Chapter 4 Tissues Muse 2430 lecture #2 1/14/13. The Cell Cycle.
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Transcript of Chapter 4 Tissues Muse 2430 lecture #2 1/14/13. The Cell Cycle.
Chapter 4
Tissues
Muse 2430 lecture #21/14/13
The Cell Cycle
Stem and Progenitor Cells
What is a Tissue?
A tissue is a group of cells Common embryonic origin Function together to carry out specialized
activities
Hard (bone), semisolid (fat), or liquid (blood) Histology is the science that deals with the
study of tissues. Pathologist specialized in laboratory studies
of cells and tissue for diagnoses
Development of Tissues
Tissues of the body develop from three primary germ layers:
Ectoderm, Endoderm, and Mesoderm Epithelial tissues develop from all three
germ layers All connective tissue and most muscle
tissues drive from mesoderm Nervous tissue develops from ectoderm
A little embryology
Four Types of Tissues
Tissues are collections of cells and cell
products that perform specific, limited
functions
Types of tissue
Epithelial tissue Covers exposed surfaces
Lines internal passageways
Forms glands
Four Types of Tissues
Types of Tissue (cont’d) 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
Epithelial Tissues
Epithelia
Layers of cells covering internal or external
surfaces
Glands
Structures that produce secretions
Epithelial Tissues
Characteristics of Epithelia
Cellularity (cell junctions)
Polarity (apical and basal surfaces)
Attachment (basal lamina)
Avascularity
Regeneration
Epithelial Tissues
Figure 4–1 The Polarity of Epithelial Cells.
Epithelial Tissues
Functions of Epithelial Tissue
Provide physical protection
Control permeability
Provide sensation
Produce specialized secretions (glandular
epithelium)
Epithelial Tissues
Specializations of Epithelial Cells Move fluids over the epithelium (protection)
Move fluids through the epithelium (permeability)
Produce secretions (protection and messengers)
Free Surface and Attached Surface
Polarity Apical surfaces:
– microvilli increase absorption or secretion
– cilia (ciliated epithelium) move fluid
Basolateral surfaces
Epithelial Tissues
Maintaining the Integrity of Epithelia
Intercellular connections
Attachment to basal lamina
Epithelial maintenance and repair
Epithelial Tissues
Intercellular Connections
Support and communication
CAMs (cell adhesion molecules):
– transmembrane proteins
Intercellular cement:
– proteoglycans
Hyaluronan (hyaluronic acid):
– glycosaminoglycans
Cell Junctions
Contact points between the plasma membranes of tissue cells 5 most common types:
Tight junctions Adherens junctions Desmosomes Hemidesmosomes Gap junctions
Epithelial Tissues
Cell Junctions Occluding (Tight) junctions—between two plasma
membranes Adhesion belt attaches to terminal web
Prevents passage of water and solutes
Isolates wastes in the lumen
Gap junctions—allow rapid communication Held together by channel proteins (junctional proteins,
connexons)
Allow ions to pass
Coordinate contractions in heart muscle
Epithelial Tissues
Cell Junctions Macula adherens (Desmosomes)
CAMs, dense areas, and intercellular cement
Spot desmosomes– tie cells together
– allow bending and twisting
Hemidesmosomes– attach cells to the basal lamina
Epithelial Tissues
Attachment to the Basal Lamina Clear layer (Lamina lucida)
Thin layer
Secreted by epithelia
Barrier to proteins
Dense layer (Lamina densa) Thick fibers
Produced by connective tissue
Strength and filtration
Epithelial Tissues
Figure 4–2 Intercellular Connections
Epithelial Tissues
Figure 4–2 Intercellular Connections
Epithelial Tissues
Figure 4–2 Intercellular Connections
Epithelial Tissues
Figure 4–2 Intercellular Connections
Epithelial Tissues
Epithelial Maintenance and Repair
Epithelia are replaced by division of
germinative cells (stem cells)
Near basal lamina
Classification of Epithelia
Singular epithelium; plural epithelia
Classes of Epithelia Based on shape
Squamous epithelia: thin and flat
Cuboidal epithelia: square shaped
Columnar epithelia: tall, slender rectangles
Based on layers Simple epithelium: single layer of cells
Stratified epithelium: several layers of cells
Classification of Epithelia
Classification of Epithelia
Classification of Epithelia
Squamous Epithelia
Simple squamous epithelium
Absorption and diffusion
Mesothelium
Lines body cavities
Endothelium
Lines heart and blood vessels
Classification of Epithelia
Figure 4–3 Squamous Epithelia.
Classification of Epithelia
Squamous Epithelia
Stratified squamous epithelium
Protects against attacks
Keratin protein adds strength and water resistance
Classification of Epithelia
Figure 4–3 Squamous Epithelia.
