Transcript Chapter 4: The Tissue Level of Organization

Chapter 4:
The Tissue Level of
Organization
Introduction
• Tissue:
– Collection of specialized cells that perform
limited number of functions
• Histology:
– The study of tissues
What are the four tissues of the body?
The four tissues of the Body
• Epithelial Tissue: “covering”
– Covers exposed surfaces
– Lines internal passageways
– Forms glands
• Connective Tissue: “support”
– Fills internal spaces
– Provides structure and strength to support
other tissues
– Transports materials
– Stores energy
The four tissues of the Body
• Muscle Tissue: “movement”
– Specialized for contraction
– Skeletal muscle, heart muscle, and walls of
hollow organs
• Neural Tissue: “control”
– Carries electrical signals from 1 part of the
body to another
Primary Germ Layer
• Embryonic layers give rise to all four tissue
types in adults
– Ectoderm: nervous, epithelial (epidermis)
– Mesoderm: muscle, connective, epithelial
(endothelium + mesothelium)
– Endoderm: epithelial (mucosa)
KEY CONCEPT
• Tissues are collections of cells and cell
products that perform specific, limited
functions
• 4 tissue types form all the structures of
the human body:
– epithelial, connective, muscle, and neural
Epithelial Tissues
• 2 categories:
– Epithelia:
• layers of cells covering internal or external
surfaces
– Glands:
• structures that produce fluid secretions
Special structures and
functions of
Epithelial Tissues.
Characteristics of Epithelia
Structures of Epithelia:
• Cellularity:
•
little extracellular matrix, mostly cells
Contacts:
•
•
cells linked by tight junctions
Polarity:
•
•
apical + basal surfaces, separate functions
Attachment:
•
•
attached to connective tissue (CT) via basal lamina
Avascularity:
•
•
diffusion of CT
Regeneration:
•
•
high turnover, stem cells at basal surface
Characteristics of Epithelia
Functions of Epithelia:
• Provide physical protection:
• abrasion, dehydration, infection
• Control permeability:
• semi-permeability, covers all surfaces
• Provide sensation:
• sensory neurons
• Produce specialized secretions (glandular
epithelium):
• protection, chemical messengers
Free Surface and Attached Surface
1. Apical Surface:
exposed to
environment, may have:
• Microvilli: absorption or secretion
• Cilla: fluid movement
2. Basolateral Surface: attachment
to neighboring cells via intercellular
connections
Figure 4–1
Intercellular Connections
• Support and communication
• 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 hyaluronan (proteoglycan):
– Attach adjacent membranes
• Specific Adhesion=Cell Junctions
1. Tight Junctions
2. Gap Junctions
3. Desmosomes
Cell Junctions
• Form bonds with other cells or
extracellular material:
–
Tight Junctions:
• interlocking proteins, bind lipid portion of
membrane, water tight seal
–
Gap Junctions:
• connexons form channel, allow molecules to pass
for communication
–
Desmosomes:
• CAMs + intercellular cement on dense area
attached to cytoskeleton, resist stretching and
twisting
Tight Junctions
• Between 2 cell
membranes
• interlocking proteins,
bind lipid portion of
membrane, water tight
seal
• Prevents passage of
water and solutes
Figure 4–2b
Gap Junctions
Connexons form protein
channels, allow
molecules to pass for
communication
– Rapid communication
• Allow ions to pass
• Coordinated
contractions in heart
muscle
Figure 4–2c
Desmosomes
Cell Adhesion Molecules +
intercellular cement on dense area
are attached to the cytoskeleton
- resist stretching and twisting
1.
2.
3.
Belt Desmosomes:
-continuous band in apical region, attached to
microfilaments
Button Desmosomes:
- “spot weld”, attached to intermediate filaments
Hemidesmosomes:
- Half button desmosome at basal
surface, attaches to basal lamina
Figure 4–2d
Basal Lamina
(a.k.a. basement membrane)
• Lamina lucida:
– Produced by epithelia
– Glycoproteins + fine filaments restrict large molecule
movement
• Lamina densa:
– Produced by connective tissue
– Coarse protein fibers
– Provides strength and filtration
Repairing and Replacing Epithelia
• Epithelia stem cells are anchored to
lamina lucida
• Epithelia are replaced by division of
germinative cells (stem cells)
– Stem cells divide and migrate toward apical
region
Classes of Epithelia
•
•
Based on shape and layers
Shape: (all are hexagonal from the top)
1. Squamous: flat, disc shaped nucleus
2. Cuboidal: cube or square, center round nucleus
3. Columnar: tall, basal oval nucleus
Table 4–1
Layers
• Simple epithelium:
– single layer of cells
– Function:
• absorption, secretion, filtration
• Stratified epithelium:
– 2 or more layers of cells
– Function:
• Protection
**In stratified, name for apical cell shape**
Eight Types of Epithelial Tissues
1.
