Histology and Basic Tissue Types Quiz

Histology

• Histology is the study of the microscopic structure of normal cells, tissues, and organs.
• Aims to correlate the structure and arrangement of cells to their functions.
• Understanding normal cellular architecture is crucial for pathology comprehension.
• The human body consists of cells, tissues, organs, and systems, with each part playing specific roles.

Basic Tissue Types

• Epithelial Tissue: Covers body surfaces and lines cavities.
• Nervous Tissue: Facilitates communication and control within the body.
• Connective Tissue: Supports and connects other tissues.
• Muscular Tissue: Responsible for movement.

Cytology

• Cytology focuses on the structure of normal cells.
• Microscopy is essential due to the small size of cells.

Microscopes

• Light Microscope (LM): Used for general observation; limited detail.
• Electron Microscope (EM): Provides higher resolution, revealing cellular structures in greater detail.

Staining Techniques

• Staining is required to visualize colorless tissues.
• Hematoxylin and Eosin (H&E): Most common staining method; Hematoxylin stains acidic components blue (basophilic), while Eosin stains basic components red (acidophilic).

Cell Structure

• Cells vary in shape and size; all contain cytoplasm and a nucleus.
• Cytoplasm Components:
  • Organelles: Living structures essential for cell life.
  • Inclusions: Nonliving structures not essential for life.
  • Cytosol: Viscous fluid supporting organelles.

Organelles

• Organelle classification:
  • Membranous Organelles: Enclosed by membranes (e.g., mitochondria).
  • Non-Membranous Organelles: Not enclosed (e.g., ribosomes).

Cell Membrane

• The cell membrane (plasma membrane) envelops the cell, crucial for maintaining cellular integrity.
• Structure (by EM): Appears trilaminar (three-layered) with two electron-dense layers and one electron-lucent layer.
• Composition:
  • Lipids: Primarily phospholipids and cholesterol.
  • Proteins: Integral proteins (embedded) and peripheral proteins (loosely attached).
  • Carbohydrates: Glycolipids and glycoproteins contribute to the glycocalyx.

Glycocalyx

• A fuzzy layer on the cell surface formed by glycoproteins and glycolipids.
• Functions include cell recognition and intercellular adhesion.

Functions of Cell Membrane

• Maintains cell structural integrity.
• Regulates substance movement via transport systems:
  • Passive Transport: Movement along concentration gradients without energy (e.g., diffusion, facilitated diffusion).
  • Active Transport: Movement against gradients requiring energy (e.g., sodium-potassium pump).
  • Vesicular Transport: Large molecule transport via vesicle formation (endocytosis and exocytosis).

Endocytosis and Exocytosis

• Endocytosis: Uptake of materials into the cell.
  • Phagocytosis: "Cell eating" of solids.
  • Pinocytosis: "Cell drinking" of liquids.
  • Receptor-Mediated Endocytosis: Specific uptake involving receptors.
• Exocytosis: Release of substances outside the cell, such as secretory proteins.

Key Identification Questions

• Characteristic structure of the cell membrane includes trilaminar appearance by EM high magnification and phospholipids arranged in two rows.
• Uptake of extracellular fluids by cells is termed pinocytosis.