Body tissues 2014

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


Body Tissues

Tissues


Four primary types


Connective tissue

Muscle tissue

Nervous tissue


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



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


Body Tissues

Tissues


Four primary types


Connective tissue

Muscle tissue

Nervous tissue


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

– ErythrocytesErythrocytes –red blood cells– LeukocytesLeukocytes –white blood cells– PlateletsPlatelets -blood clotting



Figure 3.19h


Body Tissues

Tissues


Four primary types


Connective tissue

Muscle tissue

Nervous tissue


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


Body Tissues

Tissues


Four primary types


Connective tissue

Muscle tissue

Nervous tissue


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

Science

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