Sympathetic (adrenergic) system

which are the major neurotransmitters in the adrenergic system?

at the adrenergic neurones, an action potential causes depolarisation and an influx of calcium ions. THis triggers catecholamin release by exocytosis, followed by activation of postjunctional receptors. The mechanisms that may account for inactivation of catecholamines in the nervous system include [blank_start]neuronal[blank_end] uptake ([blank_start]sodium[blank_end] dependent in the cytoplasm and [blank_start]magnesium[blank_end] dependent in the granules), [blank_start]absorption[blank_end] in surrounding tissue, [blank_start]MAOs[blank_end] deaminating catecholamines and [blank_start]COMT[blank_end] inactivating catecholamines.

just like the cholinergic system, effects of adrenergic sympathetic activation are mediated through a series of complex G-coupled protein receptors. The most common receptors and their distribution in the adrenergic system are as follows: 1. [blank_start]alpha 1[blank_end] - smooth muscles, blood vessels, CNS 2. [blank_start]Alpha 2[blank_end] - some organ systems, CNS pre-synaptic 3. [blank_start]beta 1[blank_end] - mainly heart 4. [blank_start]beta 2[blank_end] - some organ systems, lungs some large blood vessels 5. [blank_start]dopamine[blank_end] - brain, coronary, kidney and mesenteric.

what physiological change is characteristic of a generalised sympathetic discharge and what receptors mediate this effect?

what is the effect of sympathomimetics on heart rate and force of cardiac contraction?

beta 2 receptors are considered inhibitory and therefore useful for induction of smooth muscle relaxation. What grouop of autonomic system modifying drugs would you consider to be useful against allergen induced bronchoconstriction and heaves in a horse?

Your patient is a large breed, spayed female dog with incontinence due to urethral spinchter incompetence mainly controlled by alpha 1 receptors. What autonomic modifying drug may be appropriate for this problem?

stimualteion of alpha 1 receptors in the bladder neck and proximal urethra narrows the bladder outlet maintaining continence. THe inappropriate contraction of the bladder neck or muscular urethra during the voiding phase prevents normal urine outflow and is termed 'functional urethra obstruction' . Which of the following drugs would you prescribe for a dog with functional urethra obstruction?

you are presented with a dog showing signs of severe sympathetic discharge, cardiac arrhythmias and hypertrophic cardiomyopathy, what adrenergic drug would you administer to minimize these catecholamine-induced cardiac effects?

adrenergic effects may be modified by specific receptor agonists or antagonists, which of the following compounds directly stimulates alpha receptors?

adrenergic effects may be modified by specific receptor agonists or antagonists, which of the following compounds directly stimulates beta receptors?

alpha 2 receptors are stimulated by catecholamines such as noradrenaline. In the CNS (brain and spinal cord), the inhibitory nature of these receptors plays a critical role in controlling vital physiological functions including wakefulness/sleep, skeletal muscle tone and pain. What represents two commonly used alpha 2 receptor agonists for induction of sedation, muscle relaxation and analgesia in veterinary medicine?

For which of the following clinical conditions would you administer alpha/beta receptor agonists?

the diagram represents part of the sympathetic nerve supply to the myocardium, the sinoatrial node, the atrioventricular node and the HIS purkinje system. What adrenergic receptor subtype is responsible for physiological changes at neuro-effector junction in the heart structures identified in the diagram?

the diagram is an illustration of physiological changes in heart rate and blood pressure following the administration of a sympathomimetic drug (dobutamine). what explains why dobutamine causes an increase in heart rate and cardiac contractility with minimal effect on blood pressure.

norepinephrine, epinephrine and isoproterenol were administered to a small cat. The tracings show measured heart rate, blood pressure, pulse rate, myocardial contractility and dopller assisted assessment of femoral and renal blood flow. Identify the adrenergic receptors (either alpha, beta 1 or beta 2)that may be involved in mediating the physiological effects at sites 1-13. 1. [blank_start]alpha[blank_end] 2. [blank_start]alpha[blank_end] and [blank_start]beta 2[blank_end] 3. [blank_start]beta 2[blank_end] 4. [blank_start]alpha[blank_end] 5. [blank_start]beta 2[blank_end] 6. [blank_start]beta 2[blank_end] 7. [blank_start]alpha[blank_end] 8. [blank_start]alpha[blank_end] 9. [blank_start]beta 1[blank_end] and [blank_start]beta 2[blank_end] 10-13. [blank_start]beta 1[blank_end].

Shown is a tracing of blood pressure easurement for an old cat that was given a therapeutic dose of epinephrine immediately after administering phenoxybenzamine. The penomenon where tehe blood pressure drops is known as '[blank_start]epinephrine reversal[blank_end]' in the presence of [blank_start]alpha -receptor[blank_end] blockers, epinephrine exergs an exaggerated [blank_start]beta-receptor[blank_end] activation including beta-2 receptors in the peripheral. The resultant effect is [blank_start]vasodilation[blank_end], decreased [blank_start]peripneral resistance and blood pressure[blank_end].