Download 1 Chapter 4: The Tissue Level of Organization What are the four

Epithelial Tissue
Chapter 4: The Tissue
Level of Organization
• Covers exposed surfaces
• Lines internal passageways
• Forms glands
Connective Tissue
What are the four
tissues of the body?
•
•
•
•
Fills internal spaces
Supports other tissues
Transports materials
Stores energy
1
Muscle Tissue
• Specialized for contraction
• Skeletal muscle, heart muscle, and
walls of hollow organs
Epithelial Tissues
• Epithelia:
– layers of cells covering internal or
external surfaces
• Glands:
– structures that produce secretions
Neural Tissue
• Carries electrical signals from 1 part of
the body to another
What are the special
structures and functions
of epithelial tissues?
2
Characteristics of Epithelia
1.
2.
3.
4.
5.
Cellularity (cell junctions)
Polarity (apical and basal surfaces)
Attachment (basal lamina)
Avascularity
Regeneration
Free Surface and
Attached Surface
• Polarity:
– apical and basolateral surfaces
Figure 4–1
Specializations of Epithelial Cells
1. Move fluids over the epithelium
(protection)
2. Move fluids through the epithelium
(permeability)
3. Produce secretions (protection and
messengers)
Increasing Surface Area
• Microvilli increase absorption or
secretion
• Cilia (ciliated epithelium) move fluids
3
Effective Barriers
Cell Junctions
• Physical integrity is maintained by:
• Form bonds with other cells or
extracellular material:
– intercellular connections
– attachment to basal lamina
– maintenance and repair
– tight junctions
– gap junctions
– desmosomes
Intercellular Connections
Tight Junctions
• Support and communication
• Between 2 cell membranes
Figure 4–2a
Figure 4–2b
4
Tight Junctions
Gap Junctions
• Adhesion belt attaches to terminal web
• Prevents passage of water and solutes
• Isolates wastes in the lumen
Gap Junctions
• Held together by channel proteins
(junctional proteins, connexons)
• Allow ions to pass
• Coordinated contractions in heart
muscle
Desmosomes
• Allow rapid communications
• CAMs, dense areas, and intercellular
cement
Figure 4–2c
Figure 4–2d
5
Desmososmes
Classes of Epithelia
• Button desmosomes
• Ties cells together
• Allow bending and twisting
• Based on shape and layers
Table 4–1
Attachment to Basal Lamina
Layers
• Hemidesmosomes
• Simple epithelium:
– single layer of cells
• Stratified epithelium:
– several layers of cells
Figure 4–2e
6
Cell Shape
Simple Squamous Epithelium
• Squamous epithelia:
– flat shaped
• Cuboidal epithelia:
– square shaped
• Columnar epithelia:
– tall shaped
Figure 4–3a
Squamous Epithelia
Stratified Squamous Epithelium
• Simple squamous epithelium:
– absorption and diffusion
• Mesothelium:
– lines body cavities
• Endothelium:
– lines heart and blood vessels
Figure 4–3b
7
Stratified Squamous Epithelium
• Protects against attacks
• Keratin proteins add strength and
water resistance
Simple Cuboidal Epithelium
• Kidney tubules
Figure 4–4a
Cuboidal Epithelia
• Simple cuboidal epithelium:
Stratified Cuboidal Epithelium
• Sweat gland ducts
– secretion and absorption
• Stratified cuboidal epithelia:
– sweat and mammary ducts
Figure 4–4b
8
Transitional Epithelium
Simple Columnar Epithelium
• Urinary bladder
• Intestinal lining
Figure 4–4c
Columnar Epithelia
• Simple columnar epithelium:
Figure 4–5a