2.
3.
4.
5.
6.
7.
8.
Simple squamous epithelium
Stratified squamous epithelium
Simple cuboidal epithelium
Stratified cuboidal epithelium
Transitional epithelium
Simple columnar epithelium
Pseudostratified columnar epithelium
Stratified columnar epithelium
1. Simple Squamous Epithelium
• Thin, delicate
• Locations: found in protected regions
– Mesothelium (serosa), endothelium (blood vessels,
heart), kidney tubules, cornea, and alveoli of lungs
• Functions:
– Absorption, diffusion, filtration, or secretion
Figure 4–3a
2. Stratified Squamous Epithelium
•
•
•
•
Basal cells look cuboidal, apical cells squamous
Found on exposed surfaces
Functions: provide protection from abrasion, pathogens, and chemicals
Two types:
A. Nonkeratinized = mucosa
- Kept moist
- All cells are nucleated
Location: mouth, esophagus, anus, and vagina
B. Keratinized = epidermis
- dry, apical cells dead
- cells contain keratin protein to resist dehydration and adds strength
Figure 4–3b
3. Simple Cuboidal Epithelia
• Location:
–
–
–
–
Kidney tubules
Pancreas
Salivary glands
Thyroid
* Functions:
- Secretion
-Absorption
4. Stratified Cuboidal Epithelium
• Rare
• Typically 2 layers
• Location:
– Some sweat glands
– Some mammary glands
* Function:
- Secretion
- Absorption
Figure 4–4b
5. Transitional Epithelium
• Relaxed: looks like stratified cuboidal
• Stretched: looks squamous
• Location:
* Function
– Urinary bladder
– Ureters
- tolerate excessive stretching
Figure 4–4c
Columnar Epithelia
• Simple columnar epithelium:
– absorption and secretion
• Pseudostratified columnar epithelium:
– cilia movement
• Stratified columnar epithelium:
– protection
6. Simple Columnar Epithelium
• Nuclei line up near the basal lamina
• Apical surface of cells often has microvilli = “brush
border” (in intestine)
• Goblet cells often present: secrete mucus
• Locations:
– Stomach, intestine, gall bladder, uterine tubes, and collecting
ducts of kidney
• Functions:
– Absorption or secretion
Figure 4–5a
7. Pseudostratified Columnar Epithelium
•
•
•
•
•
•
•
Several cell types: varying shapes and functions
All cells contact basal lamina
Some too short to reach apical surface
Nuclei scattered so it appears stratified
Tall cells have cilia on apical surface
Goblet cells (mucus) often present
Location:
Function:
– Nasal cavity, trachea, bronchi
- move material
– Male reproductive tract
across surface
– Female uterine tubes
Figure 4–5b
8. Stratified Columnar Epithelium
• Rare
• Two layers or multiple 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
Glandular Epithelia
For secretion, makes up glands
1.
Endocrine glands: “internally secreting”
-secrete into interstital fluid  blood
-secretions = hormones
-regulate and coordinate activities
e.g. pancreas, thyroid, thymus, pituitary
2.
