On September 29, World Heart Day, organisations across India hold camps to help the public"know their numbers" blood pressure (BP), blood sugar and body weight. A BP of 120/80 mmHg (millimetre mercury) or below is considered normal. More than 140/90, signifying Stage 1 hypertension, and more than 160/100, signifying Stage 2, can damage the brain, eyes, heart and kidneys. When studying blood pressure, scientists have been intrigued by the giraffe, the gentle giant of Africa. How does it pump blood through its body that rises to 18 feet? With what force does it pump blood up the six-foot-long neck to its brain? What protects the giraffe from giddiness as it bends down to drink water and then lifts its head up? Despite standing almost all the time, why doesn't a giraffe faint? The answers to these questions hold answers to protect human beings from brain haemorrhage due to high BP and fainting due to low BP. The giraffe's strong heart generates a pressure of 300 mmHg needed to pump blood all the way up its long neck. Yet, when scientists measured the BP in its brain, it was a constant 120/80 mmHg. A network of blood vessels in the upper neck helps reduce the BP. The network and valves in major veins maintain a constant pressure in the giraffe's brain even when it stoops to drink water and lifts its neck up to its full height. Human beings lack this stabilising mesh and need to protect the brain by other means, avoiding tobacco, consuming less salt, coping with stress, taking medicines and above all by detecting hypertension through periodic check-ups. The giraffe doesn't have these complications! Standing still for long, weak leg muscles and the effects of some medicines can cause pooling of blood in the legs, lowering the BP. Getting up from bed suddenly, stiff arteries and reduced water intake can sometimes cause a significant drop in BP on standing up. Whatever the cause, dizziness due to low BP is often relieved by allowing blood to flow freely into the brain by making the patient lie flat on the ground. Lifting the legs facilitates the flow of blood.
Analyzing Giraffe Physiology Puzzles
This question asks us to identify which aspect of giraffe physiology is NOT a subject of scientific puzzlement, according to the provided text. We need to carefully examine the text to see which points are presented as observed facts versus unanswered questions.
Understanding Scientific Intrigue
The passage highlights that scientists are "intrigued" by several aspects of the giraffe's circulatory system. Let's break down the options:
Option 1: Why the giraffe does not faint when it bends down?
The text explicitly asks: "What protects the giraffe from giddiness as it bends down to drink water and then lifts its head up?". This indicates that the mechanism preventing fainting or giddiness when changing head position is indeed a puzzle for scientists.
Option 2: What is the normal BP of a giraffe?
The text states: "Yet, when scientists measured the BP in its brain, it was a constant $120/80$ mmHg." This statement presents the normal blood pressure in the giraffe's brain as a measured, observed fact. While the *reason* or *mechanism* for maintaining this pressure is intriguing, the value itself ($120/80$ mmHg) is not presented as a question scientists are asking, but rather as a finding.
Option 3: How does the blood reach up to its brain?
The text poses direct questions like: "How does it pump blood through its body that rises to 18 feet?" and "With what force does it pump blood up the six-foot-long neck to its brain?". These clearly show that the process of pumping blood to the brain is a significant area of scientific inquiry.
Option 4: Why it does not faint even after standing for a long time?
The passage directly asks: "Despite standing almost all the time, why doesn't a giraffe faint?". This question is stated as something scientists are trying to understand, making it a puzzle.
Conclusion on Scientific Puzzles
Based on the text:
- The prevention of giddiness when bending (Option 1) is a puzzle.
- The process and force of pumping blood to the brain (Option 3) is a puzzle.
- The reason for not fainting after prolonged standing (Option 4) is a puzzle.
- The normal blood pressure in the giraffe's brain ($120/80$ mmHg) is presented as a measured fact, not a puzzle itself. The puzzle lies in how this pressure is maintained.
Therefore, the aspect that does NOT puzzle scientists is the normal blood pressure reading in the giraffe's brain.
Similar Questions
- Why did John remain steadfast in his traditional farming methods?
- What can we infer about John's character from the story?
- What was the name of the old farmer in the story?
- What did the young farmers do when they came to the village?
- What would be an appropriate title for this story?
- Select the most appropriate word to fill in blank no. 5.
- "Avoiding tobacco, consuming less salt, coping with stress, taking medicines". In whatcontext does the writer mention these things?
- Why does dizziness due to low BP occur?
- If one has a blood pressure of 150/90, what stage would it be?
- Which of the following key measurements of health is NOT included in the phrase "knowtheir numbers"?
Important Questions from Reading Comprehension
- Which framework globally guides national policies on Community Centered Disaster Risk Reduction?
- In the context of disaster governance, which principle emphasizes empowering local to take the lead in risk mitigation strategies?
- What distinguishes participatory disaster management from top-down approaches?
- Which of the following is a major barrier to effective local disaster risk reduction implementation in developing countries?
- How can technology most effectively support community-based disaster resilience?
