Table of contents

1. Introduction to Biology2h 40m
2. Chemistry3h 40m
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 20m
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 52m
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 Transport2m
- Water Potential
  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 System10m
- Digestion
  3m
- Blood Sugar Homeostasis
  7m
40. Circulatory System1h 57m
41. Immune System1h 12m
42. Osmoregulation and Excretion50m
- Osmoregulation and Excretion
  50m
43. Endocrine System4m
- Endocrine System
  4m
44. Animal Reproduction2m
- Animal Reproduction
  2m
45. Nervous System55m
- Neurons and Action Potentials
  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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Multiple Choice

When you exhale, __________.

both the diaphragm and rib muscles contract

the rib muscles contract and the air pressure in the alveoli becomes lower than atmospheric pressure

the volume of the chest cavity increases

the diaphragm relaxes and the lungs expand

both the diaphragm and the rib muscles relax

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Verified step by step guidance

Understand the process of exhalation: Exhalation is the process of releasing air from the lungs. It is a passive process that occurs when the muscles involved in inhalation relax.

Identify the muscles involved: During inhalation, the diaphragm and the intercostal muscles (rib muscles) contract to increase the volume of the chest cavity. During exhalation, these muscles relax.

Consider the changes in the chest cavity: When the diaphragm and rib muscles relax, the volume of the chest cavity decreases, which increases the air pressure inside the alveoli compared to the atmospheric pressure.

Understand the pressure changes: The increase in pressure inside the alveoli relative to the outside atmosphere causes air to flow out of the lungs, resulting in exhalation.

Conclude with the correct answer: Since exhalation involves the relaxation of both the diaphragm and the rib muscles, the correct answer is that both the diaphragm and the rib muscles relax.