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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
DIFFERENTIATION
Differentiation is the process by which an unspecialized cell (such as a fertilized egg cell), divides many times to produce specialized cells that work together and make up the body.
Every cell in the body was originated from a single fertilized egg, the zygote, that divides many times to produce an embryo.
Embryonic cells differentiate into many different cell types (250), from a new-born baby to an elderly adult.
A differentiated cell will develop specific structures and perform certain functions.
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Body Tissues
Tissues
Groups of cells with similar structure and function
Four primary types
Epithelial tissue (epithelium)
Connective tissue
Muscle tissue
Nervous tissue
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Body Tissues
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Body Tissues
Tissues
Groups of cells with similar structure and function
Four primary types
Epithelial tissue (epithelium)
Connective tissue
Muscle tissue
Nervous tissue
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Epithelial Tissues
Locations
Body coverings
Glandular tissue
Functions
Protection
Absorption
Filtration
Secretion
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Epithelium Characteristics
Cells fit closely together and often form sheets
Regenerate easily if well nourished
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Epithelium Characteristics
Figure 3.17a
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Classification of Epithelia
Number of cell layers
Simple—one layer
Stratified—more than one layer
Figure 3.17a
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Classification of Epithelia
Shape of cells
Squamous
flattened
Cuboidal
cube-shaped
Columnar
column-likeFigure 3.17b
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Simple Epithelia
Simple squamous
Single layer of flat cells (much wider than they are thick).
(The thinnest tissue of the body).
Usually forms membranes
Lines body cavities, lungs and capillaries
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Simple Squamous Epithelia
Figure 3.18a
Allows transport across membranes in lungs and capillaries, secretes fluid in serous membranes (pericardial and pleural), covers organs…
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Simple Epithelia
Simple cuboidal
Single layer of cube-like cells
Common in exocrine glands and their ducts
Forms walls of kidney tubules and covers the ovaries
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Simple Cuboidal Epithelia
Figure 3.18b
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Simple Epithelia
Simple columnar
Single layer of tall cells
Often includes mucus-producing goblet cells or microvilli at surface for absortion.
Lines digestive tract.
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Simple Columnar Epithelia
Figure 3.18c
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Simple Epithelia
Pseudostratified columnar
Single layer, but some cells are shorter than others. It often looks like a double layer of cells
Sometimes ciliated, such as in the respiratory tract
May function in absorption or secretion
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Simple Pseudostratified Epithelia
Figure 3.18d
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Stratified Epithelia
Stratified squamous
Cells at the apical surface are flattened
Found as a protective covering where friction is common
Locations
Skin
Mouth
Esophagus
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Stratified Squamous Epithelia
Figure 3.18e
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Glandular Epithelium
Gland
One or more cells responsible for secreting a particular product
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Glandular Epithelium
Two major gland types
Endocrine gland
Ductless secretions diffuse into blood vessels
All secretions are hormones
Exocrine gland
Secretions empty through ducts to the epithelial surface
Include sweat and oil glands
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Glandular Epithelium
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Body Tissues
Tissues
Groups of cells with similar structure and function
Four primary types
Epithelial tissue (epithelium)
Connective tissue
Muscle tissue
Nervous tissue
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Connective Tissue
Found everywhere in the body
Functions
Binds body tissues together
Supports the body
Provides protection
Cells widely separated from each other in a matrix.
Extracellular matrix: Non-living material that surrounds living cells and is produced by them.
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Extracellular Matrix
Two main elements
Ground substance (mostly water with proteins and polysaccharides)
Fibers
Produced by the cells
Three types
Collagen (white) fibers
Elastic (yellow) fibers
Reticular fibers
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Connective Tissue Types
Bone (osseous tissue)
Cartilage
Dense connective tissue
Loose (Areaolar) Connective Tissue:
Areaolar
Adipose
Reticular
Blood
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Connective Tissue Types
Bone (osseous tissue)
Composed of
Bone cells (osteocytes) in lacunae (cavities)
Hard matrix of calcium salts
Used to protect and support the body
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Connective Tissue Types
Figure 3.19a
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Connective Tissue Types
Cartilage
Composed of
Abundant collagen fibers and elastic fibers
Rubbery matrix
Chondrocytes
Locations
Larynx, fetal skeleton, cushion-like discs between vertebrae, bronchi, nose, ears…
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Connective Tissue Types
Figure 3.19b
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Connective Tissue Types
Dense connective tissue (dense fibrous tissue)
Main matrix element is collagen fiber
Locations
Tendons—attach skeletal muscle to bone
Ligaments—attach bone to bone at joints
Dermis—lower layers of the skin
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Connective Tissue Types
Figure 3.19d
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Connective Tissue Types
Loose connective tissue types
Adipose tissue
Matrix is an areolar tissue in which fat globules predominate
Many cells (adipocytes) contain large lipid deposits
Functions
Insulates the body
Protects some organs
Serves as a site of fuel storage
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Connective Tissue Types
Figure 3.19f
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Connective Tissue Types
Blood (vascular tissue)
Blood cells surrounded by fluid matrix called blood plasma
Fibers are visible during clotting
Functions as the transport vehicle for materials
Formed elements
– ErythrocytesErythrocytes –red blood cells– LeukocytesLeukocytes –white blood cells– PlateletsPlatelets -blood clotting
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Connective Tissue Types
Figure 3.19h
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Body Tissues
Tissues
Groups of cells with similar structure and function
Four primary types
Epithelial tissue (epithelium)
Connective tissue
Muscle tissue
Nervous tissue
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Muscle Tissue
Function is to produce movement
Three types
Skeletal muscle
Cardiac muscle
Smooth muscle
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Muscle Tissue Types
Skeletal muscle
Under voluntary control
Contracts to pull on bones or skin
Produces gross body movements or facial expressions
Characteristics of skeletal muscle cells
Striated
Multinucleate (more than one nucleus)
Long, cylindrical (each cell is the length of the muscle)
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Muscle Tissue Types
Figure 3.20a
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Muscle Tissue Types
Cardiac muscle
Under involuntary control
Found only in the heart
Function is to pump blood
Characteristics of cardiac muscle cells
Cells are attached to other cardiac muscle cells at intercalated disks
Striated
One nucleus per cell
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Muscle Tissue Types
Figure 3.20b
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Muscle Tissue Types
Smooth muscle
Under involuntary muscle
Found in walls of hollow organs such as stomach, uterus, and blood vessels
Characteristics of smooth muscle cells
No visible striations
One nucleus per cell
Spindle-shaped cells
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Muscle Tissue Types
Figure 3.20c
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Body Tissues
Tissues
Groups of cells with similar structure and function
Four primary types
Epithelial tissue (epithelium)
Connective tissue
Muscle tissue
Nervous tissue
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Nervous Tissue
Composed of neurons and nerve support cells
Sends impulses to other areas of the body
Irritability
Conductivity
Neurons and glial cells
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Nervous Tissue
Figure 3.21