Respiratory System Overview

Respiratory System Functions

• On average, people breathe in and out 15 times per minute, moving more than 10,000 liters of air in and out of the lungs daily.
• Breathing rate increases with physical activity.
• The respiratory system provides oxygen to the body and removes carbon dioxide, a byproduct of energy production.
• It works closely with the circulatory system to transport these substances.

Respiratory System Components

• The respiratory system consists of the nasal cavity, mouth, pharynx, trachea, bronchi, lungs, and diaphragm.

Respiratory System Pathway of Air

• Air travels from the mouth or nose, through the pharynx, trachea, bronchi, and into the bronchioles, ultimately reaching the alveoli in the lungs.
• Inside the lungs, bronchioles branch into alveoli, where gas exchange occurs.

Trachea (Windpipe)

• The trachea is supported by cartilage rings for strength and flexibility.
• It keeps the airway open.
• Ciliated epithelial cells produce mucus to trap and remove foreign particles (like dust).
• Hair-like projections called cilia move the mucus and debris out of the airways.

Bronchi and Bronchioles

• The trachea branches into two bronchi, one for each lung.
• Bronchi further divide into progressively smaller tubes called bronchioles.
• Epithelial cells in bronchi produce mucus to help filter air.
• Cilia help with filtering air.
• Bronchioles further branch into tiny air sacs called alveoli.

Alveoli

• Alveoli are tiny air sacs at the end of bronchioles.
• They have thin walls surrounded by capillaries, facilitating efficient gas exchange.
• Oxygen from the air diffuses into the blood.
• Carbon dioxide from the blood diffuses into the alveoli.

Alveoli: Gas Exchange

• The circulatory system supplies blood to the lungs.
• The concentration of oxygen in the blood is lower than in the air in the alveoli.
• Oxygen diffuses from the air in the alveoli into the blood.
• Carbon dioxide diffuses from the blood into the alveoli.

Diaphragm

• The diaphragm is a thin, dome-shaped muscle beneath the ribs.
• When relaxed, it is dome-shaped.
• When contracted, it flattens, increasing the volume of the chest cavity.

Breathing

• Breathing is an involuntary process controlled by the brain.
• The brain monitors carbon dioxide levels in the blood.
• Higher carbon dioxide levels trigger an increase in breathing rate and heart rate.

Inhalation

• Inhalation involves the contraction of the diaphragm and intercostal muscles (muscles between the ribs).
• This action increases the volume of the chest cavity.
• The increased volume causes a decrease in pressure, allowing air to rush into the lungs.

Exhalation

• Exhalation happens when the diaphragm and intercostal muscles relax.
• This action decreases the volume of the chest cavity.
• The decrease in volume causes an increase in pressure, forcing air out of the lungs.

Diseases of the Respiratory System

• Tuberculosis (TB): An infectious disease caused by bacteria that can affect the lungs and other parts of the body.
• Lung Cancer: A serious disease caused by tobacco smoke, containing carcinogens.

Respiratory Systems in Other Animals (Fish)

• Fish use gills for respiration, which are specialized organs for gas exchange.
• Oxygen from the water diffuses into the blood in the gills, and carbon dioxide diffuses from the blood into the water.

Homework

• Read pages 91-95 in the textbook and answer questions 2-4 on page 95.