The sensation of pain cannot accurately be described as “located”

Question

The sensation of pain cannot accurately be described as “located” at the point of an injury, or, for that matter, in any one place in the nerves or brain. Rather, pain signals—and pain relief—are delivered through a highly complex interacting circuitry.

When a cell is injured, a rush of prostaglandins sensitizes nerve endings at the injury. Prostaglandins are chemicals produced in and released from virtually all mammalian cells when they are injured: these are the only pain signals that do not originate in the nervous system. Aspirin and other similar drugs (such as indomethacin and ibuprofen) keep prostaglandins from being made by interfering with an enzyme known as prostaglandin synthetase, or cyclooxygenase. The drugs’ effectiveness against pain is proportional to their success in blocking this enzyme at the site of injury.

From nerve endings at the injury, pain signals move to nerves feeding into the spinal cord. The long, tubular membranes of nerve cells carry electrical impulses. When electrical impulses get to the spinal cord, a pain-signaling chemical known as substance P is released there. Substance P then excites nearby neurons to send impulses to the brain. Local anesthetics such as novocaine and xylocaine work by blocking the electrical transmission along nerves in a particular area. They inhibit the flow of sodium ions through the membranes, making the nerves electrically quiescent; thus no pain signals are sent to the spinal cord or to the brain.
Recent discoveries in the study of pain have involved the brain itself—the supervising organ that notices pain signals and that sends messages down to the spinal cord to regulate incoming pain traffic. Endorphins—the brain’s own morphine—are a class of small peptides that help to block pain signals within the brain itself. The presence of endorphins may also help to explain differences in response to pain signals, since individuals seem to differ in their ability to produce endorphins. It now appears that a number of techniques for blocking chronic pain—such as acupuncture and electrical stimulation of the central brain stem—involve the release of endorphins in the brain and spinal cord.   1 
 1. The passage is primarily concerned with

(A) analyzing ways that enzymes and other chemicals influence how the body feels pain
(B) describing the presence of endorphins in the brain and discussing ways the body blocks pain within the brain itself
(C) describing how pain signals are conveyed in the body and discussing ways in which the pain signals can be blocked
(D) demonstrating that pain can be influenced by acupuncture and electrical stimulation of the central brain stem
(E) differentiating the kinds of pain that occur at different points in the body’s nervous system

2 
 2. According to the passage, which of the following is one of the first things to occur when cells are injured?

(A) The flow of electrical impulses through nerve cells at the site of the injury is broken.
(B) The production of substance P traveling through nerve cells to the brain increases.
(C) Endorphins begin to speed up the response of nerve cells at the site of the injury.
(D) A flood of prostaglandins sensitizes nerve endings at the site of the injury.
(E) Nerve cells connected to the spinal cord become electrically quiescent.

3 
 3. Of the following, which is most likely attributable to the effect of endorphins as described in the passage?

(A) After an injection of novocaine, a patient has no feeling in the area where the injection was given.
(B) After taking ibuprofen, a person with a headache gets quick relief.
(C) After receiving a local anesthetic, an injured person reports relief in the anesthetized area.
(D) After being given aspirin, a child with a badly scraped elbow feels better.
(E) After acupuncture, a patient with chronic back pain reports that the pain is much less severe.

4 
 4. It can be inferred from the passage that if the prostaglandin synthetase is only partially blocked, which of the following is likely to be true?

(A) Some endorphins will be produced, and some pain signals will be intensified.
(B) Some substance P is likely to be produced, so some pain signals will reach the brain.
(C) Some sodium ions will be blocked, so some pain signals will not reach the brain.
(D) Some prostaglandins will be produced, but production of substance P will be prevented.
(E) Some peptides in the brain will receive pain signals and begin to regulate incoming pain traffic.

gmatexam439 · Accepted Answer

The sensation of pain cannot accurately be described as “located” at the point of an injury, or, for that matter, in any one place in the nerves or brain. Rather, pain signals—and pain relief—are delivered through a highly complex interacting circuitry.

When a cell is injured, a rush of prostaglandins sensitizes nerve endings at the injury. Prostaglandins are chemicals produced in and released from virtually all mammalian cells when they are injured: these are the only pain signals that do not originate in the nervous system. Aspirin and other similar drugs (such as indomethacin and ibuprofen) keep prostaglandins from being made by interfering with an enzyme known as prostaglandin synthetase, or cyclooxygenase. The drugs’ effectiveness against pain is proportional to their success in blocking this enzyme at the site of injury.

