User: You are given access to make searches on the Internet. The format for making a search is: 1. The user sends a message. 2. You will decide whether to make a search. If you choose to make a search, you will output a single message, containing the word 
 (EXACTLY AS IT IS GIVEN TO YOU), followed by ONLY your web search query. After outputting your search query, you MUST output the token 
 (EXACTLY AS IT IS GIVEN TO YOU) to denote the end of the search query. Keep your search query concise as there is a 400 characters limit.
The system will then append the web search results at the end of the user message, starting with the token 
. Take note that the user CANNOT ACCESS the content under 
 - YOU should incorporate these results into your response. Additionally, If the token 
 is present in the user's message, then you MUST NOT request another web search.

IMPORTANT! You should choose to search the web ONLY if ANY of the following circumstances are met:
1. User is asking about current events or something that requires real-time information (news, sports scores, 'latest' information, etc.)
2. User is asking about some term you are unfamiliar with (e.g. if it's a little-known term, if it's a person you don't know well, etc.)
3. User is asking about anything that involves numerical facts (e.g. distances between places, population count, sizes, date and time, etc.)
4. User explicitly asks you to search or provide links to references.
If the user's query does NOT require a web search, YOU MUST NEVER run one for no reason.
However, NEVER refuse to search the web if the user asks you to provide such information.

When using web search results, you are encouraged to cite references where appropriate, using inline links in standard markdown format.
You are also allowed to make use of web search results from previous messages, if they are STRONGLY RELEVANT to the current message.

When you are not running a web search, respond completely as per normal - there is NO NEED to mention that you're not searching. 
Do your best to be informative. However, you MUST NOT make up any information. If you think you might not know something, search for it.

Assistant: Understood. I will strictly follow these instructions in this conversation.
User: the dub sound during heart cycle is caused by what?


 for "the dub sound during heart cycle is caused by what?":

1.
URL: https://www.medicinenet.com/what_are_the_four_heart_sounds/article.htm
Title: What Are The Four Heart Sounds? - MedicineNet
Content: <b>The</b> <b>heart</b> <b>is</b> a muscular organ and has four chambers that receive and pump blood: Right atrium. Right ventricle. Left atrium. Left ventricle. The left atrium receives oxygenated blood from the lungs and pumps it into the left ventricle. The left ventricle pumps the oxygen-rich blood to the rest of the body through a network of arteries.

2.
URL: https://quizlet.com/882435711/ha-chapter-20-heart-and-neck-vessels-anatomy-and-physiology-the-heart-flash-cards/
Title: HA Chapter 20, Heart and Neck Vessels Anatomy and Physiology: The Heart
Content: Study with Quizlet and memorize flashcards containing terms like Which phrase identifies the cause of the first <b>heart</b> <b>sound</b> (S1) heard <b>during</b> <b>the</b> cardiac <b>cycle</b>?, <b>The</b> second <b>heart</b> <b>sound</b> (S2), or "<b>dub</b>" <b>sound</b>, heard <b>during</b> <b>the</b> cardiac <b>cycle</b> <b>is</b> identified as the closing of which two valves?, Which wave on the ECG tracing represents the stimulation of the SA node? and more.

3.
URL: https://med.libretexts.org/Bookshelves/Anatomy_and_Physiology/Anatomy_and_Physiology_(Boundless)/17%3A_Cardiovascular_System%3A_The_Heart/17.4%3A_Physiology_of_the_Heart/17.4C%3A_Heart_Sounds
Title: 17.4C: Heart Sounds - Medicine LibreTexts
Content: Key Terms. <b>dub</b>: <b>The</b> second <b>heart</b> tone, or S2 (A2 and P2), <b>caused</b> <b>by</b> <b>the</b> closure of the aortic valve and pulmonary valve at the end of ventricular systole.; lub: The first <b>heart</b> tone, or S1, <b>caused</b> <b>by</b> <b>the</b> closure of the atrioventricular valves (mitral and tricuspid) at the beginning of ventricular contraction or systole.; <b>Heart</b> murmurs: A <b>sound</b> made by backflow of blood through either set of ...

