brain

A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a vertebrate's body. In a human, the cerebral cortex contains approximately 14–16 billion neurons, and the estimated number of neurons in the cerebellum is 55–70 billion. Each neuron is connected by synapses to several thousand other neurons. These neurons typically communicate with one another by means of long fibers called axons, which carry trains of signal pulses called action potentials to distant parts of the brain or body targeting specific recipient cells. 大脑是所有脊椎动物和大多数无脊椎动物神经系统的中枢。它位于头部，通常靠近视觉等感觉器官。它是脊椎动物体内最复杂的器官。人类的大脑皮层包含大约140-160亿个神经元，而小脑中的神经元数量估计为550-700亿。每个神经元通过突触与数千个其他神经元相连。这些神经元通常通过被称为轴突的长纤维相互交流，轴突将一系列被称为动作电位的信号脉冲传递到大脑或身体的遥远部位，靶向特定的受体细胞。

Chimpanzee brain refers to the upper part of the central nervous system of chimpanzee, displaying numerous signs of intelligence, from the ability to remember symbols to cooperation, tool use, and perhaps language while human brain refers to the command center for the human nervous system with the same basic structure as other mammal brains but is larger in relation to body size than any other brains.

The average adult brain size of the chimpanzee is 384 g while the average adult human brain size is 1,352 g. Chimpanzee brain contains around 28 billion neurons while human brain contains around 86 billion neurons.

The operations of individual brain cells are now understood in considerable detail but the way they cooperate in ensembles of millions is yet to be solved. Recent models in modern neuroscience treat the brain as a biological computer, very different in mechanism from an electronic computer, but similar in the sense that it acquires information from the surrounding world, stores it, and processes it in a variety of ways. 单个脑细胞的运作现在已经被相当详细地理解了，但它们在数以百万计的群体中合作的方式仍有待解决。现代神经科学的最新模型将大脑视为一台生物计算机，在机制上与电子计算机有很大不同，但在从周围世界获取信息、存储信息和以各种方式处理信息的意义上是相似的。

A neuron or nerve cell is an electrically excitable cell that communicates with other cells via specialized connections called synapses. It is the main component of nervous tissue in all animals except sponges and placozoa. Plants and fungi do not have nerve cells. 神经元或神经细胞是一种电兴奋性细胞，通过称为突触的特殊连接与其他细胞进行通信。它是所有动物神经组织的主要成分，但海绵和扁盘动物除外。植物和真菌没有神经细胞。The Placozoa are a basal form of marine free-living multicellular organism.

Neurons are typically classified into three types based on their function. Sensory neurons respond to stimuli such as touch, sound, or light that affect the cells of the sensory organs, and they send signals to the spinal cord or brain. Motor neurons receive signals from the brain and spinal cord to control everything from muscle contractions to glandular output. Interneurons connect neurons to other neurons within the same region of the brain or spinal cord. A group of connected neurons is called a neural circuit. 神经元通常根据其功能分为三种类型。感觉神经元对触觉、声音或光等刺激做出反应，这些刺激会影响感觉器官的细胞，并向脊髓或大脑发送信号。运动神经元接收来自大脑和脊髓的信号，控制从肌肉收缩到腺体输出的一切。中间神经元将神经元连接到大脑或脊髓同一区域内的其他神经元。一组相连的神经元称为神经回路。怪不得三层就叫深度学习。

 六级/考研单词: billion, fibre, pulse, intellect, cooperate, mammal, million, compute, electron, excite, component, tissue, sponge, marine, organism, classify, affection, cord, motor