Exocrine glands: “externally secreting”
-secrete into duct  epithelial surface
-e.g. digestive enzymes, perspiration, tears, milk, and
mucus
-Classified three ways:
1. Mode of Secretion
2. Type of Secretion
3. Structure
A. Modes of Secretion
1. Merocrine secretion:
-product released from
secretory vesicles by
exocytosis
-e.g. mucus, sweat
2. Apocrine Secretion:
- product accumulates
in vesicles
- apical region of cell
which vesicles is shed
to release product
-e.g. milk
Figure 4–6a
Modes of Secretion
3. Holocrine secretion
- product accumulates in vesicles
- whole cell is lysed to release product
- cell dies, must be replaced by stem cells
e.g. sebum
Figure 4–6c
B. Types of Secretion
1. Serous Glands: water + enzymes
- e.g. parotid salivary gland
2. Mucus Glands: mucin
(+water = mucus)
- e.g. goblet cell
3. Mixed exocrine glands:
(serous + mucus secretion)
-e.g. submandibular salivary gland
C. Gland Structure
• Exocrine glands can be classified as:
– unicellular glands: 1 cell
• E.g. goblet cell which are scattered among
epithelia
– Found in intestinal lining
– multicellular glands: group of cells named
for shape and structure
Structure of Multicellular
Exocrine Glands
• Structural classes of exocrine glands
Simple Glands = undivided
tube shape
blind pockets chamberlike
Figure 4–7 (1 of 2)
Structure of Multicellular
Exocrine Glands
Compound Glands = Divided
tube shaped
blind pockets
chamberlike
Figure 4–7 (2 of 2)
Which of the following is NOT a
characteristic of epithelial tissue?
A.
B.
C.
D.
It
It
It
It
is composed entirely of cells.
stores energy reserves.
is avascular.
is capable of regeneration.
An epithelial surface bears many
microvilli. What is the probable
function of this epithelium?
A.
B.
C.
D.
absorption
secretion
transportation
sensation
What is the functional significance
of gap junctions?
A. They maintain water-tight
passages.
B. They resist stretching and
twisting.
C. They coordinate the function of
tissue.
D. They attach cells to extracellular
matrix.
Using a light microscope, you examine a
tissue and see a simple squamous epithelium
on the outer surface.
Can this be a sample of the skin surface?
A. Yes
B. No
Why do the pharynx, esophagus,
anus, and vagina have the same
epithelial organization?
A. All are subject to mechanical
trauma.
B. All are subject to abrasion.
C. All must be able to expand.
D. A and B are correct.
The secretory cells of sebaceous glands fill
with secretions and then rupture, releasing
their contents.
Which type of secretion is this?
A.
B.
C.
D.
acinar
apocrine
merocrine
holocrine
A gland has no ducts to carry the glandular
secretions, and the gland’s secretions are
released directly into the extracellular fluid.
Which type of gland is this?
A.
B.
C.
D.
exocrine gland
endocrine gland
acinar gland
tubular gland
Structures
and functions of different
types of
Connective Tissues.
•
Connective Tissues
Features:
– Never exposed to the environment
– Usually vascularized
– Consists of cells in a matrix
• Components:
1. Specialized cells:
- Produce matrix, provide protection
2. Extracellular protein fibers:
- Support, strength
3. Ground Substance:
- gel fluid, consists of:
* interstitial fluid, cell adhesion molecules, and
GAGs (glycosaminoglycans)
- proteoglycans that form a gel
Fibers + Ground Substance = Matrix
The Matrix
• The extracellular components of
connective tissues (fibers and ground
substance):
– majority of cell volume
– determines specialized function
Functions of Connective Tissue
1.
2.
3.
4.
5.
6.
7.
Establish structural framework
Transport fluid and dissolved materials
Protect organs
Support, surround, interconnect tissues
Store energy reserves
Insulate body
Defend against pathogens
Classification of
Connective Tissues
•
Connective tissue proper:
–
Many cell types and fiber types in thick ground
substance
a. Loose: open fiber framework
b. Dense: tightly packed fibers
•
Fluid connective tissues:
–
•
May cell types in watery matrix with soluble
fibers
Supportive connective tissues:
–
Limited cell population in tightly packed matrix
Connective Tissues
Derived from Mesenchyme
Embryonic CT:
- mesenchymal cells in gelatinous matrix with fine fibers
1. Connective Tissue Proper
• Viscous ground substance
• Varied extracellular fibers
• Varied cell population
Ground substance: rich in GAG
-viscous, prevents microbe
penetration
Fiber types:
1. Collagen fibers: collagen protein
2. Reticular fibers: collagen protein
3. Elastic fibers: elastin protein
Figure 4–8
1. Connective Tissue Proper
Fiber types:
1. Collagen fibers: collagen protein
-rope like, long, straight
-resists force
-most common
2. Reticular fibers: collagen protein
-branchy, forms framework
-framework of an organ = stroma
(functional cells of an organ = parenchyma)
3. Elastic fibers: elastin protein
-wavy, flexible
- Designed to stretch
8 Cell Types of
Connective Tissue Proper
•
•
•
•
Fibroblasts
Macrophages
Adipocytes
Mesenchymal cells
• Mast cells
• Lymphocytes
• Microphages
Cell Types of CT Proper
1.
