Vacuoles swell and shrink
Vacuoles swell and shrink

lipid bilayer



                              ur-rhythm two
Ur-rhythm two: Expansion and contraction

     As soon as bioactive proto-cells exist, aggregation and dispersal produces expansion and contraction. You can observe it in the pulsing rhythms of whole organisms. Their movements, outward from a center and back toward it, depend on the presence of a bounding membrane that isolates the internal world of the organism from the external environment. Even the simplest bacterial cells have bounding membranes. Christian De Duve considered encapsulation essential for the creation of life.
     In expanding and contracting, cells necessarily pull on their micro-tubular and microfilament skeletal structure, the harp inside them, which changes the tuning of the harp.
actin riggingThe strings play an active part in cellular growth and development. They appear and disappear, lengthen and shorten. The cell creates and disassembles them as needed. They form the mitotic spindles in the rhythmic dance of cell division. The actin-myosin molecules seated in the anchor points of the microfilaments have been conserved for billions of years.
     Animal cells expand and contract by passing substances through the cell membrane, and this membrane structure, the lipid bilayer, is widely conserved across every phylum. The membrane is itself alive. Its trans-membrane pumps and channels open and close as certain molecular signals glom onto them. The cell senses. It has chemical senses that separate self from other.
     The same two-part movement of expansion/contraction and swelling/shrinking underlies motility. Healthy skeletal muscle tissue maintains muscle tone by oscillatory processes organized from the rhythmic inflow and outflow of calcium ions at 5-10 HZ from the sarcoplasmic reticulum.32 The calcium ion signals are themselves basic bio-oscillators. The muscle movements in turn produce behavioral rhythms.
     When an amoeba moves away from an acid droplet, for example, it shrinks away by sending its protoplasm inward in one direction and then outward in another creating a temporary pseudopod to move it to safety. The amoeba must be able to tell inside from outside and make distinctions between good and bad outer environments. It does this through chemical senses that work by binding environmental molecules to sites along the cell membrane. Chemical sensing is a simple process conserved through life. We have it in our sense of smell. An aggregation and dispersal of molecules on membrane binding sites shrinks and expands cell organelles. In amoeba, it produces gliding motility.
     You see expansion/contraction everywhere inside cells. It is there in intracellular transport vesicles moving to and from docking sites. They upload and offload their cargoes either outside the cell or in other compartments inside the cell. The release of neurotransmitter substances into synapses depends on the filling, transport and emptying of vesicles, and the diffusion of neurotransmitters across membranes itself requires an aggregation and dispersion correlated with the binding and reuptake of molecules. Through these expansion-contraction events, nerve cells secrete neurotransmitters, secretory cells send out substances.
     Primordial expansion and contraction is bi-phasic. There is no filling without emptying, no dilation without compression. The extremes are connected; they are part of one polar process, not antagonisms or oppositions but continuities.