Overview
This lesson explains how nutrients and gases are transported in the human body by the respiratory and circulatory systems, including their structures and how they work together.
The Respiratory System
- The respiratory system (breathing system) brings in oxygen and removes carbon dioxide.
- Oxygen enters the body through the nose and mouth.
- Air passes through nasal cavities, warming and cleaning it.
- The pharynx (throat) and larynx (voice box) guide air to the trachea (windpipe).
- The trachea carries air to the lungs, which have two sides: right and left.
- Bronchi are two tubes connecting the trachea to the lungs; bronchioles are smaller tubes leading to alveoli.
- Gas exchange occurs in alveoli (tiny air sacs).
- During inhalation: oxygen enters, ribs move out, chest space increases, diaphragm contracts (moves down).
- During exhalation: carbon dioxide exits, ribs move in, chest space decreases, diaphragm relaxes (moves up).
The Circulatory System
- The circulatory system (cardiovascular system) delivers nutrients and oxygen to cells and removes waste.
- Major parts: heart (pumps blood), blood vessels, and blood.
- Types of blood vessels: arteries (carry blood away from the heart), veins (carry blood toward the heart), and capillaries (where exchange occurs).
- Blood carries nutrients, oxygen, and wastes.
- The heart is about the size of a fist and has four chambers: two atria (receive blood) and two ventricles (pump blood).
- Valves in the heart prevent blood from flowing backward.
- Blood flow: body → right atrium → right ventricle → lungs (gets oxygen) → left atrium → left ventricle → body.
Respiratory and Circulatory Systems Working Together
- Oxygen enters lungs, moves to the heart, then is pumped throughout the body.
- Cells use oxygen to process nutrients and release energy, producing carbon dioxide as waste.
- Carbon dioxide returns to the heart, then is sent to the lungs to be exhaled.
Types of Circulation
- Pulmonary circulation: heart ↔ lungs.
- Coronary circulation: blood flow within the heart's tissues.
- Systemic circulation: heart ↔ rest of the body (except the lungs).
Key Terms & Definitions
- Respiratory system — brings in oxygen, removes carbon dioxide.
- Circulatory system — moves blood, nutrients, and waste.
- Alveoli — tiny sacs in the lungs for gas exchange.
- Arteries — blood vessels carrying blood away from the heart.
- Veins — blood vessels carrying blood toward the heart.
- Capillaries — smallest blood vessels for exchange.
- Atria — top chambers of the heart that receive blood.
- Ventricles — bottom chambers of the heart that pump blood.
- Pulmonary circulation — heart-lung blood flow.
- Coronary circulation — blood flow in heart tissue.
- Systemic circulation — blood flow to the body.
Action Items / Next Steps
- Review the flow of blood through the heart and lungs.
- Memorize the parts and functions of the respiratory and circulatory systems.
- Know the difference between the three types of blood vessels.