Question

Respiratory Case Study

Priya is a healthy 22-year-old woman who just graduated from BU and has lived in Boston her whole life. She goes to Colorado to visit a friend and together they drive to the top of Pike’s Peak, a mountain with a peak elevation of approximately 14,000 ft above sea level. While walking around taking pictures at the top of the peak Priya finds that she needs to sit down and catch her breath several times, even though she is not exercising intensively. During those breaks she also notices that she is taking breaths much more deeply and frequently than normal. She walks to the weather station to rest and glances at a barometer hanging overhead. It reads 450 mmHg. She thinks back to what she learned in BI 315 and realizes that she may be experiencing altitude sickness.

1. Relative to sea level, the P in Priya’s (1) alveoli, (2) systemic arterial blood, and (3) systemic venous blood is:

A (1) lower; (2) lower; (3) the same.

B (1) the same; (2) the same; (3) the same.

C (1) lower; (2) lower; (3) lower.

D (1) lower; (2) the same; (3) the same.

2. From a mechanistic perspective, what caused Priya to begin breathing more quickly immediately when she arrived at the top of the peak?

A Increased peripheral chemoreceptor firing rate caused by low arterial P.

B #Increased peripheral chemoreceptor firing rate caused by high arterial P.

C Decreased peripheral chemoreceptor firing rate caused by low arterial P.

D Increased peripheral chemoreceptor firing rate caused by high arterial ​[H].

3. Once Priya has been at high altitude for a short time (e.g., a few hours), what do you predict will be true of the P of her systemic arterial blood?

A It will be lower than when she was at sea level.

B It will be higher than when she was at sea level.

4. Once Priya has been at high altitude for a short time (e.g., a few hours), what do you predict will be true of the pH of her systemic arterial blood?

A It will be lower than when she was at sea level.

B It will be higher than when she was at sea level.

C It will be the same as when she was at sea level.

5. Holding all else equal, which of the following chronic responses do you predict would be homeostatic and reduce the severity of Priya’s altitude sickness?

A A decrease in the amount of hemoglobin contained in each red blood cell.

B A reduction in capillary density in her metabolically active tissues (e.g. her skeletal muscles).

C Increased tonic level of constriction of her respiratory airways due to elevated levels of smooth muscle contraction.

D Biochemical changes in her cells that increase the average number of ATPs generated per O molecule by cellular respiration.

6. One chronic change that occurs robustly when humans move to high altitude is an increase in red blood cell differentiation, leading to a very high red blood cell count in the plasma (polycythemia). This was long regarded as a clear example of adaptive physiological acclimation to low atmospheric O in humans. However, it has recently been argued that this is actually an instance where a physiological change (increased red blood cell differentiation) that might be homeostatic in some contexts (e.g. low tissue O levels due to low red blood cell counts after a hemorrhage) might in fact be harmful in the wrong context (e.g. low tissue O levels due to low atmospheric O levels). Which of the following scenarios is a plausible reason why polycythemia might be harmful to Priya’s overall health?

A Polycythemia reduces the partial pressure of O freely dissolved in the blood plasma.

B Polycythemia increases the viscosity of her blood, which increases resistance to flow, which increases blood pressure and puts added strain on the chambers of her heart when pumping blood.

C Polycythemia shifts the O-hemoglobin dissociation curve of the blood to the left, increasing the affinity of the blood for O.

D Polycythemia reduces the oxygen carrying capacity of her blood.

7. After a while, Priya’s friend Tenzin comes to visit her at the visitor’s center. Tenzin’s family immigrated to the US from Tibet before Tenzin was born. Even though Tenzin has never lived anywhere but Boston, Priya and Tenzin notice that he experiences relatively mild symptoms of altitude sickness when he arrives at Pike’s Peak. They do some research and find recent peer-reviewed studies by evolutionary biologists demonstrating that several human populations, including ethnic Tibetans, have adapted to life at high altitudes over the past several thousand years. This gets Priya and Tenzin thinking about what those physiological adaptations could plausibly be.

Respiratory Case Study.07

HomeworkAnswered

All of the following evolutionary adaptations might be predicted to improve the physiological performance of human populations living at high altitude EXCEPT:

A Globally lower resistance to blood flow through the vasculature due to the effects of local vasodilators such as nitric oxide.

B Increased ability of the kidneys to filter out and excrete HCO in the urine.

C Increased chest circumference and higher lung volumes (including tidal volume and vital capacity).

D Lower endogenous bursting rates in the neurons of the respiratory rhythmicity centers in the medulla.

Answer 1

It is concept of acclimatization.

Adaptive changes happen to low pressure when person goes to high altitude .

Let's see changes occurs .

As we go high above sea level there is pressure start to decreases atmospheric pressure at altitude is low and low oxygen .

1. Relative to sea level there is low pressure in alveoli , systemic arterial, and venous pressure .

But pulmonary venous pressure increases due to hypoxia pulmonary particle are sensitive and constrict potently and causes raise in pressure

Ans C

2.at altitude Low O2 pressure causes carving to air O2 and rapid ventilation started to wash out more Co2 from lung .

Low o2 is detected by peripheral chemo receptors which are highly sensitive for O2 changes .situated in aortic and carotid bodies .

They are active at low O2 pressure

Hypoxia triggers the peripheral chemoreceptors

Ans A.

3.ans A pressure in systemic arteries lower than at sea level .. as increases altitude decreases pressure.

4.Ans B .

Due to low O2 , and high Co2 in lung PH become alkaline .

Result respiratory alkalosis....to avoid this to wash out co2 that's why rapid breathing started .

5 . ANS D

High altitude changes .

Increase in RBC count polycythemia .

Increase in HB concentration in each RBC .

Due to hypoxia, increase capillary bed density ...in lung and brain .

Biochemical changes increases mitochondria, cell organelles to fulfill demand of cell for oxygen...

6. Ans B

Polycythemia is acclimatization change occurs in body ti fulfill oxygen demand .

There is increase no of RBC and HB concentration in each RBC .

Increases oxygen carrying capacity .

Shift o2 dissociation curve to right side

But due to sudden raise in RBC there is increase viscosity of blood that cause decrease speed flow .

Stagnant flow occurs result into clot thrombosis .

More force required to heart to pump the blood .

So this is dangerous condition.

7.D . Central chemoreceptors nothing to do with acclimatization changes .