Classification of Epithelia
Cuboidal Epithelia
Simple cuboidal epithelium
Secretion and absorption
Stratified cuboidal epithelia
Sweat ducts and mammary ducts
Classification of Epithelia
Figure 4–4 Cuboidal Epithelia.
Classification of Epithelia
Figure 4–4 Cuboidal Epithelia.
Classification of Epithelia
Transitional Epithelium
Tolerates repeated cycles of stretching and recoiling
and returns to its previous shape without damage
Appearance changes as stretching occurs
Situated in regions of the urinary system (e.g. urinary
bladder)
Classification of Epithelia
Figure 4–4 Cuboidal Epithelia.
Classification of Epithelia
Columnar Epithelia
Simple columnar epithelium
Absorption and secretion
Pseudostratified columnar epithelium
Cilia movement
Stratified columnar epithelium
Protection
Classification of Epithelia
Figure 4–5 Columnar Epithelia.
Classification of Epithelia
Figure 4–5 Columnar Epithelia.
Classification of Epithelia
Figure 4–5 Columnar Epithelia.
Classification of Epithelia
Modes of Secretion in Glandular Epithelia Merocrine secretion
Is produced in Golgi apparatus Is released by vesicles (exocytosis) For example, sweat glands
Apocrine secretion Is produced in Golgi apparatus Is released by shedding cytoplasm For example, mammary gland
Holocrine secretion Is released by cells bursting, killing gland cells Gland cells replaced by stem cells For example, sebaceous gland
Classification of Epithelia
Figure 4–6 Modes of Glandular Secretion.
Classification of Epithelia
Figure 4–6 Modes of Glandular Secretion.
Classification of Epithelia
Figure 4–6 Modes of Glandular Secretion.
Classification of Epithelia
Figure 4–6 Modes of Glandular Secretion.
Classification of Epithelia
Glandular Epithelia
Types of secretions
Serous glands:
– watery secretions
Mucous glands:
– secrete mucins
Mixed exocrine glands:
– both serous and mucous
Classification of Epithelia
Glandular Epithelia
Gland structure
Unicellular glands
– Mucous (goblet) cells are the only unicellular
exocrine glands:
» scattered among epithelia
» for example, in intestinal lining
Classification of Epithelia
Glandular Epithelia Gland structure
Multicellular glands:– structure of the duct:
» simple (undivided)» compound (divided)
– shape of secretory portion of the gland:» tubular (tube shaped)» alveolar or acinar (blind pockets)
– relationship between ducts and glandular areas:» branched (several secretory areas sharing one duct)
Classification of Epithelia
Figure 4–7 A Structural Classification of Exocrine Glands.
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
Connective Tissues
Characteristics of Connective Tissues Specialized cells
Solid extracellular protein fibers
Fluid extracellular ground substance
The extracellular components of connective tissues (fibers and ground substance) make up the matrix
Majority of tissue volume
Determines specialized function
Connective Tissues
Classification of Connective Tissues
Connective tissue proper
Connect and protect
Fluid connective tissues
Transport
Supportive connective tissues
Structural strength
Connective Tissues
Categories of Connective Tissue Proper
Loose connective tissue
More ground substance, less fibers
For example, fat (adipose tissue)
Dense connective tissue
More fibers, less ground substance
For example, tendons
Connective Tissues
Fibroblasts Fibrocytes Macrophages Adipocytes Mesenchymal cells
Melanocytes Mast cells Lymphocytes Microphages
Nine Cell Types of Connective Tissue Proper
Connective Tissues
Connective Tissue Proper Cells Fibroblasts
The most abundant cell type:
– found in all connective tissue proper
– secrete proteins and hyaluronan (cellular cement)
Fibrocytes The second most abundant cell type:
– found in all connective tissue proper
– maintain the fibers of connective tissue proper
Connective Tissues
Connective Tissue Proper Cells Macrophages
Large, amoeba-like cells of the immune system:– eat pathogens and damaged cells
– fixed macrophages stay in tissue
– free macrophages migrate
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.
Connective Tissues
Connective Tissue Proper Cells
Melanocytes
Synthesize and store the brown pigment melanin
Mast Cells
Stimulate inflammation after injury or infection:
– release histamine and heparin
Basophils are leukocytes (white blood cells) that
also contain histamine and heparin
Connective Tissues
Connective Tissue Proper Cells
Lymphocytes
Specialized immune cells in lymphoid (lymphatic) system:
– For example, lymphocytes may develop into plasma cells
(plasmocytes) that produce antibodies
Microphages
Phagocytic blood cells:
– respond to signals from macrophages and mast cells
– For example, neutrophils and eosinophils
Connective Tissues
Connective Tissue Fibers
Collagen fibers
Most common fibers in connective tissue proper
Long, straight, and unbranched
Strong and flexible
Resist force in one direction
For example, tendons and ligaments
Connective Tissues
Connective Tissue Fibers
Reticular fibers
Network of interwoven fibers (stroma)
Strong and flexible
Resist force in many directions
Stabilize functional cells (parenchyma) and
structures
For example, sheaths around organs
Connective Tissues
Connective Tissue Fibers
Elastic fibers
Contain elastin
Branched and wavy
Return to original length after stretching
For example, elastic ligaments of vertebrae
Connective Tissues
Ground Substance
Is clear, colorless, and viscous
Fills spaces between cells and slows
pathogen movement
Connective Tissues
Figure 4–8 The Cells and Fibers of Connective Tissue Proper.
