Human Biology Overview and Tissues

Human Biology Overview

• Human biology studies the human body, focusing on basic foundational topics that will be expanded on in subsequent courses (anatomy and histology).
• Histology is the study of tissues.

Tissue Hierarchy

• Cells combine to form tissues.
• Tissues combine to form organs.
• Organs combine to form systems.

Types of Tissues

• Tissues are groups of cells working together to perform specific functions.
• Four main tissue types: epithelial, connective, muscular, and nervous.

Epithelial Tissue

• Epithelial tissues cover surfaces.
• Cells rest on a basement membrane.
• There is little material between the tissue cells.
• Types of epithelial tissues include:
  • Simple epithelial tissue: One layer of cells.
  • Compound epithelial tissue: More than one layer of cells.
    • Types of compound epithelial tissue:
      • Simple squamous epithelial tissue: Location: digestive system; Function: protection.
      • Cuboidal epithelial tissue: Location: glands, kidney; Function: secretion
      • Columnar epithelial tissue: Location: glands of the stomach, villi of the small intestine; Function: absorption.
      • Compound squamous epithelial tissue: Location: skin, esophagus; Function: protection.
      • Pseudo compound ciliated epithelial tissue: Location: nose, trachea; Function: protection from dust and germs.

Connective Tissue

• Connective tissues do not cover surfaces.
• They are not anchored to basement membranes.
• The substance between cells is abundant.
• Types of connective tissues include:
  • Proper connective tissue:
    • Adipose connective tissue: Location: under skin; Function: energy storage, insulation, and shock absorption.
    • Elastic connective tissue: Location: lungs, blood vessels, vocal cords; Function: elasticity.
    • Fibrous connective tissue: Location: tendons; Function: connects muscles to bones.
    • Reticular connective tissue: Location: spleen, liver, bone marrow; Function: connection.
  • Vascular connective tissue: Blood with blood cells (WBCs, RBCs, platelets).
    • White blood cells (WBCs): Location: blood; Function: defense mechanism.
      • WBCs are the largest blood cells and lack hemoglobin. They have various forms depending on their specific role in the immune system.
      • Normal WBC count: 4000-11000. Abnormal counts can indicate various diseases:
        • Higher than 12000: possible flu
        • Higher than 90000: possible blood cancer (leukemia)
        • Lower than 1000: possible AIDS (HIV) or typhoid fever.
    • Red blood cells (RBCs): Location: blood; Function: gaseous exchange.
      • smaller than WBCs
      • have a disc biconcave shape
      • are enucleated (no nucleus)
      • lifespan: 90-120 days
      • dead cells go to the spleen and liver
      • bone marrow produces new cells
      • contain hemoglobin
    • Platelets: Location: blood; Function: clotting factors.

Skeletal Connective Tissue

• Types of skeletal connective tissue include:
  • Bone: Location: skeletal system; Function: movement, protection, support, attachment defining body shape, mineral storage, and blood cell production.
  • Compact bone has a Haversian system or osteon, with Haversian canals.
  • Cartilage: Location: trachea, nose, ear pinnae; Function: Provides structural support.
    • Types of cartilage:
      • Hyaline cartilage: Location: trachea; Function: keep airway open always
      • Elastic cartilage: Location: nose, ear pinnae; Function: elasticity
      • Fibro-cartilage: Location: between tendons and bones; Function: allows movement

Muscular Tissue

• Types of muscular tissue:
  • Smooth muscle: Location: wall of digestive system; Function: movement.
  • Skeletal muscle: Location: skeletal system; Function: movement.
  • Cardiac muscle: Location: wall of heart; Function: blood pumping.

Nervous Tissue

• Location: nervous system
• Function: transmitting nerve impulses

This quiz covers the foundational concepts of human biology, focusing on the structure and functions of human tissues. It explores the hierarchy of biological organization from cells to systems, including the four main types of tissues: epithelial, connective, muscular, and nervous. Prepare for further studies in anatomy and histology through this essential overview.