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Barrow means pressure or stretch so
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Barrow receptors are special nerve cells
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or receptors that sense blood pressure
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by the way that the walls of the blood
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vessels stretch that information is sent
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from the barrel receptors to the brain
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to help keep blood pressure
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balanced so Barrow receptors are
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actually groups of nerve endings found
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within the blood vessel walls and they
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can be classified into two types based
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on their location the arterial ones and
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the cardiopulmonary ones the arterial
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Barrel receptors can be found on the
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wall of the aortic Arch as well as on
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the wall of the kateed sinus which is
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basically a bulge of the internal kateed
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artery just above its split from the
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common kateed artery in the neck in the
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aortic Arch these nerve endings join up
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to form the vegus or 10th cranial nerve
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and in the kateed sinus they form the
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glossop Fingal or ninth cranial nerve
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both of these cranial nerves travel up
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towards the brain stem carrying
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information about the stretch they sense
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in the
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arteries these guys synapse at the
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nucleus tractus solitarius in the Medela
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oblongata of the brain stem which then
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relays the information to the
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cardiovascular
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centers the cardiovascular centers are
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areas in the lower one-third of the
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ponds in Medela oblongata of the brain
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stem and they're responsible for the
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autonomic or involuntary control of the
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cardiac and vascular function they do
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that by coordinating the sympathetic and
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parasympathetic branches of the
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autonomic nervous system there are two
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main cardiovascular centers the first is
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the vasom motor control center which
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controls the diameter of the blood
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vessels using the sympathetic nerve
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fibers to cause Vaso
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constriction the second is the cardiac
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control center which is further divided
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into the cardiac accelerator and the
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cardiac decelerator
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centers the cardiac accelerator Center
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speeds up the heart rate and increases
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cardiac contractility
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through the sympathetic outflow tract
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while the cardiac decelerator center
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slows down the heart rate through the
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parasympathetic outflow tract notice
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that both the sympathetic and
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parasympathetic systems affect the heart
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rate but only the sympathetic system has
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an effect on the diameter of the blood
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vessels as well as the contractility of
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the heart
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muscle this whole process is known as
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the barrel receptor reflex or Barrel
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reflex in short and takes place in
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seconds to minutes allowing us to w
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rapidly adjust our blood
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pressure all right so as blood pulses
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through the cored sinus in the aortic
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Arch the arterial walls get stretched
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out and in response the barrel receptors
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start firing more nerve impulses up to
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those cardiovascular
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centers the higher the pressure the
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higher the frequency of nerve
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impulses so let's say you're running to
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catch the bus and your blood pressure
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Rises the increased pressure stretches
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the walls of the aortic arch in the
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cored sinus and the barrel receptors
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start firing at an increased
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frequency the glossop Fingal and vagus
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nerve carry that increased signal to the
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cardiovascular centers of the brain
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stem to bring the pressure back down to
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normal these centers inhibit the
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sympathetic and stimulate the
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parasympathetic nervous systems
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specifically the vasom motor Center
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decreases the vasoconstrictive effect of
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the sympathetic nervous system in other
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words the arterials dilate decreasing
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total Peripheral arterial resistance and
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there's decreased constriction of veins
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which allows blood to pull in the
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periphery rather than returning to the
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heart decreased Venus return means that
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there's less preload or less diastolic
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filling of the heart and that also
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decreases cardiac
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output meanwhile remember that the
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cardiac accelerator Center is also
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inhibited reducing the sympathetic
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effect on the heart and letting the
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heart work slower and less forcefully in
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other words decreasing the heart rates
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and
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contractility while the cardiac
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decelerator center is activated boo
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boosting the parasympathetic effects on
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the heart which again slows down the
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heart rate combined these effects result
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in a decreased cardiac output since
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blood pressure roughly equals cardiac
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output times total peripheral resistance
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the decrease in cardiac output and the
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decreasing total peripheral resistance
