pratcice 1

1. During inhalation, the diaphragm contracts and the chest cavity expands. What happens to pressure inside the lungs?

Pressure decreases below atmospheric pressure, allowing air to enter.

2. What happens to alveoli when surfactant production decreases?

Surface tension increases, making alveoli more likely to collapse.

3. During intense exercise, muscles produce more carbon dioxide. How does breathing respond?

Breathing rate and depth increase to remove more carbon dioxide.

4. What happens when lung compliance decreases?

The lungs become stiffer and harder to expand.

5. What happens to breathing when blood carbon dioxide levels increase?

Breathing rate and depth generally increase.

6. What is the primary function of Type I alveolar cells?

Allow oxygen and carbon dioxide to diffuse across the alveolar membrane.

7. How does increased body temperature affect oxygen unloading from hemoglobin?

Hemoglobin releases oxygen more easily.

8. What happens to blood carbon dioxide levels when someone breathes faster and deeper?

Carbon dioxide levels generally decrease.

9. Which cells produce surfactant?

Type II alveolar cells.

10. What happens to blood pH when carbon dioxide increases?

Blood pH decreases because more hydrogen ions are produced.

11. What causes air to leave the lungs during normal expiration?

Lung volume decreases, pressure increases, and air moves out.

12. What is the function of alveolar macrophages?

Engulf dust, bacteria, and other foreign particles.

13. What does the Bohr effect explain?

Increased carbon dioxide and acidity cause hemoglobin to release oxygen more easily.

14. What happens when the medulla oblongata is damaged?

The basic breathing rhythm and respiratory control can be disrupted.

15. Why does air enter the lungs during inspiration?

Lung pressure becomes lower than atmospheric pressure.

16. In which direction does carbon dioxide diffuse when body tissues produce more carbon dioxide?

From body tissues into the blood.

17. What happens when hemoglobin production decreases?

The blood's ability to transport oxygen decreases.

18. What happens to carbon dioxide levels when a person breathes too slowly?

Carbon dioxide builds up in the blood.

19. What happens when lung elastic recoil decreases?

The lungs have more difficulty passively pushing air out during expiration.

20. What happens to blood pH when hydrogen ion concentration increases?

Blood pH decreases and becomes more acidic.

21. Which receptors detect dangerously low blood oxygen levels?

Peripheral chemoreceptors.

22. What do central chemoreceptors primarily detect?

Changes in cerebrospinal fluid pH caused by carbon dioxide.

23. What happens when the diaphragm relaxes during inspiration?

Inspiration becomes difficult to maintain because chest cavity volume decreases.

24. What process allows oxygen and carbon dioxide to cross the alveolar membrane?

Diffusion.

25. Why does oxygen move from the alveoli into the pulmonary blood?

Oxygen moves from higher partial pressure in the alveoli to lower partial pressure in the blood.

26. In what form is most carbon dioxide transported in the blood?

Bicarbonate ions.

27. What is the function of carbonic anhydrase?

It speeds up the conversion reactions between carbon dioxide, water, carbonic acid, and bicarbonate.

28. What happens during the chloride shift?

Bicarbonate leaves red blood cells while chloride enters to maintain electrical balance.

29. How does increased acidity affect hemoglobin's affinity for oxygen?

It decreases oxygen affinity, allowing more oxygen to be released.

30. What is external respiration?

Gas exchange between the alveoli and pulmonary blood.

31. What is internal respiration?

Gas exchange between systemic blood and body tissues.

32. How does increased ventilation affect blood pH?

It removes carbon dioxide, reduces acidity, and generally raises blood pH.

33. What is the function of the pons in breathing?

It helps modify and coordinate the breathing rhythm.

34. How does surfactant help the lungs?

It reduces surface tension and helps prevent alveoli from collapsing.

35. According to Boyle's law, what happens to pressure when lung volume increases?

Pressure decreases because pressure and volume are inversely related.

36. What changes help active muscles receive more oxygen?

Increased carbon dioxide, increased temperature, and decreased pH promote oxygen unloading.

37. What happens when intrapulmonary pressure equals atmospheric pressure?

There is no net airflow.

38. Why is intrapleural pressure normally negative?

It helps keep the lungs expanded against their natural tendency to recoil.

39. What substance decreases when Type II alveolar cells are damaged?

Surfactant.

40. What happens to hydrogen ion concentration when carbon dioxide increases?

Hydrogen ion concentration generally increases.

41. What respiratory process allows oxygen to move from alveoli into the blood?

External respiration.

42. Why does carbon dioxide move from pulmonary blood into the alveoli?

Carbon dioxide has a higher partial pressure in the blood than in the alveoli.

43. How does the body compensate for increased blood acidity through breathing?

It increases ventilation to remove carbon dioxide.

44. What is elastic recoil?

The ability of the lungs to return toward their original size after being stretched.

45. Why does a thicker alveolar membrane interfere with gas exchange?

It increases the diffusion distance and makes gas exchange less efficient.

46. What happens after peripheral chemoreceptors detect low oxygen?

They send signals to respiratory control centers to increase ventilation.

47. Which gas is removed more quickly during increased ventilation?

Carbon dioxide.

48. What is the purpose of the chloride shift?

To maintain electrical balance when bicarbonate moves into or out of red blood cells.

49. How does increased carbon dioxide help active tissues receive oxygen?

It causes hemoglobin to release oxygen more readily.

50. What happens during normal expiration?

The diaphragm relaxes, lung volume decreases, pressure increases, and air exits.

