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Tissues
Todays Topics
• Four Major Tissue Types• Epithelial Tissue• Connective Tissue• Muscle• Nervous Tissue• Tissue Response to Injury
Tissue Types
What are tissues?
• Tissues
• 4 tissue types form all the structures of the human body: – epithelial, connective, muscle, and neural
Epithelial Tissue
• Covers exposed surfaces
• Lines internal passageways
• Forms glands
Connective Tissue
• Fills internal spaces
• Supports other tissues
• Transports materials
• Stores energy
Muscle Tissue
• Specialized for contraction
• Skeletal muscle, heart muscle, and walls of hollow organs
Neural Tissue
• Carries electrical signals from one part of the body to another
• Support Cells
Epithelial Tissue
Epithelial Tissues
• Epithelia:
• Glands:
What are the special structures and functions
of epithelial tissues?
Characteristics of Epithelia
1. Cellularity
2. Polarity
3. Attachment
4. Avascularity
5. Regeneration
Functions of Epithelial Tissue
1. Provide physical protection
2. Control permeability
3. Provide sensation
4. Produce specialized secretions
Specializations of Epithelial Cells
1. Move fluids over the epithelium
2. Move fluids through the epithelium
3. Produce secretions
Figure 4–1
Free Surface and Attached Surface
• Polarity: – apical and basolateral surfaces
Increasing Surface Area
• Microvilli increase absorption or secretion
• Cilia move fluids
Effective Barriers
• Physical integrity is maintained by:– intercellular connections
– attachment to basal lamina
– maintenance and repair
Figure 4–2a
Intercellular Connections
• Support and communication
Large Connections
• CAMs (cell adhesion molecules):
• Intercellular cement:
Cell Junctions
• Form bonds with other cells or extracellular material:
Tight Junctions
• Between 2 cell membranes
Figure 4–2b
Tight Junctions
• Adhesion belt attaches to terminal web
• Prevents
• Isolates
Gap Junctions
• Allow rapid communications
Figure 4–2c
Gap Junctions
• Held together by channel proteins
• Allow ions to pass
Desmosomes
• CAMs, dense areas, and intercellular cement
Figure 4–2d
Desmososmes
• Ties cells together
• Allow bending and twisting
Basal Lamina
• Lamina lucida:
• Lamina densa:
Repairing and Replacing Epithelia
• Epithelia are replaced by division of germinative cells (stem cells)
• Near basal lamina
Classes of Epithelia
• Based on shape and layers
Table 4–1
Squamous Epithelia
• Simple squamous epithelium:
• Mesothelium:
• Endothelium:
Simple Squamous Epithelium
Stratified Squamous Epithelium
• Protects against attacks
Stratified Squamous Epithelium
Cuboidal Epithelia
• Simple cuboidal epithelium:
• Stratified cuboidal epithelia:
Simple Cuboidal Epithelium
Stratified Cuboidal Epithelium
Transitional Epithelium
• Urinary bladder
Columnar Epithelia
• Simple columnar epithelium:
• Pseudostratified columnar epithelium:
• Stratified columnar epithelium:
Simple Columnar Epithelium
• Intestinal lining
Pseudostratified Columnar Epithelium
• Trachea
Stratified Columnar Epithelium
• Salivary gland duct
Glandular Epithelia
• Endocrine and exocrine glands
Figure 4–6
Endocrine Glands
• Release hormones:– into interstitial fluid– no ducts
Exocrine Glands
• Produce secretions:– onto epithelial surfaces– through ducts
Modes of Secretion
• Merocrine secretion
Figure 4–6a
Modes of Secretion
• Apocrine secretion
Figure 4–6b
Modes of Secretion
• Holocrine secretion
Figure 4–6c
Types of Secretions
• Serous glands:
• Mucous glands:
• Mixed exocrine glands:
Gland Structure
• Exocrine glands can be classified as:– unicellular glands– multicellular glands
Unicellular Glands
• Goblet cells are the only unicellular exocrine glands:
3 Characteristics of MEGs
• Structure of the duct:
• Shape of the secretory portion of the duct
• Relationship between ducts and glandular areas
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)
Connective Tissue
What are the structures and functions of different types of
connective tissues?
Connective Tissues
• Connect epithelium to the rest of the body
• Provide structure
• Store energy
• Transport materials
Characteristics of Connective Tissues
• Specialized cells
• Solid extracellular protein fibers
• Fluid extracellular ground substance
The Matrix
• The extracellular components of connective tissues (fibers and ground substance):
Classification of Connective Tissues
• Connective tissue proper:
• Fluid connective tissues:
• Supportive connective tissues:
Categories of Connective Tissue Proper
• Loose connective tissue:
• Dense connective tissue:
8 Cell Types of Connective Tissue Proper
• Fibroblasts
• Macrophages
• Adipocytes
• Mesenchymal cells
• Melanocytes
• Mast cells
• Lymphocytes
• Microphages
Connective Tissue Proper
Figure 4–8
Fibroblasts
• The most abundant cell type:– found in all connective tissue proper
Macrophages
• Large, amoeba-like cells of the immune system:
Adipocytes
• 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.
