Human Respiratory System Overview

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Questions and Answers

What is the primary function of the alveoli in the lungs?

  • To facilitate the exchange of respiratory gases (correct)
  • To filter air as it enters the lungs
  • To produce mucus for the respiratory tract
  • To provide structural support for the lungs

What is the average diameter of an individual alveolus in the human lung?

  • 0.1 mm
  • 0.2 mm (correct)
  • 0.05 mm
  • 0.5 mm

What is the thickness of the walls of the alveoli?

  • 0.01 mm
  • 0.1 mm
  • 0.001 mm (correct)
  • 0.0001 mm

What is the approximate number of alveoli in the human lungs?

<p>300 million (A)</p> Signup and view all the answers

Where does the exchange of respiratory gases (oxygen and carbon dioxide) occur?

<p>In the capillary beds surrounding the alveoli (B)</p> Signup and view all the answers

What is the role of the capillaries in the respiratory system?

<p>To facilitate the exchange of oxygen and carbon dioxide (D)</p> Signup and view all the answers

What happens to the deoxygenated blood as it passes through the capillary beds around the alveoli?

<p>It absorbs oxygen and becomes oxygenated (B)</p> Signup and view all the answers

What happens to the carbon dioxide in the deoxygenated blood as it passes through the capillary beds around the alveoli?

<p>It is released into the air in the alveoli (C)</p> Signup and view all the answers

What is the purpose of the extensive network of bronchioles in the lungs?

<p>To deliver air to the millions of alveoli (D)</p> Signup and view all the answers

What is the main purpose of the dense network of capillaries surrounding the alveoli?

<p>To facilitate the exchange of respiratory gases between the alveoli and the bloodstream (D)</p> Signup and view all the answers

Flashcards

Alveoli

Tiny air sacs in the lungs where gas exchange takes place.

Gas Exchange in Alveoli

The primary function of the alveoli is to facilitate the exchange of oxygen and carbon dioxide between the air in the lungs and the blood.

Alveoli Size

The average diameter of an alveolus in the human lung is approximately 0.2 mm.

Alveoli Wall Thickness

The walls of the alveoli are incredibly thin, measuring only 0.001 mm thick.

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Number of Alveoli

The human lungs contain approximately 300 million alveoli, providing a vast surface area for gas exchange.

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Capillaries and Alveoli

The network of capillaries surrounding each alveolus enables the exchange of oxygen and carbon dioxide.

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Blood Oxygenation

Deoxygenated blood arriving at the alveoli absorbs oxygen and releases carbon dioxide.

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Bronchiole Function

The bronchioles are a network of small airways within the lungs that deliver air to the alveoli.

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Efficient Gas Exchange

The close proximity and extensive surface area of the capillaries surrounding the alveoli allows for efficient gas exchange.

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Capillary Role in Gas Exchange

The capillaries surrounding the alveoli play a crucial role in the exchange of oxygen and carbon dioxide between the air and the blood.

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Study Notes

Diffusion in Humans

  • In the lungs, oxygen and carbon dioxide molecules diffuse down their own concentration gradients between the moisture on the inner lining of the alveoli and the blood.
  • This diffusion occurs down a concentration gradient.

Air Sacs and Alveoli

  • Alveoli are perfectly adapted for the process of diffusion, having thin and moist walls that help oxygen and carbon dioxide to diffuse.
  • A single alveolus has a thin wall, one cell thick, and is surrounded by a dense network of capillaries.
  • The capillaries also have very thin walls, which helps the diffusion of oxygen and carbon dioxide into and from the blood.

How the Alveoli and Capillaries Work

  • Air containing oxygen enters the lungs and passes into each alveolus from outside.
  • Deoxygenated blood containing carbon dioxide comes from the rest of the body.
  • Oxygen diffuses into the blood from the alveoli, while carbon dioxide diffuses from the blood into the alveoli.
  • The blood becomes oxygenated, and oxygenated blood leaves the lungs and returns to the heart.

Inhaled and Exhaled Air

  • Inhaled air into the lungs: 20.95% oxygen, 79% nitrogen, 0.04% carbon dioxide, and 0.01% water vapor.
  • Exhaled air out of the lungs: 16% oxygen, 79% nitrogen, 4.0% carbon dioxide, and 1% water vapor.

Breathing

  • Breathing is the process of moving air in and out of the lungs.
  • Breathing is achieved by making the chest cavity larger or smaller, which results in a change in pressure within the lungs.
  • This change in pressure forces air either in (inhale) or out (exhale) of the lungs, known as ventilation of the lungs.
  • Inspiration (breathing in) involves the contraction of rib muscles and diaphragm muscle, which increases the volume of the chest cavity.

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