Respiratory System Overview

Overview

The respiratory system is a complex biological process that brings oxygen into the body and removes carbon dioxide. It is essential for the survival of all living organisms.

Functions

• Brings oxygen into the body
• Removes carbon dioxide from the body
• Regulates pH levels by removing hydrogen ions

Organs Involved

• Nose and mouth (entry points for oxygen)
• Trachea (windpipe)
• Bronchi (airways)
• Lungs (gas exchange)
• Diaphragm (muscle that separates chest cavity from abdominal cavity)
• Intercostal muscles (muscles between ribs that help expand chest cavity)

Process of Breathing

1. Inhalation:
   • Diaphragm contracts and flattens
   • Intercostal muscles contract and ribs move outward
   • Chest cavity expands and air enters nostrils or mouth
   • Air passes through trachea and into bronchi
   • Air enters lungs and oxygen diffuses into bloodstream
2. Exhalation:
   • Diaphragm relaxes and rises
   • Intercostal muscles relax and ribs move inward
   • Chest cavity decreases in size and air is pushed out of lungs
   • Air passes out of nostrils or mouth

Gas Exchange

• Occurs in alveoli (small air sacs in lungs)
• Oxygen diffuses from alveoli into bloodstream
• Carbon dioxide diffuses from bloodstream into alveoli
• Oxygen-rich blood transported to heart and pumped to body
• Carbon dioxide-rich blood transported to heart and pumped to lungs for exhalation

Respiratory System Overview

• The respiratory system is a complex biological process that brings oxygen into the body and removes carbon dioxide, essential for the survival of all living organisms.

Functions

• Brings oxygen into the body through inhalation
• Removes carbon dioxide from the body through exhalation
• Regulates pH levels by removing hydrogen ions

Organs Involved

• Nose and mouth: entry points for oxygen
• Trachea: windpipe that passes air into bronchi
• Bronchi: airways that branch into lungs
• Lungs: site of gas exchange, where oxygen is absorbed and carbon dioxide is removed
• Diaphragm: muscle that separates chest cavity from abdominal cavity, contracts and relaxes to facilitate breathing
• Intercostal muscles: muscles between ribs that help expand chest cavity during inhalation

Breathing Process

• Inhalation: diaphragm contracts and flattens, intercostal muscles contract, and chest cavity expands, allowing air to enter nostrils or mouth and pass into lungs
• Exhalation: diaphragm relaxes and rises, intercostal muscles relax, and chest cavity decreases in size, pushing air out of lungs

Gas Exchange

• Occurs in alveoli, small air sacs in lungs
• Oxygen diffuses from alveoli into bloodstream
• Carbon dioxide diffuses from bloodstream into alveoli
• Oxygen-rich blood is transported to heart and pumped to body
• Carbon dioxide-rich blood is transported to heart and pumped to lungs for exhalation

Lungs Structure

• Protected by the rib cage in the thoracic cavity
• Consist of 2 lungs, each divided into lobes (right lung: 3 lobes, left lung: 2 lobes)
• Composed of alveoli, bronchi, bronchioles, and pleura

Alveoli

• Tiny air sacs where gas exchange occurs
• Responsible for exchanging oxygen and carbon dioxide between the lungs and bloodstream

Bronchi and Bronchioles

• Airways that branch into smaller tubes (bronchi) and lead to alveoli (bronchioles)
• Enable air to reach the alveoli for gas exchange

Pleura

• Double-layered membrane that surrounds the lungs
• Protects the lungs and allows for expansion and contraction

Gas Exchange

• Occurs in the alveoli, where oxygen diffuses into the bloodstream and carbon dioxide diffuses out
• Factors affecting gas exchange:
  • Surface area: larger surface area increases gas exchange
  • Thickness: thinner membrane increases gas exchange
  • Partial pressure: difference in pressure between oxygen and carbon dioxide

Oxygenation

• Oxygen diffuses from the alveoli into the pulmonary capillaries
• Bound to hemoglobin in red blood cells, forming oxyhemoglobin
• Oxygen-rich blood is transported to the heart and then to the body

Breathing Process

• Involves inspiration and expiration
• Inspiration:
  • Diaphragm contracts
  • Rib cage expands
  • Air enters the lungs
• Expiration:
  • Diaphragm relaxes
  • Rib cage descends
  • Air leaves the lungs

Respiratory Control

• Controlled by the nervous system
• Brainstem: regulates automatic breathing
• Voluntary control: can override automatic breathing

Respiratory Muscles

• Diaphragm:
  • Primary muscle of inspiration
  • Contracts and relaxes to change the volume of the thoracic cavity
• Intercostal muscles:
  • Assist the diaphragm in expanding the thoracic cavity
  • Located between the ribs
• Accessory muscles:
  • Used during forced breathing or heavy exercise
  • Include muscles of the neck, back, and abdomen