Facultad de Ciencias de la Salud
Prof. Ana María Rojido Inglés I 2014
Human brain
Thehuman brainis the center of the humannervous systemand is a highly complex organ. Enclosed in the cranium, it has the same general structure as the brains of othermammals, but is over three times as large as the brain of a mammal with an equivalent body size.Most of the expansion comes from thecerebral cortex, a convoluted layer of neural tissue that covers the surface of the forebrain. Especially expanded are thefrontal lobes, which are involved inexecutive functionssuch as self-control, planning, reasoning, and abstract thought. The portion of the brain devoted to vision is also greatly enlarged in human beings.
The adult human brain weighs on average about 3lb(1.5kg)with asizeof around 1130cubic centimetres(cm3) in women and 1260 cm3in men, although there is substantial individual variation.
Situated at the top and covered with a convolutedcortex, the cerebral hemispheres form the largest part of the human brain .Underneath the cerebrum lies thebrainstem, resembling a stalk on which the cerebrum is attached. At the rear of the brain, beneath the cerebrum and behind the brainstem, is thecerebellum, a structure with a horizontallyfurrowed surface that makes it look different from any other brain area. The same structures are present in other mammals, although the cerebellum is not so large relative to the rest of brain. As a rule, the smaller the cerebrum, the less convoluted the cortex. The cortex of a rat or mouse is almost completely smooth. The cortex of a dolphin or whale, on the other hand, is more convoluted than the cortex of a human.The cerebral cortex in humans is so large that it overshadows every other part of the brain.
The cerebral cortex is nearly symmetric in outward form, with left and right hemispheres. Each hemisphere of the brain interacts primarily with one half of the body, but for reasons that are unclear, the connections are crossed: the left side of the brain interacts with the right side of the body, and vice versa.The two cerebral hemispheres are connected by a very large nerve bundle called thecorpus callosum, which crosses the midline above the level of the thalamus. There are also two much smaller connections, theanterior commisureand hippocampal commisure, as well as many subcortical connections that cross the midline. The corpus callosum is the main avenue of communication between the two hemispheres, though. It connects each point on the cortex to the mirror-image point in the opposite hemisphere, and also connects to functionally related points in different cortical areas. In most respects, the left and right sides of the brain are symmetrical in terms of function. For example, the counterpart of the left-hemisphere motor area controlling the right hand is the right-hemisphere area controlling the left hand. There are, however, several very important exceptions, involving language and spatial cognition. In most people, the left hemisphere is dominant for language: a stroke that damages a key language area in the left hemisphere can leave the victim unable to speak or understand, whereas equivalent damage to the right hemisphere would cause only minor impairment to language skills.
A- Responda en español las siguientes preguntas según el texto.
1- Qué es la corteza cerebral?
2- Dónde están situados y qué forman los hemisferios cerebrales?
3- Dónde está ubicado el cerebelo?
4- Cómo se llama lo que conecta los dos hemisferios cerebrales?
B.- Explique en español el significado de los siguientes grupos de palabras.
1 -… but is over three times as large as the brain ……………………………………………………….
2 -… thefrontal lobes, which are involved inexecutive functionssuch as self-control…………………
…………………………………………………………………………………………………………………………..
3 - The portion of the brain devoted to vision is also greatly enlarged in human beings……………
………………………………………………………………………………………………………………………..
4 -the cerebral hemispheres form the largest part of the human brain
………………………………………………………………………………………………………………………….
5 -… The cortex of a dolphin or whale, on the other hand, is more convoluted than the cortex of a
human. ……………………………………………………………………………………………………………..
6 - There are also two much smaller connections, ………………………………………………….
…………………………………………………………………………………………………………………………..
7 - ….. as well as many subcortical connections that cross the midline.
…………………………………………………………………………………………………………………………..
8- There are, however, several very important exceptions,……………………………………………….
…………………………………………………….……………………………………………………………..
9- In most people, the left hemisphere is dominant for language:…………………………………………..
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