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Brain cells make up the functional tissue of the brain. The rest of the brain tissue is the structural stroma that includes connective tissue such as the meninges , blood vessels , and ducts. The two main types of cells in the brain are neurons , also known as nerve cells, and glial cells , also known as neuroglia. [ 1 ]
Astrocytes express water channels called aquaporins. [10] Until 2000, no physiological function had been identified that explained their presence in the mammalian CNS. Aquaporins are membrane-bound channels and regulate the flux of water into and out of cells. Relative to simple diffusion, they increases water permeability 3– to 10-fold. [11]
The Neuronal cell cycle represents the life cycle of the biological cell, its creation, reproduction and eventual death. The process by which cells divide into two daughter cells is called mitosis. Once these cells are formed they enter G1, the phase in which many of the proteins needed to replicate DNA are made. After G1, the cells enter S ...
Glial cells play a major role in brain metabolism by controlling the chemical composition of the fluid that surrounds neurons, including levels of ions and nutrients. [85] Brain tissue consumes a large amount of energy in proportion to its volume, so large brains place severe metabolic demands on animals.
The brain also uses glucose during starvation, but most of the body's glucose is allocated to the skeletal muscles and red blood cells. The cost of the brain using too much glucose is muscle loss. If the brain and muscles relied entirely on glucose, the body would lose 50% of its nitrogen content in 8–10 days. [13]
Photoreceptors are the cells that convert light to electric signals that travel to the brain so you can see. Rod cells, or photoreceptors that respond best to dim light, are located mostly in the ...
Studies suggest that the entire cycle of exocytosis, retrieval, and reformation of the synaptic vesicles requires less than 1 minute. [21] In full collapse fusion, the synaptic vesicle merges and becomes incorporated into the cell membrane. The formation of the new membrane is a protein mediated process and can only occur under certain conditions.
The cells of the brain include neurons and supportive glial cells. There are more than 86 billion neurons in the brain, and a more or less equal number of other cells. Brain activity is made possible by the interconnections of neurons and their release of neurotransmitters in response to nerve impulses.