The Second Body among us is Astral or Emotional Body which is represented by the Palm in our Hand. This part is nurtured by Lymph vessels in our body, these Lymph vessels are directly correlated to the Sap (collective of Xylem and Phloem) of Plant Body which provides water, sugar, proteins, etc to the Emotional or Plant Body respectively. A lymph node in Human Body is correlated to Root nodule of Plant, which helps filtering of unwanted substance. This is the reason why Living Being with good Astral Body does not get Ill easily, it helps maintain our Feeling normal to good, but when we get Ill our way of Feeling distorts, which usually occurs due to defect in our Astral or Emotional Body. It is not like any Plant does not feel it when we cut any Branch of it or pluck any Fruit from it but we do it easily because it does not cause pain to any Tree, i.e. why we prefer to be Vegetarian then to be Non-Vegetarian in which Animal get Feeling of Pain due to the presence of the Nervous system in them. It is the Nervous System which creates the sensation of Pain within us but it is not likely that if you are Vegetarian you are not hurting any Being for your own appetite, so it does not matter either you are Vegetarian or Non-Vegetarian, it is just the cycle/flow of energy we want to circulate through us. But as we come at the top of Food Chain we Feel we are Born to get what we want(but it is only Food Chain in which we are on Top otherwise there a/re many Being above us for Example Gurus like Sun & Moon, or Angels, etc. who treat us the same way we are treating our inferiors because it is the Energy which does same to you as you did to your lower as it is beautifully said "what you sow you reap" and "what we give we get with multiplications") but we should learn from the Trees that how to be solitude even with performing all of its work, they prepare their own food without hurting anyone, they just give they possess if you want from them and they multiply and give their offsprings and at last they leave the world without doing bad to anyone, they are just Givers what we should be learning from them, they are the best example of any Being who comes alone, do/give their best to the existence, multiplies and go alone. And it is not like we can't feel them as we possess the same body within us which they have but the difference is that we get puzzled because of other bodies within us, but if we perform one task at a Time then we can get Success easily and finally realize peacefully who we are and what do we intend for.
To Co-Relate better, Palm of our Hand to Plant Existence, our Palm just tilt just like Branches/Stem of Trees bend/tilts, Palm is not like Thumb which is Flexible similar to Physical body. Marking/ Lines in Palm represent the direction of flow of Energy within our Body, It represents the channels of Ida and Pingala Nadi representing right and left side of our Body (i.e. Inner World including Sushumna Nadi), which is the connection to Outer World via different Energy wheels also known as Chakras.
There is an Emotional Permanent Seed which is present in the physical spleen. This is the seed which contains the blueprint of our Emotional body. Any Spiritual Person started his Spiritual journey soon develop good Astral Body and have less chances of getting diseased. The Emotional Body dies after sometime, when the body dies. According to me, best way to heal Astral Body or Emotional Body or disease of Feelings is Yoga and Ayurvedic Medicine, i.e. why it is said Eat good and be Healthy.