Body tissues 2015

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.


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-likeFigure 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

Figure 3.18a

Allows transport across membranes in lungs and capillaries, secretes fluid in serous membranes (pericardial and pleural), covers organs…


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


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


Glandular Epithelium


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


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


Connective Tissue Types

Figure 3.19a


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…



Figure 3.19b


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



Figure 3.19d


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



Figure 3.19f


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



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 2015

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