Chapter 4
Tissues
Organization of Tissues Types
There are four major tissue types:
1. Epithelium
2. Connective
3. Muscle
4. Nervous
Characteristics of Epithelial
tissue
•High cellularity - lots of densely packed cells with …
•Specialized intercellular contacts - such as tight junctions,
desmosomes and gap junctions.
•Basement membranes & other c.t. support - anchors to connective
tissue.
•Polarity - it has an apical side and a basal side (a free edge and a
fixed edge).
•Avascular - no blood supply. Receive oxygen and nutrients by
diffusion
•Highly mitotic - cells readily regenerate.
Free Surface and Attached Surface
• Polarity:
– apical and basolateral surfaces
Intercellular
Connections
• Support and
communication
Tight
Junctions
• Between
2 cell
membranes
Gap Junctions
• Allow rapid communications
Desmosomes
• CAMs, dense areas, and intercellular cement
Attachment to Basal Lamina
• Hemidesmosomes
Typical
arrangement
of epithelium
Subcategories of epithelial tissue
i.
Simple
1. squamous
2. cuboidal
3. columnar
ii. Stratified
1. squamous
2. cuboidal
3. columnar
iii. Special (doesn’t fall neatly into either of the above)
1. Pseudostratified columnar
2. Transitional
Classes of Epithelia
Simple Squamous Epithelium
Figure 4–3a
Simple Squamous
Top view
Thyroid tissue
Kidney
Stratified Squamous
Epithelium
Stratified
squamous
Keratin layer
of dead cells
Keratinizing
Stratified
Squamous
Simple Cuboidal Epithelium
Figure 4–4a
Simple Cuboidal
Simple squamous cell
Nuclei
Stratified Cuboidal Epithelium
Figure 4–4b
Stratified Cuboidal
Simple Columnar Epithelium
Simple Columnar
Basement membrane
Goblet cells
Stratified Columnar Epithelium
Stratified Columnar
Stratified Columnar
Apical layer
Rare, found in the male urethra and few other places.
Basal layer
Pseudostratified
Columnar Epithelium
Pseudostratified columnar a.
Pseudostratified columnar b.
Cilia
Transitional Epithelium
Transitional
Found only in the
urinary tract
Glandular
Epithelium:
exocrine
glands
Modes of Secretion
• Merocrine secretion – sweat glands
Modes of Secretion
• Apocrine secretion – mammary glands
Modes of Secretion
• Holocrine secretion – sebaceous (oil) glands
Types of Secretions
• Serous glands:
– watery secretions
• Mucous glands:
– secrete mucins
• Mixed exocrine glands:
– both serous and mucous
Unicellular Glands
• Goblet cells are the only unicellular
exocrine glands:
– scattered among epithelia
– e.g., in intestinal lining
Structure of Multicellular Exocrine Glands
• Structural classes of exocrine glands
Figure 4–7 (1 of 2)
Structure of Multicellular
Exocrine Glands
Figure 4–7 (2 of 2)
Characteristics of Connective Tissue
• Common developmental origin - it is all from mesoderm
• Mostly well vascularized (except cartilages, tendons and ligaments)
• Low cellularity - the general arrangement is a variable (often scant)
number of cells in a non-living matrix.
• The matrix:
• fibers of protein (collagen, elastic & reticular)
• ground substance (proteoglycans, cell adhesion molecules &
interstitial fluid
Connective tissue
Subcategories of Connective tissue
i.
ii.
1.
1.
2.
3.
4.
5.
Embryonic
Mesenchyme
Connective tissue proper
Loose
a.
Areolar
b.
Adipose
c.
Reticular
Dense
a.
Irregular (elastic or yellow)
b.
Regular (white fibrous)
Cartilage
a.
Hyaline
b.
Elastic
c.
Fibrocartilage
Bone (osseous)
Blood
Mesenchyme
Loose c.t.: areolar
Reticular Tissue
• Provides support
Figure 4–10b
Loose c.t.: reticular
Adipose Tissue
• Contains many adipocytes (fat cells)
Figure 4–10a
Loose c.t.: adipose
Types of Adipose Tissue
• White fat:
– most common
– stores fat
– absorbs shocks
– slows heat loss (insulation)
Types of Adipose Tissue
• Brown fat:
– more vascularized
– adipocytes have many mitochondria
– breaks down fat
– produces heat
Dense Regular Connective Tissue
• Attachment and stabilization
Dense regular c.t.
