Overview

An organ is a collection of tissues that are organized to carry out one or more specific functions in a living organism. Organs represent an intermediate level of biological organization between tissues and organ systems, forming the building blocks of complex multicellular life.

Structure and Organization

Organs typically consist of multiple types of tissues arranged in specific patterns:

• epithelial tissue for covering and lining
• connective tissue for support and connection
• muscle tissue for movement and stability
• nervous tissue for signaling and coordination

Major Categories

Vital Organs

These organs are essential for survival:

• heart - Blood circulation
• lungs - Respiration and gas exchange
• brain - Central control and consciousness
• liver - Metabolism and detoxification
• kidneys - Filtration and homeostasis

Digestive Organs

A connected series including:

• stomach
• small intestine
• large intestine
• pancreas
• gallbladder

Sensory Organs

Specialized for environmental interaction:

• eyes
• ears
• nose
• tongue
• skin

Function and Regulation

Organs operate through complex homeostasis mechanisms, maintaining balance through:

• hormones
• nervous system control
• blood circulation
• immune system

Clinical Significance

Understanding organ function is crucial for:

• disease diagnosis and treatment
• organ transplantation
• regenerative medicine
• artificial organs

Evolution and Development

Organs evolved through increasing specialization of tissues, with:

• embryonic development showing formation patterns
• evolutionary adaptations across species
• comparative anatomy revealing common origins

The study of organs continues to reveal new insights about biological organization and the maintenance of life processes, forming a crucial bridge between cellular and systemic functions.