From nerve endings at the injury, pain signals move to nerves feeding into the spinal cord. The long, tubular membranes of nerve cells carry electrical impulses. When electrical impulses get to the spinal cord, a pain-signaling chemical known as substance P is released there. Substance P then excites nearby neurons to send impulses to the brain. Local anesthetics such as novocaine and xylocaine work by blocking the electrical transmission along nerves in a particular area. They inhibit the flow of sodium ions through the membranes, making the nerves electrically quiescent; thus no pain signals are sent to the spinal cord or to the brain.
Recent discoveries in the study of pain have involved the brain itself—the supervising organ that notices pain signals and that sends messages down to the spinal cord to regulate incoming pain traffic. Endorphins—the brain’s own morphine—are a class of small peptides that help to block pain signals within the brain itself. The presence of endorphins may also help to explain differences in response to pain signals, since individuals seem to differ in their ability to produce endorphins. It now appears that a number of techniques for blocking chronic pain—such as acupuncture and electrical stimulation of the central brain stem—involve the release of endorphins in the brain and spinal cord.   1. The passage is primarily concerned with

(A) analyzing ways that enzymes and other chemicals influence how the body feels pain - This is partially correct. The passage also details the process by which the body suffers pain 
(B) describing the presence of endorphins in the brain and discussing ways the body blocks pain within the brain itself - Very specific 
(C)  describing how pain signals are conveyed in the body and discussing ways in which the pain signals can be blocked 
(D) demonstrating that pain can be influenced by acupuncture and electrical stimulation of the central brain stem - Very specific 
(E) differentiating the kinds of pain that occur at different points in the body’s nervous system - kinds of pain?

2. According to the passage, which of the following is one of the first things to occur when cells are injured?

(A) The flow of electrical impulses through nerve cells at the site of the injury is broken. - Not stated in the passage 
(B) The production of substance P traveling through nerve cells to the brain increases. - This step occurs after prostaglandins are secreted  
(C) Endorphins begin to speed up the response of nerve cells at the site of the injury. - They come much much later into the picture 
(D)  A flood of prostaglandins sensitizes nerve endings at the site of the injury. 
(E) Nerve cells connected to the spinal cord become electrically quiescent. - This occurs after prostaglandins are secreted

3. Of the following, which is most likely attributable to the effect of endorphins as described in the passage?

(A) After an injection of novocaine, a patient has no feeling in the area where the injection was given.  Incorrect 
(B) After taking ibuprofen, a person with a headache gets quick relief.  Incorrect 
(C) After receiving a local anesthetic, an injured person reports relief in the anesthetized area.  Incorrect 
(D) After being given aspirin, a child with a badly scraped elbow feels better.  Incorrect 
(E)  After acupuncture, a patient with chronic back pain reports that the pain is much less severe .

4. It can be inferred from the passage that if the prostaglandin synthetase is only partially blocked, which of the following is likely to be true?

(A) Some endorphins will be produced, and some pain signals will be intensified. - We can't say whether endorphins will be produced or not. Also, if the endorphins are produced, then the pain should reduce. This option is totally incorrect 
(B)  Some substance P is likely to be produced, so some pain signals will reach the brain .
(C) Some sodium ions will be blocked, so some pain signals will not reach the brain. - Sodium ions come after substance p in the heirarchy. So we can't guess whether they will come into picture or not 
(D) Some prostaglandins will be produced, but production of substance P will be prevented. - This is an exaggerated answer. We don't know for sure whether substance p will be prevented from secretion or not. 
(E) Some peptides in the brain will receive pain signals and begin to regulate incoming pain traffic. - This is last in the hierarchy. We can't comment on this

tapasgupta · Answer

1.  The passage is primarily concerned with  - the first word of the answer choice will decide the summary of the passage

(A) analyzing ways that enzymes and other chemicals influence how the body feels pain  -Incorrect. No analyzing is done
 (B) describing the presence of endorphins in the brain and discussing ways the body blocks pain within the brain itself  - Incorrect. Not only specific to endorphins
 (C) describing how pain signals are conveyed in the body and discussing ways in which the pain signals can be blocked  - It is described in every passage
 (D) demonstrating that pain can be influenced by acupuncture and electrical stimulation of the central brain stem  - Incorrect. Not specific to the acupuncture
 (E) differentiating the kinds of pain that occur at different points in the body’s nervous system  - out of scope.

