By respiratory system we usually mean the passages that transport incoming air to the lungs and to the microscopic air sacs called alveoli where gases are exchanged. The term respiration refers to the whole chain of processes from the inhalation of air to the use of oxygen in the cells. Index. Reference.
Phagocytes are the white blood cells that protect the body by eating (phagocytosing) dirt, bacteria and dead or dying cells. They are important for fighting infections. They are also important for becoming immune. Phagocytes are important in all animals and are very complex in vertebrates.
Astrocytes are the most numerous cell type within the central nervous system (CNS) and perform a variety of tasks, from axon guidance and synaptic support, to the control of the blood brain barrier and blood flow.To perform these roles, there is a great variety of astrocytes.In this review, we summarize the function of astrocytes, in particular, their role in maintaining homeostasis at the synapse, regulating neuronal signaling, protecting neurons from oxidative damage, and determining the fate of endogenous neural precursors.o perform these roles, there is a great variety of astrocytes. In this review, we summarize the function of astrocytes, in particular, their role in maintaining homeostasis at the synapse, regulating neuronal signaling, protecting neurons from oxidative damage, and determining the fate of endogenous neural precursors.