Table of contents

1. Introduction to Anatomy & Physiology5h 43m
2. Cell Chemistry & Cell Components12h 39m
3. Energy & Cell Processes10h 8m
4. Tissues & Histology10h 3m
5. Integumentary System2h 28m
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 System3h 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

Passive vs. Active Transport

Anatomy & Physiology

2. Cell Chemistry & Cell Components

Passive vs. Active Transport

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Multiple Choice

A cell has a membrane potential of –100 mV (more negative inside than outside) and has 1,000 times more calcium ions outside the cell than inside. Which of the following best describes a mechanism by which Ca²⁺ enters the cell?

Movement of Ca²⁺ into the cell through an ion channel down its concentration gradient

Passive diffusion of Ca²⁺ into the cell down its electrochemical gradient

Cotransport of Ca²⁺ into the cell with Cl^–

Movement of Ca²⁺ into the cell through a carrier protein down its electrical gradient

Facilitated diffusion of Ca²⁺ into the cell down its electrochemical gradient

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Verified step by step guidance

Understand the concept of membrane potential: The membrane potential is the difference in electric potential between the inside and outside of a cell. A negative membrane potential indicates that the inside of the cell is more negatively charged compared to the outside.

Recognize the concentration gradient: The problem states that there are 1,000 times more calcium ions (Ca2+) outside the cell than inside, creating a concentration gradient that favors the movement of Ca2+ into the cell.

Consider the electrochemical gradient: The electrochemical gradient is the combined effect of the concentration gradient and the electrical gradient. Since the inside of the cell is negatively charged, positively charged ions like Ca2+ are attracted to move into the cell.

Identify the mechanism of facilitated diffusion: Facilitated diffusion is a type of passive transport that allows ions to move across the cell membrane through specific ion channels or carrier proteins without the use of energy, driven by the electrochemical gradient.

Apply the concept to the problem: Given the strong concentration gradient and the negative membrane potential, Ca2+ will move into the cell down its electrochemical gradient through facilitated diffusion, which involves ion channels or carrier proteins.