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1 Introduction

Figure 1.31: Overview of glycogen and lipid metabolism.

surround it with a surfactant that lowers the surface energy. Another is to surround the

particle with a surfactant that is charged, so that the particles, all with the same charge

on the surface, will repel each other (“charge-stabilization”). One can also simply cover

the surface of something bulky, like a polymer that not only reduces the surface energy

but also hinders interaction between the particles due to sterics (“steric stabilization”).

The same principle can be used for all nanoparticles, not only metal ones.

1.4 The Brain and the Functioning of Nerve Cells

When talking about sensing and movement, one has to also talk about the human ner-

vous system (NS, Figure 1.32). A bit of vocabulary first: “Sensory” (or “afferent”) neurons

carry information into the central nervous system from sense organs. “Motor” (or “ef-

ferent”) neurons carry information away from the central nervous system (for muscle

control). “Somatic” neurons connect the skin or muscle with the central nervous system.

“Visceral” neurons connect the internal organs with the central nervous system.

Automatic responses are carried out by the autonomic peripheral NS (Figure 1.32).

The analysis of the senses and controlled, planned movement are performed in the

brain. The midbrain controls sensory processes. It relays signals concerned with motor

function to other sections in the brain. The cerebrum contains two hemispheres con-