Lecture 4 tissue level of organization

Copyright © 2010 Pearson Education, Inc.
C h a p t e r 4
The Tissue Level of
Organization

4-1 The four tissue types
are epithelial, connective,
muscle, and neural

Four Types of Tissues
• Tissues are collections of cells and cell
products that perform specific, limited
functions

Tissues of the Body
Figure 4-1

4-2 Epithelial tissue covers
body surfaces, lines cavities
and tubular structures, and
serves essential functions

Epithelial Tissues
• Characteristics of Epithelia
– Cellularity (cell junctions)
– Polarity (apical and basal surfaces)
– Attachment
– Avascularity
– Regeneration

Epithelial Tissues
• Functions of Epithelial Tissue
– Provide physical protection
– Control permeability
– Provide sensation
– Produce specialized secretions (glandular
epithelium)

Intercellular Connections
• Support and Communication
– CAMs (cell adhesion molecules):
• Transmembrane proteins
– Intercellular cement:
• Proteoglycans
– Hyaluronan (hyaluronic acid):
• Glycosaminoglycans

• Cell junctions
– Form bonds with other cells or extracellular material:
• Occluding (tight) junctions
• Gap junctions
• Macula adherens (desmosomes)

Figure 4-2

The Surface of Epithelial Cells
Figure 4-3

Epithelial Renewal and Repair
• Epithelia are replaced by division of
germinative cells (stem cells)
• Near basal lamina

4-3 Cell shape and number of
layers determine the
classification of epithelia

Classification of Epithelia
• Singular epithelium; plural epithelia
• Classes of Epithelia
– Based on layers:
• Simple epithelium: single layer of cells
• Stratified epithelium: several layers of cells
– Based on shape:
• Squamous epithelia: thin and flat
• Cuboidal epithelia: square shaped
• Columnar epithelia: tall, slender rectangles

Figure 4-4

Figure 4-5

Glandular Epithelia
• Endocrine Glands
– Release hormones:
• Into interstitial fluid
• No ducts
• Exocrine Glands
– Produce secretions:
• Onto epithelial surfaces
• Through ducts
Mechanisms of Glandular Secretion

Glandular Epithelia
• Mechanism of Secretion
– 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

Mechanisms of Secretion
Figure 4-6

Glandular Epithelia
• Types of Secretions
– Serous glands:
• Watery secretions
– Mucous glands:
• Secrete mucins
– Mixed exocrine glands:
• Both serous and mucous

4-4 Connective tissue
provides a protective
structural framework for other
tissue types

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
• Support and protection
• Transportation of materials
• Storage of energy reserves
• Defense of the body

Major Types of Connective Tissue
Figure 4-7

Connective Tissues
• Cell Types of Connective Tissue
Proper
–Fibroblasts
–Macrophages
–Adipocytes
–Mast cells

Connective Tissues
• Connective Tissue Fibers
– Collagen fibers
– Reticular fibers
– Elastic fibers

Connective Tissues
• Ground Substance
– Is clear, colorless, and viscous
– Fills spaces between cells and slows
pathogen movement

Types 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

Cells and Fibers of Connective Tissue
Proper
Figure 4-8

Connective Tissue Proper
Figure 4-9

Connective Tissue Proper
Figure 4–9

Connective Tissues
• Fluid Connective Tissues
– Blood and lymph
– Watery matrix of dissolved proteins
– Carry specific cell types (formed elements)
• Formed elements of blood
– red blood cells (erythrocytes)
– white blood cells (leukocytes)
– platelets

Supportive Connective Tissues
• Cartilage
– Gel-type ground substance
– For shock absorption and protection
• Bone
– Calcified (made rigid by calcium salts, minerals)
– For weight support

• Cartilage Matrix
– Proteoglycans derived from chondroitin sulfates
– Ground substance proteins
• Chondrocytes (cartilage cells) surrounded by
lacunae (chambers)

• Cartilage Structure
– No blood vessels:
• Chondrocytes produce antiangiogenesis factor
– Perichondrium:
• Outer, fibrous layer (for strength)
• Inner, cellular layer (for growth and maintenance)

• Types of Cartilage
– Hyaline cartilage:
• Stiff, flexible support
• Reduces friction between bones
• Found in synovial joints, rib tips, sternum, and trachea
– Elastic cartilage:
• Supportive but bends easily
• Found in external ear and epiglottis
– Fibrous cartilage (fibrocartilage):
• Limits movement
• Prevents bone-to-bone contact
• Pads knee joints
• Found between pubic bones and intervertebral discs

Types of Cartilage
Figure 4-10

• Bone or osseous tissue
– Strong (calcified: calcium salt deposits)
– Resists shattering (flexible collagen fibers)
• Bone cells or osteocytes
– Arranged around central canals within matrix
– Small channels through matrix (canaliculi) access
blood supply
• Periosteum
– Covers bone surfaces
– Fibrous layer
– Cellular layer

Bone
Figure 4-11

4-5 Membranes are physical
barriers of four types: mucous,
serous, cutaneous, and
synovial

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 4-12

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

4-6 The three types of muscle
tissue are skeletal, cardiac,
and smooth

Muscle Tissue
• Specialized for contraction
• Produces all body movement
• Three types of muscle tissue
– Skeletal muscle:
• Large body muscles responsible for movement
– Cardiac muscle:
• Found only in the heart
– Smooth muscle:
• Found in walls of hollow, contracting organs (blood vessels;
urinary bladder; respiratory, digestive, and reproductive
tracts)

Muscle Tissue
Figure 4-13

4-7 Neural tissue responds to
stimuli and conducts electrical
impulses throughout the body

Neural Tissue
• Also called nervous or nerve tissue
– Specialized for conducting electrical impulses
– Rapidly senses internal or external
environment
– Processes information and controls
responses

Neural Tissue
• Neural tissue is concentrated in the
central nervous system
– Brain
– Spinal cord

Neural Tissue
• Two Kinds of Neural Cells
– Neurons:
• Nerve cells
• Perform electrical communication
– Neuroglia:
• Supporting cells
• Repair and supply nutrients to neurons

Neural Tissue
• 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

Neural Tissue
Figure 4-14

4-8 The response to tissue
injury involves inflammation
and regeneration

Tissue Injuries and Repair
• Tissues respond to injuries to maintain
homeostasis
– Cells restore homeostasis with two
processes:
• Inflammation
• Regeneration

• Inflammation = inflammatory response
– The tissue’s first response to injury
• Signs and symptoms of the inflammatory
response include
– Swelling
– Redness
– Heat
– Pain

• Inflammatory Response
– Can be triggered by:
• Trauma (physical injury)
• Infection (the presence of harmful pathogens)

4-9 With advancing age,
tissue repair declines and
cancer rates increase

Aging and Tissue Structure
• Speed and efficiency of tissue repair
decrease with age due to
– Slower rate of energy consumption
(metabolism)
– Hormonal alterations
– Reduced physical activity

Aging and Cancer Incidence
• Cancer rates increase with age
– 1 in 4 people in the United States develops cancer
– Cancer is the #2 cause of death in the United States
– Environmental chemicals and cigarette smoke cause
cancer

Lecture 4 tissue level of organization

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