Little is said in the Bible about the spiritual body, i.e., the body that we will have in heaven. Not that Christians have been without understanding about various aspects of the resurrection body. The early Christians used a seed analogy to differentiate between the present earthly body and the resurrection body. 1 Corinthians 15:39-45 points out that our present bodies will have a different flesh than our resurrected bodies. Several verses about the post-resurrection appearances of Jesus also give us some hints as to what our post-resurrection bodies will be like. (A good summary of the Biblical teaching can be found in the Blue Letter Bible article on the spiritual body.)
It is certainly true that our life in the world to come will be fundamentally different than the present life. In Matthew 22:22-32, Jesus reminds us that the marriages of this life do not carry forward to the next life. Luke 24 suggests that the spiritual body can eat, but does not necessarily need to do so. But these are hints -- suggestions -- of what life will be like following the resurrection.
Perelandra, the second book of C.S. Lewis' space trilogy, has an interesting thought on the nature of our post-resurrection bodies hidden early in the description of the description of the trip that Ransom, the main character, made to the planet of Perelandra in translucent coffin. (I know it sounds bizarre, but that's what happens, and it makes perfect sense in the context of the story.) According to Lewis, the person from whose point of view the story is written, Ransom never directly described the trip to Perelandra in any detail, but at times some of the feelings or revelations that occurred during the trip came out in conversation. According to Lewis:
Another hint came out when a skeptical friend of ours called McPhee was arguin against the doctrine of the resurrection of the human body. I was his victim at the moment and he was pressing on me in his Scots way with such questions as "So you think you're going to have guts and palate for ever in a world where there'll be no eating, and gential organs in a world without copulation? Man, ye'll have a grand time of it!" when Ransom suddenly burst out with great excitement, "Oh, don't you see, you ass, that there's a difference between a trans-sensuous life and a non-sensuous life?" That, of course, directed McPhee's fire to him. What emerged was that in Ransom's opinion the present functions and appetites of the body would disappear, but not because they were atrophied but because they were "engulfed."
In my experience, this is typical. The skeptic wants to limit what God does. He wants to say that man has been limited. The skeptic wants to argue that we will have sexual organs (because the spiritual body is our body resurrected and changed), but that we will have no sex. But that is not necessary. Rather, we will not be denied sexuality -- we will transcend it. That is an important difference.