Table of contents

Skip topic navigation

1. Introduction to Anatomy & Physiology5h 43m
2. Cell Chemistry & Cell Components12h 36m
3. Energy & Cell Processes10h 6m
4. Tissues & Histology10h 3m
5. Integumentary System2h 20m
6. Bones & Skeletal Tissue2h 16m
7. The Skeletal System2h 35m
8. Joints2h 17m
9. Muscle Tissue2h 33m
10. Muscles1h 11m
11. Nervous Tissue and Nervous System1h 35m
12. The Central Nervous System1h 6m
- Introduction to the Central Nervous System
  18m
- The Cerebrum
  48m
13. The Peripheral Nervous System1h 26m
14. The Autonomic Nervous System1h 38m
15. The Special Senses2h 41m
16. The Endocrine System2h 48m
17. The Blood3h 22m
18. The Heart2h 42m
19. The Blood Vessels3h 35m
20. The Lymphatic System3h 16m
21. The Immune System14h 37m
22. The Respiratory System3h 20m
23. The Digestive System2h 5m
24. Metabolism and Nutrition4h 0m
25. The Urinary System2h 39m
26. Fluid and Electrolyte Balance, Acid Base Balance37m
27. The Reproductive System2h 5m
28. Human Development1h 21m
29. Heredity3h 32m

21. The Immune System

First-Line Defenses: Chemical Barriers

Anatomy & Physiology

21. The Immune System

First-Line Defenses: Chemical Barriers

Previous problemNext problem

Struggling with Anatomy & Physiology?

Join thousands of students who trust us to help them ace their exams!Watch the first video

Multiple Choice

Which of the following statements about the defensive roles of saliva and gastric juices are true?

Saliva’s main function is to move microbes through and out of the gastrointestinal system.

Saliva possesses enzymes that inhibit microbial growth and digest microbes.

Gastric juice’s main function is to destroy microbes and toxins eaten by the host.

Gastric juice is incredibly acidic which breaks down most pathogens.

All of the above are true statements.

Previous problemNext problem

Verified step by step guidance

Begin by understanding the role of saliva in the digestive system. Saliva contains enzymes such as lysozyme, which can break down bacterial cell walls, thus inhibiting microbial growth.

Consider the mechanical function of saliva. It helps in the movement of food and microbes through the gastrointestinal tract, facilitating their removal from the body.

Examine the composition of gastric juice. It contains hydrochloric acid, which creates a highly acidic environment in the stomach.

Understand the defensive role of gastric juice. The acidity of gastric juice is effective in destroying many microbes and toxins that are ingested, providing a protective barrier against pathogens.

Review the statements provided in the problem. Each statement accurately describes a defensive role of saliva or gastric juice, confirming that all statements are true.