Overview

This topic examines the major organ systems in animals and how they work together to maintain homeostasis. It includes system-specific functions such as circulation, digestion, respiration, excretion, immune defense, and coordination by the nervous and endocrine systems.

Key Concepts and Structures

• Homeostasis: The process by which internal conditions are maintained within a narrow range despite external changes (e.g., body temperature, pH, glucose levels).
• Circulatory System: Includes the heart, blood, and blood vessels. Transports oxygen, nutrients, and hormones while removing wastes.
• Respiratory System: Brings oxygen into the body and removes carbon dioxide. Gas exchange occurs in the alveoli of the lungs.
• Digestive System: Breaks down food into nutrients for absorption and eliminates undigested waste. Includes mouth, esophagus, stomach, intestines, and accessory organs.
• Excretory System: Removes metabolic waste from the blood through structures like the kidneys, ureters, bladder, and urethra.
• Nervous System: Detects and responds to stimuli through a network of neurons. Coordinates voluntary and involuntary functions using the brain, spinal cord, and peripheral nerves.
• Endocrine System: Uses hormones released into the bloodstream by glands (e.g., pituitary, thyroid, pancreas) to regulate body processes over time.
• Immune System: Defends against pathogens using white blood cells, antibodies, and barriers like the skin. Includes both innate and adaptive responses.
• Musculoskeletal System: Provides structure, support, and movement. Muscles contract to move bones at joints, coordinated by nervous signals.
• Integumentary System: Protects the body with skin, hair, and nails. Assists in temperature regulation and barrier defense.

Quick Tip