BRAIN PARTS

Brain Structures and their Functions

The nervous system is your body's decision and communication center. The central nervous system (CNS) is made of the brain and the spinal cord and the peripheral nervous system (PNS) is made of nerves. Together they control every part of your daily life, from breathing and blinking to helping you memorize facts for a test. Nerves reach from your brain to your face, ears, eyes, nose, and spinal cord... and from the spinal cord to the rest of your body. Sensory nerves gather information from the environment, send that info to the spinal cord, which then speed the message to the brain. The brain then makes sense of that message and fires off a response. Motor neurons deliver the instructions from the brain to the rest of your body. The spinal cord, made of a bundle of nerves running up and down the spine, is similar to a superhighway, speeding messages to and from the brain at every second.

The brain is made of three main parts: the forebrain, midbrain, and hindbrain. The forebrain consists of the cerebrum, thalamus, and hypothalamus (part of the limbic system). The midbrain consists of the tectum and tegmentum. The hindbrain is made of the cerebellum, pons and medulla. Often the midbrain, pons, and medulla are referred to together as the brainstem.

The Cerebrum: The cerebrum or cortex is the largest part of the human brain, associated with higher brain function such as thought and action. The cerebral cortex is divided into four sections, called "lobes": the frontal lobe, parietal lobe, occipital lobe, and temporal lobe. Here is a visual representation of the cortex:

What do each of these lobes do?

• Frontal Lobe- associated with reasoning, planning, parts of speech, movement, emotions, and problem solving
• Parietal Lobe- associated with movement, orientation, recognition, perception of stimuli
• Occipital Lobe- associated with visual processing
• Temporal Lobe- associated with perception and recognition of auditory stimuli, memory, and speech

Note that the cerebral cortex is highly wrinkled. Essentially this makes the brain more efficient, because it can increase the surface area of the brain and the amount of neurons within it. We will discuss the relevance of the degree of cortical folding (or gyrencephalization) later.

A deep furrow divides the cerebrum into two halves, known as the left and right hemispheres. The two hemispheres look mostly symmetrical yet it has been shown that each side functions slightly different than the other. Sometimes the right hemisphere is associated with creativity and the left hemispheres is associated with logic abilities. The corpus callosum is a bundle of axons which connects these two hemispheres.

Nerve cells make up the gray surface of the cerebrum which is a little thicker than your thumb. White nerve fibers underneath carry signals between the nerve cells and other parts of the brain and body.

The neocortex occupies the bulk of the cerebrum. This is a six-layered structure of the cerebral cortex which is only found in mammals. It is thought that the neocortex is a recently evolved structure, and is associated with "higher" information processing by more fully evolved animals (such as humans, primates, dolphins, etc). For more information about the neocortex,

The Cerebellum: The cerebellum, or "little brain", is similar to the cerebrum in that it has two hemispheres and has a highly folded surface or cortex. This structure is associated with regulation and coordination of movement, posture, and balance.

The cerebellum is assumed to be much older than the cerebrum, evolutionarily. What do I mean by this? In other words, animals which scientists assume to have evolved prior to humans, for example reptiles, do have developed cerebellums. However, reptiles do not have neocortex.

Limbic System: The limbic system, often referred to as the "emotional brain", is found buried within the cerebrum. Like the cerebellum, evolutionarily the structure is rather old.

This system contains the thalamus, hypothalamus, amygdala, and hippocampus. Here is a visual representation of this system, from a midsagittal view of the human brain:

Click on the words to learn what these structures do:

• Thalamus
• Hypothalamus
• Amygdala
• Hippocampus

Brain Stem: Underneath the limbic system is the brain stem. This structure is responsible for basic vital life functions such as breathing, heartbeat, and blood pressure. Scientists say that this is the "simplest" part of human brains because animals' entire brains, such as reptiles (who appear early on the evolutionary scale) resemble our brain stem. The brain stem is made of the midbrain, pons, and medulla.

Novel Memory-Enhancing Mechanism in Brain

In collaboration with scientists at Germany's University of Munster, the UCI team found that a small protein called neuropeptide S can strengthen and prolong memories of everything from negative events to simple objects.

