How blood pressure works - Wilfred Manzano

Aug 24, 2023

How blood pressure works - Wilfred Manzano

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ถ้าคุณเอาเส้นเลือดทั้งหมดในตัวคุณมาเรียงต่อกัน มันจะยาว 60,000 ไมล์ และทุกๆ วันมันจะนำเอาเลือดประมาณสองหมื่นแกลลอนไปยังเนื้อเยื่อของร่างกาย แรงดันนี้มีผลอย่างไรต่อผนังของเส้นเลือด วิลเฟรด แมนซาโน เล่าถึงข้อเท็จจริงเกี่ยวกับความดันเลือด

บทเรียนโดย วิลเฟรด แมนซาโน แอนิเมชั่นโดย Fox Animation Domination High-def

Content

6.828 -> If you lined up all the blood vessels in your body,

11.388 -> they'd be 95,000 kilometers long

15.429 -> and everyday, they carry the equivalent of over 7,500 liters of blood,

21.984 -> though that's actually the same four or five liters recycled over and over,

27.508 -> delivering oxygen, and precious nutrients

30.041 -> like glucose and amino acids to the body's tissues.

34.96 -> All that blood exerts a force on the muscular walls of the blood vessels.

40.24 -> That force is called blood pressure,

43.066 -> and it rises and falls with the phases of the heartbeat.

46.999 -> It's highest during systole,

48.995 -> when the heart contracts to force blood through the arteries.

52.854 -> This is your systolic blood pressure.

55.196 -> When the heart is at rest between beats,

57.694 -> blood pressure falls to its lowest value, the diastolic pressure.

62.436 -> A typical healthy individual produces a systolic pressure

65.862 -> between 90 and 120 millimeters of mercury,

70.348 -> and diastolic pressure between 60 and 80.

74.11 -> Taken together, a normal reading is a bit less than 120 over 80.

79.572 -> The blood traverses the landscape of the body

81.891 -> through the pipes of the circulatory system.

84.977 -> In any plumbing system,

86.477 -> several things can increase the force on the walls of the pipes:

89.945 -> the properties of the fluid,

91.556 -> extra fluid,

92.708 -> or narrower pipes.

94.76 -> So if the blood thickens,

96.19 -> a higher pressure is needed to push it, so the heart will pump harder.

101.437 -> A high-salt diet will lead to a similar result.

104.782 -> The salt promotes water retention,

106.933 -> and the extra fluid increases the blood volume and blood pressure,

111.397 -> and stress, like the fight or flight response,

114.456 -> releases hormones, like epinephrine and norepinephrine

118.365 -> that constrict key vessels,

120.55 -> increasing the resistance to flow and raising the pressure upstream.

125.211 -> Blood vessels can usually handle these fluctuations easily.

128.772 -> Elastic fibers embedded in their walls make them resilient,

133.521 -> but if your blood pressure regularly rises above about 140 over 90,

138.606 -> what we call hypertension, and stays there,

141.846 -> it can cause serious problems.

143.97 -> That's because the extra strain on the arterial wall

146.694 -> can produce small tears.

148.456 -> When the injured tissue swells up,

150.619 -> substances that respond to the inflammation,

153.214 -> like white blood cells, collect around the tears.

156.583 -> Fat and cholesterol floating in the blood latch on, too,

161.014 -> eventually building up to form a plaque

163.586 -> that stiffens and thickens the inner arterial wall.

167.694 -> This condition is called atherosclerosis,

170.498 -> and it can have dangerous consequences.

172.646 -> If the plaque ruptures, a blood clot forms on top of the tear,

176.692 -> clogging the already narrowed pipe.

179.605 -> If the clot is big enough,

180.922 -> it can completely block the flow of oxygen and nutrients to cells downstream.

186.745 -> In vessels that feed the heart,

188.374 -> that will cause a heart attack,

190.401 -> when oxygen-deprived cardiac muscle cells start to die.

194.892 -> If the clot cuts off blood flow to the brain,

197.576 -> it causes a stroke.

200.266 -> Dangerously clogged blood vessels can be widened

202.991 -> by a procedure called an angioplasty.

205.797 -> There, doctors thread a wire through the vessel

208.87 -> to the obstructed site,

210.829 -> and then place a deflated balloon catheter over the wire.

214.903 -> When the balloon is inflated, it forces the passageway open again.

218.894 -> Sometimes a rigid tube called a stent

221.833 -> is placed in a vessel to held hold it open,

225.118 -> letting the blood flow freely

226.747 -> to replenish the oxygen-starved cells downstream.

230.28 -> Staying flexible under pressure is a tough job for arteries.

233.911 -> The fluid they pump is composed of substances

236.673 -> that can get sticky and clog them,

239.278 -> and your typical healthy heart beats about 70 times a minute,

242.93 -> and at least 2.5 billion times during an average lifetime.

247.723 -> That may sound like an insurmountable amount of pressure,

250.899 -> but don't worry, your arteries are well suited for the challenge.

Source: https://www.youtube.com/watch?v=Ab9OZsDECZw