Connective Tissues
Figure 4–8 The Cells and Fibers of Connective Tissue Proper.
Connective Tissues
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
Connective Tissues
Figure 4–9 Connective Tissues in Embryos.
Connective Tissues
[INSERT FIG. 4.9b]
Figure 4–9 Connective Tissues in Embryos.
Connective Tissues
Loose Connective Tissues
The packing materials of the body
Three types in adults
Areolar
Adipose
Reticular
Connective Tissues
Areolar Tissue
Least specialized
Open framework
Viscous ground substance
Elastic fibers
Holds blood vessels and capillary beds
For example, under skin (subcutaneous layer)
Connective Tissues
Adipose Tissue Contains many adipocytes (fat cells) Types of adipose tissue
White fat:– most common – stores fat– absorbs shocks– slows heat loss (insulation)
Brown fat: – more vascularized – adipocytes have many mitochondria– when stimulated by nervous system, fat break down
accelerates, releasing energy – absorbs energy from surrounding tissues
Connective Tissues
Adipose Tissue
Adipose cells Adipocytes in adults do not divide:
– expand to store fat
– shrink as fats are released
Mesenchymal cells divide and differentiate:
– to produce more fat cells
– when more storage is needed
Connective Tissues
Reticular Tissue
Provides support
Complex, three-dimensional network
Supportive fibers (stroma)
Support functional cells (parenchyma)
Reticular organs
Spleen, liver, lymph nodes, and bone marrow
Connective Tissues
Figure 4–10 Adipose and Reticular Tissues.
Connective Tissues
Figure 4–10 Adipose and Reticular Tissues.
Connective Tissues
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
Connective Tissues
Dense Regular Connective Tissue
Tightly packed, parallel collagen fibers
Tendons attach muscles to bones
Ligaments connect bone to bone and stabilize
organs
Aponeuroses attach in sheets to large, flat
muscles
Connective Tissues
Figure 4–11 Dense Connective Tissues.
Connective Tissues
Dense Irregular Connective Tissue
Interwoven networks of collagen fibers
Layered in skin
Around cartilages (perichondrium)
Around bones (periosteum)
Form capsules around some organs (e.g., liver,
kidneys)
Connective Tissues
Figure 4–11 Dense Connective Tissues.
Connective Tissues
Elastic Tissue
Made of elastic fibers
For example, elastic ligaments of spinal vertebrae
Connective Tissues
Figure 4–11 Dense Connective Tissues.
Membranes
Membranes
Are physical barriers
That line or cover portions of the body
Consist of
An epithelium
Supported by connective tissues
Membranes
Four Types of Membranes
Mucous membranes
Serous membranes
Cutaneous membrane
Synovial membranes
Membranes
Mucous membranes (mucosae)
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
Lamina propria
Is areolar tissue
Membranes
Serous Membranes
Line cavities not open to the outside
Are thin but strong
Have fluid transudate to reduce friction
Have a parietal portion covering the cavity
Have a visceral portion (serosa) covering the
organs
Membranes
Three Serous Membranes Pleura:
Lines pleural cavities Covers lungs
Peritoneum: Lines peritoneal cavity Covers abdominal organs
Pericardium: Lines pericardial cavity Covers heart
Membranes
Figure 4–16 Membranes.
Membranes
Cutaneous membrane
Is skin, surface of the body
Thick, waterproof, and dry
Synovial membranes
Line moving, articulating joint cavities
Produce synovial fluid (lubricant)
Protect the ends of bones
Lack a true epithelium
Membranes
Figure 4–16 Membranes.
Neural Tissue
Figure 4–19 Neural Tissue.
Tissue Injuries and Repair
Tissues respond to injuries to maintain
homeostasis
Cells restore homeostasis with two processes
Inflammation
Regeneration
Tissue Injuries and Repair
Inflammation = inflammatory response The tissue’s first response to injury
Signs and symptoms of the inflammatory
response include Swelling
Redness
Heat
Pain
Tissue Injuries and Repair
Inflammatory Response
Can be triggered by
Trauma (physical injury)
Infection (the presence of harmful pathogens)