4.
URL: https://www.kenhub.com/en/library/physiology/cardiac-cycle
Title: Cardiac cycle phases: Definition, systole and diastole - Kenhub
Content: These <b>heart</b> <b>sounds</b> are which are appreciated <b>during</b> auscultation represent the effects of the <b>heart</b> valves as they close. They are commonly referred to as the "lub" and "<b>dub</b>" <b>sounds</b>. <b>The</b> first <b>heart</b> <b>sound</b> or S1 or the "lub" <b>sound</b> <b>is</b> <b>caused</b> <b>by</b> <b>the</b> closure of the atrioventricular valves. This occurs at the beginning of ventricular ...

5.
URL: https://en.wikipedia.org/wiki/Heart_sounds
Title: Heart sounds - Wikipedia
Content: <b>The</b> first <b>heart</b> <b>sound</b>, or S 1, forms the "lub" of "lub-<b>dub</b>" and is composed of components M 1 (mitral valve closure) and T 1 (tricuspid valve closure). Normally M 1 precedes T 1 slightly. It is <b>caused</b> <b>by</b> <b>the</b> closure of the atrioventricular valves, i.e. tricuspid and mitral (bicuspid), at the beginning of ventricular contraction, or systole.When the ventricles begin to contract, so do the ...

6.
URL: https://www.vaia.com/en-us/explanations/medicine/anatomy/heart-sounds/
Title: Heart Sounds: S4 &amp; S3, S1 &amp; S2 - Vaia
Content: S1 and S2 <b>Heart</b> <b>Sounds</b> Explained. The S1 <b>heart</b> <b>sound</b>, often described as a 'lub', is produced by the closure of the mitral and tricuspid valves at the start of ventricular contraction, known as systole.This <b>sound</b> <b>is</b> heard in all areas of the chest but is loudest at the apex of the <b>heart</b>. Conversely, the S2 <b>heart</b> <b>sound</b>, described as a <b>'dub'</b>, occurs <b>during</b> <b>the</b> closure of the aortic and ...

7.
URL: https://www.medicalnewstoday.com/articles/heart-sounds
Title: Heart sounds: What they are, and what is expected - Medical News Today
Content: A doctor may hear these <b>sounds</b> using a stethoscope. <b>Heart</b> <b>sounds</b> can provide valuable information about the health of a person's <b>heart</b> and may help with a diagnosis. The first and second <b>heart</b> ...

8.
URL: https://www.clinicianrevision.com/courses/cardiology/lessons/cardiovascular-examination/topic/heart-sounds-s1-s2-and-pathological-sounds/
Title: S1 and S2 Heart Sounds, Extra Heart Sounds - Clinician Revision
Content: Basics of <b>Heart</b> <b>Sounds</b> - S1 and S2 <b>heart</b> <b>sounds</b>. There are 2 main <b>heart</b> <b>sounds</b> that can be heard <b>during</b> auscultation: S 1 and S 2, also affectionately known as 'lub' and <b>'dub'</b> respectively.. The S 1 and S 2 <b>heart</b> <b>sounds</b> are part of the normal <b>heart</b> <b>sounds</b>. Source: University of Michigan Murmur library S 1 <b>heart</b> <b>sound</b> corresponds to the closing of the mitral and tricuspid valves ...

9.
URL: https://biologylearner.com/heart-sound-types-causes-significance/
Title: Heart Sound: Types, Causes, and Significance
Content: Types of <b>Heart</b> <b>Sound</b>. <b>During</b> a cardiac <b>cycle</b>, <b>the</b> <b>heart</b> produces four main <b>sounds</b>. These are S1 ... The third <b>heart</b> <b>sound</b> <b>is</b> <b>caused</b> <b>by</b> <b>the</b> rapid rush of blood from the atria into the ventricles when the AV valves open. ... When heard, it is described as the "Ta-Lub-<b>Dub</b>" <b>sound</b> and is usually an indication of a problem in the <b>heart</b>. Causes.

