Body tissues 2014

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

Body Tissues

Epithelial Tissues
 Locations
 Body coverings
 Glandular tissue
 Functions
 Protection
 Absorption
 Filtration
 Secretion

Epithelium Characteristics
 Cells fit closely together and often form
sheets
 Regenerate easily if well nourished

Epithelium Characteristics
Figure 3.17a

Classification of Epithelia
 Number of cell layers
 Simple—one layer
 Stratified—more
than one layer
Figure 3.17a

Classification of Epithelia
 Shape of cells
 Squamous
 flattened
 Cuboidal
 cube-shaped
 Columnar
 column-like
Figure 3.17b

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

Simple Squamous Epithelia
 Allows transport across membranes in lungs and capillaries,
secretes fluid in serous membranes (pericardial and pleural),
covers organs…
Figure 3.18a

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

Simple Cuboidal Epithelia
Figure 3.18b

Simple Epithelia
 Simple columnar
 Single layer of tall cells
 Often includes mucus-producing goblet cells
or microvilli at surface for absortion.
 Lines digestive tract.

Simple Columnar Epithelia
Figure 3.18c

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

Simple Pseudostratified Epithelia
Figure 3.18d

Stratified Epithelia
 Stratified squamous
 Cells at the apical surface are flattened
 Found as a protective covering where friction
is common
 Locations
 Skin
 Mouth
 Esophagus

Stratified Squamous Epithelia
Figure 3.18e

Glandular Epithelium
 Gland
 One or more cells responsible for secreting a
particular product

 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

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.

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

Connective Tissue Types
 Bone (osseous tissue)
 Cartilage
 Dense connective tissue
 Loose (Areaolar) Connective Tissue:
 Areaolar
 Adipose
 Reticular
 Blood

 Bone (osseous tissue)
 Composed of
 Bone cells (osteocytes) in lacunae
(cavities)
 Hard matrix of calcium salts
 Used to protect and support the body

Figure 3.19a

 Cartilage
 Composed of
 Abundant collagen fibers and elastic
fibers
 Rubbery matrix
 Chondrocytes
 Locations
 Larynx, fetal skeleton, cushion-like discs
between vertebrae, bronchi, nose, ears…

Figure 3.19b

 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

Figure 3.19d

 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

Figure 3.19f

 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
– EErryytthhrrooccyytteess –red blood cells
– LLeeuukkooccyytteess –white blood cells
– PPllaatteelleettss -blood clotting

Figure 3.19h

Muscle Tissue
 Function is to produce movement
 Three types
 Skeletal muscle
 Cardiac muscle
 Smooth muscle

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)

Muscle Tissue Types
Figure 3.20a

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

Muscle Tissue Types
Figure 3.20b

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

Muscle Tissue Types
Figure 3.20c

Nervous Tissue
 Composed of neurons and nerve support cells
 Sends impulses to other areas of the body
 Irritability
 Conductivity
 Neurons and glial cells

Nervous Tissue
Figure 3.21

Body tissues 2014

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Body tissues 2014