Thursday, April 14, 2011

Neuroanatomy- Post #4- The Hypothalamus

            The hypothalamus, which serves a number of autonomic, appetitive, and regulatory functions, lies below and in front of the thalamus; it forms the floor and lower walls of the third ventricle. External landmarks of the hypothalamus are the optic chiasm; the tuber cinereum, with its infundibulum extending to the posterior lobe of the hypophysis; and the mamillary bodies lying between the cerebral peduncles.

The hypothalamus can be divided into an anterior portion, the chiasmatic region, including the lamina terminalis; the central hypothalamus, including the tuber cinereum and the infundibulum (the stalk connecting the pituitary to the hypothalamus); and the posterior portion, the mamillary area.

The right and left sides of the hypothalamus each have a medial hypothalamic area that contains many nuclei and a lateral hypothalamic area that contains fiber systems (eg, the medial forebrain bundle) and diffuse lateral nuclei.
            It is through these pathways that the hypothalamus relays afferent and efferent signals. The hypothalamus receives (afferent) inputs from limbic structures, thalamus and cortex, visceral and somatic afferents, and sensors such as osmoreceptors, which permit it to monitor the circulation.
Efferent tracts from the hypothalamus include the hypothalamohypophyseal tract, which runs from the supraoptic and paraventricular nuclei to the neurohypophysis, the mamillotegmental tract going to the tegmentum; and the mamillothalamic tract, from the mamillary nuclei to the anterior thalamic nuclei. There are also the periventricular system, including the dorsal fasciculus to the lower brain levels; the tuberohypophyseal tract, which goes from the tuberal portion of the hypothalamus to the posterior pituitary; and fibers from the septal region, by way of the fornix, to the hippocampus. The table below gives a summary of the major tracts and their roles.
********* TABLE WOULD NOT POST !!!!!!!!!! ***********
            The next topic to talk about would be the functions of the hypothalamus. These include: eating, autonomic functions, body temperature regulation, water balance, Circadian Rhythm regulation, anterior pituitary functions, some control of emotions. Naturally problems can occur within each of these categories. So that’s what I’m going to talk about next.
            For example, damage to the feeding center leads to anorexia and severe loss of body weight. This damage can occur either through physical trauma or through lesions within this area. Generally, the first employment route for treatment would be appetite increasing medications. This is used to avoid drastic health problems. Of course, this doesn’t solve the problem. So the next route is surgery. Of course, if lesions are the problem then they are removed before any medication is given, but if the cause is from blunt trauma, then usually medications are used.
Another problem can occur if there is misregulation of water balance. Hypothalamic influence on vasopressin secretion within the posterior pituitary is activated by osmoreceptors within the hypothalamus, particularly in neurons within a "thirst center" located near the supraoptic nucleus. Lack of secretion of vasopressin caused by hypothalamic or pituitary lesions can result in diabetes insipidus, which is characterized by polyuria (increased urine excretion) and polydipsia (increased thirst). Generally this is treated with a combination of surgery and diet management.
Finally, a third pathology can be associated with Circadian Rhythm malfunction. Within the hypothalamus, a specific cell group, the suprachiasmatic nucleus, functions as an intrinsic clock. Cells within this nucleus show circadian rhythms in metabolic and electrical activity, and in neurotransmitter synthesis, and appear to keep the rest of the brain on a day–night cycle. Obviously lesions within this area can lead to a malfunction of all circadian rhythms throughout the body, resulting in many problems.

References
1.)     Molina PE, "Chapter 2. The Hypothalamus & Posterior Pituitary Gland" (Chapter). Molina PE: Endocrine Physiology, 3e: http://www.accessmedicine.com/content.aspx?aID=6169265.
2.)     Hopper AH, Samuels MA, "Chapter 27. The Hypothalamus and Neuroendocrine Disorders" (Chapter). Ropper AH, Samuels MA: Adams and Victor's Principles of Neurology, 9e: http://www.accessmedicine.com/content.aspx?aID=3634491.

3 comments:

  1. Nobel Prize physiology 2017 about circadian rhythms, but... 3D Bioprinting-Immortality (biological timers)... Forever young with modified Biological Timers... Which are the biological timers?, where are them? (genes, hypothalamus...), how functioning them? (ordering stop growth at finish of adolescence...ordering start to grow-old at beginning of adulthood), how can modify them (telomerase...) for maintenance the hormones production, enzymes, cellular regeneration...all Eternity at same level of the 18 years old?... Have to accelerate Research about Memory and the Space´s Colonization... Immortality comes...

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  2. ...interstellar travel constant acceleration (Sun-Deneb: 1000g)... Earth...the 2 ships that will go formation flying for mutual assisting if there are problems...indestructible structures made of Hexapentas material, awaiting in airport the arrival of passengers... Day 1: zero-speed... THE SHIPS TAKEOFF... navigation computer places on screen the spacecraft in the center of sphere...spherical\tridimensional\spatial Heading: Deneb... Antimatter rocket engines...ON... Here we go...goooooo!...1g...10g...100g...constant acceleration cruise: 1000g (9.8 kms/sec²)... Inside the living areas (the same as going submerged in water: constant acceleration downwards...less...constant thrust, constant acceleration, from water upwards)...the gravitational transformers, perfectly synchronized with the acceleration, running: 1000g constant acceleration toward the floor (motors)...less...999g constant acceleration toward the ceiling (gravitational transformers) = 1g constant acceleration toward the floor... 8.5 hours: light-speed = 1c...the fusion reactor as an artificial sun illuminating the immense Vital Support Gardens to lowering, from their comfortable apartments, cheerful passage to the pool...the electromagnetic shield anti-radiation...antigravity fields generator run forward, working: light objects away from the path of the ship...and trajectory ship away from the heavy objects...superluminal-speed > 1c... 42.5 hours: reaches hyperluminal-speed = 5c... Day 508: Half Journey...1000 light years...high hyperluminal-speed = 1435.39c... OFF engines...a few minutes of weightlessness during maneuver...the ship rotates 180º around its axis...motors ON again and... STARTS TO BRAKE... Day 1017 (2.79 years): End Path party...2000 light years...zero-speed... The forever young passage of the 1st Immortal Generation (3D Bioprinting...Telomerase...modified Biological Timers...) disembarks at destination: an extra-stellar planet which came errant to orbit of Deneb giant. ((typewrite: interstellar travel constant acceleration))

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  3. ...interstellar travel constant acceleration (immortals new body)... 3D Bioprinting...the technology used to print documents is also being utilized to create living tissue, in a not too distant future to "print" overlapping layer upon layer, whole organs such as a heart, a liver, a kidney, and one day a whole body. In the beginning the basic technique was exactly the same as using a normal inkjet printer, when printing a document (or image) inks of different colors are distributed on the paper in a specific pattern. It all started in this way: at Clemson University (years ago) have replaced printer inks for some "ink cells" alive. The ink cartridges were refilled with some cell solutions and software was rescheduled. The "paper" is a biodegradable gel, designed at the University of Washington, which solidifies to reach 32 ºC of temperature. Still need it much? for to be a reality with great performances. The main problem is that it is still unable to create an organ which circulates the blood, but it can print a tissue with thickness of a kidney in just 2 hours. The next step is to print the tiniest (capillaries) parts of an organ, just those that make it work (plasma with O2 and nutrients towards...↔▓↔...and CO2 which go into from...). If this is achieved would be very near the Eternity for human being.

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