Pathology and Disease Processes

Fundamentals of Histology

• The germ layer is the starting point for embryonic development, consisting of three basic layers: endoderm, mesoderm, and ectoderm
• Endoderm develops into cells such as lung cells, thyroid cells, and digestive cells
• Mesoderm develops into cells such as cardiac muscle cells, skeletal muscle cells, and connective tissue cells
• Ectoderm develops into cells such as epithelial cells and nervous tissue cells

Types of Tissues

• Epithelial tissue: provides protection, found in skin and linings of organs and passages
• Connective tissue: provides blood supply to epithelium, connects tissue to bones and tendons, and provides nutrients and blood supply to the body
• Muscular tissue: involved in movement, divided into three types: skeletal muscle, cardiac muscle, and smooth muscle
• Nervous tissue: sends signals, impulses, and messages from the brain to other parts of the body

Connective Tissue

• Collagen is the major ingredient in all connective tissue
• Types of connective tissue: loose, dense, regular, irregular, elastic, cartilage, bone, and blood

Pathology

• Divided into two major areas: histopathology and other responses
• Histopathology: study of changes within cells and tissues, visualized using histopathologic techniques
• Other responses: autophagy, intracellular accumulation of substances, pathologic calcification, and cellular aging

Importance of Histopathology

• Understanding the changes that are characteristic of a disease requires detailed knowledge of normal histology of cells and tissues
• Knowledge of the type of tissue and their composition is important in the selection of the appropriate histopathologic technique and stain to be used
• Hippocrates is considered the father of medicine, and the Hippocratic oath is in line with the principles of Hippocrates