Key Terms for Respiratory & Circulatory Systems
Ever wonder how oxygen gets from the air to your toes? Your respiratory system starts with air entering your nasal cavity (nose), traveling through your pharynx (throat) and larynx (voice box), down your trachea (windpipe), into the bronchi, and finally reaching tiny air sacs called alveoli where gas exchange happens.
Breathing involves two main processes. During inhalation, your diaphragm (the muscle below your lungs) contracts while intercostal muscles between your ribs lift upward, expanding your chest cavity and drawing air in. During exhalation, these muscles relax, pushing air out.
Your circulatory system takes over from there! The heart pumps blood through blood vessels including arteries (carrying blood away from the heart), veins (returning blood to the heart), and tiny capillaries where nutrients and gases are exchanged with cells. Blood itself consists of cells suspended in a liquid called plasma.
💡 Fun fact: Your heart has four chambers - two upper atria that receive blood and two lower ventricles that pump it out. These chambers are separated by a wall called the septum to keep oxygenated and deoxygenated blood from mixing!
