Human Respiratory System Overview

Primary Function of the Respiratory System

• The primary function is to facilitate gas exchange, taking in oxygen and releasing carbon dioxide.

Air Pathway During Inhalation

• Air enters through the nose or mouth.
• Passes through the pharynx (throat).
• Travels through the larynx (voice box).
• Enters the trachea (windpipe).
• Branches into two bronchi, leading to each lung.
• Bronchi further divide into smaller tubes called bronchioles.
• Bronchioles end in tiny air sacs called alveoli.

Role of the Diaphragm in Breathing

• The diaphragm is a dome-shaped muscle located beneath the lungs.
• During inhalation, the diaphragm contracts and flattens, increasing the volume of the chest cavity.
• This creates a lower pressure in the lungs, drawing air in.
• During exhalation, the diaphragm relaxes and returns to its dome shape, decreasing the chest cavity volume.
• This increases pressure in the lungs, forcing air out.

Oxygen Entry into the Bloodstream

• Oxygen diffuses from the alveoli into the capillaries surrounding them.
• Capillaries are tiny blood vessels.
• Oxygen binds to hemoglobin in red blood cells, carrying it throughout the body.

Alveoli Description

• Alveoli are tiny air sacs in the lungs where gas exchange occurs.
• Their thin walls allow for efficient diffusion of gases.
• Their large surface area maximizes gas exchange.

Exhalation of Carbon Dioxide

• Carbon dioxide, a waste product of cellular respiration, diffuses from the blood into the alveoli.
• This is the reverse process of oxygen diffusion.
• Exhaled air carries away the carbon dioxide.

Inhaling vs. Exhaling

• Inhalation: Active process involving muscle contraction (diaphragm) to increase lung volume and decrease pressure.
• Exhalation: Passive process involving muscle relaxation (diaphragm) to decrease lung volume and increase pressure.

Damaged Alveoli Consequences

• Damaged alveoli impair gas exchange.
• Lung function decreases, potentially leading to breathing difficulties and respiratory illnesses.

Asthma Description and Impact

• Asthma is a chronic respiratory condition characterized by inflammation and narrowing of the airways.
• This narrowing makes breathing difficult and can cause wheezing, coughing, and shortness of breath.

Smoking Impact on the Respiratory System

• Smoking damages the alveoli, reducing their surface area and impairing gas exchange.
• It can lead to chronic bronchitis and emphysema.
• Increased risk of respiratory infections and lung cancer.