The microscopic study of tissue.

It is important to know the structure and function of tissues In order to understand how individual cells are organizedAnd how tissues work to form organs and organ systems.

Learner Objectives

• To analyze the relationships between the structures and functions of tissues.

• To evaluate the cause and effect of disease and trauma on the structure and function of tissues.

• To research embryological development of tissues.

Epithelial Tissues

Overall classification is based on the fact that they havevery little extra-cellular matrix between the cells.

These tissues cover organs, form structures, and has a “freesurface.”

They all have basement membrane – opposite the free surface; binds cells to underlying tissues.

Blood supply does not penetrate the basement membrane. Diffusion of all gasses and nutrients; cells close to basement

membrane are active, and those further away will die in stratified tissue.

Classification of Epithelium – by number of cell layers and the shape of

cells.Simple

Stratified

Pseudostratified

Squamous

Cuboidal

Columnar

Transitional

Cell Surfaces

1) Free surface – faces away from underlying tissue

2) Lateral - surfaces which face other cells

3) Basal – surface facing the basement membrane

If the free surface is smooth:

If the free surface has microvilli:

If the free surface has cilia:

Function:

Function:

Function:

Function:

Connective Tissue

The essential Characteristic that distinguishes Connective tissue from

the other 3 types of tissue isThe non-living extra Cellular matrix.

The specialized cells of the variousConnective tissues are –Blasts, -Cytes, and

-Clasts.

The structure of the matrix gives Connective tissue types most of their

Functional characteristics, Such as the Ability of bones and cartilage to bear weight,

Of tendons and ligaments to withstand Tension, and the Dermis to withstand

abrasions.

The Matrix is composed of:

1)Protein Fibers (Collagen, reticular, And Elastin).

2)Ground Substance – the shapeless Background against which the fibers

Are seen.Hyaluronic acid is a long, unbranched,

Polysaccharide chain composed of Repeating disaccharide units.

It gives a very slippery quality to theFluids that contain it.

Proteoglycans are formed from proteinsAnd polysaccharides – it is a molecule

That can trap large quanities of water, Which gives them the capacity to return To their original shape when compressed.

Special Connective Tissue

Adipose, reticular and hemopoietic

Adipose consists of adipocytes and comesIn yellow and brown forms.

Reticular tissue forms the framework of Lymphatic tissue, bone marrow, and the

Liver.

Hemopoietic is blood forming tissue – it isMostly found in the marrow – Red marrow.

Fig. 4.6

Loose (Fibrous) Connective Tissue

AreolarThe protein fibers form a lacy network with numerous

Fluid filled spaces.

Loose packing material in organs and attachment to the Skin. It contains collagen and elastin fibers and a variety of

Cells, but mostly fibroblasts.

Fig. 4.5

Dense (Fibrous) Connective Tissue

RegularProtein fibers packed and fill almost all of the extra

Cellular space. The fibers are oriented predominately in one direction.

(Tendon or Ligaments)Irregular

Protein fibers packed and fill almost all of the extraCellular space. The fibers are oriented in a random

meshwork.(Dermis of the skin)

Fig. 4.7

Solid Connective TissueMatrix with both protein fibers and ground substance (50/50)

Cartilage – composed of chondrocytes located in spaceswithin the crystalized matrix called lacunae; protein is

within the matrix (collagen and elastin) plus proteoglycanaggregate (hyaluronic acid and proteoglycan).

* Lack of blood supply = slow healing

3 types:Hyaline – large amounts of collagen and proteoglycans;

fine collagen fibers evenly spaced in the ground substance (rib cage and trachea and joints).

Fibrocartilage – more collagen than proteoglycans; thickerbundles of protein; slightly compressible and very tough

(jaw, between vertebrae)Elastic cartilage – elastic fibers (ears)

Fig. 4.8

Solid Connective TissueMatrix with both protein fibers and ground substance (50/50)

Bone – Hydroxyapatite (mineral inorganic portion- calciumphosphate crystals of bone);

osteocytes (bone cells in the lacunae).

2 types:Cancellous – spongy; has spaces between trabeculae

(plates of compact bone).Compact – compact, has no spaces between the lamina

(thin layers of bone that wrap in a circular pattern.)

Fig. 4.9

Predominantly Fluid Matrix

Blood – composed of formed elements and plasma.

Plasma is the liquid matrix with dissolved ions and nutrients.The formed elements are the cells and cell fragments:

Erythrocytes – red blood cellsLeukocytes – White blood cells

Thrombocytes – platelets

The fluid nature of blood allows movement of cells,Allowing transportation of oxygen, nutrients, wastes, etc.

Muscle Tissue

Muscle tissue is contractile, and through contractions is designed to

move the body, pump blood, and decrease the size of hollow organs.

3 types are classified by structure and function:SkeletalCardiacSmooth

Table 4.3

Fig. 4.11

Fig. 4.12

Fig. 4.13

Nervous TissueConducts electrical signals called “action

potentials”Neurons – nerve cells – composed of 3 parts: cell

body, dendrites, and axons.

Types of neurons:Multipolar

BipolarUnipolar

Support cells – support cells of the brain, spinal cord, and peripheral nerves. Also form myelin

sheaths around axons and produce cerebrospinal fluid.

Schwann cellsneuroglia

Fig. 4.14

End of all tissues structure and function