Respiratory and Circulatory Systems in the Human Body

Respiratory System

This system oxygenates the blood and removes carbon dioxide. It consists of the lungs and airways.

Components of the Respiratory System

• Nostrils: Two cavities that warm and humidify the air.
• Pharynx: Common tube leading to the larynx.
• Larynx: Contains the vocal cords.
• Trachea: Carries air to the lungs.
• Lungs: Facilitate gas exchange.
• Bronchi: Two conduits that branch into smaller bronchioles, eventually forming pulmonary alveoli.

Oxygen and carbon dioxide exchange occurs in the pulmonary alveoli by diffusion, moving from areas of high concentration to low concentration.

The Internal Environment

The fluids surrounding the cells of an organism provide nutrients and oxygen to the cells and remove waste products. These fluids consist of:

• Interstitial Fluid: Fluid between cells.
• Blood: Contained within blood vessels.
• Lymph: Found in the lymphatic system.

Double Circulation

The circulatory system is called "double" because blood passes through the heart twice in one complete circuit. This system is "complete" because oxygenated and deoxygenated blood do not mix.

Types of Circulation

• Pulmonary Circulation: Between the heart and lungs. Deoxygenated blood travels to the lungs to release carbon dioxide and absorb oxygen. Oxygenated blood then returns to the heart.
• Systemic Circulation: Carries oxygenated blood from the heart to the rest of the body, delivering oxygen and nutrients while collecting carbon dioxide and other waste products. This oxygenated blood travels through the aorta, branching into smaller arteries and capillaries within the organs.

Lymphatic Circulation

• Collects excess fluids between cells and transports them back to the circulatory system.
• Lymphatic Capillaries: Absorb interstitial fluid.
• Lymphatic Vessels: Carry lymph toward the circulatory system.
• Lymph Nodes: Filter waste and foreign substances, and play a role in the development and maturation of certain white blood cells.

Circulatory System Diseases

• Atherosclerosis: Hardening of the arteries due to cholesterol buildup, which can lead to blockages and disrupt blood flow.
• Myocardial Infarction (MI): Interruption of blood flow to the heart.

Urinary System

This system eliminates waste products from the blood.

Components of the Urinary System

• Kidneys: Composed of nephrons that filter waste from the blood to produce urine.
• Urinary Tract: Transports urine from the kidneys to the outside of the body. It includes the ureters, bladder, and urethra.

Other Excretory Organs

• Lungs: Remove carbon dioxide during respiration.
• Liver: Processes waste from digestion and produces urea.
• Sweat Glands: Produce sweat, which helps regulate body temperature.