Respiratory system

Breathing :-

The process in which air moves in and out of the lungs is known as breathing. This is carried out through various respiratory organs. In other words, breathing is a simple give and take process.

When we breathe, we take in air rich in oxygen from the atmosphere, in return of which, we give out carbon dioxide-rich in the atmosphere which is utilized by the plants for photosynthesis.This is a continuous process and goes on throughout the life of an organism.
The process of taking in oxygen-rich air is called inhalation. On the contrary, the process of giving out air that is rich in carbon dioxide is known as exhalation.

In a day, a person breathes several times. One breath comprises one inhalation and one exhalation. In a minute, the number of times a person breathes is termed as his/her breathing rate. By calculating the breathing rate, we can know the number of times we breathed in a day.

However, the breathing rate varies which is dependant upon a person’s activity. It raises when a person is brisk walking, running or after a heavy exercise; similarly, decreases when a person is calm.

The breathing rate of an adult is 15-18 times per minute. However, during heavy exercise, breathing rate exceeds 25 times per minute.

Components of the respiratory defence system

The respiratory system consists of the upper respiratory tract (nasal passages), the airway conduction system (larynx, trachea, bronchi, bronchioles, and terminal bronchioles), and the lower respiratory tract (alveolar ducts and alveoli)

Organs in your respiratory system include your:

The 3 protective mechanisms of the respiratory system.

The respiratory system has protective mechanisms to avoid damage. In the nasal cavity, hairs and mucus trap small particles, viruses, bacteria, dust, and dirt to prevent entry. If particulates make it beyond the nose or enter via the mouth, the bronchi and bronchioles contain several protective device.

There are five functions of the respiratory system.
Gas Exchange – oxygen and carbon dioxide.
Breathing – movement of air.
Sound Production.
Olfactory Assistance – sense of smell.
Protection – from dust and microbes entering body through mucus production, cilia, and coughing.

How the lungs work:-

Lungs lie on each side of your heart inside your chest cavity. The right lung is divided into three lobes (sections), and the left lung is divided into two lobes. Your left lung is slightly smaller than your right lung, since your heart takes up some space on the left side. When you breathe in, air enters your airways and travels down into the alveoli (air sacs) in your lungs. This is where gas exchange takes place.

The airways are pipes that carry oxygen-rich air to the alveoli in your lungs. They also carry the waste gas carbon dioxide out of your lungs. The airways include these parts of your body:
Nose and linked air passages called the nasal cavity and sinuses.
Larynx (voice box)
Trachea (windpipe)
Tubes called bronchial tubes, or bronchi, and their branches
Small tubes called bronchioles that branch off of the bronchial tubes

Air comes into the body
Air first enters your body through your nose or mouth, which moistens and warms the air since cold, dry air can irritate your lungs. The air then travels past your voice box and down your windpipe. Rings of tough tissue, called cartilage, acts as a support to keep the bronchial tubes open.
Inside your lungs, the bronchial tubes branch into thousands of thinner tubes called bronchioles. The bronchioles end in clusters of tiny air sacs called alveoli.

Air fills your lungs air sac
Your lungs have about 150 million alveoli. Normally, your alveoli are elastic, meaning that their size and shape can change easily. Alveoli are able to easily expand and contract, because their insides are coated with a substance called surfactant. Surfactant reduces the work it takes to breathe by helping the lungs inflate more easily when you breathe in and preventing the lungs from collapsing when you breath out.
Each of these alveoli is made up of a mesh of tiny blood vessels called capillaries. The capillaries connect to a network of arteries and veins that move blood through your body.

Blood low in oxygen flows through the lungs
The pulmonary artery and its branches deliver blood to the capillaries that surround the alveoli. This blood is rich in carbon dioxide and low in oxygen.

Oxygen flows into the blood
Carbon dioxide moves from the blood into the air inside the alveoli. At the same time, oxygen moves from the air into the blood in the capillaries.


When the lungs exhale, the diaphragm relaxes, and the volume of the thoracic cavity decreases, while the pressure within it increases. As a result, the lungs contract and air is forced out.


When you breathe in, or inhale, your diaphragm contracts and moves downward. This increases the space in your chest cavity, and your lungs expand into it. . They contract to pull your rib cage both upward and outward when you inhale. As your lungs expand, air is sucked in through your nose or mouth.

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