Respiratory System

Main Parts and Functions

The respiratory system is responsible for the exchange of gases (oxygen and carbon dioxide) between the body and the environment.

Nose:
- Function: Filters, warms, and moistens the inhaled air. Contains olfactory receptors for smell.
Pharynx (Throat):
- Function: A common passageway for both air and food. Connects the nasal cavity and mouth to the larynx and esophagus.
Larynx (Voice Box):
- Function: Contains vocal cords and is responsible for sound production (voice).
Trachea (Windpipe):
- Function: A tube that carries air from the larynx to the bronchi. It is supported by C-shaped cartilaginous rings to prevent collapse.
Bronchi:
- Function: The trachea divides into two main bronchi, one leading to each lung. They further branch into smaller bronchioles, carrying air into the lungs.
Lungs:
- Function: The primary organs of respiration, where gas exchange occurs in tiny air sacs called alveoli.

Feature	Respiration	Breathing
Process	Biochemical process (cellular level)	Physical process (mechanical)
Energy	Releases energy from food	Involves intake and expulsion of air
Location	Occurs inside cells (mitochondria)	Occurs in the lungs and respiratory passages
Enzymes	Involves many enzymes	No enzymes involved

Breathing is a physical process involving two main phases: inhalation and exhalation.

Inhalation (Breathing In):
- Diaphragm: Contracts and moves downwards.
- Ribs: Intercostal muscles contract, pulling the ribs upwards and outwards.
- Effect: This increases the volume of the chest cavity, reducing the pressure inside the lungs. Air from the outside (higher pressure) rushes into the lungs (lower pressure).
Exhalation (Breathing Out):
- Diaphragm: Relaxes and moves upwards.
- Ribs: Intercostal muscles relax, allowing the ribs to move downwards and inwards.
- Effect: This decreases the volume of the chest cavity, increasing the pressure inside the lungs. Air from the lungs (higher pressure) is forced out.

Asthma: A chronic inflammatory disease of the airways that causes difficulty breathing, wheezing, coughing, and chest tightness.
Bronchitis: Inflammation of the lining of the bronchial tubes, which carry air to and from the lungs, causing a cough with mucus.
Pneumonia: An infection that inflames the air sacs in one or both lungs, which may fill with fluid or pus, causing cough, fever, chills, and difficulty breathing.
Tuberculosis (T.B.): A serious infectious bacterial disease that mainly affects the lungs but can also affect other parts of the body.