Respiration and Gas Exchange

Shock lung (ARDS) shows diffuse alveolar damage with hyaline membranes, alveolar edema, and inflammation. Diffuse alveolar edema is the hallmark histological finding. Hemosiderosis indicates iron overload, while interstitial pneumonia is a different pathological process.

Bronchiolitis obliterans causes permanent obstruction following an insult (often viral infection). The progression from mild stridor to obstructive PFT with hyperlucency on imaging, along with initial improvement on antibiotics then worsening with wheezing, fits BO perfectly. Post-viral syndrome is too vague, and other options don't match.

The findings (mediastinal shift to right, scaphoid abdomen, pulse impulse shifted right) in an intubated child indicate left-sided tension pneumothorax or massive gastric distension from air trapping. Placing a nasogastric tube to decompress the stomach is the immediate next step. Removing ETT is unsafe, surgery is premature, and chest tube is for pneumothorax (but rule out gastric issue first).

The pulmonary circulation is powered by the right atrium (which receives deoxygenated blood from the body) and the right ventricle (which pumps this blood to the lungs). The left atrium and ventricle handle systemic circulation. Both chambers work together to power pulmonary flow.

Lateral wall of the nasal cavity is mainly made up by the maxilla, however there is a deficiency that is compensated by: the perpendicular plate of the palatine bone, the medial pterygoid plate, the labyrinth of the ethmoid and the inferior concha. The nasal cavity is enclosed by the nasal bone.

Spirometry is the standard pulmonary function test for measuring lung volumes. Vital capacity is specifically measured by having a patient inhale maximally and exhale forcefully into the spirometer, which records the volume expelled.

Alveoli are the tiny sacs within our lungs that allow oxygen and carbon dioxide to move between the lungs and the bloodstream.

R.Q. is the ratio of the volume of CO₂ released to the volume of O₂ absorbed during respiration.

R.Q. for carbohydrates is the volume of CO₂ released to the volume of O₂ consumed, i.e. 6CO₂/6O₂ = 1.

Alveolus is the tiny air sac (only 1 cell thick) in the lungs at the end of the smallest airways, where the exchange of oxygen and carbon dioxide takes place. This is the functional unit of lungs.

The branches of trachea entering into the lungs are called bronchi. They are further branched into secondary and tertiary bronchi, which further branch in bronchioles.

The gaseous exchange in fishes takes through gills. Gills also known as branchiae, are small portions of richly vascularised tissues, internal or external to the body and in direct contact with the surrounding water.

Increase in the volume of thoracic cavity is both due to contraction of intercostal/rib muscles and diaphragm.

In cutaneous respiration molecular oxygen penetrates through the skin and it is collected by the blood circulation that then distributes the gas to the tissues. Carbon dioxide is also collected from the tissues by the blood and taken to the skin to be eliminated to the environment. So, there is important participation of blood in cutaneous respiration.