Table of contents

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 Heart3h 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

2. Cell Chemistry & Cell Components

Biological Membranes

Anatomy & Physiology

2. Cell Chemistry & Cell Components

Biological Membranes

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Multiple Choice

Why does a plasma membrane act as a barrier to the free passage of water-soluble substances?

Because it is made of proteins that repel water-soluble substances.

Because it contains large pores that allow only lipid-soluble substances to pass through.

Because it is a rigid structure that prevents any substance from passing through.

Because it is composed of a lipid bilayer that is hydrophobic in nature.

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Verified step by step guidance

Understand the structure of the plasma membrane: The plasma membrane is primarily composed of a lipid bilayer, which consists of two layers of phospholipids.

Recognize the nature of phospholipids: Each phospholipid molecule has a hydrophilic (water-attracting) 'head' and two hydrophobic (water-repelling) 'tails'.

Identify the arrangement of phospholipids: In the lipid bilayer, the hydrophobic tails face inward, shielded from water, while the hydrophilic heads face outward, towards the aqueous environment inside and outside the cell.

Explain the barrier function: The hydrophobic core of the lipid bilayer acts as a barrier to water-soluble substances, preventing their free passage through the membrane.

Conclude with the selective permeability: The plasma membrane's structure allows it to be selectively permeable, permitting the passage of lipid-soluble substances while restricting water-soluble substances.