2.
3.
4.
Fibroblasts:
- most common, most abundent
- secretes ground substance:
hyaluronan + protein = GAGs
- secrete fiber proteins (collagen, elastin)
- some specialized types: chondrocytes (cartilage)
osteocytes (bone)
Mesenchymal Cells:
- stem cells
- differentiate to replace CT cells after
Injury (e.g. fibroblasts, adipocytes)
Adipocytes (fat cells):
- store triglycerides
- organelles pushed to periphery
-number, size and location of cells varies
Macrophages:
- phagocytic for defense
- (eat pathogens and damaged cells)
- some fixed in tissues
- others migrate from blood to tissues after injury
Cell Types of CT Proper
5.
Microphages:
- neutrophils and eosinophils
- phagocytic
- migrate from:
blood to site of injury
6.
Lymphocytes: B and T cells
- involved in immune response
- make antibodies
- attack foreign cells
- increased number during infection
- constantly migrate between:
- blood and tissues and lymph
7.
Mast cells:
- contain histamine and heparin
- stimulate inflammation in response
to injury
Categories of
Connective Tissue Proper
• Loose connective tissue:
– more ground substance, less fibers
– e.g., fat (adipose tissue)
• Dense connective tissue:
– more fibers, less ground substance
– e.g., tendons
A. Loose Connective Tissue
• Highly vascularized
• Varied cell types
• Functions:
–
–
–
–
Fill space
Cushion & support tissues
Store fat
Feed epithelial layers
• Three types:
1. Areolar CT
2. Adipose Tissue
3. Reticular Tissue
A. Loose Connective Tissue:
Areolar CT
1. Areolar CT
– Most common
– Least specialized
– Open framework:
• Matrix mostly ground substance
– All fiber types
– Location: deep to epithelium
– Functions:
• Reservoir for water and salts
• Absorbs shock and distortion
• Fills space
• Feeds epithelium
A. Loose Connective Tissue:
Adipose Tissue
2. Adipose Tissue
-90% adipocytes
- Locations:
- deep to skin, surrounding eyeballs, kidneys, heart
- Functions:
- padding, insulation, and energy storage
-Two types:
- White fat: adults, triglyceride storage, insulation
- Brown fat: infants, high mitochondria content for heat
generation
A. Loose Connective Tissue:
Adipose Tissue
3.
Reticular Tissue
-stroma (supportive fibers) of organs
-consists of reticular fibers
Locations: some organ
e.g. lymph nodes, bone marrow, liver
Function: support parenchyma (functional) cells
B. Dense Connective Tissue
•
•
•
•
Poorly vascularized
Mostly fibers, little ground substance
Only fibroblasts
Three types:
1. Dense Regular CT
2. Dense Irregular CT
3. Elastic CT
B. Dense Connective Tissue
Dense Regular CT
1.
Dense Regular CT
-bundles of parallel collagen fiber, aligned with direction
of force
-Location:
- tendons (muscle to bone)
- ligaments (bone to bone)
- muscle coverings and fascia
-Function:
- high strength attachment
- stabilize positions
B. Dense Connective Tissue
Dense Irregular CT
2. Dense Irregular CT
- mesh of collagen fibers
- Location:
-capsules of organs
-perioteum (sheath around bone)
-perichondrium (around cartilage
-dermis (deep skin)
-Function:
-resist tension from
many directions
-attachment
*Strength in Many Directions
B. Dense Connective Tissue
Elastic CT
1. Elastic CT:
-mostly elastic fibers, some collagen
-Location:
-vertebral ligaments and artery walls
-Function: Strength with stretch and flex
Figure 4–11c
Fluid Tissue Transport Systems
• Cardiovascular system (blood):
– arteries
– capillaries
– veins
• Lymphatic system (lymph):
– lymphatic vessels
Fluid Connective Tissues
• Fluid connective tissues:
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
Plasma  Interstitial Fluid  Lymph  Plasma
Formed Elements of Blood
• Erythrocytes (RBCs): carry oxygen
• Leukocytes (WBCs): defense
– Neutrophils, Eosinophils, Basophils, Lymphocytes
(B and T cells), Monocytes (Macrophages)
• Platelets: carry clotting factors
Figure 4–12
Fluid Connective Tissues
B. Lymph:
-Matrix: lymph (recollected plasma fluid)
-Cells: lymphocytes (immune defense)
-Location:
-contained in lymphatic vessels
-Function:
-purify and return fluid to blood
Lack of vitamin C in the diet interferes
with the ability of fibroblasts to produce
collagen. What effect might this
interference have on connective tissue?
