Lungs

• Respiratory System


  Oxygen Delivery System
• Respiratory System


  • Set of organs that allows a person to breathe and exchange oxygen and carbon dioxide throughout the body
  • Integrated system of organs involved in the intake and exchange of oxygen and carbon dioxide between the body and the environment and including the nasal passages, larynx, trachea, bronchial tubes, and lungs
• Major tasks of the respiratory system


  • Exchanging air between the body and the outside environment (external respiration)
  • Bringing oxygen to the cells and removing carbon dioxide from them (internal respiration)
• Functions of the Respiratory System


  • Supplies the body with oxygen and disposes of carbon dioxide
  • Filters inspired air
  • Produces sound
  • Contains receptors for smell
  • Rids the body of some excess water and heat
  • Helps regulate blood pH
• Breathing (pulmonary ventilation)


  1. Inhalation (inspiration) - draws gases into the lungs

  2. Exhalation (expiration) - forces gases out of the lungs
• External Respiration


  • Air from the outside environment enters the nose or mouth during inspiration (inhalation)
  • Composed of the nose and nasal cavity, paranasal sinuses, pharynx (throat), larynx
• Parts of the Respiratory System


  • Nose
  • Throat (pharynx)
  • Nostril
  • Mouth
  • Voice box (Larynx)
• Nose


  • Also called external nares
  • Divided into two halves by the nasal septum
  • Contains the paranasal sinuses where air is warmed
  • Contains cilia which is responsible for filtering out foreign bodies
• Parts of the Nose and Nasal Cavities


  • Frontal sinus
  • Nasal concha
  • Sphenoid sinus
  • Middle nasal concha
  • Internal naris
  • Inferior nasal concha
  • Nasopharynx
  • External naris
• Internal nares


  Opening to exterior
• External nares


  Opening to pharynx
• Nasal conchae


  • Folds in the mucous membrane that increase air turbulence and ensures that most air contacts the mucous membranes
• Functions of the Nose and Nasal Cavities


  • Provides an airway for respiration
  • Moistens and warms entering air
  • Filters and cleans inspired air
  • Resonating chamber for speech
  • Detects odors in the air stream
• Pharynx


  • Common space used by both the respiratory and digestive systems
  • Commonly called the throat
  • Originates posterior to the nasal and oral cavities and extends inferiorly near the level of the bifurcation of the larynx and esophagus
  • Common pathway for both air and food
  • Walls are lined by a mucosa and contain skeletal muscles that are primarily used for swallowing
  • Flexible lateral walls are distensible in order to force swallowed food into the esophagus
• Sections of the Pharynx


  • Nasopharynx
  • Oropharynx
  • Laryngopharynx
• Nasopharynx


  • Contains the pharyngeal tonsils (adenoids) which aid in the body's immune defense
• Oropharynx


  • Back portion of the mouth that contains the palatine tonsils which aid in the body's immune defense
• Laryngopharynx


  • Bottom section of the pharynx where the respiratory tract divides into the esophagus and the larynx
• Larynx


  • Voice box is a short, somewhat cylindrical airway ends in the trachea
  • Prevents swallowed materials from entering the lower respiratory tract
  • Conducts air into the lower respiratory tract
  • Produces sounds
  • Supported by a framework of nine pieces of cartilage (three individual pieces anc three cartilage pairs) that are held in place by ligaments and muscles
• Parts of the Larynx


  • Hyoid Bone
  • Epiglottis
  • Thyrahyoid Membrane
  • Cricothyroid Ligament
  • Thyroid Cartilage
  • Cricothyroid Muscles
  • Cricothyroid Cartilage
  • Trachea
• Trachea


  • A flexible tube also called windpipe
  • Extends through the mediastinum and lies anterior to the esophagus and inferior to the larynx
  • Cartilage rings reinforce and provide rigidity to the tracheal wall to ensure that the trachea remains open at all times
  • At the level of the sternal angle, the trachea bifurcates into two smaller tubes, called the right and left primary bronchi
  • Each primary bronchus projects laterally toward each lung
• Lungs


  • Each lung has a conical shape. Its wide, concave base rests upon the muscular diaphragm
  • Its superior region called the apex projects superiorly to a point that is slightly superior and posterior to the clavicle
  • Both lungs are bordered by the thoracic wall anteriorly, laterally, and posteriorly, and supported by the rib cage
  • Toward the midline, the lungs are separated from each other by the mediastinum
  • The relatively broad, rounded surface in contact with the thoracic wall is called the costal surface of the lung
• Lobes of the Lungs


  • Left lung - divided into 2 lobes by oblique fissure, smaller than the right lung, cardiac notch accommodates the heart
  • Right lung - divided into 3 lobes by oblique and horizontal fissure, located more superiorly in the body due to liver on right side
• Pleura


  • The outer surface of each lung and the adjacent internal thoracic wall are lined by a serous membrane called pleura
  • The outer surface of each lung is tightly covered by the visceral pleura
  • The internal thoracic walls, the lateral surfaces of the mediastinum, and the superior surface of the diaphragm are lined by the parietal pleura
  • The parietal and visceral pleural layers are continuous at the hilus of each lung
• Pleural Cavities


  • The potential space between the serous membrane layers is a pleural cavity
  • The pleural membranes produce a thin, serous pleural fluid that circulates in the pleural cavity and acts as a lubricant, ensuring minimal friction during breathing
  • Pleural effusion - pleuritis with too much fluid
• How Lungs Work


  1. Air enters your lungs through a system of pipes called the bronchi

  2. The alveoli are where the important work of gas exchange takes place between the air and your blood. Covering each alveolus is a whole network of little blood vessel called capillaries

  3. It is important that the air in the alveoli and the blood in the capillaries are very close together, so that oxygen and carbon dioxide can move (or diffuse) between them

  4. When you breathe in, air comes down the trachea and through the bronchi into the alveoli

  5. This fresh air has lots of oxygen in it, and some of this oxygen will travel across the walls of the alveoli into your blood stream

  6. Travelling in the opposite direction is carbon dioxide, which crosses from the blood in the capillaries into the air in the alveoli and is then breathed out

  7. In this way, you bring in to your body the oxygen that you need to live, and get rid of the waste product carbon dioxide