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's made up of the nose, pharynx, larynx, trachea, bronchi, bronchioles, and terminal bronchioles.

Respiratory Zone

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

Air Traversal of Respiratory Tract

• Air passes through the nasal cavity, pharynx, larynx, trachea, primary bronchi, secondary bronchi, tertiary bronchi, bronchioles, and finally alveoli.
• The lungs have 150 million alveoli.

Nasal Concha

• Nasal conchae increase the surface area of the nasal cavity.
• This allows more air to come into contact with the cavity walls, warming and humidifying the air before it reaches the lungs.
• Openings, or meatuses, exist under each nasal concha for the nasal lacrimal duct (drains sinus secretions and tears into the nose).

Olfactory Nerves

• Olfactory nerves pierce the cribriform plate to carry smell information from the nose to the brain.

Pharynx

• The pharynx is a hollow tube that functions as a passageway for air and food, a resonating chamber, and houses the tonsils.
• The pharynx has three anatomical regions: nasopharynx, oropharynx, and laryngopharynx.
• The nasopharynx contains the pharyngeal tonsils (adenoids) along with Eustachian tube openings (auditory tubes).
• The laryngopharynx lies inferiorly and opens into the larynx and esophagus, participating in both respiratory and digestive functions.

Larynx

• The larynx connects the laryngopharynx to the trachea (the windpipe).
• The thyroid cartilage, the Adam's apple, is a landmark for emergency airway creation (cricothyrotomy).
• Cricothyrotomy is an incision made through the skin and cricothyroid membrane to open a patient's airway.
• The epiglottis is a flap at the entrance of the glottis (opening between vocal folds) that's held anteriorly for breathing and pulled backward to close off the glottic opening during swallowing.
• Vocal folds are located high in the larynx.

Trachea

• The trachea is a semi-rigid tube about 12 cm long.
• It extends from the inferior larynx into the mediastinum and branches into right and left primary bronchi.
• The carina is an internal ridge at the junction of the two primary bronchi that triggers the cough reflex.

Bronchi

• The primary bronchi divide into secondary and tertiary bronchi.
• The tertiary bronchi divide into bronchioles; the smallest are the terminal bronchioles.

Alveoli

• Alveoli are cup-shaped outpouchings (tiny air sacs) where gas exchange between air and blood occurs.
• Alveoli are composed mostly of type I alveolar cells for gas exchange and type II alveolar cells that secrete surfactant preventing alveolar collapse during exhalation.

Lungs

• Each lung is enclosed by a double-layered pleural membrane.
• The parietal pleura lines the thoracic cavity walls.
• The visceral pleura adheres to the lung surface.
• Pleural fluid exists between the layers, reducing friction and creating surface tension allowing sliding.
• The pleura mechanically couples the chest wall and lung, making them move together.
• The apex of the lung is superior and extends above the clavicles.
• The base rests on the diaphragm.
• The cardiac notch in the left lung makes it 10% smaller than the right lung.

Pulmonary Ventilation

• Pulmonary ventilation is the movement of air between the atmosphere and alveoli; it involves inhalation and exhalation.
• The diaphragm is the primary breathing muscle. During inhalation it moves down. During exhalation it moves up.

Measuring Ventilation

• Ventilation can be measured via spirometry.
• A spirometer measures the volume of inspired and expired air.
• Key volumes include: Tidal Volume (Vt), Inspiratory Reserve Volume (IRV), Expiratory Reserve Volume (ERV), Vital Capacity (VC), and Residual Volume (RV).

Transport of O2 and CO2

• In the blood, some O2 dissolves as a gas; most is bound to hemoglobin (Hb).
• Oxygenated Hb is called oxyhemoglobin.
• O2 is transported in the blood (Po2 = 100 mmHg) and is needed in tissues to make ATP (Po2 = 40 mmHg at capillaries).
• CO2 diffuses from tissues (Pco2 = 45 mmHg) to the blood (Pco2 = 40 mmHg).
• SaO2 is the amount of Hb saturated with O2, measuring the percentage of oxygen-bound hemoglobin in arterial blood. It's typically 95-98%.

Respiratory Control and Acid-Base Balance

• The medulla rhythmicity area, in the brainstem, controls basic respiratory patterns.
• The inspiratory center stimulates the diaphragm and intercostal muscles.
• Acid-base balance is maintained, with pH ranging from 7.35 to 7.45 (blood).

Diseases and Disorders

• Asthma is a hyper-reactive airway disease causing wheezing, coughing, and mucus production, typically triggered by allergens.
• Chronic bronchitis and emphysema are caused by chronic irritation and inflammation, often linked to cigarette smoking. Patients frequently cough up green-yellow sputum.
• Pneumonia is an acute infection of the lower respiratory tract where small bronchioles and alveoli fill with inflammatory fluid, usually caused by bacteria, viruses, or fungi.