Academy of Neuroscience: NC150S05

Tuesday, March 4, 2008

NC150S05

NC150S05馥榕

Ch5 summary馥榕

The neuron is the fundamental unit of the nervous system. Its major characteristic is the ability to communicate within the nervous system, with other parts of the body, and with the environment. With billions of multisynaptic connections, the nerve cells serve higher mental functions that include memory, thinking, reasoning, calculation, and language. Neuroglial cells, which support and protect nerve cells, are important in tissue repair and participate in phagocytizing cellular debris. Nerve cells communicate with one another through nerve impulses that represent all neuronal activity. The nerve impulses have a chemical component that underlies the electric potential of the cells. A neurotransmitter is a chemical substance released at a synapse that transmits signals across neurons. There are two types of transmitters in the nervous system: small molecules and large molecules (peptides). Small-molecules neurotransmitters include acetylcholine, dopamine, norepinephrine, serotonin, glutamate, and GABA. They are known to have short-lasting effects. Large-molecule peptides produce long-lasting effects on postsynaptic nerve cells.

神經元是神經系統的基本單位，Its major characteristic is the ability其主要的功能為to communicate溝通within the nervous system神經系統、with other parts of the body身體其餘部分and with the environment及環境。With billions of multisynaptic connections因為具有極大量的multisynaptic connections突觸連結，the nerve cells serve higher mental functions使得神經細胞能夠提供較高等的心智功能，包含記憶、思考、推理、計算及語言。具有支持及保護神經細胞的神經膠細胞，對於組織的修補及參與細胞殘骸的吞噬作用是相當重要的。神經細胞藉由神經脈衝來聯絡彼此communicate with one another through nerve impulses that represent all neuronal activity，而這就象徵了所有的神經性活動。神經脈衝have a chemical component的化學組成that underlies the electric potential of the cells為構成細胞電位的基礎，而神經傳導物neurotransmitter是由突觸所釋放released at a synapse的化學性物質，用來傳遞神經元間的訊號。神經系統中具有下列兩種傳導物質：小分子與大分子(縮氨酸peptides胜,)。小分子神經傳導物包含乙醯膽鹼、多巴胺、正腎上腺素、血清素、榖氨酸鹽glutamate及伽馬氨基丁酸GABA。這些都具有短期的效用。而大分子縮氨酸在神經細胞的後突觸postsynaptic nerve cells可產生較長期的效用。