Dense regular c.t.: tendon
Dense Irregular Connective
Tissue
• Strength in many directions
Figure 4–11b
Dense irregular c.t.
More dense irregular c.t.
Elastic Tissue
• Made of elastic fibers:
– e.g., elastic ligaments of spinal vertebrae
Cartilage Matrix
• Proteoglycans derived from chondroitin
sulfates
• Ground substance proteins
• Cells (chondrocytes) surrounded by
lacunae (chambers)
Cartilage Growth (1 of 2)
• Interstitial growth
Figure 4–13a
Cartilage Growth (2 of 2)
• Appositional growth
Figure 4–13b
Types of Cartilage
• Hyaline cartilage:
– translucent matrix
– no prominent fibers
• Elastic cartilage:
– tightly packed elastic fibers
• Fibrocartilage:
– very dense collagen fibers
Hyaline Cartilage
• Reduces friction in joints
Figure 4–14a
Hyaline Cartilage
Elastic Cartilage
• Flexible support
Figure 4–14b
Elastic Cartilage
Fibrocartilage
• Resists compression
Bone
• Also called osseous tissue:
– strong (calcified: calcium salt deposits)
– resists shattering (flexible collagen fibers)
Bone: compact
Bone
Fluid Connective Tissues
• Fluid connective tissues:
– blood and lymph
– watery matrix of dissolved proteins
– carry specific cell types (formed elements)
Formed Elements of Blood
Figure 4–12
Blood
4 Types of
Membranes
1.
2.
3.
4.
Mucous
Serous
Cutaneous
Synovial
Figure 4–16
Mucous Membrane
• Mucous membranes (mucosae):
– line passageways that have external
connections
– also in digestive, respiratory, urinary, and
reproductive tracts
Structure of Mucous
Membrane
Figure 4–16a
Serous Membranes
• Line cavities not open to the outside
• Are thin but strong
• Have fluid transudate to reduce friction
Structure of Serous
Membrane
Figure 4–16b
Structure of
Cutaneous Membrane
3 Types of Fasciae
• Superficial fascia
Figure 4–17
3 Types of Fasciae
• Deep fascia
Figure 4–17
3 Types of Fasciae
• Subserous fascia
Figure 4–17
Muscle tissue
• It contracts (shortens with force).
• It is irritable (responsive).
• There are three types
1. Skeletal
2. Smooth
3. Cardiac
Skeletal Muscle
•
•
•
•
•
Most abundant
Striated
Multinucleate with peripheral nuclei
Long, parallel fibers
Voluntary
l.s
c.s.
Skeletal Muscle
Skeletal muscle
Smooth Muscle
•
•
•
•
•
Involuntary
Not striated (hence the name “smooth”)
Uninucleate
Small, spindle-shaped fibers
Found lining the walls of hollow organs
Skeletal Muscle
• Striated, voluntary, and multinucleated
Figure 4–18a
Cardiac Muscle
•
•
•
•
•
•
Striated
Uninucleate (occasionally binucleate)
Short, fat, branched fibers
Intercalated discs
Involuntary
Found in the heart
Cardiac Muscle Tissue
• Striated, involuntary, and single nucleus
Figure 4–18b
Cardiac
muscle
Smooth Muscle Tissue
• Nonstriated, involuntary, and single
nucleus
Figure 4–18c
Smooth muscle
Neural Tissue
• Also called nervous or nerve tissue:
– specialized for conducting electrical
impulses
– rapidly senses internal or external
environment
– process information and controls
responses
2 Kinds of Neural Cells
1. Neurons:
– nerve cells
– perform electrical communication
2. Neuroglia:
– support cells
– repair and supply nutrients to neurons
Neuroglia
Figure 4–19
The Neuron
Figure 4–19
Nervous tissue
Nervous tissue
Neurons
That’s it!