Blood flow in arteries
- Dashboard
- Blood flow in arteries
Most Recent Score Report
| Questions Correct | Questions Answered | Time Spent | Status | Attempt Date | |
|---|---|---|---|---|---|
| -- | -- | -- | -- | -- |
Previous Score Reports
| Questions Correct | Questions Answered | Time Spent | Status | Attempt Date | |
|---|---|---|---|---|---|
| -- | -- | -- | -- | -- |
Blood flow in arteries
Array
(
[passage] => WP_Post Object
(
[ID] => 558080
[post_author] => 12815
[post_date] => 2025-01-09 07:48:48
[post_date_gmt] => 2025-01-09 12:48:48
[post_content] => Practice Passage (Question 1-5)
*This passage is the property of Khan Academy and has been reformatted into an AAMC-style interface in their entirety by MedLife Mastery. MedLife Mastery does not endorse and is not an affiliate of Khan Academy.
An adult patient is admitted to the hospital after complaining about heart problems. The doctor treating the patient thinks that there may be a problem with the patient’s main pulmonary artery. The main pulmonary artery (MPA) is a short and wide tube shaped artery that carries deoxygenated blood from the heart to the lungs. See Figure 1 for details.
Figure 1. A diagram of the heart. The main pulmonary artery is indicated by the red box.
Tests are run to determine the dimensions of the patient’s (MPA) as well as the constant speed with which blood flows through the patient’s MPA. The results of the tests are shown in in the following table, along with values for a normal adult.
Table 1. Results of the MPA test compared to normal values.
In an effort to improve the patient’s blood flow to the lungs, a physician performs an angioplasty to dilate the radius of the MPA. In the first step of the process, the surgeon inserts a special catheter into the heart. The physician immediately follows this by inserting a deflated balloon into the vessel. She pumps the balloon with air, and in doing so enlarges the MPA. Finally, she inserts a permanent metal stent into the vessel wall to support the new expansion.
[post_title] => Blood flow in arteries
[post_excerpt] =>
[post_status] => publish
[comment_status] => closed
[ping_status] => closed
[post_password] =>
[post_name] => blood-flow-in-arteries
[to_ping] =>
[pinged] =>
[post_modified] => 2025-01-09 07:48:48
[post_modified_gmt] => 2025-01-09 12:48:48
[post_content_filtered] =>
[post_parent] => 0
[guid] => https://medlifemastery.com/?post_type=passage&p=558080
[menu_order] => 0
[post_type] => passage
[post_mime_type] =>
[comment_count] => 0
[filter] => raw
)
[questions] => Array
(
[0] => Array
(
[quiz_unique_key] => 578908434
[question] => How long does it take a blood cell to completely pass through the entire length of the main pulmonary artery of the patient?
[value] => Array
(
[answer] => 2
[description] => Reason for the Correct Answer:
The average speed of the blood through the main pulmonary artery is 40 cm/sec
The definition of average speed is average speed=distance/time
40cm/sec=6.0cm/time, so time =6.0cm/(40cm/s)=0.15seconds
)
[answers] => Array
(
[0] => Array
(
[each_answer] => A. 0.05 seconds
)
[1] => Array
(
[each_answer] => B. 0.15 seconds
)
[2] => Array
(
[each_answer] => C. 0.74 seconds
)
[3] => Array
(
[each_answer] => D. 6.7 seconds
)
)
)
[1] => Array
(
[quiz_unique_key] => 3873426850
[question] => If the angioplasty causes the blood flow speed to be cut in half, how will this affect the time required for a blood cell to make it all the way through the length of the MPA?
[value] => Array
(
[answer] => 2
[description] => Reason for the Correct Answer:
The blood flow is cut in half
The formula for speed is speed = distance/time
If the speed is cut in half, and the distance has not been changed, it will require twice the time since time=distance/speed
)
[answers] => Array
(
[0] => Array
(
[each_answer] => A. It will triple the time taken
)
[1] => Array
(
[each_answer] => B. It will double the time taken
)
[2] => Array
(
[each_answer] => C. It will not affect the time taken
)
[3] => Array
(
[each_answer] => D. It will cut the time in half
)
)
)
[2] => Array
(
[quiz_unique_key] => 83407773
[question] => What is the speed of a normal person’s blood flow in meters/second through the MPA?
[value] => Array
(
[answer] => 2
[description] => Reason for the Correct Answer:
1 meter = 100 centimeters
The blood will travel less meters per second, than it travels centimeters per second
60 cm/s (1m/100cm)=0.6m/s
)
[answers] => Array
(
[0] => Array
(
[each_answer] => A. 6 m/s
)
[1] => Array
(
[each_answer] => B. 0.6 m/s
)
[2] => Array
(
[each_answer] => C. 0.06 m/s
)
[3] => Array
(
[each_answer] => D. 6000 m/s
)
)
)
[3] => Array
(
[quiz_unique_key] => 2261298308
[question] => In order for the angioplasty to give the patient a normal blood flow speed, how long should it take for a blood cell to make it through the patient’s main pulmonary artery?
[value] => Array
(
[answer] => 4
[description] => Reason for the Correct Answer:
The length of the patient’s MPA is not going to change
The length of the patient’s MPA is 6.0 cm and normal speed of blood flow is 60 cm/sec
Speed = distance/time, time=distance/speed= 6cm/(60cm/s)=0.1sec
)
[answers] => Array
(
[0] => Array
(
[each_answer] => A. 0.4 seconds
)
[1] => Array
(
[each_answer] => B. 0.3 seconds
)
[2] => Array
(
[each_answer] => C. 0.2 seconds
)
[3] => Array
(
[each_answer] => D. 0.1 seconds
)
)
)
[4] => Array
(
[quiz_unique_key] => 574431310
[question] => What extra piece of information would be needed to determine the velocity of the patient’s blood flow through the MPA?
[value] => Array
(
[answer] => 1
[description] => Reason for the Correct Answer:
You already know the speed of the blood flow
Speed is a scalar and velocity is a vector
A vector has size and direction, so you would need to know the direction of the blood flow
)
[answers] => Array
(
[0] => Array
(
[each_answer] => A. The direction of the patient’s blood flow through the MPA
)
[1] => Array
(
[each_answer] => B. The altitude of the doctors office
)
[2] => Array
(
[each_answer] => C. The volume of the patient’s blood that flows per second through the MPA
)
[3] => Array
(
[each_answer] => D. The density of the patient’s blood in the MPA
)
)
)
)
[total_question] => 5
[correct_answers] => Array
(
[558080|1] => B
[558080|2] => B
[558080|3] => B
[558080|4] => D
[558080|5] => A
)
[hide_display_feedback_settings] =>
[hide_solutions] =>
)
Tests are run to determine the dimensions of the patient’s (MPA) as well as the constant speed with which blood flows through the patient’s MPA. The results of the tests are shown in in the following table, along with values for a normal adult.
Table 1. Results of the MPA test compared to normal values.
