Generate a series of (instruction, response) pairs that are similar in context and structure to the example provided below. Each pair should consist of a concise instruction followed by an appropriate, detailed response. The instruction should pose a clear task or question, while the response should provide a comprehensive answer or solution that could be understood by someone with a basic understanding of the subject.

Example pair: 
Instruction: Sum up what the following article says about why Americans are experiencing a “friendship recession.”

So it is alarming that Americans are experiencing a “friendship recession.”

The startling decline of friendship
Modern living is tough on friendship.Unlike our ancestors who knew everyone in their tribe, most people now live in cities where the default is anonymity. As children and young adults, school may provide a social community. Indeed, the number of friends people have peaks around age 25, but then substantially drops around age 30, when work and the nuclear family take over.

Americans, especially those who are highly educated and high-earning, work longer hours and are more likely to move for work than ever before. Parents also spend twice as much time with their children than previous generations. This saps the ability to maintain close friendships.

The last decade has seen a startling further fall in the number and quality of friendships.
Response: There are many reasons why Americans are seeing a decline in the number and quality of friendships over the last decade. A couple of these reasons may be attributed to many Americans working longer hours and parents spending more time with their children than in prior generations.

Your task is to generate more pairs that maintain this level of clarity and detail. The topic is Summarization. Write a long text of instruction by yourself, then summarize the given instruction in a response. Ensure that the responses are informative and accurate, suitable for an educational context. 

Store the generated pairs in valid JSON format, with each pair as an object within an array. Each object should have two key-value pairs: "instruction" and "response". For instance: 

{"contents": [{"instruction": "text", "response": "text"}, {"instruction": "text", "response": "text"}, ...]} 

Remember to maintain consistency in the format and ensure the generated pairs are diverse and cover a broad range of subjects. You must return the response in the asked format and you must not add any additional text in your response.

Summarize the main points about the structure and function of the human heart from the following text:

The human heart is a muscular organ that pumps blood throughout the body's circulatory system. It is located in the chest cavity, slightly offset to the left side. The heart has four chambers: two upper chambers called atria and two lower chambers called ventricles. The right atrium receives deoxygenated blood from the body and pumps it into the right ventricle, which then pumps it to the lungs for oxygenation. The left atrium receives oxygenated blood from the lungs and pumps it into the left ventricle, which then pumps it out to the rest of the body through the aorta. The heart is made up of cardiac muscle tissue and is surrounded by a protective sac called the pericardium. Its contractions are controlled by an electrical conduction system, and it is supplied with oxygen and nutrients by the coronary arteries. The heart plays a vital role in maintaining the circulation of blood, which carries oxygen and nutrients to the body's cells and removes waste products.
user
The main points about the structure and function of the human heart are: 1) It is a muscular organ that pumps blood throughout the circulatory system. 2) It has four chambers: two atria (upper) and two ventricles (lower). 3) The right side receives deoxygenated blood from the body and pumps it to the lungs for oxygenation. 4) The left side receives oxygenated blood from the lungs and pumps it out to the body. 5) It is made of cardiac muscle tissue and surrounded by a protective sac called the pericardium. 6) Its contractions are controlled by an electrical conduction system, and it is supplied with oxygen and nutrients by the coronary arteries. 7) The heart plays a vital role in circulating blood, which carries oxygen, nutrients, and waste products throughout the body.
assistant