Download - Histology
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