Overview of the Respiratory System and Its Functions

Primary function of the respiratory system

To support gas exchange by taking in oxygen and removing carbon dioxide. It also helps regulate body temperature, produce sound, and house sensory neurons for smell.

Main functions of the respiratory system

Breathing (pulmonary ventilation), Gas exchange (oxygen and carbon dioxide), Vocal sound production via the vocal cords, Body temperature regulation by expelling heat, Sense of smell (olfaction)

Three processes involved in gas delivery

1. Pulmonary ventilation (physical movement of air) 2. Respiration (gas exchange) 3. Oxygenation (oxygen delivery to cells)

Pulmonary ventilation

The physical act of breathing, including inhalation (air in) and exhalation (air out).

Respiration and its two types

The exchange of gases in the body. • External respiration: Exchange between air in lungs and bloodstream • Internal respiration: Exchange between bloodstream and body tissues

Oxygenation process

The process of supplying oxygen to body cells during external respiration. Steps: 1. O₂ enters red blood cells and binds with hemoglobin. 2. Red blood cells travel through the bloodstream. 3. Oxygen is released to tissue cells for use.

Two main divisions of the respiratory system

• Upper respiratory tract: Nose, nasal cavity, sinuses, pharynx, larynx • Lower respiratory tract: Trachea, bronchial tree, lungs

Function of the nose in respiration

Primary air passageway. It filters air using nasal hairs and mucus and warms/moistens it before it enters deeper airways.

How the mouth helps the respiratory system

It provides an alternative air passage, especially during high oxygen demand.

Function of the nasal cavity and sinuses

• Moistens and filters air • Regulates air temperature • Enhances voice resonance

Pharynx and its function

A muscular tube behind the nasal cavity and mouth that channels air to the larynx and food to the esophagus.

Epiglottis and its function

A flap of cartilage that directs food into the esophagus and keeps it out of the respiratory tract by closing over the larynx when swallowing.

Structures contained in the larynx

• Vocal cords • Thyroid cartilage • Cricoid cartilage

Trachea and its role in the respiratory system

A tube that connects the upper airway to the lungs. It transports air and warms/moistens it before it reaches the lungs.

Carina

A ridge of cartilage at the base of the trachea that splits airflow into the right and left bronchi.

Lungs and their coverings

Soft, spongy organs for gas exchange. Covered by a double membrane called the pleura, with pleural fluid to reduce friction during breathing.

Difference between bronchi and bronchioles

• Bronchi are large, cartilage-supported airways that branch from the trachea. • Bronchioles are smaller, narrower airways that branch from the bronchi and lead to the alveoli.

Alveoli and their function

Tiny air sacs surrounded by capillaries where gas exchange (O₂ and CO₂) occurs. There are about 500 million in adult lungs.

Tuberculosis (TB)

A contagious bacterial infection that usually attacks the lungs and can spread through airborne droplets.

Asthma

A chronic condition where bronchial tubes become inflamed and constricted, making breathing difficult.

Atelectasis

A complete or partial collapse of a lung, leading to reduced or absent gas exchange.

Emphysema and its effect

Caused by damage to alveoli, reducing oxygen exchange and leading to shortness of breath.

Lung cancer (lung carcinoma)

A malignant tumor in the lungs caused by uncontrolled cell growth, often due to smoking or environmental factors.

Chronic Obstructive Pulmonary Disease (COPD)

A group of chronic conditions that block airflow in the lungs. Includes: • Emphysema • Chronic bronchitis • Chronic obstructive asthma

Pneumonia

An infection that inflames alveoli in the lungs, often filling them with fluid or pus, which impairs oxygen exchange.