Respiratory System Anatomy Quiz

Respiratory System Anatomy

• The upper respiratory tract includes the nose, pharynx, and associated structures.
• The lower respiratory tract includes the larynx, trachea, bronchi, and lungs.

Conducting Zone

• The conducting zone brings air to the site of external respiration.
• It includes the nose, pharynx, larynx, trachea, bronchi, bronchioles, and terminal bronchioles.

Respiratory Zone

• The respiratory zone is the main site of gas exchange.
• It is made up of respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli.

Air Traversal Through Respiratory Tract

• Air passes through the nasal cavity, pharynx, larynx, trachea, primary bronchi, secondary bronchi, tertiary bronchi, bronchioles, and alveoli (150 million/lung).

Nasal Conchae

• Increase the surface area of the nasal cavity.
• Allows more air to contact the cavity walls.
• Helps warm and humidify the air before it reaches the lungs.
• Nasolacrimal duct drains secretions from sinuses and tears into the nose.

Olfactory Nerves

• Pierce the cribriform plate.
• Carry smell information from the nose to the brain.

Pharynx

• A hollow tube.
• Functions as a passageway for air and food, a resonating chamber, and housing for the tonsils.
• Has three anatomical regions: nasopharynx, oropharynx, and laryngopharynx.

Nasopharynx

• Contains the pharyngeal tonsils (adenoids).
• Has openings for the Eustachian tubes (auditory tubes).
• Separated from the oropharynx by the hard and soft palate.

Laryngopharynx

• Lies inferiorly and opens into the larynx (voice box) and esophagus.
• Participates in both respiratory and digestive functions.

Larynx

• Forms a short passageway connecting the laryngopharynx to the trachea (windpipe).
• Thyroid cartilage (Adam's apple) is a landmark for creating an emergency airway (cricothyrotomy).
• Cricothyrotomy is an incision through the skin and cricothyroid membrane to create a patient airway.

Epiglottis

• A flap at the entrance to the glottis (opening between vocal folds).
• Held anteriorly during breathing, then pulled backward to close off the glottic opening during swallowing.

Vocal Folds

• Located high in the larynx, below where the larynx and esophagus separate from the pharynx.

Trachea

• A semi-rigid pipe, approximately 12 cm long.
• Extends from the inferior portion of the larynx into the mediastinum, where it divides into right and left primary ("mainstem") bronchi.

Carina

• An internal ridge at the junction of the two mainstem bronchi.
• A sensitive area for triggering the cough reflex.

Bronchi

• The primary bronchi divide to form secondary and tertiary bronchi.
• Tertiary bronchi divide into bronchioles.
• The smallest bronchioles are the terminal bronchioles.

Alveoli

• Cup-shaped outpouchings (tiny air sacs).
• Participate in gas exchange between air and blood.
• Delicate structures composed primarily of type I alveolar cells for gas exchange with pulmonary capillaries.
• Type II cells secrete surfactant to prevent alveolar collapse during exhalation.

Lungs

• The apex is superior and extends slightly above the clavicles.
• The base rests on the diaphragm.
• The cardiac notch in the left lung makes it 10% smaller than the right lung.

Pleura

• Each lung is enclosed by a double-layered pleural membrane.
• Parietal pleura lines the walls of the thoracic cavity.
• Visceral pleura adheres tightly to the surface of the lungs.
• Pleural fluid reduces friction and allows the layers to slide across each other.
• The visceral & parietal pleura create a mechanical coupling, enabling the lungs to move together.

Pulmonary Ventilation

• Movement of air between the atmosphere and alveoli.
• Consists of inhalation and exhalation..

Diaphragm

• Primary muscle of respiration.

Measuring Ventilation

• Using spirometry.
• Spirometer measures the volume of air inspired and expired by the lungs.
• Key measurements (specific volumes):
  • Tidal Volume (Vt)
  • Inspiratory Reserve Volume (IRV)
  • Expiratory Reserve Volume (ERV)
  • Vital Capacity (VC)
  • Residual Volume (RV)
• Only about 70% of tidal volume reaches the respiratory zone - the other 30% (anatomic dead space).
• Minute Ventilation = (12 breaths/min) x (500 ml air/breath)
• Alveolar Ventilation = (12 breaths/min) x (350 ml air/breath)

Transport of O2 and CO2

• Some O2 is dissolved in plasma.
• Most O2 (about 98.5%) is carried bound to hemoglobin (Hb).
• Oxygenated hemoglobin is called oxyhemoglobin.
• O2 is needed in tissues to make ATP
• CO2 constantly diffuses from tissues to be transported in blood.
• SaO2 is a measurement of the percentage of oxygen-bound hemoglobin in arterial blood.
• Normal SaO2 is close to 95-98%.

pH

• Blood pH is critical for respiratory regulation.
• Acidosis and alkalosis are classified by blood pH.

Control of Respiration

• The medulla rhythmicity area in the brainstem controls basic respiratory patterns.
• The inspiratory center stimulates the diaphragm (via phrenic nerve) and external intercostal muscles (via intercostal nerves).

Diseases and Disorders

• Asthma: disease of hyper-reactive airways; wheezing, coughing, mucus production. Typically triggered by allergens.
• Chronic bronchitis and emphysema: caused by chronic irritation and inflammation, leading to lung destruction; patients may cough up green-yellow sputum due to infection and mucus secretion (productive cough). Mostly caused by cigarette smoke.
• Pneumonia: acute infection of the lower respiratory tract; small bronchioles and alveoli become filled with inflammatory fluid exudate. Typically caused by infectious agents like bacteria, viruses, or fungi.