Pseudostratified
Columnar Epithelium
• Trachea
– absorption and secretion
• Pseudostratified columnar epithelium:
– cilia movement
• Stratified columnar epithelium:
– protection
Figure 4–5b
9
Stratified Columnar Epithelium
• Salivary gland duct
Endocrine Glands
• Release hormones:
– into interstitial fluid
– no ducts
Figure 4–5c
Glandular Epithelia
Exocrine Glands
• Endocrine and exocrine
glands
• Produce secretions:
– onto epithelial surfaces
– through ducts
Figure 4–6
10
Modes of Secretion
Modes of Secretion
• Merocrine secretion
• Apocrine secretion
Figure 4–6a
Merocrine Secretions
• Are produced in Golgi apparatus
• Are released by vesicles (exocytosis)
• e.g., sweat glands
Figure 4–6b
Apocrine Secretions
• Are produced in Golgi apparatus
• Are released by shedding cytoplasm
• e.g., mammary gland
11
Modes of Secretion
Gland Structure
• Holocrine secretion
• Exocrine glands can be classified as:
– unicellular glands
– multicellular glands
Figure 4–6c
Holocrine Secretions
• Are released by cells bursting, killing
gland cells
• Gland cells replaced by stem cells
• e.g., sebaceous gland
Unicellular Glands
• Goblet cells are the only unicellular
exocrine glands:
– scattered among epithelia
– e.g., in intestinal lining
12
Structure of Multicellular
Exocrine Glands
• Structural classes of exocrine glands
3 Characteristics of MEGs
• Structure of the duct:
– simple (undivided)
– compound (divided)
Figure 4–7 (1 of 2)
Structure of Multicellular
Exocrine Glands
3 Characteristics of MEGs
• Shape of secretory portion of the
gland:
– tubular (tube shaped)
– alveolar (blind pockets)
– acinar (chamberlike)
Figure 4–7 (2 of 2)
13
Characteristics of
Connective Tissues
What are the structures
and functions of different
types of connective tissues?
Connective Tissues
• Connect epithelium to the rest of the
body (basal lamina)
• Provide structure (bone)
• Store energy (fat)
• Transport materials (blood)
• Have no contact with environment
• Specialized cells
• Solid extracellular protein fibers
• Fluid extracellular ground substance
The Matrix
• The extracellular components of
connective tissues (fibers and ground
substance):
– majority of cell volume
– determines specialized function
14
Classification of
Connective Tissues
Categories of
Connective Tissue Proper
• Connective tissue proper:
• Loose connective tissue:
– connect and protect
– more ground substance, less fibers
– e.g., fat (adipose tissue)
• Fluid connective tissues:
• Dense connective tissue:
– transport
– more fibers, less ground substance
– e.g., tendons
• Supportive connective tissues:
– structural strength
8 Cell Types of
Connective Tissue Proper
Connective Tissue Proper
•
•
•
•
Fibroblasts
Macrophages
Adipocytes
Mesenchymal
cells
•
•
•
•
Melanocytes
Mast cells
Lymphocytes
Microphages
Figure 4–8
15
Adipocytes
Fibroblasts
• The most abundant cell type:
– found in all connective tissue proper
– secrete proteins and hyaluronan (cellular
cement)
Macrophages
• Large, amoeba-like cells of the
immune system:
– eat pathogens and damaged cells
– fixed macrophages stay in tissue
– free macrophages migrate
• Fat cells:
– each cell stores a single, large fat
droplet
Mesenchymal Cells
• Stem cells that respond to injury or
infection:
– differentiate into fibroblasts,
macrophages, etc.
