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Archive for the ‘Physiology’ Category

Approach to Hyponatremia

Posted by medliorator on August 24, 2009

The first question to ask yourself is: Is this a true hyponatremia? …is there truly an imbalance between the ratio of sodium to free water

To calculate what the true sodium level would be in the face of hyperglycemia, take the current level, and add 1.6 times the glucose level minus 100 divided by a hundred.

next consider volume status.  If the patient is dehydrated, then the low sodium is likely due to the compensatory response of ADH, and the treatment is to gently rehydrate the patient using normal saline. However, if the patient is volume overloaded and edematous, think about causes such as cirrhosis, renal failure, or congestive heart failure and treat those as needed. If the patient has normal volume status, they might have syndrome of inappropriate antidiuretic hormone (SIADH) or something more esoteric

How To Work Up Hyponatremia [Scrub Notes]

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Heart Sounds & Cardiac Exam Primer

Posted by medliorator on October 29, 2008

Blaufuss Medical Multimedia Laboratories offer a free interactive tutorial worthy of a closer look.

  • Cardiac Exam Module
    • heart sounds tutorial
    • quiz
    • detailed animation of S2 splitting.
  • Electrocardiogram Module
    • Supraventricular tachycardia tutorial
    • Interactive ECG viewer
    • interpretations & detailed explanations.

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Relaxation Response and Genetic Expression

Posted by medliorator on July 10, 2008

eliciting the relaxation response — a physiologic state of deep rest — influences the activation patterns of genes associated with the body’s response to stress.

Herbert Benson, MD, director emeritus of the Benson-Henry Institute and co-senior author of the PloS One report. “Now we’ve found how changing the activity of the mind can alter the way basic genetic instructions are implemented.”

The first phase compared gene expression patterns of 19 long-term practitioners of different relaxation response techniques with those of 19 individuals who had never engaged in such practices. Those control participants then went through an 8-week training program to investigate whether initiating relaxation response practice would change gene expression over time.

Both phases of the study indicated that the relaxation response alters the expression of genes involved with processes such as inflammation, programmed cell death and how the body handles free radicals

We found that no matter which particular technique is used — different forms of meditation and yoga, breath focus, or repetitive prayer — the mechanism involved is the same.

Relaxation Response Can Influence Expression Of Stress-related Genes [Science Daily]

The RR is characterized by decreased oxygen consumption, increased exhaled nitric oxide, and reduced psychological distress. It is believed to be the counterpart of the stress response that exhibits a distinct pattern of physiology and transcriptional profile. We hypothesized that RR elicitation results in characteristic gene expression changes that can be used to measure physiological responses elicited by the RR in an unbiased fashion.

We assessed whole blood transcriptional profiles in 19 healthy, long-term practitioners of daily RR practice (group M), 19 healthy controls (group N1), and 20 N1 individuals who completed 8 weeks of RR training (group N2). 2209 genes were differentially expressed in group M relative to group N1 (p<0.05) and 1561 genes in group N2 compared to group N1 (p<0.05). Importantly, 433 (p<10−10) of 2209 and 1561 differentially expressed genes were shared among long-term (M) and short-term practitioners (N2).

Genomic Counter-Stress Changes Induced by the Relaxation Response [PLos ONE]

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Physiology of Sleep Deprivation

Posted by medliorator on February 8, 2008

what happens when you don’t have time for even 6 hours of sleep? Without adequate rest, the brain’s ability to function quickly deteriorates. The brain works harder to counteract sleep deprivation effects, but operates less effectively: concentration levels drop, and memory becomes impaired.


Similarly, the brain’s ability to problem solve is greatly impaired. Decision-making abilities are compromised, and the brain falls into rigid thought patterns that make it difficult to generate new problem-solving ideas. Insufficient rest can also cause people to have hallucinations. Other typical effects of sleep deprivation include:

  • depression
  • heart disease
  • hypertension
  • irritability
  • slower reaction times
  • slurred speech
  • tremors

Because the amount and quality of the sleep we get affects our hormone levels, namely our levels of leptin and ghrelin, many physiological processes that depend on these hormone levels to function properly, including appetite, are affected by our sleep.


While leptin is a hormone that affects our feelings of fullness and satisfaction after a meal, ghrelin is the hormone that stimulates our appetites. When you suffer from sleep deprivation, your body’s levels of leptin fall while ghrelin levels increase. This means that you end up feeling hungrier without really feeling satisfied by what you eat, causing you to eat more and, consequently, gain weight.

Cheat on the Need to Sleep [Wired HowTo]

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