Respiratory System Overview

Respiratory System Overview

• The respiratory system is a group of organs that provides oxygen to living things and removes waste products like carbon dioxide.
• Respiration isn't the same as breathing. Respiration is the entire process of bringing oxygen into the body, distributing it to cells, and removing carbon dioxide. Breathing is only one part of respiration.

Steps of Respiration in Humans

• 1. Breathing:

  • Inspiration (inhaling): Taking in oxygen-rich air into the lungs.
  • Expiration (exhaling): Removing waste air from the lungs.

• 2. External Respiration:

  • This is the exchange of gases (oxygen and carbon dioxide) between the lungs and the blood.
  • Gas exchange involves delivering oxygen from the lungs to the blood and removing carbon dioxide from the blood to the lungs.

• 3. Internal Respiration:

  • The exchange of gases (oxygen and carbon dioxide) between the blood and body's tissue cells.

• 4. Cellular Respiration:

  • The series of energy-releasing chemical reactions in the cells (inside mitochondria). This process uses oxygen and releases carbon dioxide as a waste product.

Composition of Air

• The air we breathe is mostly nitrogen (78%). Oxygen makes up 21% and carbon dioxide and other trace elements, like argon, make up the remaining 1%. A common misconception is we breathe in pure oxygen and exhale pure carbon dioxide. That's not accurate.

General Functions of the Respiratory System

• The primary function is to facilitate gas exchange, enabling the intake of oxygen for cellular needs and the removal of carbon dioxide produced by cells. This also maintains blood pH balance.
• Breathing and sound production are additional roles.

Human Adaptations for Efficient Gas Exchange

• Water must be present in the respiratory surface; gases are dissolved in water, allowing respiration in moist environments.
• The respiratory surface must be adequately large to support the necessary rate of gas exchange.

Main Respiratory Organs in Humans

• The lungs are the central organs of respiration in humans. Lungs are located deep within the body and require specialized pathways for air from the outside to reach the inner respiratory surfaces. This is the respiratory tract.

Anatomy of the Upper Respiratory Tract

• Nose and Mouth: Entry points for air and food. The nasal cavity filters and warms the air.
• Pharynx: Connects the nasal and oral cavities to the larynx. Filters food and air.
• Epiglottis: A flap that prevents food from entering the trachea.
• Larynx: Contains vocal chords for sound production.
• Trachea: Conducts air to and from the lungs; a passageway lined with cilia and mucus for filtration.

Anatomy of the Lower Respiratory Tract

• Bronchi: Tubes that branch off from the trachea, leading air into the lungs.
• Bronchioles: Smaller branches of bronchi, delivering air to smaller regions of the lung.
• Alveoli: Tiny air sacs in the lungs where gas exchange occurs.
• Pleural Membrane: The membrane surrounding and protecting the lungs (two layers reducing internal friction) to allow efficient gas exchange.

Structure of the Bronchi/Bronchioles

• Bronchi: Each bronchus (singular) leads to a separate lung.
• Bronchioles: Highly branching tubes that increase surface area to allow effective oxygen exchange.

Human Lung Structure

• The trachea branches into two bronchi.
• One bronchus enters each lung. The lungs are surrounded by the pleural membrane which is a thin flexible sac with two layers and fluid between the layers reducing internal friction.
• The right lung has three lobes, and the left has two lobes.

Function and Structure of the Diaphragm and Intercostal Muscles

• Diaphragm: A dome-shaped muscle, separating the lungs from the stomach and liver, contracting to expand the thoracic cavity, decreasing pressure, creating space for air to enter.
• Intercostal Muscles: Muscles between the ribs; contracting to expand the rib cage, promoting inhalation. When they relax, the rib cage and lungs return to their normal size, exhaling.

Mechanics of Breathing

• Inhalation and exhalation involve coordinated movements of the diaphragm and intercostal muscles.
• The brain's respiratory center controls these movements to maintain continuous air exchange.
• Air does not flow into and out of the lungs spontaneously. The brain regulates the process.

Pleural Membrane Protection

• The constant movement of the lungs would cause friction on delicate tissues.
• The pleural membrane, with fluid, reduces friction between the lungs and the chest cavity during respiration. This allows efficient breathing. The membrane protects the respiratory system from irritation during respiration.

Explore the intricate functions of the respiratory system, focusing on the steps of respiration in humans. Understand the differences between breathing and respiration, and learn how oxygen and carbon dioxide are exchanged in various processes. Perfect for students studying human biology or anatomy.