16
Melanocytes
• Synthesize and store the brown
pigment melanin
Lymphocytes
• Specialized immune cells in lymphatic
system:
– e.g., plasma cells which produce
antibodies
Mast Cells
• Stimulate inflammation after injury or
infection:
– release histamine and heparin
• Basophils are mast cells carried by
blood
Microphages
• Phagocytic blood cells:
– respond to signals from macrophages and
mast cells
– e.g., neutrophils and eosinophils
17
Fibers in Connective
Tissue Proper
• Collagen fibers:
–
–
–
–
–
most common fibers in CTP
long, straight, and unbranched
strong and flexible
resists force in 1 direction
e.g., tendons and ligaments
Fibers in Connective
Tissue Proper
• Reticular fibers:
–
–
–
–
network of interwoven fibers (stroma)
strong and flexible
resists force in many directions
stabilizes functional cells (parenchyma)
and structures
– e.g., sheaths around organs
Fibers in Connective
Tissue Proper
• Elastic fibers:
–
–
–
–
contain elastin
branched and wavy
return to original length after stretching
e.g., elastic ligaments of vertebrae
Ground Substance
• In connective tissue proper and ground
substance:
– is clear, colorless, and viscous
– fills spaces between cells and slows
pathogens
18
Embryonic Connective Tissues
• Are not found in adults
• Mesenchyme (embryonic stem cells):
– the first connective tissue in embryos
• Mucous connective tissue:
– loose embryonic connective tissue
Areolar Tissue
•
•
•
•
•
Least specialized
Open framework
Viscous ground substance
Elastic fibers
Holds blood vessels and capillary beds:
– e.g., under skin (subcutaneous layer)
Loose Connective Tissues
• The packing materials of the body
• 3 types in adults:
Adipose Tissue
• Contains many adipocytes (fat cells)
– areolar
– adipose
– reticular
Figure 4–10a
19
Types of Adipose Tissue
• White fat:
–
–
–
–
Reticular Tissue
• Provides support
most common
stores fat
absorbs shocks
slows heat loss (insulation)
Figure 4–10b
Types of Adipose Tissue
• Brown fat:
–
–
–
–
more vascularized
adipocytes have many mitochondria
breaks down fat
produces heat
Reticular Tissue
• Complex, 3-dimensional network
• Supportive fibers (stroma):
– support functional cells (parenchyma)
• Reticular organs:
– spleen, liver, lymph nodes, and bone
marrow
20
Dense Connective Tissues
Dense Regular Connective Tissues
• Connective tissues proper, tightly
packed with high numbers of collagen
or elastic fibers:
– dense regular connective tissue
– dense irregular connective tissue
– elastic tissue
• Tightly packed, parallel collagen
fibers:
– tendons attach muscles to bones
– ligaments connect bone to bone and
stabilize organs
– aponeuroses attach in sheets on large, flat
muscles
Dense Regular Connective Tissue
Dense Irregular Connective Tissue
• Attachment and stabilization
• Strength in many directions
Figure 4–11a
Figure 4–11b
21
Dense Irregular Connective Tissues
• Interwoven networks of collagen
fibers:
–
–
–
–
Fluid Connective Tissues
• Fluid connective tissues:
layered in skin
around cartilages (perichondrium)
around bones (periosteum)
form capsules around some organs (e.g.,
liver, kidneys)
Elastic Tissue
– blood and lymph
– watery matrix of dissolved proteins
– carry specific cell types (formed
elements)
Formed Elements of Blood
• Made of elastic fibers:
– e.g., elastic ligaments of spinal vertebrae
Figure 4–11c
Figure 4–12
22
Formed Elements of Blood
• Red blood cells (erythrocytes)
• White blood cells (leukocytes)
• Platelets
Supportive Connective Tissues
• Support soft tissues and body weight:
– cartilage:
• gel-type ground substance
• for shock absorption and protection
– bone:
• calcified (made rigid by calcium salts,
minerals)
• for weight support
Lymph
Cartilage Matrix
• Extracellular fluid:
–
–
–
–
collected from interstitial space
monitored by immune system
transported by lymphatic system
returned to venous system
• Ground substance proteins
• Cells (chondrocytes) surrounded by
lacunae (chambers)
23
Cartilage Structure
• No blood vessels:
Hyaline Cartilage
• Reduces friction in joints
– chondrocytes produce antiangiogenesis
factor
• Perichondrium:
– outer, fibrous layer (for strength)
– inner, cellular layer (for growth and
maintenance)
Figure 4–14a
Types of Cartilage
• Hyaline cartilage:
– translucent matrix
– no prominent fibers
• Elastic cartilage:
– tightly packed elastic fibers
Hyaline Cartilage
• Hyaline cartilage:
– stiff, flexible support
– reduces friction between bones
– found in synovial joints, rib tips, sternum,
and trachea
• Fibrocartilage:
– very dense collagen fibers
24
Elastic Cartilage
Fibrocartilage
• Flexible support
• Resists compression
Figure 4–14b
Figure 4–14c
Elastic Cartilage
• Elastic cartilage:
– supportive but bends easily
– found in external ear and epiglottis
Fibrocartilage
•
•
•
•
Limits movement
Prevents bone-to-bone contact
Pads knee joints
Found between pubic bones and
intervertebral discs
25
Bone
Bone Cells
• Also called osseous tissue:
• Osteocytes:
– strong (calcified: calcium salt deposits)
– resists shattering (flexible collagen fibers)
Structures of Bone
– arranged around central canals within
matrix
– small channels through matrix (canaliculi)
access blood supply
Bone Surface
• Periosteum:
– covers bone surfaces
– fibrous layer
– cellular layer
Figure 4–15
26
4 Types of Membranes
How do epithelial and
connective tissues combine to
form 4 types of membranes?
