Chapter 19 Nervous Regulation Of The Circulation And Rapid Control Of Arterial Pressure Flashcards
What is the most important component of autonomic nervous system in regulating the circulation?
The sympathetic nervous system. The parasympathetic division is responsible for regulating the heart function
What is the distribution of the sympathetic innervation of the blood vessels?
The arteries, veins and arterioles and venules are densely innervated. In most tissues all the vessels except the capillaries are innervated. However, in mesenteric blood vessels the metarterioles and precapillary vessels are innervated.
What is the sympathetic vasoconstriction effect distribution on various organs ?
It is powerful on the skin, kidneys, spleen and the skin. It is much less powerful on the brain, heart, and the skeletal muscle.
What is the location of the vasoconstrictor area ?
Bilateral anterolateral portion of the upper medulla. It sends sympathetic fibers throughout the spinal cord that excite preganglionic vasoconstrictor neurons.
Which is the sensory nucleus and nerves involved in blood pressure regulation?
Nucleus tractus solitarius located posterior lateral pontomedulary junction as well as the vagus and the glossopharyngeal nerves.
What is sympathetic vasoconstrictor tone?
It is the partial pan constriction of blood vessels across the body by the continues stimulation of sympathetic nerve stimulation which occurs at a rate of 0.5 to 2 impulse per second. It is responsible for the baseline vasomotor tone.
The vasomotor center anatomy and it’s function?
It is a regulatory network of neurons located within the medulla oblongata. The lateral portion of the vasomotor center is responsible for sympathetic stimulation of the heart, when there is a need for increasing the heart rate. Conversely, when there is a need to reduce the heart rate, the vasomotor center medial portion sends parasympathetic stimulation through the dorsal nucleus of vagus nerve and through the vagus nerve into the heart.
What is the general pattern of excitation and inhibition of the medullary vasomotor center by the reticular substance?
The reticular substance is a network of nuclei extending from the reticular substance to the pons. In general the lateral and superior portion of the reticular substance excite the vasomotor center and the medial and inferior portions inhibits.
Regulatory effect of hypothalamus on vasomotor center?
The posterio-lateral portions excites the vasomotor center and the anterior portion inhibits the vasomotor center
What is the principle sympathetic vasoconstrictor neurotransmitter?
Norepinephrine which act on the alpha adrenergic receptors of the vascular smooth muscles to cause vasoconstriction
What is the relationship between adrenal medulla and the sympathetic vasoconstrictor system?
The sympathetic vasoconstrictor system stimulates adrenal medulla along with vascular smooth muscles, which causes the adrenal medulla to secrete epinephrine and norepinephrine which causes pan vasoconstriction effect on the blood vessels with the exception of some organs such as the heart where epinephrine acts on the beta 2 adrenergic receptors causing vasodilation.
The sympathetic nerves to the skeletal muscle carries both___and ____ fibers.
The vasodilator and the vasoconstrictor fibers.
In human what is the cause of the vasodilator effect?
Epinephrine induced beta adrenergic receptor activation vasodilation of the muscle vasculature.
Which is the principle control center of the vasodilator system?
Anterior hypothalamus.
What is the pathophysiology of emotional fainting?
It is caused by the simultaneous occurring of the epinephrine mediated muscle vasodilation and the activation of vagal cardio-inhibitory center by the emotional cortex through the anterior hypothalamus causes a rapid fall in arterial pressure which results in fainting.
