三十九难曰∶经言腑有五，脏有六者，何也？然∶六腑者，正有五腑也。五脏亦有六脏者，
谓肾有两脏也。其左为肾，右为命门。命门者，精神之所舍也；男子以藏精，女子以系胞，其气与肾
通。故言脏有六也。腑有五者，何也？然∶五脏各一腑，三焦亦是一腑，然不
属于五脏，故言腑有五焉。
四十难曰∶经言，肝主色，心主臭，脾主味，肺主声，肾主液。鼻者，肺之候，而反知香臭；耳
者，肾之候，而反闻声。其意何也？然∶肺者，西方金也，金生于巳，巳者南方火，火者心，心
主臭，故令鼻知香臭；肾者，北方水也，水生于申，申者西方金，金者肺，肺主声，故令耳闻声。
四十一难曰∶肝独有两叶，以何应也？然∶肝者，东方木也。木者、春也。万物始生，其尚
幼小，意无所亲，去太阴尚近，离太阳不远，犹有两心，故有两叶，亦应木叶也。
四十二难曰∶人肠胃长短，受水谷多少，各几何？然∶胃大一尺五寸，径五寸，长二尺六寸，
横屈受水谷三斗五升，其中常留谷二斗，水一斗五升。小肠大二寸半，径八分分之少半，长三丈
二尺，受谷二斗四升，水六升三合合之大半。回肠大四寸，径一寸半，长二丈一尺，受谷一斗，水七
升半。广肠大八寸，径二寸半，长二尺八寸，受谷九升三合八分合之一。故肠胃凡长五丈八尺四寸，合
受水谷八斗七升六合八分合之一，此肠胃长短，受水合之数也。
肝重二斤四两，左三叶，右四叶，凡七叶，主藏魂。心重十二两，中有七孔三毛，盛精汁三
合，主藏神。脾重二斤三两，扁广三寸，长五寸，有散膏半斤，主裹血，温五脏，主藏意。肺重三斤三
两，六叶两耳，凡八叶，主藏魄。肾有两枚，重一斤一两，主藏志。胆在肝之短叶间∶重三两三铢，
盛精汁三合。胃重二斤二两，纡曲屈伸，长二尺六寸，大一尺五寸，径五寸，盛谷二斗，水一斗
五升。小肠重二斤十四两，长三丈二尺，广二寸半，径八分分之少半，左回叠积十六曲，盛谷二斗四
升，水六升三合合之大半。大肠重二斤十二两，长二丈一尺，广四寸，径一寸，当脐右回十六曲，
盛谷一斗，水七升半。膀胱重九两二铢，纵广九寸，盛溺九升九合。口广二寸半，唇至齿，长九分。
齿以后至会厌，深三寸半，大容五合。舌重十两，长七寸，广二寸半。咽门重十二两，广二寸半，至胃长
一尺六寸。喉咙重十二两，广二寸，长一尺二寸，九节。肛门重十二两，大八寸，径二寸大半，
长二尺八寸，受谷九升三合八分合之一。
第三十九难问：医经中说六腑有五个，五脏有六个，这是什么意思？回答说：六腑实际上只有五个正腑。五脏也有六个脏的说法，是指肾脏有两个部分。左边的称为肾，右边的称为命门。命门是精神寄居的地方；男子用它来储藏精气，女子用它来维系子宫（胞宫），其气与肾相通。所以说脏有六个。至于为什么说腑有五个呢？回答说：五脏各配一个腑，三焦也是一个腑，但它不直接隶属于某一脏，所以称腑有五个。
第四十难问：医经说肝主管视觉颜色，心主管嗅觉气味，脾主管味觉味道，肺主管听觉声音，肾主管体液津液。鼻子是肺的外候，却反而能辨别香臭；耳朵是肾的外候，却反而能听到声音。这是什么道理？回答说：肺属西方金，金生于巳时，巳时对应南方火，火对应心，心主管嗅觉，所以能使鼻子辨别香臭；肾属北方水，水生于申时，申时对应西方金，金对应肺，肺主管听觉声音，所以能使耳朵听到声音。
第四十一难问：肝脏唯独有两叶，这是对应什么道理？回答说：肝属东方木。木对应春季。万物开始生长，此时尚幼小，心意没有特定的亲近对象，离太阴（冬季/水）还近，离太阳（夏季/火）不远，如同还有两心未定，所以有两叶，这也对应树木的叶子。
第四十二难问：人的肠胃长短如何，能容纳多少水谷，各是多少？回答说：胃大口径一尺五寸，直径五寸，长二尺六寸，弯曲部分能容纳水谷三斗五升，其中常留有谷物二斗，水一斗五升。小肠大口径二寸半，直径八分又三分之一分，长三丈二尺，能容纳谷物二斗四升，水六升三合又三分之二合。回肠大口径四寸，直径一寸半，长二丈一尺，能容纳谷物一斗，水七升半。广肠大口径八寸，直径二寸半，长二尺八寸，能容纳谷物九升三合八分之一合。所以肠胃总共长五丈八尺四寸，合计能容纳水谷八斗七升六合八分之一合，这就是肠胃长短及容纳数量的数据。
肝脏重二斤四两，左有三叶，右有四叶，共七叶，主要功能是储藏魂。心脏重十二两，中有七个孔和三毛，盛放精汁三合，主要功能是储藏神。脾脏重二斤三两，扁平宽三寸，长五寸，旁边有散膏半斤，主要功能是包裹血液，温煦五脏，主要功能是储藏意。肺脏重三斤三两，有六叶和两个耳状突起，共八叶，主要功能是储藏魄。肾脏有两个，重一斤一两，主要功能是储藏志。胆囊位于肝脏短叶之间，重三两三铢，盛放精汁三合。胃重二斤二两，迂曲伸缩，长二尺六寸，大口径一尺五寸，直径五寸，盛放谷物二斗，水一斗五升。小肠重二斤十四两，长三丈二尺，宽二寸半，直径八分又三分之一分，向左回旋折叠十六个弯曲，盛放谷物二斗四升，水六升三合又三分之二合。大肠重二斤十二两，长二丈一尺，宽四寸，直径一寸，在脐部右侧回旋十六个弯曲，盛放谷物一斗，水七升半。膀胱重九两二铢，纵径横径均为九寸，盛放尿液九升九合。口腔宽二寸半，从嘴唇到牙齿，长九分。从牙齿后方到会厌，深三寸半，容量五合。舌头重十两，长七寸，宽二寸半。咽门重十二两，宽二寸半，通向胃部长一尺六寸。喉咙重十二两，宽二寸，长一尺二寸，有九个节段。肛门重十二两，大口径八寸，直径二寸大半，长二尺八寸，能容纳谷物九升三合八分之一合。
