How does the pressure in the lungs compare to the pressure in the atmosphere during inhalation?

How does the pressure in the lungs compare to the pressure...

Key Concepts

Respiratory Mechanics

This concept encompasses the overall process and physical principles involved in breathing. It includes the changes in lung volume and pressure that occur during the respiratory cycle, explaining how muscles change the thoracic cavity dimensions, leading to variations in intrapulmonary pressure and facilitating air movement into and out of the lungs.

Pressure Gradient

A pressure gradient is the difference in pressure between two areas, which drives the movement of air from high pressure to low pressure. In respiratory mechanics, the small differences in pressure between the alveoli and the external environment create this gradient, leading to inhalation when the lung pressure is lower than atmospheric pressure, and exhalation when it is higher.

Atmospheric Pressure

Atmospheric pressure is the pressure exerted by the weight of the air in the atmosphere surrounding us. It serves as the benchmark relative to which changes in lung pressure are measured during the respiratory cycle.

Intrapulmonary Pressure

This is the pressure within the lung alveoli, which is not constant but varies slightly during the breathing cycle. During the process of breathing, the intrapulmonary pressure becomes slightly lower than atmospheric pressure during inhalation to allow air to flow in, and slightly higher during exhalation to propel air out.

Transcript

00:01 Hi, so this video is going to go over problem eight in chapter 31 of biology concepts and investigations third edition.

00:09 Chapter 31 goes over the respiratory system.

00:12 And this question is specifically asking about pressure changes during inhalation and exhalation, and to compare that to the atmospheric pressure.

00:22 Okay, so when we have a pair of lungs, i'm going to try to draw this.

00:32 Is probably not going to be the best.

00:38 Our lungs aren't muscles themselves.

00:42 They're actually just tissue that's evolved to transfer gases and stuff like that across the membrane into the blood or the capillaries.

00:57 So they cannot move themselves.

01:00 What actually moves them is you have muscles that are somewhat attached.

01:07 So you have a diaphragm, and then you have some intercostal muscles or muscles in between the ribs.

01:14 So that's what intercostal means.

01:18 In those, when they contract, they will open up the lungs.

01:23 And what happens is you have a membrane that surrounds your lungs pretty closely.

01:33 And then you have another membrane that is attached to these muscles.

01:37 And in the middle of these membranes is liquid.

01:43 And so they stick together.

01:45 The two membranes stick together.

01:47 So it's important to remember that the muscles are not directly attached to the lungs, and the lungs cannot move themselves.

01:54 The liquid in between these two membranes kind of acts like if you've ever had two pieces of glass with water in between, they stick together.

02:05 It acts like that.

02:06 When there's holes introduced into these membranes, that's when you can get collapsed lungs and not be able to breathe.

02:14 So what happens during inhalation or inspiration, is the muscles contract.

02:26 And a lot of people think, well, expiration is forceful, but that's not true.

02:31 Inhalation is what, when you contract your muscles, that's what's happening.

02:36 Expiration is a relaxation of those muscles.

02:39 So what happens is those muscles contract...

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