Human Biology Overview: Tissues and Epithelia

Human Biology Overview

• Human biology studies the human body, including core building blocks (cells) progressing to tissues, organs, and systems.
• Key foundational subjects are anatomy and histology (tissue science).
• Key progression: Cell + Cell = Tissue, Tissue + Tissue = Organ, Organ + Organ = System.

Tissue Types

• Tissues are groups of similar cells working together for a specific function.
• Main tissue types: Epithelial, Connective, Muscular, and Nervous.

Epithelial Tissue

• Features: Always cover surfaces, rest on basement membranes, minimal intercellular substance.
• Types: Simple, Pseudostratified ciliated, and Compound.
• Simple epithelial: Single layer of cells
• Compound epithelial: Multiple layers of cells
• Examples:
  • Simple Squamous: Digestive system wall, protective function.
  • Cuboidal: Glands, kidneys, secretion function.
  • Columnar: Stomach glands, small intestine villi, absorption function.
  • Compound Squamous: Skin, esophagus, protective function.
  • Pseudostratified Ciliated: Nose, trachea, protection against dust/germs.

Connective Tissue

• Features: Do not cover surfaces, do not rest on basement membranes, large amounts of intercellular material.
• Types: Proper, Vascular, Skeletal.
• Proper Connective Tissue examples:
  • Adipose: Under skin, energy storage, insulation, shock absorption.
  • Elastic: Lungs, blood vessels, vocal cords, elasticity.
  • Fibrous: Tendons, connecting muscles and bones.
  • Reticular: Spleen, liver, bone marrow, providing structural support.
• Vascular Connective Tissue examples: Blood, composed of:
  • Red Blood Cells (RBCs): Gas exchange (90-120-day lifespan), contain hemoglobin. (Smaller than white blood cells, biconcave disc shape, no nucleus).
  • White Blood Cells (WBCs): Defense mechanisms, production in bone marrow, (4000-11000 normal count), larger with a nucleus (five types).
  • Platelets: Blood clotting factors.

Skeletal Tissue

• Types: Bone, cartilage (hyaline, elastic, fibro).
• Bone: Compact bone (allows movement, protection, support, shape, mineral storage, blood cell production) with Haversian canal systems and Osteiocytes (bone cells).
• Cartilage examples:
  • Hyaline: Trachea (keeps airway open).
  • Elastic: Nose, ear pinnae (elasticity).
  • Fibro: Between tendons/bones, for movement.

Muscular Tissue

• Types: Smooth, Skeletal, and Cardiac.
• Smooth: Digestive system, allowing movement.
• Skeletal: Skeletal system, allowing movement.
• Cardiac: Heart wall, aiding in blood pumping.

Nervous Tissue

• Location: Nervous system
• Function: Transmitting nerve impulses, with Dendrites, Cell bodies, Axons.