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Your heart has four tiny doors that never sleep — opening and closing with such perfect rhythm that you don’t even notice they’re working. But these valves are the real architects of every heartbeat. Let’s walk through them in the exact sequence your blood travels: ⸻ 1️⃣ Aortic Valve...

39,049 просмотров • 6 месяцев назад •via X (Twitter)

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I love your observation and it will make me discuss the remarkable adaptations that prevents giraffes from passing out and suffering brain damage when bending to drink water and when standing up. ADAPTATION 1 Did you know that the distance from the giraffe's heart to its brain is about 2 meters or more? That's more than the average humans height! Pumping blood up to that great distance and working against gravity is not a joke! That's where the giraffe's heart comes in. A giraffe's heart is unique in several ways. First, it is quite large, weighing up to 11kg and measuring about 2 feet long, which is necessary to pump blood up the long neck to the brain. Second, it has thick walls to generate enough pressure to overcome gravity and push the blood up to the head. ADAPTATION 2 Now, let's move to the neck. Before discussing the incredible roles the valves in the jugular veins perform, let's look at what can happen without them, and then the solution. Problem I: When the giraffe bends down to drink, blood rushes downward to the head. Gravity pulls a huge volume of blood toward the brain, which could cause dangerously high pressure in the head and potentially burst vessels or cause other damage. Solution: They have one-way valves in the jugular veins (the large veins in the neck). These prevent blood from rushing backward uncontrollably into the head when lowered. These valves help regulate and slow the downward flow, avoiding a massive pressure surge to the brain. Also, the neck veins can act as temporary blood storage unit, storing over 1 litre of blood. This prevents blood from flooding the brain and also reduces the amount of blood returning to the heart. As a result, the heart pumps with lower pressure while the head is lowered. This buffers the high head pressure that gravity would otherwise cause. Problem II: When they raise their head up immediately after drinking, blood pressure drops sharply to the brain. A sudden drop could starve the brain of oxygen, causing fainting. This is similar to but much more extreme than the dizziness some people feel when standing up quickly. Solution: When the giraffe raises its head, that stored blood rushes back to the heart quickly. The heart responds with a strong, high-pressure beat that immediately pushes blood back up to the brain, preventing a dangerous drop in cerebral pressure. Impressive right?!

Arojinle

33,422 просмотров • 4 месяцев назад