Overview
This lecture explains how the respiratory and circulatory systems transport nutrients and gases in the human body, including their main parts and how they work together.
Respiratory System
- The respiratory system (breathing system) takes in oxygen and expels carbon dioxide.
- Nose and mouth are entry points for oxygen.
- Nasal cavity warms, moistens, and cleans incoming air.
- Pharynx is the throat; larynx is the voice box.
- Trachea (windpipe) carries air to the lungs.
- Lungs are the main organs for gas exchange.
- Bronchi are two tubes connecting trachea to lungs.
- Bronchioles are small tubes leading to alveoli, where gas exchange occurs.
- During inhalation, oxygen enters, ribs move out, chest space increases, and diaphragm contracts (moves down).
- During exhalation, carbon dioxide exits, ribs move in, chest space decreases, and diaphragm relaxes (moves up).
Circulatory System
- The circulatory (cardiovascular) system delivers nutrients and oxygen, and removes waste.
- The heart pumps blood throughout the body.
- Blood vessels include arteries (away from heart), veins (towards heart), and capillaries (site of gas/nutrient exchange).
- Blood transports oxygen, nutrients, and waste.
Parts of the Heart and Blood Flow
- The heart is about the size of your fist and has four chambers: right/left atria (receiving), right/left ventricles (pumping).
- Valves between chambers prevent blood from flowing backward.
- Deoxygenated blood enters through superior/inferior vena cava, received by right atrium, passes tricuspid valve, pumped by right ventricle through pulmonary valve to pulmonary artery to the lungs.
- Oxygenated blood returns via pulmonary vein to left atrium, passes bicuspid valve, pumped by left ventricle through aortic valve to aorta and the rest of the body.
How the Systems Work Together
- Oxygen enters the lungs, goes to the heart, and is pumped through the body.
- Blood delivers oxygen and nutrients to cells; cells release energy and produce carbon dioxide as waste.
- Blood carries carbon dioxide back to the heart and then to the lungs for exhalation.
Types of Circulation
- Pulmonary circulation: heart → lungs → heart.
- Coronary circulation: blood flow within heart tissues.
- Systemic circulation: heart → whole body (except lungs) → heart.
Key Terms & Definitions
- Respiratory system — body system for breathing and gas exchange.
- Circulatory system — body system for transporting blood, nutrients, and waste.
- Trachea — windpipe carrying air to the lungs.
- Bronchi/Bronchioles — tubes directing air into lungs and alveoli.
- Alveoli — tiny sacs for gas exchange in lungs.
- Arteries — vessels carrying blood away from the heart.
- Veins — vessels carrying blood to the heart.
- Capillaries — smallest blood vessels for exchange of gases and nutrients.
- Atrium/Ventricle — heart chambers for receiving and pumping blood.
- Valve — structure preventing backward blood flow.
Action Items / Next Steps
- Review the pathways of air and blood flow through both organ systems.
- Study the differences between pulmonary, coronary, and systemic circulation.
- Memorize the main parts and functions of the respiratory and circulatory systems.