Resource delivery

The CA is a string of cells consisting of  a core which does not interact with other CA, and a rim which produces cells. When the CA elongates cells are produced, and when cells are delivered (exfoliated) it shrinks. The core consists of everlasting progenitors. The inner most cells are stem cells. During each time step CA cells accumulate resources, which are depicted by  the graph below. Since core cells continually accumulate resources the graph rises. Whenever cells are shed off, the graph declines (*).The CA cycle is 46 days, and it produces 44 cells. On the average it delivers daily 0.94 cells. 

The experiment illustrates the effect of a rising demand for resources on CA structure. The system is a two CA proliferon, consisting of a stem and  a transitory process. Only the transitory process is depicted. The timing of resource delivery is determined by a set point. When CA  length reaches it resources are delivered.  At the set point all CA cells deliver some of their resources, and when their resources are exhausted, they die and are shed off. The set point of CA-1 is 25 cells and it delivers on the average 0.94 cells daily.

The set point of CA-2 is 24 cells. Initially it grows, and when attaining the length of 25 cells, all its cells deliver some of their resources. Some exhaust their resources and die. The CA shrinks below the set point and stops delivering resources. Gradually it recuperates starts growing and when reaching the set point it delivers.

The declining set point determines the maximal CA- length.

The following images depict resource variation of two CA.  Both start with 700 resource units.  Their initial lengths exceed their set points and they delivered resources.  When their length dropped below the set point they accumulated resources until the set point was reached, and so on.

The graphs below depict maximal CA length and average daily cell production. Initially as set point  decline so does  cell production. When  CA become smaller their average daily cell production rises.

Cell death

Two factors cause cell death. 1. Rule dependent cell elimination like in the CA-1 rim, and 2. death due to resource depletion, which occurs when CA length reaches the set point.  Some cell exhaust their resources and dies. In the subsequent states death is determined by the rule.

nca=2;  restoreparams[1,1,1]; restoreparams[2,1,1]; If [sa[[2]] >=k, deleteon =1; {k, 25, 7,-1}; If [sa[[2]] <=2, deleteon = 0]; If[ deleteon == 1, donate[2,2]]; If[nowdat[[2,8]]< 0, newzygote[2]];

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