2. According to the passage, which of the following is one of the first things to occur when cells are injured?

( A) The flow of electrical impulses through nerve cells at the site of the injury is broken.  - out of scope.
 (B) The production of substance P traveling through nerve cells to the brain increases.  - out of scope. It happens way after
 (C) Endorphins begin to speed up the response of nerve cells at the site of the injury.  - out of scope
 (D) A flood of prostaglandins sensitizes nerve endings at the site of the injury.  - given in 2nd para
 (E) Nerve cells connected to the spinal cord become electrically quiescent.  - out of scope

3. Of the following, which is most likely attributable to the effect of endorphins as described in the passage?

(A) After an injection of novocaine, a patient has no feeling in the area where the injection was given.  - out of scope. Not the role of endorphin
 (B) After taking ibuprofen, a person with a headache gets quick relief. - out of scope. Not the role of endorphin
 (C) After receiving a local anesthetic, an injured person reports relief in the anesthetized area.  - out of scope. Not the role of endorphin
 (D) After being given aspirin, a child with a badly scraped elbow feels better.  - out of scope. Not the role of endorphin
 (E) After acupuncture, a patient with chronic back pain reports that the pain is much less severe.  - as stated in last para last line

4. It can be inferred from the passage that if the prostaglandin synthetase is only partially blocked, which of the following is likely to be true?

(A) Some endorphins will be produced, and some pain signals will be intensified. - extreme
( B) Some substance P is likely to be produced, so some pain signals will reach the brain.  - stated in 3rd para
 (C) Some sodium ions will be blocked, so some pain signals will not reach the brain.  - opposite
 (D) Some prostaglandins will be produced, but production of substance P will be prevented.  - opposite
 (E) Some peptides in the brain will receive pain signals and begin to regulate incoming pain traffic.  - out of scope

100mitra · Answer

RC#5 Long passage

Pharaphase   
  Para 1:   Pain signals—and pain relief—are delivered through a highly complex interacting circuitry.
  Para 2:   Pain signals prostaglandins produced and Drugs like aspirin, function to block prostaglandins interfering with an enzyme
  Para 3:   
  Process 1 :   Pain to brain cycle: Cell is injured> a rush of prostaglandins @ nerve ending> pain signals @ spinal cord > generates nerve cells > creates electrical impulses > release prostaglandins> prostaglandins release neurons > neurons impulse brain.
  Process 2 :   Function of Local anaesthetic’s> blocking the electrical transmission along nerves >inhibit the flow of sodium ions through the membranes > making the nerves electrically quiescent >thus no pain signals are sent to the spinal cord or to the brain >Supervising organ regulate incoming pain traffic.
  Endorphin’s function and response to block pain traffic within brain, depend on individual ability to produce it . 
  Way ahead conclusion:   It now appears that a number of techniques for blocking chronic pain—such as acupuncture and electrical stimulation of the central brain stem—involve the release of endorphins in the brain and spinal cord.

1. The passage is primarily concerned with  
(A) analysing ways that enzymes and other chemicals influence how the body feels pain
  Wrong:   Easy elimination, passage does not analyse enzymes and other chemicals
(B) describing the presence of endorphins in the brain and discussing ways the body blocks pain within the brain itself
  Wrong:   Endorphins are the brain’s own morphine, it gives information about endorphins functions, not about the entire process.
  (C) describing how pain signals are conveyed in the body and discussing ways in which the pain signals can be blocked
Correct: as explained in para 3.  
(D) demonstrating that pain can be influenced by acupuncture and electrical stimulation of the central brain stem
  Wrong:   It is one of the techniques, passage does not conclude about it.
(E) differentiating the kinds of pain that occur at different points in the body’s nervous system
  Wrong:   No information mentioned in passage.

2. According to the passage, which of the following is one of the first things to occur when cells are injured?  
  Explanation:   Pain to brain cycle: Cell is injured> a rush of prostaglandins @ nerve ending> pain signals @ spinal cord > generates nerve cells > creates electrical impulses > release prostaglandins> prostaglandins release neurons > neurons impulse brain.
 A, B, C and E can be eliminated as per above process. only D is correct 
(A) The flow of electrical impulses through nerve cells at the site of the injury is broken
(B) The production of substance P traveling through nerve cells to the brain increases.
(C) Endorphins begin to speed up the response of nerve cells at the site of the injury.
  (D) A flood of prostaglandins sensitizes nerve endings at the site of the injury  .
(E) Nerve cells connected to the spinal cord become electrically quiescent