Difficulty 39 asks: The classic texts state that there are five Fu organs and six Zang organs. What is the meaning of this? The answer is: There are indeed only five regular Fu organs. However, there is also a concept of six Zang organs, referring to the fact that the Kidney has two parts. The left side is called the Kidney (Shen), and the right side is called the Mingmen (Gate of Life). The Mingmen is where the Spirit (Shen) resides; in men, it stores Essence (Jing), and in women, it connects to the Baozhong (uterus/womb). Its Qi communicates with the Kidney. Therefore, it is said that there are six Zang organs. Why then are there said to be five Fu organs? The answer is: Each of the five Zang organs corresponds to one Fu organ. The Sanjiao (Triple Burner) is also a Fu organ, but it does not directly belong to any specific Zang organ. Thus, it is said that there are five Fu organs.
Difficulty 40 asks: The classic texts state that the Liver governs color perception, the Heart governs smell, the Spleen governs taste, the Lung governs sound, and the Kidney governs fluids. The nose is the external indicator of the Lung, yet it perceives odors; the ear is the external indicator of the Kidney, yet it hears sounds. What is the rationale behind this? The answer is: The Lung belongs to Metal in the West. Metal is born in Si (the Snake hour/direction associated with Fire). Si corresponds to Fire in the South. Fire corresponds to the Heart. Since the Heart governs smell, this allows the nose to perceive odors. The Kidney belongs to Water in the North. Water is born in Shen (the Monkey hour/direction associated with Metal). Shen corresponds to Metal in the West. Metal corresponds to the Lung. Since the Lung governs sound, this allows the ear to hear sounds.
