The Respiratory System

Overview

• The respiratory system is responsible for bringing oxygen into the body and removing carbon dioxide.
• It consists of the upper and lower respiratory tracts, lungs, and breathing muscles.

Upper Respiratory Tract

• Includes the nose, mouth, pharynx, larynx, and trachea
• Responsible for:
  • Filtering, warming, and humidifying inhaled air
  • Detecting and removing foreign particles and pathogens
  • Regulating airflow and pressure

Lower Respiratory Tract

• Includes the bronchi, bronchioles, and alveoli
• Responsible for:
  • Exchanging oxygen and carbon dioxide through gas exchange
  • Regulating gas exchange through ventilation and perfusion

Lungs

• Paired organs located in the thoracic cavity
• Composed of:
  • Bronchi and bronchioles (airways)
  • Alveoli (gas exchange units)
  • Pleura (outer lining)
• Functions:
  • Gas exchange
  • Oxygenation of blood
  • Removal of carbon dioxide

Breathing Muscles

• Diaphragm: primary muscle responsible for inhalation
• Intercostal muscles: assist with inhalation and exhalation
• Accessory muscles: used during forced breathing (e.g., sternocleidomastoid and scalene muscles)

Ventilation

• Process of moving air in and out of the lungs
• Types:
  • Inspiration (inhalation): diaphragm contracts, rib cage expands
  • Expiration (exhalation): diaphragm relaxes, rib cage descends
• Regulation:
  • Controlled by the brainstem's respiratory center
  • Influenced by factors such as CO2 levels, O2 levels, and pH

Gas Exchange

• Process of exchanging oxygen and carbon dioxide between the lungs and bloodstream
• Occurs in the alveoli through diffusion
• Factors affecting gas exchange:
  • Ventilation-perfusion ratio
  • Alveolar surface area and thickness
  • Oxygen and carbon dioxide partial pressures

Respiratory System Overview

• Brings oxygen into the body and removes carbon dioxide
• Consists of upper and lower respiratory tracts, lungs, and breathing muscles

Upper Respiratory Tract

• Components: nose, mouth, pharynx, larynx, and trachea
• Functions:
  • Filters, warms, and humidifies inhaled air
  • Detects and removes foreign particles and pathogens
  • Regulates airflow and pressure

Lower Respiratory Tract

• Components: bronchi, bronchioles, and alveoli
• Functions:
  • Exchanges oxygen and carbon dioxide through gas exchange
  • Regulates gas exchange through ventilation and perfusion

Lungs

• Paired organs in the thoracic cavity
• Components:
  • Bronchi and bronchioles (airways)
  • Alveoli (gas exchange units)
  • Pleura (outer lining)
• Functions:
  • Gas exchange
  • Oxygenates blood
  • Removes carbon dioxide

Breathing Muscles

• Diaphragm: primary muscle for inhalation
• Intercostal muscles: assist with inhalation and exhalation
• Accessory muscles: used during forced breathing (e.g., sternocleidomastoid and scalene muscles)

Ventilation

• Process of moving air in and out of the lungs
• Types:
  • Inspiration (inhalation): diaphragm contracts, rib cage expands
  • Expiration (exhalation): diaphragm relaxes, rib cage descends
• Regulation:
  • Controlled by the brainstem's respiratory center
  • Influenced by CO2 levels, O2 levels, and pH

Gas Exchange

• Process of exchanging oxygen and carbon dioxide between lungs and bloodstream
• Occurs in alveoli through diffusion
• Factors affecting gas exchange:
  • Ventilation-perfusion ratio
  • Alveolar surface area and thickness
  • Oxygen and carbon dioxide partial pressures

Lungs

Structure

• Located in the thoracic cavity, protected by the rib cage
• Divided into two parts: left and right lung
• Each lung has an apex (upper part), base (lower part), and hilum (region where bronchi, blood vessels, and nerves enter)

Functions

• Responsible for gas exchange (oxygen and carbon dioxide)
• Filter out dust, bacteria, and other particles from inhaled air
• Regulate pH levels by removing excess hydrogen ions

Respiratory Pathway

• Bronchi: airways that branch into smaller tubes, eventually leading to alveoli
• Bronchioles: smaller airways that branch from bronchi
• Alveoli: tiny sacs where gas exchange occurs
• Alveoli characteristics: richly supplied with capillaries for efficient exchange

Lung Membrane

• Pleura: double-layered membrane surrounding the lung, with a space between the layers (pleural space) that contains fluid

Lung Tissue

• Alveolar epithelium: thin layer of cells lining the alveoli
• Type I pneumocytes: squamous cells that form the majority of the alveolar epithelium
• Type II pneumocytes: cuboidal cells that produce surfactant, a substance that reduces surface tension and helps expand the lungs

Blood Supply

• Pulmonary arteries: carry deoxygenated blood from the heart to the lungs
• Pulmonary veins: carry oxygenated blood from the lungs to the heart

Nerve Supply

• Vagus nerve: responsible for regulating breathing rate and depth
• Phrenic nerve: responsible for controlling diaphragm movement