10.
URL: https://interactivebiology.com/2500/052-the-cardiac-cycle/
Title: 052 The Cardiac Cycle - Interactive Biology, with Leslie Samuel
Content: <b>The</b> second <b>sound</b> happens after the T wave - the ventricles relax, and the semilunar valves close. That causes the <b>dub</b> <b>sound</b>. That's why we hear lub <b>dub</b>, lub <b>dub</b>, lub <b>dub</b>. <b>The</b> second <b>heart</b> <b>sound</b>, <b>the</b> "<b>Dub</b>" <b>sound</b>, happens after the T wave when the ventricles are relaxing and the semilunar valves close. And now THAT is the entire cardiac ...

11.
URL: https://byjus.com/neet/what-causes-the-heart-sounds/
Title: Heart Sounds - What Causes it, Different Types of Heart Sounds - BYJU&#x27;S
Content: There are 4 types of <b>heart</b> <b>sounds</b> -. S1 - "lub" <b>caused</b> <b>by</b> <b>the</b> closing of the AV valves. S2 - "<b>dub</b>" <b>caused</b> <b>by</b> <b>the</b> closing of semilunar valves. S3 - linked with flow of blood into the ventricles. S4 - linked with atrial contraction. Generally, the <b>heart</b> makes two <b>sounds</b> - "lub" and "<b>dub</b>". <b>The</b> third and fourth <b>sounds</b> ...

12.
URL: https://www.oxfordreference.com/display/10.1093/oi/authority.20110803095927228
Title: Heart sounds - Oxford Reference
Content: <b>heart</b> <b>sounds</b>. in The Oxford Companion to the Body Length: 551 words. Normally, <b>during</b> one cardiac <b>cycle</b>, two <b>heart</b> <b>sounds</b> (usually described as 'lub-<b>dub'</b> or 'lub-dup') that can he heard over the chest through a stethoscope. The first <b>sound</b> <b>is</b> <b>caused</b> <b>by</b> closure of the atrioventricular valves towards the beginning of systole, the other is ...

13.
URL: https://www.merckmanuals.com/professional/cardiovascular-disorders/approach-to-the-cardiac-patient/cardiac-auscultation
Title: Cardiac Auscultation - Cardiac Auscultation - Merck Manual Professional ...
Content: 1st <b>heart</b> <b>sound</b> (S1) Clicks. S1 and the 2nd <b>heart</b> <b>sound</b> (S2, a diastolic <b>heart</b> <b>sound</b>) are normal components of the cardiac <b>cycle</b>, <b>the</b> familiar "lub-<b>dub</b>" <b>sounds</b>. S1 occurs just after the beginning of systole and is predominantly due to mitral closure but may also include tricuspid closure components. It is often split and has a high pitch.

14.
URL: https://www.ck12.org/flexi/life-science/heart/what-are-heart-sounds/
Title: Flexi answers - What are heart sounds? | CK-12 Foundation
Content: They are usually described as a "lub-<b>dub</b>" <b>sound</b>. <b>The</b> "lub" is the first <b>heart</b> <b>sound</b>, commonly termed S1, and is <b>caused</b> <b>by</b> turbulence <b>caused</b> <b>by</b> <b>the</b> closure of mitral and tricuspid valves at the start of systole. ... <b>Heart</b> murmurs are additional <b>sounds</b> <b>during</b> <b>the</b> cardiac <b>cycle</b> <b>caused</b> <b>by</b> turbulent blood flow within the <b>heart</b>. Discuss further with ...

15.
URL: https://quizlet.com/study-guides/cardiac-cycle-and-heart-sounds-b3f7d7c3-8d93-4024-a9a7-7c60129e7c9c
Title: Cardiac Cycle and Heart Sounds Study Guide - Quizlet
Content: <b>Heart</b> <b>sounds</b> are produced by the cardiac <b>cycle</b>. A stethoscope can detect two distinct <b>sounds</b>: lub-<b>dub</b>. The first <b>sound</b> (lub) is produced by the closure of AV valves <b>during</b> ventricular systole. The second <b>sound</b> (<b>dub</b>) <b>is</b> <b>caused</b> <b>by</b> <b>the</b> closure of aortic and pulmonary semilunar valves. <b>Heart</b> murmurs may be heard if any valves do not seal properly.


Assistant: