Homeostatic Control of Breathing

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Questions and Answers

What triggers an increase in breathing rate during strenuous physical activity?

  • Increased levels of carbon dioxide in the blood (correct)
  • Decreased demand for energy
  • Increased heart rate
  • Decreased levels of oxygen in the body

What primarily causes oxygen to diffuse from the alveolus into the blood?

  • The direct contact between alveoli and tissues
  • Active transport mechanisms in red blood cells
  • The high concentration of oxygen in the alveolus (correct)
  • The low concentration of oxygen in the blood

How is most carbon dioxide transported in the blood?

  • Dissolved in plasma
  • Combined with oxygen to form carbhamoglobin
  • In a complex with nutrients
  • As bicarbonate ions (correct)

During gaseous exchange at the tissues, which condition facilitates oxygen diffusion into cells?

<p>Lower concentration of oxygen in the tissue fluid (A)</p> Signup and view all the answers

What percentage of oxygen is dissolved in blood plasma?

<p>1.5% (C)</p> Signup and view all the answers

The reaction of carbon dioxide with water in blood plasma primarily forms which substance?

<p>Bicarbonate ions (C)</p> Signup and view all the answers

What happens to oxyhemoglobin when it reaches the body tissues?

<p>It dissociates into oxygen and haemoglobin (A)</p> Signup and view all the answers

In what form is most carbon dioxide released from the body during exhalation?

<p>As gaseous carbon dioxide in the alveoli (D)</p> Signup and view all the answers

Flashcards

Homeostatic control of breathing

Adjusting breathing rate to meet the body's energy needs, typically increasing during strenuous activity to absorb more oxygen and expire more carbon dioxide.

Gaseous exchange in lungs

Oxygen diffuses from alveoli into blood; carbon dioxide diffuses from blood into alveoli, driven by concentration gradients.

Gaseous exchange at tissues

Oxygen diffuses from blood into tissues; carbon dioxide diffuses from tissues into blood, driven by concentration gradients.

Oxygen transport (blood)

Most oxygen (98.5%) binds to haemoglobin forming oxyhaemoglobin; a small amount (1.5%) is dissolved in the blood plasma.

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Carbon dioxide transport (blood)

CO2 is transported in blood as dissolved gas (7%), bound to haemoglobin (23%), and bicarbonate ions (70%).

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Medulla oblongata

Part of the brain stem that regulates breathing rate in response to blood $CO_2$ levels.

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Haemoglobin

Iron-containing protein in red blood cells that carries oxygen.

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Concentration gradient

Difference in concentration of a substance across a surface, driving diffusion.

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Alveoli

Tiny air sacs in the lungs where gas exchange occurs.

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Capillaries

Tiny blood vessels surrounding alveoli and tissues that facilitate gas exchange.

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Study Notes

Homeostatic Control of Breathing

  • Strenuous activity increases the body's need for energy, which in turn demands more oxygen intake and more carbon dioxide expulsion.
  • The breathing rate increases and more blood flows to the lungs.

Gaseous Exchange in the Lungs

  • Capillaries surround alveoli, these have a high COâ‚‚ concentration and low oxygen concentration.
  • Air in the alveoli has a high oxygen and low COâ‚‚ concentration.
  • Concentration gradient causes diffusion.
  • Oxygen dissolves in moisture lining alveoli and diffuses into blood stream.
  • COâ‚‚ diffuses out of blood stream into alveoli.
  • Oxygen combines with haemoglobin in red blood cells (erythrocytes) forming oxyhaemoglobin.
  • A small amount of oxygen dissolves in blood plasma.

Gaseous Exchange at the Tissues

  • Blood in capillaries reaching tissues has high Oâ‚‚ and low COâ‚‚ concentration.
  • Tissue fluid has a higher COâ‚‚ and lower Oâ‚‚ concentration.
  • Concentration gradient causes diffusion.
  • Oxygen diffuses from blood into tissue fluid, then into cells.
  • COâ‚‚ diffuses out of cells into tissue fluid, then into blood.
  • Cellular respiration consumes oxygen and produces COâ‚‚.

Transport of Gases by the Blood

Oxygen

  • 1.5% carried dissolved in blood plasma.
  • 98.5% combines with haemoglobin inside red blood cells to form oxyhaemoglobin.
  • When it reaches the cells, oxyhaemoglobin dissociates into oxygen and haemoglobin.

Carbon Dioxide

  • 7% transported dissolved in blood plasma.
  • 23% combines with haemoglobin to form carbaminohaemoglobin.
  • 70% transported as bicarbonate ions.

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