1. Mucous
2. Serous
3. Cutaneous
4. Synovial
Figure 4–16
Membranes
• Membranes:
– are physical barriers
– that line or cover portions of the body
• Consist of:
– an epithelium
– supported by connective tissues
Mucous Membrane
• Mucous membranes (mucosae):
– line passageways that have external
connections
– also in digestive, respiratory, urinary, and
reproductive tracts
27
Structure of Mucous Membrane
Serous Membranes
• Line cavities not open to the outside
• Are thin but strong
• Have fluid to reduce friction
Figure 4–16a
Mucous Tissues
• Epithelial surfaces must be moist:
– to reduce friction
– to facilitate absorption and excretion
• Lamina propria:
Double Membranes
• Serous membranes:
– have a parietal portion covering the cavity
– and a visceral portion (serosa) covering
the organs
– is areolar tissue
28
Structure of
Cutaneous Membrane
Cavities and Serous Membranes
• Pleural membrane:
– lines pleural cavities
– covers lungs
• Peritoneum:
– lines peritoneal cavity
– covers abdominal organs
• Pericardium:
– lines pericardial cavity
– covers heart
Figure 4–16c
Cutaneous Membrane
• Cutaneous membrane:
– is skin, surface of the body
– thick, waterproof, and dry
Synovial Membranes
•
•
•
•
Line articulating (moving) joint cavities
Produce synovial fluid (lubricant)
Protect the ends of bones
Lack a true epithelium
29
Structure of Synovial Membranes
Framework of the Body
• Connective tissues:
– provide strength and stability
– maintain positions of internal organs
– provides routes for blood vessels,
lymphatic vessels, and nerves
Figure 4–16d
Fasciae
• Also called fascia:
How do connective
tissues form the
framework of the body?
– the body’s framework of connective tissue
– layers and wrappings that support or
surround organs
30
3 Types of Fasciae
3 Types of Fasciae
• Superficial fascia
• Subserous fascia
Figure 4–17
Figure 4–17
3 Types of Fasciae
• Deep fascia
What are the structures
and functions of the three
types of muscle tissue?
Figure 4–17
31
Muscle Tissue
• Is specialized for contraction
• Produces all body movement
3 Types of Muscle Tissue
• Skeletal muscle:
– large body muscles responsible for
movement
• Cardiac muscle:
– found only in the heart
3 Types of Muscle Tissue
• Smooth muscle:
– found in walls of hollow, contracting
organs (blood vessels; urinary bladder;
respiratory, digestive and reproductive
tracts)
Classification of Muscle Cells
• Striated (muscle cells with a banded
appearance):
– or nonstriated (not banded)
• Muscle cells can have a single nucleus:
– or be multinucleate
• Muscle cells can be controlled
voluntarily (consciously):
– or involuntarily (automatically)
32
Skeletal Muscle
Cardiac Muscle Tissue
• Striated, voluntary, and ultinucleated
• Striated, involuntary, and single
nucleus
Figure 4–18a
Skeletal Muscle Cells
• Skeletal muscle cells:
–
–
–
–
are long and thin
are usually called muscle fibers
do not divide
new fibers are produced by stem cells
(satellite cells)
Figure 4–18b
Cardiac Muscle Cells
• Cardiac muscle cells:
– form branching networks connected at
intercalated disks
– are regulated by pacemaker cells
33
Smooth Muscle Tissue
• Nonstriated, involuntary, and single
nucleus
What is the basic structure
and role of neural tissue?