Difficulty 41 asks: The Liver uniquely has two lobes. What does this correspond to? The answer is: The Liver belongs to Wood in the East. Wood corresponds to Spring. When all things begin to grow, they are still young and tender. Their intent has no specific attachment; they are close to Taiyin (Winter/Water) but far from Taiyang (Summer/Fire). It is as if they have two hearts undecided. Therefore, it has two lobes, which also corresponds to the leaves of trees.
Difficulty 42 asks: What are the lengths of the human intestines and stomach, and how much water and grain can they hold? The answer is: The Stomach has a large diameter of 1 chi 5 cun, an inner diameter of 5 cun, and a length of 2 chi 6 cun. Its curved portion can hold 3 dou 5 sheng of water and grain, typically containing 2 dou of grain and 1 dou 5 sheng of water. The Small Intestine has a large diameter of 2.5 cun, an inner diameter of 8 fen plus one-third of a fen, and a length of 3 zhang 2 chi. It can hold 2 dou 4 sheng of grain and 6 sheng 3 he plus two-thirds of a he of water. The Hui Chang (returning intestine) has a large diameter of 4 cun, an inner diameter of 1.5 cun, and a length of 2 zhang 1 chi. It can hold 1 dou of grain and 7.5 sheng of water. The Guang Chang (broad intestine) has a large diameter of 8 cun, an inner diameter of 2.5 cun, and a length of 2 chi 8 cun. It can hold 9 sheng 3 he plus one-eighth of a he of grain. Thus, the total length of the stomach and intestines is 5 zhang 8 chi 4 cun, and their combined capacity for water and grain is 8 dou 7 sheng 6 he plus one-eighth of a he. These are the measurements of length and capacity for the stomach and intestines.
The Liver weighs 2 jin 4 liang, has three lobes on the left and four on the right, totaling seven lobes. It primarily stores Hun (Ethereal Soul). The Heart weighs 12 liang, has seven orifices and three hairs, holds 3 he of essence fluid, and primarily stores Shen (Spirit). The Spleen weighs 2 jin 3 liang, is flat and wide 3 cun, long 5 cun, and has half a jin of loose pancreas (sangao). It primarily wraps blood, warms the five Zang organs, and stores Yi (Intellect). The Lung weighs 3 jin 3 liang, has six lobes and two ear-like structures, totaling eight lobes. It primarily stores Po (Corporeal Soul). The Kidneys are two in number, weighing 1 jin 1 liang each, and primarily store Zhi (Will). The Gallbladder is located between the short lobes of the Liver, weighs 3 liang 3 zhu, and holds 3 he of essence fluid. The Stomach weighs 2 jin 2 liang, is tortuous and flexible, is 2 chi 6 cun long, has a large diameter of 1 chi 5 cun and an inner diameter of 5 cun, and holds 2 dou of grain and 1 dou 5 sheng of water. The Small Intestine weighs 2 jin 14 liang, is 3 zhang 2 chi long, wide 2.5 cun, with an inner diameter of 8 fen plus one-third of a fen. It loops back sixteen times, holding 2 dou 4 sheng of grain and 6 sheng 3 he plus two-thirds of a he of water. The Large Intestine weighs 2 jin 12 liang, is 2 zhang 1 chi long, wide 4 cun, with an inner diameter of 1 cun. It loops back sixteen times at the navel, holding 1 dou of grain and 7.5 sheng of water. The Bladder weighs 9 liang 2 zhu, is 9 cun in both longitudinal and transverse dimensions, and holds 9 sheng 9 he of urine. The mouth is 2.5 cun wide. From lips to teeth, it is 9 fen long. From behind the teeth to the epiglottis, it is 3.5 cun deep with a capacity of 5 he. The tongue weighs 10 liang, is 7 cun long and 2.5 cun wide. The pharynx gate weighs 12 liang, is 2.5 cun wide, and extends 1 chi 6 cun to the stomach. The larynx/trachea weighs 12 liang, is 2 cun wide, 1 chi 2 cun long, and has nine segments. The anus weighs 12 liang, has a large diameter of 8 cun, an inner diameter of 2.5 cun plus half, is 2 chi 8 cun long, and can hold 9 sheng 3 he plus one-eighth of a he of grain.