Table 1. Alveolar surface likened to tennis courts in medical literature.

NO	SOURCE	ANALOGY	AREA(m2)	REFERENCE
1	Berne & Levy physiology	The lungs are contained in a space with a volume of approximately 4 L, but they have a surface area for gas exchange that is the size of a tennis court (∼85 m2).	85	2
2		This alveolar-capillary network is composed of thin epithelial cells of the alveolus and endothelial cells of the vessels and their supportive matrix and has an alveolar surface area of about 70 m2 (about the size of a tennis court).	70
3	Vander’s Human Physiology: The Mechanisms of Body Function	The total surface area of alveoli in contact with capillaries is roughly the size of a tennis court.		8
4	Murray & Nadel’s Textbook of Respiratory Medicine	This juxtaposition of capillaries with alveoli provides the vast surface area needed for effective gas exchange: approximately 70 m2 (two thirds the area of a tennis court)	70	9
5		The human lung has a large surface area, which for an average-size person approximates half a doubles tennis court, thus maximizing the approximation and apposition of capillaries to the epithelial surface.
6		The lung epithelium has a surface area approximately the size of a tennis court and represents the largest epithelial surface in the body.
7	Fishman’s Pulmonary Diseases and Disorders	Because this small mass of tissue is spread over an enormous area – nearly the size of a tennis court – the tissue framework of the lung must be extraordinarily delicate		5
8		To this end a very large area of contact between air and blood must be established; for the human lung it is sometimes compared with the area of a tennis court in size
9		The preceding section considered the overall size of the gas exchanger of the entire lung to compare it with the global performance of this organ. In reality, the surface the size of a tennis court is subdivided into some 400 million gas-exchange units.
10	Textbook of Histology	It has been estimated that the total surface area of all alveoli available for gas exchange exceeds 140 m2 (the approximate floor space of an average-sized two-bedroom apartment or the size of a singles tennis court).	140	10
11	Alveolar Structure and Function	With 85-95% of the alveolar surface surrounded by capillaries, the effective diffusion membrane created (total, both lungs) approaches 80m2, not quite as large as the singles half of a tennis court.	80	11
12	Principles of Pulmonary Medicine	It is estimated that the adult human lung has on the order of 300 million alveoli, with a total surface area approximately the size of a tennis court.		12
13	Andreoli and Carpenter's Cecil Essentials of Medicine E-Book	The alveoli are thin-walled structures with a total surface area of about 100m2. This is roughly half the size of a tennis court.	100	13
14	Tennis anyone? The lungs as a new court for systemic therapy	Medication consisting of a fine particle aerosol is carried to the alveolar epithelium, whose surface area is about 100 m2 in adults (the size of a singles tennis court) during slow deep inhalation	100	14
15	Deconvoluting lung evolution: from phenotypes to gene regulatory networks	The pulmonary gas exchanger is characterized by a very large surface of air-blood contact, nearly the size of a tennis court in humans (120 m2), a very thin tissue barrier (1mm); and a large capillary blood volume (200ml in humans), all of which determines the pulmonary diffusing capacity DLO2 (Weibel 2000; Weibel and Hoppeler 2000).	120	15
16	Endothelial Cell Mechano-Metabolomic Coupling to Disease States in the Lung Microvasculature	The lung has a prominent place in the microvasculature, as its estimated capillary surface area (as defined by diameter of a vessel 10 μm or less) is roughly 50–70 m2, which is one-fourth the size of a tennis court	50-70	16
17	Lung Parenchymal Mechanics	The parenchymal structure is thus a huge collection of tiny and fine balloons that pack an enormous surface area (close to that of a tennis court) into the chest cavity		17
18	Lung Structure and the Intrinsic Challenges of Gas Exchange	The model for structure-function correlation of the pulmonary gas exchanger so far discussed considered the whole lung: a gas-exchanging surface the size of a tennis court in humans with a capillary network containing ~200 mL of blood.		18
19	Smaller is better—but not too small: A physical scale for the design of the mammalian pulmonary acinus	To exchange oxygen and carbon dioxide, blood and air must be brought into close contact over a large surface area, nearly the size of a tennis court, in the human lung		19