The human respiratory system is the system which controls breathing and enables us to breathe. Breathing includes inhaling and exhaling of the air in the body, absorption of the oxygen from air into our body for providing energy, and removal of carbon dioxide (by-product of the respiration) out of our body.
The primary organ where respiration takes place is the lungs. Oxygen from the lungs is collected by the red blood cells and transported to the places it is needed while at the same time, carbon dioxide is transported back to the lungs by the red blood cells in order for removal from the body.
WHY DOES RESPIRATION TAKE PLACE?
Human body requires oxygen for living. Hypoxia is a condition where there is decrease in oxygen and Anoxia is when there is no oxygen whatsoever. Without oxygen, the brain cells start to die, even within four minutes, and can lead to brain damage or death.
The rate of breathing differs with age. A baby breathes almost 40 times per minute which slows down to 20-40 while in sleep. On the other hand, an adult breathes for 12-16 breaths per minute. During exercise, breathing can even increase to 45 breaths per minute.
PARTS OF RESPIRATORY SYSTEM
Oxygen enters the nose and passes the sinuses (hollow spaces in skull) during inhalation. Sinuses act as regulators of temperature and the humidity present in the air that we inhale. Trachea is the windpipe which filters the inhaled air.
Trachea further branches into bronchi (two air carrying tubes). Cilia (tiny hairs lining the bronchial tubes) move and carry mucus (the sticky fluid that collects germs, dust and other unwanted matter invading our lungs). We remove mucus by sneezing, coughing, spitting or swallowing.
Bronchi lead to lobes of lungs. Right lung has three lobes while left lung has only two lobes. Lobes have spongy small sacs called alveoli (a place where the exchange of oxygen and the carbon dioxide takes place).
Alveolar walls are thin and are composed of epithelial cell (single layer of tissue) and pulmonary capillaries (tiny blood vessels). Pulmonary artery carries blood which is rich in carbon dioxide to the air sacs and the gas is exhaled. The oxygen rich blood is carried by pulmonary vein and goes straight to the heart for pumping.
A dome shaped muscles called diaphragm controls the breathing, separating chest cavity from the abdominal cavity. During inhalation, diaphragm flattens out and pulls forward, giving more space to the lungs. During exhalation, diaphragm gets expanded and the air is pushed out.