Histological examination shows severe degeneration of Purkinje cells, reduction in the number of cells in the molecular and granular layers of the cerebellar cortex, severe loss of the number of cells in the pontine nuclei and olives, and demyelination of the middle cerebellar peduncle. The cerebellar nuclei are well preserved. The tegmentum of the pons, the corticospinal tracts, and the restiform body are also usually unaffected. In clinical cases involving extrapyramidal symptoms, degenerative changes in the striatum, espec...
A Look at Myelin and Myelin-Related Disorders
Myelin is the protective sheath around axons in the nervous system, and is often referred to as 'white matter.' It acts as an insulator to the electrical signal that is conducted down the axon as a neuron fires, and can well be compared to the insulation around an electrical wire. The myelin sheath contains a variety of fatty substances (lipids), and contains at least ten distinct chemicals (2). . From what is known, axons are not fully myelinated at birth, but myelin is formed from birth on into the second decade of life (3). The way myelination takes place is through glial cells wrapping around the axons in a spiral fashion.
The ADH hormone is secreted by the pituitary gland and helps to stimulate a person’s thirst mechanism. The secretion rate of the ADH hormone is based on the osmolality receptors (found in the hypothalamus), volume sensitive receptors (found in the atria and thoracic vessels), and the baroreceptors found in the carotid sinus, aorta and pulmonary arteries. The main job of these receptors is to help balance the body’s water in the plasma and to control blood volume which in turn will increase or decrease in response to plasma osmolality. If the receptors sense an increase in plasma osmolality, as in the case of fluid loss, excess sodium, and blood lost, the receptors will send a message to the posterior pituitary to release more of the ADH hormone which will cause thirst. An increase in fluid inta...
Moreover, vasa recta not only bring nutrients and oxygen to the medullary nephron, but also remove excess water from the medullary interstitium. The blood plasma, as it enters vasa recta is isotonic (300 mOsm) with respect to the interstitum. As plasma makes it way down into the medullary interstitial fluid, it is encountering increasingly hyperosmotic interstitial fluid (ISF). Since it’s a capillary, there is a free exchange of water and solute between the vasa recta and the medullary ISF. As plasma moves down the descending loop of Henle, due to hyperosmotic ISF, water moves out and sodium and chloride move into the bloodstream. At the end of the descending loop of Henle, the concentration of salt inside the rasa recta is around 1200 mOsm. Now, as plasma moves up the ascending loop of Henle, sodium and chloride move out and water move into the bloodstream. The ascending loop of Henle cannot remove the added water because they are water-impermeable. The vasa recta remove the water; this is why blood flow in the ascending vasa recta exceeds blood flow in the descending vasa recta. Interestingly, sodium and chloride that are moved out of the vasa recta in the ascending loop of Henle enter the descending loop of Henle and the cycle continues. The countercurrent exchange process is passive and it helps maintain an electrochemical gradient.
... that sodium ingestion (especially high contents) passes through extracellular compartments including the vascular system before getting eliminated by the kidneys. An acute increase of plasma sodium concentration can alter the mechanical properties of vascular endothelium, as long as aldosterone is present. Aldosterone not only plays a major role in adjusting sodium and potassium transport in kidneys but also on the cardiovascular system. Sodium accumulates in extracellular space when the kidneys cannot adequately adjust salt excretion to salt uptake and/or when the concentration of aldosterone is raised, leading to an increase in plasma sodium concentration. An important finding in these studies was the observed effects of amiloride, which acted to block sodium channels and prevented an increase in stiffness by reversing the increasing in cell volume and pressure.
November 25, 2012
Myotonic dystrophy, type 1, is a genetic disorder which is linked to chromosome number 19 in humans. The dystrophia myotonica protein kinase gene is located on the q arm of the chromosome at the locus of 13.32. It is an autosomal dominant disorder, which means that the individuals that are affected by this disorder and contain at least one dominant allele for the dystrophia myotonica protein kinase gene. The disorder is caused by a series of repeats of a trinucleotide region that is expanded beyond the normal levels (Musova et al., 2009). The trinucleotide region is a series of repeats of CTG in the untranslated region of the dystrophia myotonica protein kinase gene.
Why does this self-inflicted deconstruction of the myelin occur? Multiple sclerosis is said to have genetic and environmental factors to its cause. Malnutrition and free radicals can all trigger a dormant M.S. gene in a person. According to the National Multiple Sclerosis Society, What Causes MS, studies say that “Growing evidence suggests that vitamin D plays an important role. People who live closer to the equator are exposed to greater amounts of sunlight year-round. As a result, they tend to have higher levels of naturally-produced vitamin D.” In fact, vitamin D holds specific immune strengthening qualities. Make it a priority to remain nourished, keeping your immune system at optimal strength, thus preventing pos...
If diabetes is not diagnosed at an early stage, individuals will not notice the presence of the symptoms until they experience trouble with their heart, brain, kidney, and etc. Therefore, it is always best to speak to a health care provider or ones doctor regarding hypertension. In 2009, Americans visited their health care providers more than 55 million times to treat their high blood pressure. (Roger, Lloyd-Jones, 2012). One can also prevent the risk of hypertension by exercising regular, maintaining a healthy body weight, and avoiding heavy salt intake and excess alcohol use. Treatment is also available for hypertension. Various drugs like diuretics which work on the kidney to flush out excess water and salt from one’s body, beta and alpha blockers reduce nerve impulses to allow easier blood flow, and calcium channel blockers keep calcium from entering muscle cells of the heart.
Damage to the myelin causes interference in communication between the brain and spinal cord, the body’s central nervous system. The central nervous system is made up of nerves that act as the body’s messenger system. Each nerve is covered by a fatty substance called myelin that insulates the nerves and helps with the transmission of nerve impulses, or messages, between the brain and other parts of the body. When the myelin is damaged, the messages traveling along that nerve can be slowed or blocked. Damage to the nerve is caused by inflammation. This condition can also lead to an irreversible process, the deterioration of the nerves themselves.
We believe that the nervous system is one of the most important systems within our bodies. It not only controls our sensory, motor and autonomic responses to the environment, but also is arguably the system that makes us human. We were fascinated by the fact that a simple change in the myelination of cells could cause such a profound effect on th body as a whole. In addition, we have also had personal experiences with individuals who unfortunately have been diagnosed with MS. MS is a unique disease based on its etiology, causes an...