Table of contents

1. Introduction to Biology2h 42m
2. Chemistry3h 37m
3. Water1h 26m
4. Biomolecules2h 23m
5. Cell Components2h 26m
6. The Membrane2h 31m
7. Energy and Metabolism2h 0m
8. Respiration2h 40m
9. Photosynthesis2h 49m
10. Cell Signaling59m
11. Cell Division2h 47m
12. Meiosis2h 0m
13. Mendelian Genetics4h 44m
14. DNA Synthesis2h 27m
15. Gene Expression3h 6m
16. Regulation of Expression3h 31m
17. Viruses37m
- Viruses
  37m
18. Biotechnology2h 58m
19. Genomics17m
- Genomes
  17m
20. Development1h 5m
21. Evolution3h 1m
22. Evolution of Populations3h 53m
23. Speciation1h 37m
24. History of Life on Earth2h 6m
25. Phylogeny2h 31m
26. Prokaryotes4h 59m
27. Protists1h 12m
28. Plants1h 22m
29. Fungi36m
- Fungi
  19m
- Fungi Reproduction
  17m
30. Overview of Animals34m
- Overview of Animals
  34m
31. Invertebrates1h 2m
32. Vertebrates50m
33. Plant Anatomy1h 3m
34. Vascular Plant Transport1h 2m
- Water Potential
  1h 2m
35. Soil37m
- Soil and Nutrients
  20m
- Nitrogen Fixation
  16m
36. Plant Reproduction47m
- Flowers
  33m
- Seeds
  14m
37. Plant Sensation and Response1h 9m
38. Animal Form and Function1h 19m
39. Digestive System1h 10m
- Digestion
  1h 3m
- Blood Sugar Homeostasis
  7m
40. Circulatory System1h 49m
41. Immune System1h 12m
42. Osmoregulation and Excretion50m
- Osmoregulation and Excretion
  50m
43. Endocrine System1h 4m
- Endocrine System
  1h 4m
44. Animal Reproduction1h 2m
- Animal Reproduction
  1h 2m
45. Nervous System1h 55m
- Neurons and Action Potentials
  1h 8m
- Central and Peripheral Nervous System
  46m
46. Sensory Systems46m
- Sensory System
  46m
47. Muscle Systems23m
- Musculoskeletal System
  23m
48. Ecology3h 11m
49. Animal Behavior28m
- Animal Behavior
  28m
50. Population Ecology3h 41m
51. Community Ecology2h 46m
52. Ecosystems2h 36m
53. Conservation Biology24m
- Conservation Biology
  24m

40. Circulatory System

Gas Exchange

General Biology

40. Circulatory System

Gas Exchange

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2:47 minutes

Problem 7

Textbook Question

Compared with the interstitial fluid that bathes active muscle cells, blood reaching these cells in arterioles has a
a. Higher PO₂.
b. Higher PCO₂.
c. Greater bicarbonate concentration.
d. Lower pH.

Verified step by step guidance

Understand the role of arterioles: Arterioles are small blood vessels that branch out from arteries and lead to capillaries. They play a crucial role in delivering oxygenated blood to tissues, including muscle cells.

Consider the composition of blood in arterioles: Blood in arterioles is typically rich in oxygen because it is coming directly from the heart and lungs, where gas exchange occurs. Therefore, it has a higher partial pressure of oxygen (PO2) compared to interstitial fluid.

Analyze the interstitial fluid: Interstitial fluid is the fluid that surrounds cells in tissues. In active muscle cells, this fluid will have a different composition due to cellular respiration, which consumes oxygen and produces carbon dioxide.

Compare PO2 levels: Since blood in arterioles is oxygen-rich, it will have a higher PO2 compared to the interstitial fluid surrounding active muscle cells, where oxygen is being used up for energy production.

Evaluate other options: Consider the other choices (higher PCO2, greater bicarbonate concentration, lower pH) and understand that these are typically characteristics of the interstitial fluid due to the metabolic activity of muscle cells, which produce CO2 and may lower pH.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Partial Pressure of Oxygen (PO2)

Partial pressure of oxygen (PO2) refers to the pressure exerted by oxygen in a mixture of gases or in a liquid, such as blood. In the context of blood reaching active muscle cells, the PO2 is typically higher in the arterioles compared to the interstitial fluid because blood delivers oxygen to tissues, which is then used for cellular respiration.

Partial Pressure of Carbon Dioxide (PCO2)

Partial pressure of carbon dioxide (PCO2) is the pressure exerted by CO2 in a mixture of gases or in a liquid. In active muscle cells, CO2 is produced as a byproduct of metabolism, leading to higher PCO2 in the interstitial fluid compared to the blood in arterioles, which is responsible for transporting CO2 away from tissues to be exhaled.

Bicarbonate Buffer System

The bicarbonate buffer system helps maintain pH balance in the blood. It involves the equilibrium between carbonic acid and bicarbonate ions. In active tissues, CO2 is converted to bicarbonate, increasing its concentration in the blood. This system is crucial for transporting CO2 and regulating blood pH, which tends to be lower in active tissues due to increased CO2 production.

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Related Practice

Textbook Question

Countercurrent gas exchange in the gills of a fish

a. Maintains a gradient that enhances diffusion.

b. Enables the fish to obtain oxygen without swimming.

c. Means that blood and water flow at different rates.

d. Allows O₂ to diffuse against its partial pressure gradient.

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Textbook Question

When you inhale, the diaphragm

a. Relaxes and moves upward.

b. Relaxes and moves downward.

c. Contracts and moves upward.

d. Contracts and moves downward.

798

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Textbook Question

Explain how each parameter in Fick's law of diffusion is reflected in the structure of the mammalian lung.

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Textbook Question

Frog lungs have a smaller surface area for gas exchange than mammalian lungs. How do frogs compensate for this difference?

a. Frog tissue absorbs more oxygen from the blood than mammalian tissue does.

b. Frogs breathe more quickly than mammals.

c. Frogs also obtain oxygen via diffusion across the skin.

d. Frog lung tissue has a greater density of capillary beds than mammalian lung tissue.

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Textbook Question

Carp are fishes that thrive in stagnant-water habitats with low oxygen partial pressure. Compared with the hemoglobin of many other fish species, carp hemoglobin has an extremely high affinity for O₂.

Draw an oxygen–hemoglobin equilibrium curve showing separate lines for carp and a fish that lives in water with a higher oxygen partial pressure.

Explain why they differ.

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Textbook Question

What is the primary feedback used by the brain to control breathing?

a. Heart rate

b. Partial pressure of O₂

c. Blood pH, which indicates O₂ level

d. Blood pH, which indicates CO₂ level

750

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