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

Introduction to Membrane Transport

Anatomy & Physiology

2. Cell Chemistry & Cell Components

Introduction to Membrane Transport

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Multiple Choice

What property of steroid hormones allows them to cross the phospholipid bilayer?

They are charged molecules

They are large proteins

They are lipophilic

They are hydrophilic

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Verified step by step guidance

Understand the structure of the phospholipid bilayer: The cell membrane is primarily composed of phospholipids, which have hydrophilic (water-attracting) heads and hydrophobic (water-repelling) tails. This structure creates a barrier to most water-soluble substances.

Recognize the nature of steroid hormones: Steroid hormones are derived from cholesterol, which is a lipid. This means they are lipophilic, or fat-loving, and can easily interact with the hydrophobic tails of the phospholipid bilayer.

Identify the property that allows passage through the bilayer: Because steroid hormones are lipophilic, they can dissolve in the lipid bilayer and pass through it without the need for transport proteins or channels.

Contrast with other molecules: Charged molecules and large proteins typically cannot pass through the lipid bilayer directly because they are either hydrophilic or too large to fit through the membrane without assistance.

Conclude why lipophilicity is key: The lipophilic nature of steroid hormones is crucial for their ability to cross the phospholipid bilayer, allowing them to enter cells and exert their effects.