Use argument supported by evidence for how the body is a system of interacting subsystems composed of groups of cells.

Gently breathe in through your nose, mouth closed, for a count of six seconds. Don't fill your lungs too full of air. Verywell Mind articles are reviewed by board-certified physicians and mental healthcare professionals. Medical Reviewers confirm the content is thorough and accurate, reflecting the latest evidence-based research. Content is reviewed before publication and upon substantial updates. Learn more. Place one hand below your belly button, keeping your belly relaxed, and notice how it rises with each inhale and falls with each exhale. To design machines and medicines to help people whose respiratory systems are not fully functioning, engineers must thoroughly understand the human respiratory process. Some biomedical, electrical and mechanical engineers develop pulmonary function testing and diagnostic equipment (spirometers, see Figure 1), as well as artificial lungs that help seriously ill patients breathe while fighting off infections. Do you notice anything? The slow exhalation triggers your parasympathetic nervous system, lowering your blood pressure and increasing heart rate variability (HRV). A high HRV indicates your breathing and heart rate are in sync, linked to reduced stress, feelings of anger, and impulsive behavior (Cuddy, 2018).

You can choose a focus word that makes you smile, feel relaxed, or is simply neutral. Examples include peace, let go, or relax, but it can be any word that suits you to focus on and repeat through your practice.

Gently focus on the sensation of inhalation (the air coming in your nose, and your chest and stomach rising). Lion’s breath is an energizing yoga breathing practice that is said to relieve tension in your chest and face. Chen Y-F, Huang X-Y, Chien C-H, Cheng J-F. The effectiveness of diaphragmatic breathing relaxation training for reducing anxiety. Perspect Psychiatr Care. 2017 Oct;53(4):329–36. Overbreathing can cause various symptoms that can leave us feeling more stressed, including (Khazan, 2019):tonsil: Almond-shaped lymph nodes in the wall of the throat. They fight unwanted germs and can become infected. Discussion: If you were an engineer creating a set of artificial lungs, what design considerations would be important to think about? (With this open-ended design question, the teacher is looking for evidence that students are thinking about the parts of the respiratory system, its function, and what affects it. Example responses might include: Lungs should be able to stretch, lungs should be able to fit in the chest cavity, lungs should be able to carry out gas exchange, lungs should be supple, must know the person's health history, how much more the person might grow, location where the person lives and breathes, etc.) Use an oral and written argument supported by evidence to support or refute an explanation or a model for a phenomenon. Make yourself as comfortable as you can. If you can, loosen any clothes that restrict your breathing.