Although a villus, a capillary, and an alveolus are part of different organ systems, they have structural similarities that result in similar functions. discuss these structural similarities and how they lead to similar functionality

Villus- It is a worm like processes on certain membranes, especially on the mucous membrane of the small intestine, where they serve in absorbing nutriment.

Capillary-Any of the fine branching blood vessels that form a network between the arterioles and venules.

Alveolus- These tiny, balloon-shaped air sacs sit at the very end of the respiratory tree and are arranged in clusters throughout the lungs.function it is to exchange oxygen and carbon dioxide molecules to and from the bloodstream.

Now, they are all present at a very basic level and some how there are similarities between there nature of operations.

Explanation:

Both alveoli and villi help in increasing surface area of the respective organ.   As they increase the region of operations for the respective organ, on which they are present on.As both alveolus and villus  are associated with extensive blood capillary network for diffusion of important substances into blood: namely oxygen and dietary nutrients.And the most important thing all of them are present on a minute level of the bodily operations.

Mantle convection  is the slow  creepingmotion of earth's solid silicate  mantle  caused by  convection  currents carrying  heat from the interior  to the planet's surface.[1][2]  the earth's surface  lithosphere, which rides atop the  asthenosphere  (the two components of the  upper mantle), is divided into a number of  plates  that are continuously being created and consumed at their opposite  plate boundaries. accretion occurs as mantle is added to the growing edges of a plate, associated with  seafloor spreading. this hot added material cools down by  conduction  and  convection  of heat. at the consumption edges of the plate, the material has thermally contracted to become dense, and it sinks under its own weight in the process of  subduction  usually at an  ocean trench.[3]this subducted material sinks through the earth's interior. some subducted material appears to reach the lower mantle,[4]  while in other regions, this material is impeded from sinking further, possibly due to a phase transition from  spinel  to  silicate perovskiteand  magnesiowustite, an  endothermic reaction.[5]the subducted oceanic crust triggers  volcanism, although the basic mechanisms are varied. volcanism may occur due to processes that add buoyancy to partially melted mantle causing an upward flow due to a decrease in density of the partial melt.secondary forms of convection that may result in surface volcanism are postulated to occur as a consequence of intraplate extension[6]  and  mantle plumes.[7]it is because the mantle can convect that the  tectonic plates  are able to move around the earth's surface.[8]mantle convection seems to have been much more active during the  hadean  period, resulting in gravitational sorting of heavier molten  iron, and  nickel  elements and  sulphides  in the core, and lighter  silicate minerals  in the  mantle.