Reflex changes

Figure 1.2 Negative feedback. These types of responses are employed throughout the body in order to maintain homeostasis. In this example, any change in blood pressure, which is monitored within the circulatory system and processed within the CNS, will cause reflex changes in heart rate. The change in heart rate will be in the opposite direction of the change in blood pressure if blood pressure increases, then heart rate decreases if blood pressure decreases, then heart rate increases. In this way, blood pressure is adjusted back to its normal value.

Any sudden alteration in the mean arterial blood pressure tends to produce compensatory reflex changes in heart rate, contractility, and vascular tone, which will oppose the initial pressure change and restore the homeostatic balance. The primary sensory mechanisms that detect changes in the mean arterial blood pressure are stretch receptors (baroreceptors) in the carotid sinus and aortic arch. 

Injection of a drug that causes a fall in the mean arterial blood pressure triggers diametrically opposite reflex changes. There is decreased impulse traffic from the cardiac inhibitory center, stimulation of the cardiac accelerator center, and augmented vasomotor center activity. These changes in cardiac and vasomotor center activity accelerate the heart and increase sympathetic transmission to the vasculature thus, the drug-induced fall in blood pressure is opposed and blunted. 

Although vasodilators would appear to be ideal drugs for the treatment of hypertension, their effectiveness, particularly when they are used chronically, is severely limited by neuroendocrine and autonomic reflexes that tend to counteract the fall in blood pressure. How these reflexes compromise the fall in blood pressure produced by the vasodilators is shown in Fig. 20.1. The diagram does not show all of the possible interrelationships but rather is meant to draw attention to the most prominent reflex changes. These reflexes include an augmentation of sympathetic nervous activity that leads... 

Prevent baroreceptor reflex changes in heart rate see Figure II-2-4)... 

Figure 11-2-4 summarizes the effects of ganglionic blockers on drugs that modify blood pressure, causing a reflex change in heart rate, and on drugs that act directly at the SA node to change the heart rate. 

Reflex changes in heart rate involve ganglionic transmission. Activation of alphaj receptors on blood vessels by phenylephrine elicits a reflex bradycardia since mean blood pressure is increased. One of the characteristic effects of tubocurarine is its block of autonomic ganglia—this action can interfere with reflex changes in heart rate. Tubocurarine would not prevent bradycardia due to neostigmine (an inhibitor of acetylcholinesterase) since this occurs via stimulation by acetylcholine of cardiac muscarinic receptors. 

Second Additional neuromuscular symptoms (advanced general paresthesia paralysis of phalanges and extremities pupillary dilatation, reflex changes)... 

High levels of carbon dioxide in the blood lower the pH (i.e. increase the acidity). By responding to fluctuations in pH, the carotid body coordinates reflex changes in respiration rate. 

OsADCHii, L. L, Balueva, T. U., and MolnAr, J., 1967, Reflex changes in systemic vascular resistance following intracoronary injection of capsaicin and veratrine in the cat, Acta Physiol. Acad. Sci. Hung. 32 215-219. 

Patients may experience a sudden onset of low back pain with bending or lifting an object or a more gradual onset of low back pain. The pain may radiate into a lower extremity, frequently following the course of the sciatic nerve. Depending on the nerve root involved and the severity of the herniation, there may be sensor) or reflex changes or motor weakness. Neurologic-deficit helps differentiate radiculopathy from referred pain. 

The osteopathic treatment of sinusitis has several goals to relieve obstruction and pain to improve venous and lymphatic flow from the area to affect reflex changes and to improve mucociliary clearance. Several manual techniques have been designed to aid in achieving these goals. Although only one set of sinuses may produce pain, the entire series of techniques should be performed to assist drainage of all the sinus areas. 

Central nervous system reflex changes, insomnia... 

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