New year greetings

HAPPY NEW YEAR 2011
WITH THE WARMEST
OF
WISHES
FOR
THE BEST
OF
EVERYTHING

Unconventional NT-Endocannabinoids-Brain's own Marijuana?

Conventional NT is H2O soluble and is stored in high concentration in little packets or vesicles. Unconventional NT like Endocannabinoids are fats and are not stored but synthesized from components of cell membrane. Unconventional neurotransmitters have many exceptions to normal neurotransmitter.1.not stored at synapses [produced locally and used immediately].2.not exocytose [diffuses freely across the membrane] 3.very unstable and reactive.
Scientist have discovered that the brain manufactures protein that act like marijuana at specific receptors in the brain itself.[THC receptor]The main active chemical in marijuana is delta-9-tetrahydro cannabinol;THC for short. Endocannabinoids-retrograde transporters like NO- nitric oxide, and are involved in a variety of physiological processes including appetide, pain sensation, emotion, learning and memory. It is named for endocannabinoids the endogenous lipids that bind cannabinoid receptors CB1 and CB2 located in the CNS and periphery respectively [the same receptors that mediate the psychoactive effects of cannabis.CB1 receptors have been found mainly in the CNS, but also in lymphocytes, ovary, uterus, testes, vas and urinary bladder.CB2 receptors have been identified mainly in immune cells but are expressed also in astrocytes and in the brain stem.

Does stress affect memory?

PHYSIOLOGY TUTORIAL
Does stress affect memory?
The primary area of the brain that deals with stress is its limbic system. Because of its enormous influence on emotions and memory, the limbic system is often referred to as the emotional brain.
During times of stress, the body responds by releasing hormones that trigger physical changes. Chronic stress can have negative effects on our well being, leading to higher blood pressure, increased abdominal fat and decreased bone density.
Exposure to stress can damage hippocampus. The damage results from a kind of chain reactions or feedbackloop.The cycle begin when adrenal glands release steroid hormones called glucocorticoids into the bloodstream. The hippocampus has a high density of receptors for glucocorticoids and in normal circumstances it helps regulate the production of stress hormones. However hippocampus is particularly sensitive to these hormones. Studies have shown that hippocampal neurons of rodents die when they are exposed to glucocorticoids for months and the neuronal dendrites atrophy when they are exposed for few weeks of stress. As a result of the damage stress hormones continue to be secreted at increased levels, resulting in even more damage to the hippocampus
Because exposure to stress can damage the hippocampus and because hippocampus is an important brain structure associated with declarative memories for facts, researchers have been particularly interested in how stress affects our ability to remember new information.
Stress management is the solution, not stress elimination
Bear in mind that an appropriate stress response is healthy and necessary part of life. one of the things it does is to release NE ,the excitatory neurotransmitter.NE is needed to create new memories, it improves mood, problems feel like more challenges, which encourage creative thinking that stimulates our brain to grow new neuronal connections .
Sympathetic system turns on fight and flight response. In contrast the parasympathetic system promotes relaxation response. The challenge in this day and age is not to let the sympathetic system stay chronically aroused. This may require knowledge of techniques that work to activate our relaxation response.
Lifestyle, personality, and even genetic makeup influence our emotional and physiological responses to stress. But we can modify those responses by making changes in how we act, think, relate, move, and relax.
P.S –Refer, Stress and destress posted by Dr.R.vinodha in vinodha’s blog on Sep 2, 2007.

PHYSIOLOGY TUTORIAL- "Free running rhythm"

“FREE- RUNNING” CIRCADIAN RHYTHM
Most totally blind people have free-running circadian rhythm. (i.e. Not synchronized to 24 hr light dark cycle, but oscillates on a cycle slightly longer than 24 hr.).This causes insomnia and daytime sleepiness. A similar phenomenon is seen in subjects exposed to continuous absence of natural light in Antarctica during winter months.
Melatonin secretion shows a circadian rhythm, the level being higher at night, the peak at 3-4 am. This fluctuation depends on the sympathetic innervations of the pineal gland. (Nervi conarii).Further in blind melatonin level shows an approximate 24 hr rhythm, but the peak may be at any time. So, in blind the biological clock (SCN of Hypothalamus) is able to maintain circadian rhythmic secretion but not its relationship to light-dark cycle. Such a 24hr rhythm which shows no relation to light or dark is called “free-running”.since evidences support that, diurnal changes in melatonin secretion function as a timing signal that coordinates endocrine and other internal events with light-dark cycle, the blind people can be “ entrained”to 24 hr cycle with melatonin.
Note: Retino hypothalamic fibers synapse in the SCN. There are connections from SCN to intermediolateral gray column of spinal cord.preganglionic neurons pass from spinal cord to superior cervical ganglion, post ganglion neurons project from this ganglion to pineal in the nervi conarii.

HAPPY NEW YEAR 2010

HAPPY NEW YEAR 2010
Every moment in a day has its value
Don’t waste time grieving over past mistakes
Learn from them and don’t repeat the same mistake
New Year begins; let us pray for happiness &peacefulness
I wish you that your all dreams comes true.
HAPPY NEW YEAR

A VECTOR DIAGRAM OF OCULAR MUSCLE ACTION