According to study leader Rainer Reinscheid, UCI associate professor of pharmaceutical sciences, the discovery could provide important clues about how the brain stores memories and also lead to new treatments for Alzheimer's disease, dementia and other cognitive impairments.
"Additionally, it may help us better understand post-traumatic stress disorder, which involves exaggerated memories of traumatic events," he said.
In tests on mice, the researchers observed that if neuropeptide S receptors in the brain were activated immediately after a learning experience, it could be recalled for much longer and with much greater intensity.
This memory enhancement lasted up to a week, Reinscheid said, but when NPS receptor activation was disrupted, the mice didn't remember events as strongly -- if at all -- when tested just a day or two later.
Study results, which appear in a Dec. 8 advance online article for the journal Neuropsychopharmacology, are in accordance with Reinscheid's previous findings that NPS causes wakefulness and has a calming effect.
"It appears that the combination of increased alertness and reduced anxiety produced by NPS prepares the animals to learn much better," he said. "Memory is remarkably improved after activation of their NPS system, and the effects are long-lasting, independent of content."
Naoe Okamura, Celia Garau, Dee Duangdao and Stewart Clark of UCI as well as Kay Jungling and Hans-Christian Pape of the University of Munster contributed to the study, which was funded in part by the National Institute of Mental Health.
Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.

TRAQUEOTOMIA 6

TRAQUEOTOMIA 3

Rinoplastia: Cirugía Estética de la Nariz

Cartagena Clinica Medihelp cirugia oido

transplante de cornea

POLITRAUMATIZADO

Corresponde al paciente que ha sufrido un traumatismo violento, con compromiso de más de un sistema o aparato orgánico y a consecuencia de ello tiene riesgo de vida.
Esta definición que implica violencia, graves lesiones y especialmente riesgo de vida, diferencia al politraumatizado del policontundido y del polifracturado que, aun con lesiones graves, no lleva implícito un riesgo de vida.
En la actualidad los traumatismos son la principal causa de muerte dentro de las primeras cuatro décadas de la vida. Como causa global de muerte en todas las edades, el trauma es superado únicamente por el cáncer y las enfermedades cardiovasculares.
Dentro de las causas traumáticas, las más frecuentes son (Champion, 1990):

Accidentes de tránsito	49%
Caída de altura	16%
Herida de bala	10%
Herida por arma blanca	9%
Aplastamiento	5%
Otros	11%

La mortalidad en los pacientes politraumatizados sigue una distribución trimodal característica.

Primera etapa

La muerte sobreviene en los primeros segundos o minutos del accidente, y generalmente es debida a laceraciones cerebrales, médula espinal alta, tronco cerebral, lesiones cardíacas, ruptura de aorta y de grandes vasos. Muy pocos de estos pacientes pueden ser salvados.
En orden de importancia, el peligro de muerte inminente está dado por:

Lesiones del sistema respiratorio

1. Interrupción de la vía aérea permeable por cuerpos extraños en boca, laringe, tráquea o bronquios, como placas o prótesis dentarias, vómitos que se aspiran, sangre, hematomas del piso en la boca en traumatismos maxilofaciales, proyección de la lengua hacia atrás, etc.
2. Ruptura tráqueo-brónquica.
3. Hemotórax a tensión.
4. Fracturas múltiples de las costillas, con tórax volante, desviación del mediastino, etc.
5. Contusión pulmonar (pulmón de shock).

Lesiones del sistema cardio-vascular

1. Hipovolemia por hemorragia fulminante, sea interna o externa.
2. Shock en cualquiera de sus formas etio-patogénicas: hipovolémico, neurogénico, por insuficiencia cardíaca, etc.
3. Hemopericardio con taponamiento cardíaco.
4. Hemorragia masiva por ruptura de la aorta o de los grandes vasos.

Lesiones del sistema nervioso central

1. Contusión cerebral grave.
2. Hemorragia cerebral masiva.

Segunda etapa

La muerte ocurre durante los primeros minutos o después de algunas horas de producido el traumatismo. Se ha llamado "la hora de oro" del paciente politraumatizado, ya que es el período donde se pueden evitar las muertes "prevenibles" con una atención rápida y eficiente. En ésta etapa la muerte sobreviene por un hematoma subdural o epidural, hemoneumotórax, ruptura de bazo, laceración hepática, fractura de pelvis o lesiones múltiples asociadas con hemorragia masiva.

Tercera etapa

La muerte ocurre varios días o semanas posterior al traumatismo, y casi siempre es secundaria a sepsis o falla orgánica múltiple.
Conceptualmente, cuatro factores influyen en la morbimortalidad de los pacientes politraumatizados:

• Gravedad de la lesión.
• Factores del huésped (patología asociada).
• Tiempo transcurrido entre el accidente y la atención.
• Calidad de la atención.