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means that the blood pressure will
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decrease back down to normal as
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well hopefully by that point you've made
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the bus on the flip side let's say that
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you're in a terrible traumatic accident
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in start losing a lot of blood causing
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your blood pressure to fall the
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decreased pressure causes the walls of
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the aortic Arch and kateed sinus to
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become less stretched and the barrel
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receptors start firing less
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frequently the glossop ferial and vus
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nerve carry that decreased signal to the
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cardiovascular centers of the brain
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stem to bring the pressure back up to
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normal these centers stimulate the
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sympathetic and inhibit the
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parasympathetic nervous
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systems specifically the vasom motor
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Center increases the vasoconstrictive
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effect of the sympathetic nervous
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system in other words the arterials
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narrow increasing total Peripheral
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arterial resistance and there's
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increased constriction of veins which
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returns more blood to the heart rather
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than allowing it to pull in the
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periphery increased Venus return means
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that there's more preload and that also
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increases cardiac
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output meanwhile remember that the
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cardiac accelerator Center is also
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stimulated increasing the sympathetic
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effect on the heart and letting the
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heart work faster and more forcefully
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meaning that it increases the heart rate
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and
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contractility at the same time the
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cardiac decelerator center is
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deactivated which reduces the
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parasympathetic effect on the heart
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which again speeds up the heart
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rate combined these effects result in an
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increased cardiac output as well as an
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increase in total peripheral resistance
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which raises the blood pressure back to
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normal in this case these changes can
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save your life
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now the other type of barrel receptors
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are called cardiopulmonary Barrel
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receptors and they're embedded within
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the walls of the right atrium right
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ventricle and pulmonary artery and veins
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these are all relatively low press areas
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so the stretch of the walls mainly
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depends on the blood volume flowing
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through or the fullness of these
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vessels this is why these Barrow
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receptors are mainly responsible for the
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regulation of blood volume and are also
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known as low pressure or volume Barrow
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receptors if the blood volume increases
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the cardiopulmonary Barrel receptors
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start firing more frequently through the
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vagus nerve toward the cardiovascular
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centers of the brain
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stem these centers then send signals
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toward the heart increasing its rate and
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thus the cardiac
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output increased cardiac output means
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more blood reaches the kidneys so more
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water and sodium can get excreted in an
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attempt to lower blood volume this is
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called a bane Bridge
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reflex in addition when cardiopulmonary
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Barrel receptors sense high blood volume
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they also send their signal via the
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vagus nerve to the hypothalamus of the
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brain telling it to reduce the
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production of vasopressin or
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anti-diuretic
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hormone this results in decreased water
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reabsorption from the kidney letting
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more water get lost in the
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urine cardiopulmonary barel receptors
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also stimulate the secretion of atrial
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natriuretic peptide which comes from the
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atrial muscle
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cells a dnp causes renal arterials to
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dilate allowing them to receive and
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filter even more blood while also
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inhibiting water and sodium
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reabsorption on the other hand if the
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volume of blood decreases
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cardiopulmonary Barrel receptors get
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less stretched which reverses all of the
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effects the heart rate slows down more
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anti-diuretic hormone is made while less
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atrial natriuretic peptide is made all
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this results in less water and sodium
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excretion which helps restore blood vol
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volume all right as a quick recap
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arterial Barrow receptors are located in
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the aortic arch in kateed sinus and
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respond to blood pressure changes
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sending information through the glossop
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Fingal and vus nerves to the
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cardiovascular centers in the ponds in
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Medela these in turn through the
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autonomic nervous system modify total
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peripheral resistance in cardiac output
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cardiopulmonary Barrow receptors are
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found in the low press regions of the
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heart and the pulmonary vessel
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and regulate blood volume by influencing
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water excretion by the
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kidneys helping current and future
00:08:40
clinicians Focus learn retain and Thrive
00:08:44
learn
00:08:52
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