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Results for “Physiological Phenomena”

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At least 19 recordsLinked to original sources
PubMed1998

Cortical activity of REM sleep often occurs earlier than other physiological phenomena.

N300 appearing in response to sound stimulus was used as an index to determine the occurrence of cortical activity characterizing REM sleep. In 5/10 subjects, marked reduction of N300 amplitude occurred even in the period of 0.5-2.5 min immediately preceding the appearance of muscle atonia characterizing REM sleep. Neither muscle atonia nor rapid eye movements appeared prior to the marked reduction of N300 amplitude in any subject. This suggests that the cortical activity characterizing REM sleep sometimes occurs a few minutes (or less) earlier than other physiological phenomena.

Adult↗
PubMed2002

Electrocardiograms from the turtle to the elephant that illustrate interesting physiological phenomena.

This article describes a collection of ECGs from many species obtained over the past 50 years. Presented are ECGs of species in which the pacemaker is a separate contractile chamber with its own action and recovery potentials. In such species, pacemaker atrial and AV block can be produced. Shortening of the atrial refractory period and the negative inotropic effect can be produced by vagal stimulation. The cardiac electrogram and stroke volume are recorded from the turtle heart. The ECG and respiration were recorded from the snake. ECG records were obtained from the anesthetized and decapitated housefly. ECG records of the rabbit show slowing when the nose encountered irritating vapors. Records from a dog with atrial fibrillation exhibit rhythmic fibrillation frequency changes correlated with respiration. In addition, in a morphinized dog with atrial fibrillation, impulses crossed the AV node only during inspiration. The ECGs of a cow and camel exhibit long P-R intervals and biphasic P waves. Finally the elephant ECG shows a clear U wave following the T wave.

Animals↗
PubMed2000

Effects of different intensities of cold stress on certain physiological phenomena related to skeletal health in a hypogonadal rat model.

Intestinal transference pattern of calcium and associated changes in the activities of intestinal mucosal enzymes, rate of bone turnover and bone metabolism were evaluated in ovariectomized rats exposed to cold stress of various intensities i.e., mild (15 degrees C) or stronger (8 degrees C and 4 degrees C) for 5 min everyday for 7 consecutive days. Except mild cold stress-induced group (15 degrees C), rats of other two groups (8 degrees C and 4 degrees C) showed considerable decrease in the rate of in situ intestinal transference of calcium. Likewise, in these groups, the activities of intestinal mucosal enzymes, alkaline phosphatase (AP) and calcium ATPase (Ca2+-ATPase) were decreased significantly in all the segments of small intestine in a descending gradient. Also significant changes in bone turnover and bone resorption were confirmed in these animals by marked alterations in plasma AP activity, urinary calcium and phosphate excretion and urinary calcium to creatinine ratio (Ca: Cr). The skeletal changes were further ascertained by examining other physical and biochemical parameters of bone metabolism viz., body mass, bone density, ratio of mineral to matrix and mineral content of bone ash (calcium and phosphate) in the ovariectomized rat model. All these results suggest that stronger cold stress (8 degrees C and 4 degrees C) may be an important ecological factor in the development of earlier bone loss in hypogonadal rats.

Adenosine Triphosphatases↗