A. Tissue is unable to phagocytose.
B. Tissue is unable to produce
melanin.
C. Tissue is weak and prone to
damage.
D. Tissue is unable to produce
heparine.
Many allergy sufferers take antihistamines
to relieve their allergy symptoms. Which
type of cell produces the molecule that this
medication blocks?
A.
B.
C.
D.
eosinophils
mast cells
basophils
B and C
Which type of connective tissue
contains primarily triglycerides?
A.
B.
C.
D.
areolar
adipose
reticular
mesenchyme
Supportive Connective Tissues
•
•
•
•
Strong framework, few cells, fibrous matrix
Function: support and shape
Mature cells in lacunae
Two types:
1. Cartilage:
• gel-type ground substance
• for shock absorption and protection
2. Bone:
• calcified (made rigid by calcium salts, minerals)
• for weight support
1. Cartilage
• Composition:
– Matrix: 80% water, firm gel of glycoaminoglycans made
of chondroitin sulfate and hyaluronic acid, + fibers
– Cells: chondrocytes in lacunae (chambers)
• Cells formed the matrix
• Structure:
– No innervation
– Avascular (no blood vessels)
• chondrocytes produce antiangiogenesis factor
– Surrounded by Perichondrium:
• Outer layer = dense irregular CT
– Function: protection, attachment
• Inner layer = cellular (fibroblasts)
– Function: growth and repair
Growth of Cartilage:
Not common in adults
1. Interstitial Growth (embryos)
-
Chondroblasts in matrix divide
Daughters produce more matrix
-
Mature cells = chondrocytes
Figure 4–13a
Cartilage Growth
2. 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
Types of Cartilage
1. Hyaline cartilage
2. Elastic cartilage
3. Fibrocartilage
Types of Cartilage
1. Hyaline cartilage:
– translucent matrix
• Contains fine, closely packed collagen fibers
– Tough, springy
– Location:
• Ribs, nose, respiratory tract, articular surfaces
– no perichondrium
– Function:
• Provide stiff flexible support
• Reduce friction between bones
Types of Cartilage
2. Elastic cartilage:
– Matrix contains tightly packed elastic fibers
– Flexible support
– Location:
• Auricle (external) of ear, epiglottis
– Function:
• Resilient, flexible, shape holding support
Types of Cartilage
3. Fibrocartilage:
-
Matrix contains dense interwoven collagen fibers with
little ground substance
tough, durable
Location:
Function:
-
Knee (meniscus)
Pubic symphasis
Intervertebral discs
- Resist Compression
- Absorb Shock: Pads knee joints
- Prevents bone-to-bone contact
Figure 4–14c
2. Bone/Osseous Tissue
• Highly vascularized
• Little ground substance
• Matrix:
– 2/3 calcified: calcium salts deposits for strength
• Calcium phosphate + calcium carbonate
– 1/3 collagen for flexibility to resist shatter
• Cells: Osteocytes
– Cells formed the matrix
– Located in lacunae arranged around central canals
within matrix
– Connected by cytoplasmic extensions that extend
through canaliculi
• Canaliculi: excess blood supply
– Canaliculi necessary for nutrient and waste exchange,
no diffusion through calcium
Bone/Osseous Tissue
• Surrounded by Periosteum: covers bone
surfaces
– Outer: fibrous layer for attachment
– Inner: cellular layer for growth and repair
• Location: Bones
• Function:
– Support & Protection
– Levers for movement
– Storage of minerals
Structures of Bone
Canaliculi
Osteocytes
in lacunae
PERIOSTEUM
Fibrous
layer
Blood
vessels
Central canal
Cellular
layer
Matrix
LM X 362
• Osteocytes
– Connected by cytoplasmic extensions that extend
through canaliculi (small channels through matrix)
– Canaliculi necessary for nutrient and waste exchange
Figure 4–15
Comparing Cartilage
and Bone
Table 4–2
Why does cartilage heal so slowly?
