Chapter 3

Body Tissues

He he he he he…

Body TissuesBody Tissues Cells are specialized for particular functions

Tissues - Groups of cells with similar structure and function

Four primary types- Epithelium- Connective tissue- Nervous tissue- Muscle

Epithelial TissuesEpithelial TissuesLocations

Body coverings Body linings Glandular tissue

Functions Protection Absorption Filtration Secretion

Characteristics Cells close together Cells have free apical

surface Bottom surface is

basement membrane Avascular – no blood

supply Regenerate easily

Classification of EpitheliumClassification of Epithelium1. Based on # of cell layers

Simple – one layer

Stratified – more than one layer

2. Shape of cells

Squamous – flattened

Cuboidal – cube-shaped

Columnar – column-like

Simple EpitheliumSimple Epithelium

1. Simple squamous Single layer of flat cells

Usually forms membranes

Lines body cavities

Lines lungs and capillaries

2. Simple cuboidal Single layer of

cube-like cells

Common in glands and their ducts

Forms walls of kidney tubules

Covers the ovaries

3. Simple columnar

Single layer of tall cells

Often includes goblet cells, which produce mucus

Lines digestive tract

4. Pseudostratified Single layer, but

some cells are shorter than others

Often looks like a double cell layer

Sometimes ciliated, such as in the respiratory tract

May function in absorption or secretion

Stratified EpitheliumStratified Epithelium1. Stratified squamous

Cells at the free edge are flattened

Found as a protective covering where friction is common

Locations Skin Mouth Esophagus

2. Stratified cuboidal Two layers of cuboidal cells

3. Stratified columnar Surface cells are columnar, cells

underneath vary in size and shape

Both are: Found mainly in ducts of large glands

Rare in human bodyRare in human body

GlandsGlandsGland – one or more cells that secretes a

particular product

2 types

1. Endocrine gland

Ductless

Secretes hormones

2. Exocrine gland

Empty through ducts to surface

Include sweat and oil glands

4. Transitional epithelium

Shape of cells depends upon the amount of stretching

Lines organs of the urinary system

Connective TissueConnective Tissue- Most abundant and widely

distributed

- Some have good blood supply (vascularized)

- Some don’t (avascular)

- All have extracellular matrix – nonliving material surrounding cells

- Functions

Binds tissues together

Supports

Protects

Extracellular MatrixExtracellular MatrixTwo parts

1. Ground substance – mostly water along with adhesion proteins and polysaccharide molecules

2. Fibers Produced by the cells 3 types

- Collagen fibers- Elastic fibers- Reticular fibers

Connective Tissue TypesConnective Tissue Types

1. Bone (osseous tissue) Bone cells in lacunae

(cavities)

Hard matrix of calcium salts

A lot of collagen fibers

Protect & supports body

Connective Tissue TypesConnective Tissue Types

2. Hyaline cartilage Most common

cartilage

Lots of collagen fibers

Rubbery matrix

Fetal skeleton & ribs

Connective Tissue TypesConnective Tissue Types

3. Elastic cartilage

Provides elasticity

found in external ear,

epiglottis, & trachea

Connective Tissue TypesConnective Tissue Types

4. Fibrocartilage

Highly compressible

forms cushion-like discs between vertebrae

Connective Tissue TypesConnective Tissue Types

5. Dense Main matrix element is

collagen fibers

Cells are fibroblasts Tendon –

muscle to bone

Ligaments –

bone to bone

Connective Tissue TypesConnective Tissue Types6. Areolar

Most widely distributed

Soft, pliable tissue

Contains all fiber types

Can soak up excess fluid

Think “airy”

Connective Tissue TypesConnective Tissue Types7. Adipose

Similar to areolar with fat globules

Many cells contain large lipid deposits

Functions

- Insulates body

- Protects organs

- Fuel storage

Connective Tissue TypesConnective Tissue Types8. Reticular

Delicate network of fibers

Forms network of lymphoid organs

- Lymph nodes- Spleen- Bone marrow

Connective Tissue TypesConnective Tissue Types9. Blood

cells & fluid matrix

Fibers visible during clotting

Transports materials

Muscle TissueMuscle Tissue Function = produce movement

3 types

- Skeletal muscle

move muscles of skeleton

- Cardiac muscle

only found in heart

- Smooth muscle

found in organs & vessels

Muscle Type

Type of Control?

Striations? How many nuclei?

Skeletal Voluntary Yes Many per cell

Cardiac Involuntary Yes & intercalated disks

1 per cell

Smooth Involuntary No 1 per cell

Nervous TissueNervous Tissue Neurons and nerve

support cells

Function = send impulses to other areas of the body

- Irritability – able to respond to stimuli

- Conductivity – conducts messages