Question

2) Ivan Urtleg took a well deserved trip to Tahiti with his family after a long semester. While there, he discovered that the resort offered a "Snorkel With Sharks" activity. In a moment of poor decision making, he thought that it would be fun to swim with sharks. While swimming with the large predators, he decided to antagonize one by sticking his tongue out and goading it into a fight. The shark immediately bit his right leg in the superior medial region. As a result, two large blood vessels were severed and Mr. Urtleg began to bleed profusely. Thankfully, he stayed calm and made it back to the boat where he made and applied a tourniquet fashioned from a length of anchor rope and snorkel tube. On the way to the ER, Ivan complained of intense thirst.

Explain how Ivan’s blood osmolarity, blood volume, and blood pressure have changed (or not changed) due to his extreme blood loss (3 pts) Which hormone pathways will be triggered by these changes (Note this should only include pathways directly triggered by the changes in blood, NOT pathways triggered by other hormones) (2 pts)? How do these pathways cause the symptom of intense thirst and why would drinking fluid help Ivan (what effects does drinking water have in the blood) (4 pts)? What other ways do these hormones try to account for massive blood loss (what effects do they have and how do these impact blood volume, pressure, and/or osmolarity) (9 pts)? Note that nowhere in this question do we ask for you to brain dump an entire hormone step by step pathways...we are asking about specific effects of the pathways! 2 pts for essay formatting, grammar, spelling.

Answer 1

1. Blood volume refers to the total amount of fluid circulating within the arteries, capillaries, veins, venules, and chambers of the heart at any time. with severe bleeding there is decrease in blood volume known as hypovolemia,due to which there is decrease in blood pressure and increased blood osmolarity

2.  A decrease in blood volume or low blood pressure, which occurs during haemorrhage,the body can quickly sense a fall in blood pressure through its arterial and cardiopulmonary baroreceptors, and then activate the sympathetic system, This sympathetic response is to release epinephrine and norepinephrine, which results in peripheral vasoconstriction in order to conserve the circulating fluids. The renin–angiotensin system is a complex homeostatic pathway that deals with blood volume as a whole, as well as plasma osmolarity and blood pressure.The kidneys release more renin following hemorrhage leading to increased circulating levels of angiotensin II and aldosterone. This causes vascular constriction, enhanced sympathetic activity, stimulation of vasopressin release, this hormone than inserts water channels into the renal tubules which increases water reabsorption, so that blood volume and blood pressure is restored

3.When the osmoreceptors detect high plasma osmolarity,often a sign of a low blood volume, they send signals to the hypothalamus, which creates the biological sensation of thirst. Osmoreceptors also stimulate vasopressin (ADH) secretion, which starts the events that will reduce plasma osmolarity to normal levels

Drinking more fluid would cause increase in blood volume, this in turn would increase blood pressure and reduce the blood omolarity