RESPIRATORY SYSTEM

• Respiratory System- an open system that allows oxygen to enter our body and carbon dioxide to be removed out of the body
• FUNCTIONS: 1. Gas Exchange - External Respiration – gas exchange between the lungs and the blood - Internal respiration – gas exchange between the blood and the tissues 2. Regulation of blood pH 3. Voice Production 4. Olfaction – our ability to smell 5. Innate Immunity 6. Ventilation – movement of air in and out of the lungs
• I. UPPER RESPIRATORY TRACT > extends from the nose to the larynx > kept open by cartilages (non-collapsible structures that prevent collapse of tissues)
• 1. Nose - Not only the organ for smelling but also the opening of the respiratory system - The visible structure that forms a prominent feature of the face - Contains protective structures that may prevent entry of foreign bodies • Hair • Mucus – can trap foreign bodies • Nasal turbinate – may warm a cool air or cool a warm air - Nasal vestibule – region of the nose just posterior to the external nares
• 2. Nasal Cavity - Found behind the vestibule - Extends from the external openings in the nose to the pharynx - Divided by nasal septum into right and left sides - Contains olfactory mucosa and respiratory mucosa - Mucous Membrane – moistens air and traps dust particles - Hard palate – forms the floor - Nasal conchae – prominent bony ridges; allows air to bounce around so most debris get caught by mucosa
• c. Pharynx - Common passageway of both digestive and respiratory systems - Receives area from the nasal cavity and air, food, and water from mouth
• Parts of the Pharynx 1. Nasopharynx > serves as passageway of air from the nose to the larynx > uvula closes it off when swallowing
• 2. Oropharynx > common passageway for food, liquid, and air Uvula – small, pendulous structure that partially separates the oral cavity from the oropharynx
• 3. Laryngopharynx > inferior portion of pharynx; superior to larynx
• 3. d. Larynx (Voice Box)

  • Largest cartilage of the body
  • Serves as air passageway and organ for phonation or sound production
  • Located at about the level of the 4 th to 6 th cervical vertebrae
  • consists of an outer casing of 9 cartilages that are connected to each other by muscles and ligaments (6 are paired and 3 are unpaired)
• Unpaired Cartilages: 1. Thyroid cartilage

  • most prominent cartilage
  • shield-shaped structure made of hyaline cartilage
  • also called the Adam’s apple and usually larger in men
• 2. Cricoid Cartilage - inferior to thyroid cartilage - single ring of hyaline cartilage
• 3. Epiglottis - spoon-shaped; most superior cartilage of larynx Glottis – opening of the larynx over the true vocal cords
• Paired Cartilages: 1. Arytenoid Cartilage - ladle-shaped and are attached to the vocal cords and laryngeal muscles 2. Corniculate Cartilage - cone-shaped 3. Cuneiform cartilage - rod-shaped
• II. LOWER RESPIRATORY TRACT > from the trachea to the alveoli > composed of cartilages as well and its parts are lined by smooth muscles
• 1. Trachea (Windpipe) - 4–5 in. tubular passageway for air - Located anterior to the esophagus - A straight tube whose lumen is kept open by tracheal cartilages - Carina – the center point which is the most inferior portion of trachea
• b. Bronchi - larger branches - Bronchioles – smaller branches - Terminal Bronchioles – smallest bronchioles in the bronchial tree – lead to air sacs of the lung
• * Trachea splits into two tubes which enter the lungs: Main/Primary Bronchi
• • Primary bronchi are divided into Lobar/Secondary Bronchi - branches that supply each lobe of the lung
  • Secondary bronchi are divided into Segmental/Tertiary Bronchi - The extensive branching of the bronchi produces a structure called the tracheobronchial tree
• c. Lungs

  • Located in the thoracic cavity; protected by the ribs
  • Pleural membrane encloses each lung
• Right Lung

  • has 3 lobes (upper, middle, lower)
  • divided by 2 fissures (oblique, horizontal) Left Lung
  • has 2 lobes (upper, lower)
  • divided by an oblique fissure > cardiac notch – indentation occupied by the heart
• Has 2 layers of serous membranes 1. Parietal Layer - outer membrane on the chest cavity wall 2. Visceral Layer - membrane on the surface of the lungs Pleural Cavity – between the 2 layers which contains a pleural fluid that prevent friction as the lungs expand
• Bronchopulmonary segments - segments of the lung tissue that each tertiary or segmental bronchi supplies

  • Terminal bronchioles divide into respiratory bronchioles
  • These further divide into 2–11 alveolar ducts or atria
  • Around the circumference of the alveolar ducts are alveoli and alveolar sacs
• Alveoli - epithelium and elastic basement membrane surrounded externally a capillary network
• • Alveolar sac
  • two or more that share a common opening
  • The microscopic membrane through which the respiratory gases move is this alveolocapillary (respiratory) membrane
• Conducting Zones > where air is just passing by

  • Trachea
  • Primary Bronchus
  • Secondary Bronchus
  • Tertiary Bronchus
  • Terminal Bronchus
• Respiratory Zones - where gas exchange happens

  • Respiratory Bronchioles
  • Alveolar Ducts
  • Alveolar Sacs
  • Alveoli
• CELLS IN THE ALVEOLI a. Type I Pneumocyte - make up about 90% of the alveoli and are composed of simple squamous cells b. Type II Pneumocyte (septal cells) - decrease the surface tension of the lung by secreting surfactant c. Alveolar Macrophage
• Emphysema - a disease caused by the breakdown of the alveoli - a severe reduction in the surface area of the lung
• (Respiratory Function)

  Respiration > process of gas exchange > controlled by the Central Nervous System (CNS) > brain stem contains the respiratory center which can be stimulated by chemoreceptors - special cells that detect changes in partial pressure of oxygen and carbon dioxide
• Ventilation - movement of air between the lungs and the atmosphere Perfusion - refers to the flow of blood to the lungs from the right ventricle and it is carrying greater amount of carbon dioxide > also called external respiration where there is exchange of gasses between the lungs and the blood
• MECHANICS OF BREATHING 1. Inspiration/Inhalation – an active process, meaning inspiratory muscles need to contract before inspiration happens 2. Expiration/Exhalation – a passive process, meaning no muscles need to contract during expiration
• PROTECTIVE STRUCTURES OF THE RESPIRATORY

  1. Nose - presence of hair, mucus and turbinate, trap foreign body
• 2. Pseudostratified columnar ciliated epithelium with goblet cells producing mucus - not allowing entry of foreign substances by coughing them out
• 3. Alveolar macrophages -phagocytes in the alveoli - responsible for engulfing foreign cell that has entered the alveoli
• 4. Alpha 1 antitrypsin - chemical that protects the alveolar wall against enzymatic destruction
• 5. Surfactant - chemical produced by alpha 1 antitrypsin which decrease surface tension and prevents collapse of the alveolar wall