Overview
This lecture covers how the respiratory and circulatory systems transport nutrients and gases throughout the body, including the main parts, their functions, and how the systems work together.
Respiratory System
- The respiratory system (breathing system) brings in oxygen and expels carbon dioxide.
- Main parts: nose and mouth (oxygen entry), nasal cavity (warms and cleans air), pharynx (throat), larynx (voice box), trachea (windpipe), lungs (main organs; right and left), bronchi (two branches to lungs), bronchioles (small branches), alveoli (site of gas exchange).
- Inhalation: oxygen enters, ribs move out, chest space increases, diaphragm contracts (moves down).
- Exhalation: carbon dioxide exits, ribs move in, chest space decreases, diaphragm relaxes (moves up).
Circulatory System
- The circulatory system (cardiovascular system) delivers nutrients, oxygen, and removes waste.
- Main parts: heart (pumps blood), blood vessels (carry blood), and blood itself.
- Three types of blood vessels: arteries (carry blood from heart), veins (carry blood to heart), capillaries (smallest vessels for exchange of gases/nutrients).
- The heart is a hollow muscle about the size of your fist.
Heart Structure & Blood Flow
- Heart has four chambers: right and left atria (receive blood), right and left ventricles (pump blood).
- Valves between chambers prevent backflow (e.g., tricuspid and bicuspid valves).
- Deoxygenated blood flows from the body to the right atrium, through the tricuspid valve, to right ventricle, through pulmonary valve to lungs via pulmonary artery.
- Oxygenated blood returns from lungs to left atrium via pulmonary vein, through bicuspid valve, to left ventricle, through aortic valve, exits through the aorta to the body.
Integration of Systems
- Oxygen from air enters lungs, passes into blood, heart pumps oxygenated blood to body cells.
- Cells use oxygen to release energy; carbon dioxide produced as waste.
- Blood carries carbon dioxide back to the right side of the heart, then to lungs to be exhaled.
Types of Circulation
- Pulmonary circulation: blood moves heart → lungs → heart.
- Coronary circulation: blood supplies heart tissue itself.
- Systemic circulation: blood moves heart → entire body (except lungs) → heart.
Key Terms & Definitions
- Respiratory System — organs for breathing and gas exchange.
- Circulatory System — organs for transporting blood, nutrients, and wastes.
- Alveoli — small lung sacs where oxygen and carbon dioxide are exchanged.
- Arteries — vessels carrying blood away from heart.
- Veins — vessels carrying blood towards heart.
- Capillaries — tiny vessels where exchange with tissues occurs.
- Atrium (Atria) — upper heart chambers that receive blood.
- Ventricle — lower heart chambers that pump blood out.
- Diaphragm — muscle aiding in breathing.
Action Items / Next Steps
- Review diagrams of the respiratory and circulatory systems.
- Know the pathway of blood flow through the heart and lungs.
- Be able to explain how the two systems work together.