Calling posture

In moths, sex pheromone communication occurs at a particular time of the day or night depending on the species. Females, usually more than 1 day old, take up a calling posture (Fig. 27.1a) by raising the abdomen and everting glandular tissue at the end of the abdomen associated with the ovipositor from which pheromone is emitted at a rate of a few tens of picograms per second. 

Once the evaluation is done, a preferred vendor should have surfaced. Beyond the evaluation, it is up to the user, his company policy, and conscience to make the selection. Once made, a meeting with the vendor is recommended. It may be good practice to keep the second choice vendor in the background at this time. Also, under no circumstances should anyone leak the selection to the vendor. This is the first of a trading session, and until the vendor is sure he has an order, he will stay in a trading posture. If two vendors were tied or too close to call, both vendors may be called in individually. 

Provide assistance for the patient getting out of a bed or a chair if symptoms of postural hypotension are severe. Place the call light nearby and instruct patients to ask for assistance each time they get in and out of a bed or a chair. 

One of the cross-eyed men rose in the dock as his name was called. Sliding past Dr. Otto Ambros, he made his way across the well of the court, his feet toed out slightly, and this — with his erect posture — made you wonder whether he had ever been in the Army. But no — though his stride was even, there was no pace or music in it. If he had been announced as a minister of the gospel, you would believe it even before hearing the coincidence... 

In 1985, 1 finally took the county public health psychiatrist s recommendation to try Desipramine, an ostensibly mild tricyclic antidepressant. I took tiny dot doses, and for a month or so I felt encouraged except for intense muscle tension and clenching. The psychiatrist said it was not remotely possible that this response was related to the medication. I took a low dose for four more months before throwing them out. The side effects had escalated horribly, and become what I later learned are called tardive dyskinesia and tardive dystonia. Subsequently, chemical and electromagnetic field exposures, feeling compromised or ashamed, or stress can trigger uncontrollable movement, hyperactivity, rigid posture and then, frequently, paralysis. 

Free tryptophan is transported into the brain and nerve terminal by an active transport system which it shares with tyrosine and a number of other essential amino acids. On entering the nerve terminal, tryptophan is hydroxylated by tryptophan hydroxylase, which is the rate-limiting step in the synthesis of 5-HT. Tryptophan hydroxylase is not bound in the nerve terminal and optimal activity of the enzyme is only achieved in the presence of molecular oxygen and a pteridine cofactor. Unlike tyrosine hydroxylase, tryptophan hydroxylase is not usually saturated by its substrate. This implies that if the brain concentration rises then the rate of 5-HT synthesis will also increase. Conversely, the rate of 5-HT synthesis will decrease following the administration of experimental drugs such as para-chlorophenylalanine, a synthetic amino acid which irreversibly inhibits the enzyme. Para-chloramphetamine also inhibits the activity of this enzyme, but this experimental drug also increases 5-HT release and delays its reuptake thereby leading to the appearance of the so-called "serotonin syndrome", which in animals is associated with abnormal movements, body posture and temperature. 

The so-called tail suspension test applies a similar principle (Steru et id., 1985 Fujishiro et ah, 2001). Instead of being immersed in water the animal (usually a mouse) is suspended by its tail. Following an initial period of struggling, untreated (control) animals remain predominantly in an immobile posture whereas animals treated immediately before the experiment with an antidepressant drug show a reduction in the time spent immobile. 

Basal ganglia lie beneath the cortex and have effects on muscle tone and posture especially in involuntary motor movement. (This is called the extrapyrimidal motor system. The voluntary motor system is referred to as pyrimidal.)... 

The basal ganglia are part of what is referred to as the brain s extrapyra-midal system of motor control, so called to distinguish it from the pyramidal nerve tracts that control voluntary movement. The extrapyra-midal system is most directly associated with involuntary aspects of movement such as muscle tone and posture. However it has extensive connections with other parts of the brain, especially the frontal cortex, the seat of personality and rationality. This functional network... mediates volitional motor activity, saccadic eye movements, emotion, motivation, cognition and social behaviour (Wonodi, Hong, Thaker 2005, p. 340). Thus conditions that effect neurotransmission in the basal ganglia can be expected to have far-reaching functional consequences. 

It was the combination of EEG and EOG that enabled Eugene Aserinsky and Nathaniel Kleitman to make their 1953 discovery of brain activation in sleep. They called the brain activation phase of sleep REM (for rapid eye movements) because of the association of the activation of the eye movements (oculomotor activation) with activation of the brain. They asserted that dreaming might be another associated event. It was the EMG (together with the EEG and EOG) that allowed Michel Jouvet and Francois Michel to show that muscle tone supporting posture - and hence postural movement - was actively abolished in REM sleep. 

Skeletal muscles are organized into extrafusal and intrafusal fibers. Extrafusal fibers are the strong, outer layers of muscle. This type of muscle fiber is the most common. Intrafusal fibers, which make up the central region of the muscle, are weaker than extrafusal fibers. Skeletal muscles fibers are additionally characterized as fast or slow based on their activity patterns. Fast, also called white, muscle fibers contract rapidly, have poor blood supply, operate anaerobically, and fatigue rapidly. Slow, also called red, muscle fibers contract more slowly, have better blood supplies, operate aerobically, and do not fatigue as easily. Slow muscle fibers are used in movements that are sustained, such as maintaining posture. 

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