51. Why does bread taste sweeter after being chewed for a long time?

Salivary amylase breaks starch into smaller carbohydrates, including maltose.

52. What happens when salivary amylase production decreases?

The beginning of carbohydrate digestion in the mouth becomes less efficient.

53. What happens when peristalsis does not function properly?

Food has difficulty moving forward through the digestive tract.

54. What is segmentation?

Rhythmic muscular contractions that mix food with digestive juices.

55. What happens when mechanical digestion is impaired but enzymes function normally?

Food is not physically broken down as effectively.

56. What happens when digestive enzyme production decreases?

Chemical digestion becomes less efficient.

57. Which enzyme begins carbohydrate digestion in the mouth?

Salivary amylase.

58. Why does reduced stomach acid interfere with protein digestion?

Pepsinogen requires an acidic environment to become active pepsin.

59. What substance is reduced when chief cells are damaged?

Pepsinogen.

60. What two substances are reduced when parietal cells are damaged?

Hydrochloric acid and intrinsic factor.

61. What happens when pepsinogen is produced normally but hydrochloric acid is too low?

Less pepsinogen is activated into pepsin, reducing protein digestion.

62. Which hormone stimulates gastric acid secretion after eating?

Gastrin.

63. What vitamin becomes difficult to absorb when intrinsic factor is missing?

Vitamin B12.

64. Why can someone develop a vitamin B12 deficiency even when eating enough B12?

Without intrinsic factor, vitamin B12 cannot be properly absorbed in the terminal ileum.

65. How does the vagus nerve stimulate digestion?

It promotes gastric secretions and stomach motility through parasympathetic activity.

66. What is the cephalic phase of gastric secretion?

The preparation for digestion triggered by seeing, smelling, tasting, or thinking about food.

67. What happens when food stretches the stomach?

Gastric activity and secretion generally increase.

68. Which hormone stimulates the production of hydrochloric acid?

Gastrin.

69. What happens when the stomach produces too little protective mucus?

The stomach lining becomes more vulnerable to damage from acid and digestive enzymes.

70. What is chyme?

A semifluid mixture of partially digested food and gastric juices.

71. What happens when food cannot leave the stomach normally?

Gastric emptying is delayed, and food can accumulate in the stomach.

72. What is pyloric stenosis?

A narrowing of the stomach outlet that makes it difficult for stomach contents to enter the small intestine.

73. What is acid reflux?

The backward movement of stomach contents into the esophagus.

74. Why can a hiatal hernia contribute to acid reflux?

It can interfere with normal lower esophageal sphincter function, allowing stomach contents to move backward.

75. What happens when digestion is normal but absorption is impaired?

Nutrients have difficulty entering the blood or lymph.

76. Which enzyme begins protein digestion in the stomach?

Pepsin.

77. Which nutrient is primarily broken down by pepsin?

Proteins.

78. What happens to stomach pH when hydrochloric acid production increases?

Stomach pH decreases and becomes more acidic.

79. What happens when enteroendocrine cells are damaged?

Hormonal regulation of digestion can become impaired.

80. What is secretion in digestion?

The release of substances such as mucus, enzymes, acid, and hormones that help digestion.

81. What happens when peristalsis decreases?

Food moves more slowly through the digestive tract.

82. What type of digestion occurs when the stomach churns food?

Mechanical digestion.

83. What other substance may decrease when parietal cells are damaged besides hydrochloric acid?

Intrinsic factor.

84. What happens to digestion when vagus nerve stimulation decreases?

Gastric secretions and stomach motility may decrease.

85. Why does the small intestine slow gastric emptying?

To prevent receiving more chyme than it can properly process.

86. What happens when segmentation is impaired?

Food is not mixed as effectively with digestive juices, reducing digestive efficiency and contact with the intestinal lining.

87. What digestive processes are affected when someone cannot swallow normally?

Ingestion and propulsion.

88. What happens when gastrin levels increase?

Gastric acid secretion and stomach activity generally increase.

89. What protects the stomach lining from hydrochloric acid?

Mucus and bicarbonate form a protective barrier.

90. What should be investigated when someone has normal vitamin B12 intake but poor B12 absorption?

Intrinsic factor production and function.

91. What muscular process moves swallowed food toward the stomach?

Peristalsis.

92. What happens to starch when it enters the mouth?

Salivary amylase begins breaking it down into smaller carbohydrates.

93. Why is reduced stomach mucus production dangerous?

The stomach lining becomes more vulnerable to acid and pepsin damage.

94. What happens when hydrochloric acid cannot create an acidic stomach environment?

Pepsinogen activation decreases, protein digestion becomes less efficient, and the stomach has less protection against ingested microorganisms.

95. A person has normal chief cells but damaged parietal cells. What happens to protein digestion and vitamin B12 absorption?

Protein digestion decreases because less HCl is available to activate pepsinogen, and vitamin B12 absorption decreases because less intrinsic factor is produced.

96. A person has increased gastrin secretion. Predict two changes in stomach activity.

Hydrochloric acid secretion increases and gastric motility generally increases.

97. Why does the stomach release chyme gradually instead of emptying everything into the small intestine at once?

Gradual emptying allows the small intestine time to neutralize acid and digest and absorb nutrients.

98. A person has increased intestinal acidity and fat entering the small intestine. What happens to gastric emptying?

Gastric emptying slows to prevent excessive delivery of acidic and fatty chyme.