A. It lacks a direct blood supply,
necessary for proper healing.
B. Chondroitin sulfate prevents healing.
C. Matrix inhibits cellular regeneration.
D. Interstitial fluid, necessary for proper
healing, is excluded.
If a person has a herniated
intervertebral disc, which type of
cartilage has been damaged?
A.
B.
C.
D.
elastic cartilage
fibrocartilage
hyaline cartilage
areolar cartilage
Which two types of connective tissue
have a fluid matrix?
A.
B.
C.
D.
lymph and cartilage
cartilage and bone
blood and bone
blood and lymph
Connective
tissues form the
framework of the body.
Special Connective Tissue Structures
1. Fascia:
– Connective tissues that provides a
framework to connect organs to the body
– Function:
• provide strength and stability
• maintain positions of internal organs
• provides routes for blood vessels, lymphatic
vessels, and nerves
1. Fascia
• Body’s framework of connective tissue
• Layers and wrappings that support or surround organs
Provides insulation
and padding
Resists force and
anchors position
Prevents distortion
by muscles
Epithelial and
connective tissues combine to
form 4 types of membranes.
2. Membranes
• Membranes:
– are physical barriers
– that line or cover portions of the body
• Consist of:
– an epithelium
– supported by connective tissues
4 Types of Membranes
1. Mucous
2. Serous
3. Cutaneous
4. Synovial
Figure 4–16
1. Mucous Membrane
1. Mucous membranes (mucosae):
–
–
–
–
Epithelium + areolar connective tissue called lamina propria
Line passageways that connect to external environment
Epithelium kept moist with mucus secretions
Location:
• digestive, respiratory, urinary, and reproductive tracts
2. Serous Membranes
2. Serous Membranes/Serosa
- mesothelium + areolar connective tissue
- lines body cavities to reduce friction
- pleura, peritoneum, pericardium
- Double Membrane:
- Parietal layer lines cavity
- Visceral layer around organ
- Epithelium kept moist by serous fluid (transudate)
Figure 4–16b
Cavities and Serous Membranes
• Pleural membrane:
– lines pleural cavities
– covers lungs
• Peritoneum:
– lines peritoneal cavity
– covers abdominal organs
• Pericardium:
– lines pericardial cavity
– covers heart
3. Cutaneous Membrane
3. Cutaneous membrane:
– Epidermis + dermis = “skin”
– Keratinized stratified squamous epithelium
+ areolar and dense irregular connective
tissue only dry membrane
• Thick and waterproof
Figure 4–16c
4. Synovial Membranes
• Areolar connective tissue with woven
collagen, proteogycans and glycoproteins in
matrix
• Lines joint capsules
• Produce synovial fluid (lubricant)
– Reduces friction of articular (hyaline cartilage)
• Protect the ends of bones
• Lack a true epithelium
• Only membrane with no epithelium
Structure of Synovial Membranes
Figure 4–16d
Which cavities in the body are lined
by serous membranes?
A. cranial and abdomenal
B. pleural, peritoneal, and
pericardial
C. synovial and fascial
D. nasal, urinary and
reproductive
The lining of the nasal cavity is normally
moist, contains numerous goblet cells, and
rests on a layer of connective tissue called
the lamina propria.
Which type of membrane is this?
A.
B.
C.
D.
mucous
serous
cutaneous
synovial
A sheet of tissue has many layers of collagen
fibers than run in different directions in
successive layers.
Which type of tissue is this?
A.
B.
C.
D.
fascia
cutaneous
parietal
synovial
Muscle Tissue
• Function: Provide Movement
– Is specialized for contraction
• Features:
– Highly vascularized
– Contains actin and myosin for contraction
Structures
and functions of the three
types of muscle tissue.
