16b
• Are thin but strong
• Have fluid transudate to reduce friction
• Membrane has two portions:
• parietal portion covering the cavity wall
• visceral portion (serosa) covering the organs
Membranes
Three Types of Serous Membranes
A.
•
•
B.
•
•
Pleura:
Lines pleural cavities
Covers lungs
Peritoneum:
Lines peritoneal cavity
Covers abdominal organs
C. Pericardium:
• Lines pericardial cavity
• Covers heart
58
4-6 Membranes
3. Cutaneous Membrane
• Epidermis + dermis = “skin”
• Keratinized stratified squamous
epithelium + areolar and dense
irregular connective tissue
• Thick, waterproof, and dry (only dry
membrane)
Figure 4-16c & d
Membranes
4. Synovial Membranes
• Areolar connective tissue with
woven collagen, proteogycans and
glycoproteins in matrix
• Line moving, articulating joint
cavities
• Produce synovial fluid (lubricant)
• Protect the ends of bones
• Lack a “true" epithelium
59
4-7 Internal Framework of the Body
•
Connective Tissues
1. Provide strength and stability
2. Maintain positions of internal organs
3. Provide routes for blood vessels, lymphatic vessels, and
nerves
•
Fasciae
Singular form = fascia
•
•
The body’s framework of connective tissue
Layers and wrappings that support or surround organs
• Three Types of Fasciae
1. Superficial fascia (insulation & padding)
2. Deep fascia (anchors, resists force)
3. Subserous fascia (prevents distortion)
60
Figure 4-17 The Fasciae
61
4-8 Muscle Tissue
• Classification of Muscle Cells
• Striated (muscle cells with a banded appearance)
• Nonstriated (not banded; smooth)
• Muscle cells can have a single nucleus or be
multinucleate
• Muscle cells can be controlled voluntarily
(consciously)
• Muscle cells can be controlled involuntarily
(automatically)
62
4-8 Muscle Tissue
1. Skeletal Muscle Cells: Striated, voluntary, multinucleated
Cells = fibers
• Up to 1 ft long (e.g., soleus muscle of basketball player)
• No cell division
• Appear striated: actin and myosin organized into myofibrils
Myosatellite cells (stem cells) present for minor repair
Location: skeletal muscles (‘meat’)
Function: Move skeleton, Guard entrances/exits, Generate heat
Figure 4-18a Muscle Tissue
63
4-8 Muscle Tissue
2. Cardiac Muscle Cells = Cardiocytes
•
•
•
•
Striated, involuntary, mono- or multi-nucleated
Long, Branched cells
No cell division
Neighboring cells connected by intercalated discs:
• Desomosomes + intracellular cement + gap junctions
• Gap junctions help coordinate contractions (ion exchange)
• Overall pace regulated by pacemaker cells
Figure 4-18b Muscle Tissue
64
4-8 Muscle Tissue
3. Smooth Muscle Cells
• Nonstriated, involuntary, single nucleus
• Cells: small, spindle shaped
• Myofibrils poorly organized so no striations
• Capable of cell division
Location: walls of blood vessels and hollow organs
(e.g., digestive, respiratory, urinary & reproductive tracts)
Functions: move materials through the organ
Figure 4-18c Muscle Tissue
Smooth Muscle Tissue
Cells are short, spindle-shaped, and
nonstriated, with a single, central
nucleus.