Figure 4–18c
Smooth Muscle Cells
• Smooth muscle cells:
– are small and tapered
– can divide and regenerate
Neural Tissue
• Also called nervous or nerve tissue:
– specialized for conducting electrical
impulses
– rapidly senses internal or external
environment
– process information and controls
responses
34
Central Nervous System
• Neural tissue is concentrated in the
central nervous system:
– brain
– spinal cord
2 Kinds of Neural Cells
1. Neurons:
–
–
nerve cells
perform electrical communication
2. Neuroglia:
–
–
Cell Parts of a Neuron
• Cell body:
– contains the nucleus and nucleolus
• Dendrites:
– short branches extending from the cell
body
– receive incoming signals
Cell Parts of a Neuron
• Axon (nerve fiber):
– long, thin extension of the cell body
– carries outgoing electrical signals to their
destination
support cells
repair and supply nutrients to neurons
35
The Neuron
How do injuries affect
tissues of the body?
Figure 4–19
Neuroglia
Tissue Injuries and Repair
• Tissues respond to injuries to maintain
homeostasis
• Cells restore homeostasis with 2
processes:
– inflammation
– regeneration
Figure 4–19
36
Inflammation
• Inflammation:
– the tissue’s first response to injury
• Signs of inflammatory response
include:
–
–
–
–
swelling
redness
heat
pain
Inflammatory Response
• Can be triggered by:
– trauma (physical injury)
– infection (the presence of harmful
pathogens)
The Process of Inflammation
• Damaged cells release chemical signals
into the surrounding interstitial fluid:
– prostaglandins
– proteins
– potassium ions
The Process of Inflammation
• As cells break down:
–
–
–
–
lysosomes release enzymes
that destroy the injured cell
and attack surrounding tissues
tissue destruction is called necrosis
37
The Process of Inflammation
• Necrotic tissues and cellular debris
(pus) accumulate in the wound:
– abscess:
• pus trapped in an enclosed area
The Process of Inflammation
• Injury stimulates mast cells to release:
– histamine
– heparin
– prostaglandins
The Process of Inflammation
• Dilation of blood vessels:
– increases blood circulation in the area
– causes warmth and redness
– brings more nutrients and oxygen to the
area
– removes wastes
The Process of Inflammation
• Plasma diffuses into the area:
– causing swelling and pain
• Phagocytic white blood cells:
– clean up the area
• Which dilate surrounding blood vessels
38
The Process of Regeneration
Summary: Inflammation
and Regeneration
• Fibroblasts move into necrotic area:
– lay down collagen fibers
– to bind the area together (scar tissue)
Figure 4–20
The Process of Regeneration
• Not all tissues can regenerate:
– epithelia and connective tissues
regenerate well
– cardiac cells and neurons do not
regenerate
Aging and Tissue Structure
• Speed and efficiency of tissue repair
decreases with age, due to:
– slower rate of energy consumption
(metabolism)
– hormonal alterations
– reduced physical activity
39
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
SUMMARY (1 of 14)
• Organization of specialized cells into
tissues:
–
–
–
–
epithelial tissue
connective tissue
muscular tissue
nervous tissue
SUMMARY (2 of 14)
• Division of epithelial tissues into
epithelia and glands:
– epithelia as avascular barriers for
protection
– glands as secretory structures
SUMMARY (3 of 14)
• Specializations of epithelial cells for
sensation or motion:
– microvilli
– cilia
40
SUMMARY (4 of 14)
• 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)
SUMMARY (5 of 14)
• Maintenance of epithelia:
– germinative cells
– stem cells
SUMMARY (6 of 14)
• Classification of epithelial cells:
– by number of cell layers (simple or
stratified)
– by shape of cells (squamous, columnar or
cuboidal)
SUMMARY (7 of 14)
• 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)
41
SUMMARY (8 of 14)
• The functions of connective tissues:
–
–
–
–
–
–
structure
transport
protection
support
connections
energy storage
SUMMARY (10 of 14)
• 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)
SUMMARY (9 of 14)
• The structure of connective tissues:
– matrix
– ground substance
– protein fibers
SUMMARY (11 of 14)
• The 4 types of membranes that cover
and protect organs:
–
–
–
–
mucous membranes (lamina propria)
serous membranes (transudate)
cutaneous membrane (skin)
synovial membrane (encapsulating joints)
42
SUMMARY (12 of 14)
SUMMARY (14 of 14)
• 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
• Tissue injuries and repair systems
(inflammation and regeneration)
• The relationship between aging, tissue
structure, and cancer
SUMMARY (13 of 14)
• 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)
43