Three Muscle Types
1. Skeletal Muscle
2. Cardiac Muscle
3. Smooth Muscle
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)
3 Types of Muscle Tissue
1. Skeletal muscle: Striated, voluntary, and
multinucleated
– Cells = fibers
•
•
•
•
Up to 1 ft long
Multinuclear
No cell division
Appear striated: actin and myosin organized into myofibrils
– Some satellite cells (stem cells) present for minor repair
after injury
– Location: skeletal muscles (‘meat’)
– Function:
• Move skeleton
• Guard entrances/exit
• Generate heat
3 Types of Muscle Tissue
2. Cardiac Muscle cells:
- Striated Involuntary, usually single nucleus
– Cells = cardiocytes
• Long, branched
• Usually single nucleus but up to 5
• No cell division
• Striated
• Neighboring cells connected by intercalated disc:
– Desmosomes + intercellular cement + gap junctions
*Desmosomes & cement:
- provide tight linkage of neighboring cells
*Gap junctions:
- allow exchange of ions to coordinate
contraction
Cardiac Muscle Tissue
• Striated, involuntary, and single nucleus
• Location: majority of heart
• Function: move blood through body
Figure 4–18b
3 Types of Muscle Tissue
3. Smooth Muscle Tissue:
- Nonstriated, involuntary, and single nucleus
- Cells, small, spindle shaped
- uninuclear
- capable of cell division
- no striations: no myofibril organization
- Locations:
- walls of blood vessels
- walls of hollow organs:
- digestive,respiratory,urinary,reproductive tracts
- Function: move materials through the organ
Figure 4–18c
Basic structure and role of
neural tissue.
Nervous/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
• Cells:
– Neuroglia Cells:
• Support, repair, and supply nutrients to nervous tissue
– Neurons:
•
•
•
•
•
•
•
Transmit information
Up to 3 ft long
Large soma (cell body)
Large nucleus, visible nucleoli
Many dendrites: receive info
One axon: transmits info
No Cell division
Cell Parts of a Neuron
• Cell body:
– contains the nucleus and nucleolus
• Dendrites:
– short branches extending from the cell body
– receive incoming signals
• Axon (nerve fiber):
– long, thin extension of the cell body
– carries outgoing electrical signals to their destination
Injuries affect on
tissues of the body.
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 or infection
– Characterized by: swelling, redness, warmth and
pain
– Process to remove necrotic cells and infectious
agents
The Process of Inflammation
Damaged Cells:
Release prostaglandins
Undergo necrosis
Trigger inflammation
Endothelial Cells:
Vessels leak and plasma
enters wounds delivering
leukocytes and
clotting proteins
Fibroblasts migrate to the wound and are stimulated to secrete collagen
- form a fiber scar to reinforce the clot and begin repair
Damaged tissue is Repaired or Replaced
Repair or Replacement
• Damaged tissue is repaired or replaced
depending on the injury and type of tissue
– Regeneration:
• replacement of collagen with original tissue type
• repair will not be visible
– Fibrosis:
• Visible scar of collagen
• Tissue is completely replaced by a dense collagen patch
• Tissue type function is lost at the site of the scar
Summary:
Inflammation and Regeneration
Figure 4–20
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
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
Aging and Cancer
• Cancer rates increase with age:
– 1 in 4 people in the U.S. develop cancer
– cancer is the #2 cause of death in the U.S.
– environmental chemicals and cigarette
smoke can cause cancer
Injury and Cancer
• Repeat or chronic
– Inflammation causes damage
• Dysplasia: change in normal shape, size,
organization of tissue cells (reversible)
• Metaplasia: more serious changes,
abnormal division of stem cells
(reversible)
• Anaplasia: breakdown of tissue
organization, genetic abnormalities of
stem cells (irreversible)
• Cancer = uncontrolled growth
Which type of muscle tissue has
small, tapering cells with single
nuclei and no obvious striations?
A.
B.
C.
D.
skeletal
cardiac
smooth
all of the above
A tissue contains irregularly shaped cells
with many fibrous projections, some
several centimeters long. These are
probably which type of cell?
A.
B.
C.
D.
neuroglia
neurons
myocytes
adipocytes
If skeletal muscle cells in adults are
incapable of dividing, how is new
skeletal muscle formed?
A. through the enlarging and splitting
of existing cells
B. through the atrophy of existing
cells
C. through the addition of new
striations
D. through the division and fusion of
satellite cells
If skeletal muscle cells in adults are
incapable of dividing, how is new
skeletal muscle formed?
A. through the enlarging and splitting
of existing cells
B. through the atrophy of existing
cells
C. through the addition of new
striations
D. through the division and fusion of
satellite cells
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
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)
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:
– Matrix, ground substance, and protein fibers
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)
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