3. Of the following, which is most likely attributable to the effect of endorphins as described in the passage?  
  Explanation:   From the below option (A, B, C, and D) are ones’ in which drugs are been given to person in pain. Only Option E, with process of acupuncture Endorphins—the brain’s own morphine—are a class of small peptides that help to block pain signals within the brain itself, works to reduce pain with much less severe
(A) After an injection of novocaine, a patient has no feeling in the area where the injection was given   Wrong  
(B) After taking ibuprofen, a person with a headache gets quick relief   Wrong  
(C) After receiving a local aesthetics, an injured person reports relief in the anesthetized area   Wrong  
(D) After being given aspirin, a child with a badly scraped elbow feels better   Wrong  
  (E) After acupuncture, a patient with chronic back pain reports that the pain is much less severe Correct

4. It can be inferred from the passage that if the prostaglandin synthetase is only partially blocked, which of the following is likely to be true?  
  Explanation:   
  Process 1  
Pain to brain cycle: Cell is injured> a rush of prostaglandins @ nerve ending> pain signals @ spinal cord > generates nerve cells > creates electrical impulses > release prostaglandins> prostaglandins release neurons > neurons impulse brain
  Process 2  
Function of Local anaesthetic’s> blocking the electrical transmission along nerves >inhibit the flow of sodium ions through the membranes > making the nerves electrically quiescent >thus no pain signals are sent to the spinal cord or to the brain >Supervising organ regulate incoming pain traffic

(A) Some endorphins will be produced, and some pain signals will be intensified 
  Wrong   Endorphin will reduce the pain, as it block pain signals traffic reaching to brain
  (B) Some substance P is likely to be produced, so some pain signals will reach the brain 
- Correct: as explained above in Process 1  
(C) Some sodium ions will be blocked, so some pain signals will not reach the brain 
  Wrong   More the flow sodium ions in membranes, less will be the pain 
(D) Some prostaglandins will be produced, but production of substance P will be prevented.
  Wrong   Prostaglandins will be responsible to production of substance P
(E) Some peptides in the brain will receive pain signals and begin to regulate incoming pain traffic.
  Wrong   No it will block the incoming pain traffic

GMATNinja · Answer

Question 4

As a whole, the passage discusses the "highly complex interacting circuitry" of pain signals and pain relief.

Here's the chain of events that creates a pain signal:

1. A cell is injured.
2. Prostaglandins in the cell alert the nerve endings.
3. Pain signals move along the nerve endings to the spinal cord.
4. Substance P is released in the spinal cord and sends signals to the brain.

Question 4 asks us what we can infer if "the prostaglandin synthetase is only partially blocked." In paragraph 2, we learn that "aspirin and other similar drugs (such as indomethacin and ibuprofen) keep prostaglandins from being made by interfering with an enzyme known as prostaglandin synthetase, or cyclooxygenase. The drugs’ effectiveness against pain is proportional to their success in blocking this enzyme at the site of injury."

So, from this, we know that interfering with prostaglandin synthetase impacts the second step of the pain signal process, and will have consequences for all of the steps later in the list.

Which answer choice can we infer?
 
Endorphins are mentioned in relation to pain relief, NOT pain signals. So it's hard to say exactly how partially blocking prostaglandin synthetase would impact endorphins.

Also, it's pretty clear that pain signals will NOT be intensified -- blocking some prostaglandin synthetase will actually  inhibit  pain signals to some extent.

(A) is out.

This seems reasonable. If prostaglandin synthetase isn't COMPLETELY blocked, then the rest of the chain of events will continue to some extent.

Keep (B).

Some  pain signals  will definitely be blocked and won't reach the brain, but that has nothing to do with sodium ions. Sodium ions are impacted by a completely different type of pain killer, as discussed in paragraph 3.

We can eliminate (C) because sodium ions won't be blocked in this scenario.

If just a few prostaglandins are produced, then the rest of the chain of events will follow. So, we can't say that production of substance P will be  entirely  prevented.

(D) is out.

Peptides are discussed in the final paragraph, where we learn that "endorphins—the brain’s own morphine—are a class of small peptides that help to block pain signals within the brain itself."

So the function of peptides isn't to "receive pain signals" or to "regulate incoming pain traffic." The brain  as a whole  does those things, while the peptides play a much more narrow role.

We can't infer (E), so (B) is the correct answer to question 4.

I hope that helps!

VerbalBot · Answer

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The sensation of pain cannot accurately be described as “located”

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The sensation of pain cannot accurately be described as “located”

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