These are the brain, heart, kidneys, liver, and lungs. The human brain is the body's control center, receiving and sending signals to other organs through the nervous system and through secreted hormones.
For the beetle genus, see Coprini. Synapsis (also called syndesis) is the pairing of two homologous chromosomes that occurs during meiosis. It allows matching-up of homologous pairs prior to their segregation, and possible chromosomal crossover between them. Synapsis takes place during prophase I of meiosis.
At symmetric synapses the synaptic cleft is narrower than at excitatory synapses, and the postsynaptic density is only about the same width as the presynaptic density. The postsynaptic elements at such synapses include dendritic shafts (Fig. 9.2A and Fig. 9.4) some dendritic spines (Fig.