Histologie 2: Cellules et Tissus

Histologie 2

• Cellule: Basic structural and functional unit of living organisms
  • In the human body: ~100 trillion cells, ~200 different cell types
  • Average size: ~200 µm
• Tissues: Four primary types
  • Epithelial: Covering and secretion functions
  • Connective: Supporting, protection and connection functions
  • Muscular: Movement
  • Nervous: Regulation and communication functions
• Tissue Levels: Cells with similar morphology and function grouped together
• Observation Techniques:
  • Macroscopic: Visible to the naked eye (human, chicken)
  • Microscopic: Viewed using a microscope (light microscope, colored dyes)
• Cellular Structure:
  • Cytoplasm: Internal fluid of the cell
  • Extracellular matrix: Material outside the cell membrane
  • Cell membrane: Surrounds the cell
  • Nucleus: Contains cell's genetic material
  • Intracellular fluid: Material inside the cell membrane
  • Cell junctions: Connections between cells
• Tissue: Assemblage of cells working together, with unique functions
  • Organs: Composed of different tissues with specific tasks
  • Types of tissues: Epithelial (covering), Connective, Muscular, Nervous(specialized in regulation, communication)

Histologie 6

• Endocrine Glands: Secrete hormones directly into the bloodstream, acting at a distance
  • Structure: Clusters or cords of cells
• Exocrine Glands: Secrete substances through ducts, leading to a specific location
  • Structure: Various shapes and structures
• Amphicrine Glands: Dual function, possessing both endocrine and exocrine properties (e.g., pancreas)

Histologie 1

• Organization Levels (Human Body):
  • Chemical (atoms, molecules)
  • Cellular (organelles, cells)
  • Tissue (epithelial, connective, muscular, nervous)
  • Organ (specific structures)
  • Organ system (groups of organs)
  • Organism (human body)
• Atoms in Living Things:
  • Primarily: Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N), Phosphorus (P), Sulfur (S)
  • Also: Calcium (Ca), Sodium (Na), to Potassium (K), Chlorine (Cl), Magnesium (Mg), Iron (Fe), amongst others.
• Examples of Organelles
  • Mitochondria
  • Endoplasmic Reticulum
  • Ribosomes
  • Lysosomes & Peroxisomes
  • Plasma Membrane

Histologie 3

• Epithelium: Cells tightly packed together, often with a basement membrane
  • Types: Simple squamous, stratified squamous, cuboidal, columnar, transitional
  • Functions: Covering, lining, absorption, secretion
• Specialized Epithelial Features
  • Basement Membrane (structural support)
  • Cell shapes (cuboidal, columnar, squamous for specialized function)
  • Cell layers (single or multiple for increased protection/diffusion or barrier)
• Epithelium Stratifications:
  • Simple: Single layer
  • Pseudostratified: Appears layered but cells rest on the basement membrane
  • Stratified: Multiple layers
• Types of Epithelial cells: squamous, cuboidal and columnar.

Histologie 8

• Glandular Epithelium:
  • Secretion (hormones or other substances)
  • Exocrine glands (discharge substances via ducts onto a surface)
  • Endocrine glands (release hormones directly into the bloodstream)
  • Classification based on secretion type (serous, mucous, etc.) and structure (tubular, acinar).

Histologie 7

• Connective Tissues: Support and connect other tissues and organs
  • Types: Loose, dense, cartilage, bone, blood
  • Components include cells embedded in a matrix of ground substance and fibers (collagen, elastic, reticular).
• Types of Connective Tissue:
  • Specialized
  • Non-specialized

Histologie 10

• Bone Tissue: Main component of the skeleton, providing support and protection
• Types of Bone: Compact (dense) and spongy (cancellous)
• Bone Cells: Osteoblasts (forming bone), osteocytes (maintain bone), osteoclasts (resorbing bone)
• Bone Development: Intramembranous (from fibrous membrane) and endochondral [cartilage] (from hyaline cartilage) ossification processes

Histologie 9

• Connective tissue: Provides support and connection between different tissues.
  • Characterised by cells embedded within an extracellular matrix.
  • Types: Connective tissue proper (loose and dense), cartilage, bone, blood.
  • Roles: Support, protection, connection, transportation.
• Non-specialized cells: Mesenchymal cells (stem cells), Fibroblasts(synthesizing extracellular matrix).
  • Specialized cells: Chondrocytes(cartilage), Osteocytes(bone), etc.
  • Extracellular matrix: Composed of ground substance and various types of fibers (collagen, elastic).

Histologie 11

• Nervous Tissue: Composed of neurons (transmitting electrical impulses) and glial cells (supporting and nourishing the neurons).
  • Functions: Communication, coordination, control, and perception
• Neural Tissue Structure: Neurons, with axons and dendrites; neuroglia
• Nervous System Divisions: Central nervous system (brain and spinal cord), peripheral nervous system (nerves and ganglia)
• Importance of Imaging Techniques in diagnosing nervous system diseases/tumours and/or trauma.

Ce quiz aborde les concepts fondamentaux de la histologie, en explorant la structure et la fonction des cellules et des tissus dans le corps humain. Vous découvrirez les quatre types principaux de tissus et les techniques d'observation utilisées pour les étudier. Testez vos connaissances sur la structure cellulaire et son organisation.