LOCATIONS: Found in
the walls of blood vessels
and in digestive, respiratory,
urinary, and reproductive organs
FUNCTIONS: Moves food,
urine, and reproductive tract
secretions; controls
diameter of respiratory
passageways; regulates
diameter of blood vessels
Nucleus
Smooth
muscle
cell
Smooth muscle
LM ´ 235
65
4-9 Neural Tissue
Function:
• specialized for conducting electrical (nervous) impulses
• rapidly senses internal or external environment
• process information and controls responses
Location:
• Most in brain and spinal cord: Central Nervous System
• 2% in Peripheral Nervous System
Cell Types:
• Neuroglia Cells:
• Support, repair, and supply nutrients to nervous tissue
• Neurons:
•
•
•
•
• Many dendrites: receive info
Transmit information
• One axon: transmits info
Up to 3 ft long
• No cell division
Large soma (cell body)
66
Large nucleus, visible nucleoli
4-9 Neural Tissue: Cell Parts
• Cell body
• Contains the nucleus and nucleolus
• Dendrites
• Short branches extending from the cell body
• Receive incoming signals
Figure 4-19 Neural Tissue
• Axon (nerve fiber)
• Long, thin extension of
• the cell body
• Carries outgoing
electrical signals to their
destination
67
4-10 Tissue Injuries and Repair
• Tissues respond to injuries to maintain homeostasis
• Cells restore homeostasis with 2 processes:
• Inflammation
• Regeneration (repair)
Inflammation:
• Prevent spread of injury (trauma) or infection (pathogens)
• Characterized by: swelling, redness, warmth and pain
• Process to remove necrotic cells and infectious agents
Regeneration:
• Replacement of collagen with original tissue type
68
4-10 Tissue Injuries and Repair
• Inflammatory Response
• Can be triggered by:
• Trauma (physical injury)
• Infection (the presence of harmful pathogens)
• Damaged cells release chemical signals into the surrounding
interstitial fluid
• Prostaglandins
• Proteins
• Potassium ions
• As cells break down:
• Lysosomes release enzymes that destroy the injured cell and
attack surrounding tissues
• Tissue destruction is called necrosis
69
4-10 Tissue Injuries and Repair: Inflammation
• Necrotic tissues and cellular debris (pus) accumulate in the wound
• Abscess – pus trapped in an enclosed area
• Injury stimulates mast cells to release:
• Histamine
• Heparin
• Prostaglandins
• Dilation of blood vessels
•
•
•
•
Increases blood circulation in the area
Causes warmth and redness
Brings more nutrients and oxygen to the area
Removes wastes
70
4-10 Tissue Injuries and Repair
• Plasma diffuses into the area
• Causes swelling and pain
• Phagocytic white blood cells
• Clean up the area
• Regeneration
• When the injury or infection is cleaned up
• Healing (regeneration) begins
• The Process of Regeneration
• Fibroblasts move into necrotic area
• Lay down collagen fibers
• To bind the area together (scar tissue)
71
4-10 Tissue Injuries and Repair
• The Process of Regeneration Cont.
• New cells migrate into area
• Or are produced by mesenchymal stem cells
• Not all tissues can regenerate
• Epithelia and connective tissues regenerate well
• Cardiac cells and neurons do not regenerate (or
regenerate poorly)
72
Figure 4-20 Tissue Repair
Mast Cell Activation
stimulates
When an injury damages
connective tissue, mast
cells release a variety of
chemicals. This process,
called mast cell activation,
stimulates inflammation.
Mast cell
Exposure to Pathogens and Toxins
Injured tissue contains an
abnormal concentration of
pathogens, toxins, waste
products, and the chemicals
from injured cells.
When a tissue is
injured, a general
defense mechanism
is activated.
73
Figure 4-20 Tissue Repair
Mast Cell Activation
When an injury damages
connective tissue, mast
cells release a variety of
chemicals. This process,
called mast cell activation,
stimulates inflammation.
Mast cell
Histamine
Heparin
Prostaglandins
INFLAMMATION
Inflammation produces several familiar indications of injury, including
swelling, redness, warmth, and pain. Inflammation may also result
from the presence of pathogens, such as harmful bacteria, within the
tissues; the presence of these pathogens constitutes an infection.
Increased Blood Flow
Increased Vessel Permeability
Pain
In response to the
released chemicals, blood
vessels dilate, increasing
blood flow through the
damaged tissue.
Vessel dilation is accompanied by
an increase in the permeability of
the capillary walls. Plasma now
diffuses into the injured tissue, so
the area becomes swollen.
The abnormal conditions
within the tissue and the
chemicals released by
mast cells stimulate nerve
endings that produce the
sensation of pain.
PAIN
74
Figure 4-20 Tissue Repair
Increased Local
Temperature
Increased Oxygen
and Nutrients
Increased
Phagocytosis
Removal of Toxins
and Wastes
The increased
blood flow and
permeability
causes the tissue
to become warm
and red.
Vessel dilation,
increased blood flow,
and increased vessel
permeability result in
enhanced delivery of
oxygen and nutrients.