Melanocytes
Mast Cells
• Stimulate inflammation after injury or infection:
• Basophils are mast cells carried by blood
Lymphocytes
• Specialized immune cells in lymphatic system:– e.g., plasma cells
which produce antibodies
Microphages
• Phagocytic blood cells:– respond to signals
from macrophages and mast cells
Fibers in Connective Tissue Proper
• Collagen fibers:
Fibers in Connective Tissue Proper
• Reticular fibers:
Fibers in Connective Tissue Proper
• Elastic fibers:
Ground Substance
• In connective tissue proper and ground substance: – is clear, colorless, and viscous
Embryonic Connective Tissues
• Are not found in adults
• Mesenchyme (embryonic stem cells):
• Mucous connective tissue:
Loose Connective Tissues
• The packing materials of the body • 3 types in adults:– areolar– adipose– reticular
Areolar Tissue
• Least specialized
• Open framework
• Viscous ground substance
• Elastic fibers
Adipose Tissue
• Contains many adipocytes (fat cells)
Figure 4–10a
Types of Adipose Tissue
• White fat:– most common – stores lipid
Types of Adipose Tissue
• Brown fat: – more vascularized – adipocytes have many
mitochondria
Adipose Cells
• Adipocytes in adults do not divide:
• Mesenchymal cells divide and differentiate:
Reticular Tissue
• Provides support
Figure 4–10b
Reticular Tissue
• Complex, 3-dimensional network
• Supportive fibers (stroma):
• Reticular organs:
Dense 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
Dense Regular Connective Tissue• Attachment and stabilization
• Tightly packed, parallel collagen fibers:
Figure 4–11a
Dense Irregular Connective Tissue• Strength in many directions• Interwoven networks of collagen fibers:
Figure 4–11b
Elastic Tissue
• Made of elastic fibers:– e.g., elastic ligaments of spinal vertebrae
Figure 4–11c
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
Lymph
• Extracellular fluid:– collected– monitored– transported– returned
Supportive Connective Tissues
• Support soft tissues and body weight:– cartilage:
– bone:
Cartilage Matrix
• Proteoglycans derived from chondroitin sulfates
• Ground substance proteins
• Cells surrounded by lacunae
Cartilage Structure
• No blood vessels:
• Perichondrium:
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:
• Elastic cartilage:
• Fibrocartilage:
Hyaline Cartilage
• Reduces friction in joints
Figure 4–14a
Elastic Cartilage
• Flexible support
Figure 4–14b
Fibrocartilage
• Resists compression
Figure 4–14c
Bone
• Also called osseous tissue:– Strong
– resists shattering
Structures of Bone
Figure 4–15
Bone Surface
• Periosteum: – covers bone surfaces
– fibrous layer
– Cambrium layer
Muscle Tissue
What are the structures and functions of the three
types of muscle tissue?
Muscle Tissue
• Is specialized for contraction
• Produces all body movement
3 Types of Muscle Tissue
• Skeletal muscle:
• Cardiac muscle:
• Smooth muscle:
Classification of Muscle Cells
• Striation Pattern
• Number of Nuclei
• Nervous System Control
Skeletal Muscle
• Striated, voluntary, and multinucleated
Figure 4–18a
Cardiac Muscle Tissue
• Striated, involuntary, and single nucleus
Figure 4–18b
Smooth Muscle Tissue
• Nonstriated, involuntary, and single nucleus
Figure 4–18c
Nervous Tissue
What is the basic structure and role of neural tissue?
Neural Tissue
• Also called nervous or nerve tissue:– Conduction– Sensation– Process– Control
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:– support cells– repair and supply nutrients to neurons
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
The Neuron
Figure 4–19
Neuroglia
Figure 4–19
Tissue Response to Injury
How do injuries affect tissues of the body?
Tissue Injuries and Repair
• Tissues respond to injuries to maintain homeostasis
• Cells restore homeostasis with 2 processes:– inflammation– regeneration
Inflammation
• Inflammation:
• Signs of inflammatory response include:– swelling– redness– heat – pain
Inflammatory Response
• Can be triggered by: – Trauma
– Infection
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
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
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
• New cells migrate into area:
The Process of Regeneration
• Not all tissues can regenerate:– epithelia and connective tissues regenerate well– cardiac cells regenerate slowly and neurons do
not regenerate
Summary: Inflammation and Regeneration
Figure 4–20
SUMMARY
• Organization of specialized cells into tissues:– epithelial tissue– connective tissue– muscular tissue– nervous tissue
SUMMARY
• Division of epithelial tissues into epithelia and glands:– epithelia as avascular barriers for protection– glands as secretory structures
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)
SUMMARY
• 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)
SUMMARY
• The functions of connective tissues:– structure– transport– protection– support– connections– energy storage
SUMMARY
• The structure of connective tissues:– matrix – ground substance– 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)
SUMMARY
• The 3 types of muscle tissues (skeletal, cardiac, and smooth)
• The classification of muscle tissues by striation, nucleation, and voluntary control
SUMMARY
• 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)
SUMMARY
• Tissue injuries and repair systems (inflammation and regeneration)