Phagocytes in
the tissue are
activated, and
they begin
engulfing tissue
debris and
pathogens.
Enhanced circulation
carries away toxins and
waste products,
distributing them to the
kidneys for excretion, or
to the liver for
inactivation.
O2
Toxins
and wastes
Regeneration
Regeneration is the repair that
occurs after the damaged tissue has
been stabilized and the inflammation
has subsided. Fibroblasts move into
the area, laying down a collagenous
framework known as scar tissue.
Over time, scar tissue is usually
“remodeled” and gradually assumes
a more normal appearance.
Inflammation Subsides
Over a period of hours to days,
the cleanup process generally
succeeds in eliminating the
inflammatory stimuli.
75
Figure 4-20 Tissue Repair
Normal
tissue
conditions
restored
Inhibits mast
cell activation
Regeneration
Regeneration is the repair that
occurs after the damaged tissue has
been stabilized and the
inflammation has subsided.
Fibroblasts move into the area,
laying down a collagenous
framework known as scar tissue.
Over time, scar tissue is usually
“remodeled” and gradually assumes
a more normal appearance.
76
4-11 Aging and Tissue
Hallmarks of Cancer:
Sustain proliferative signals
Evade growth suppressors
Resist cell death
Enable replicate immortality
Induce angiogenesis
Activate Invasiveness
• Speed & efficiency of tissue repair decrease with age, due to:
• Slower rate of energy consumption (metabolism)
• Hormonal alterations
• Reduced physical activity
• Effects of Aging
• Chemical and structural tissue changes
• Thinning epithelia and connective tissues
• Increased bruising and bone brittleness
• Joint pain and broken bones
• Cardiovascular disease
• Mental deterioration
• Cancer rates increase with age
• 25% of all people in the United States develop cancer
• Cancer is the #2 cause of death in the United States
• Environmental chemicals and cigarette smoke cause cancer
• Carcinoma (epithelia), sarcoma (connective), blastoma (precursor cells),
lymphoma & leukemia (-blood forming cells), etc.
77
Chapter 4 Summary
• Organization of specialized cells into tissues:
•
•
•
•
epithelial tissue
connective tissue
muscular tissue
nervous tissue
• Division of epithelial tissues into epithelia and glands:
• epithelia as avascular barriers for protection
• glands as secretory structures
• Specializations of epithelial cells for sensation or motion:
• microvilli
• cilia
78
Chapter 4 Summary
• Attachments of epithelia to other cells and underlying tissues:
• polarity (apical surface and basal lamina)
• cell adhesion molecules (CAMs)
• cell junctions (tight junctions, gap junctions and desmosomes)
• Maintenance of epithelia:
• germinative cells & stem cells
• Classification of epithelial cells:
• by number of cell layers (simple or stratified)
• by shape of cells (squamous, columnar or cuboidal)
79
Chapter 4 Summary
• Classification of epithelial glands:
•
•
•
•
by method of secretion (exocrine or endocrine)
by type of secretions (merocrine, apocrine, holocrine)
by organization (unicellular or multicellular)
by structure (related to branches and ducts)
• The functions of connective tissues:
• Structure, transport, protection, support, connections, and energy
storage
• The structure of connective tissues:
• Extracellular fibers + ground substance (= matrix) + specialized
cells
80
Chapter 4 Summary
• The classification of connective tissues:
• connective tissue proper (cell types, fiber types, and embryonic
connective tissues)
• fluid connective tissues (blood and lymph, fluid transport systems)
• supporting connective tissues (cartilage and bone)
• The 4 types of membranes that cover and protect organs:
•
•
•
•
mucous membranes (lamina propria)
serous membranes (transudate)
cutaneous membrane (skin)
synovial membrane (encapsulating joints)
81
Chapter 4 Summary
• The fasciae (superficial, deep and subserous)
• The 3 types of muscle tissues (skeletal, cardiac, and smooth)
• The classification of muscle tissues by striation, nucleation, and
voluntary control
• The 2 types of cells in neural tissue:
• neurons and neuroglia
• The parts of a neuron (nerve cell):
• cell body, dendrites, and axon (nerve fiber)
• Tissue injuries and repair systems (inflammation and
regeneration)
• The relationship between aging, tissue structure, and cancer
82