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

15. The Special Senses

Rods, Cones, and Light

Anatomy & Physiology

15. The Special Senses

Rods, Cones, and Light

Previous problemNext problem

2:15 minutes

Problem 31

Textbook Question

Describe the response of rhodopsin to light stimuli. What is the outcome of this cascade of events?

Verified step by step guidance

Rhodopsin, a photoreceptor protein found in the rods of the retina, is activated by light stimuli. When light hits rhodopsin, it causes a conformational change in its structure, specifically converting the 11-cis-retinal component to all-trans-retinal.

This structural change in rhodopsin activates the associated G-protein called transducin. Transducin then binds to GTP, initiating the next step in the signaling cascade.

Activated transducin stimulates the enzyme phosphodiesterase (PDE), which breaks down cyclic GMP (cGMP) into GMP. This reduces the concentration of cGMP in the photoreceptor cell.

The decrease in cGMP levels leads to the closure of cGMP-gated sodium channels in the photoreceptor membrane. As a result, sodium ions can no longer enter the cell, causing hyperpolarization of the photoreceptor.

The hyperpolarization of the photoreceptor reduces the release of the neurotransmitter glutamate at the synapse with bipolar cells. This change in neurotransmitter release alters the signal sent to the brain, ultimately leading to visual perception of light.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above

Video duration:

Play a video:

Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Rhodopsin Structure and Function

Rhodopsin is a light-sensitive receptor protein found in the photoreceptor cells of the retina. It consists of a protein called opsin and a chromophore called retinal, which changes shape when exposed to light. This structural change initiates the phototransduction cascade, converting light signals into electrical signals that the brain can interpret.

Phototransduction Cascade

The phototransduction cascade is a biochemical process that occurs in response to light stimuli. When rhodopsin absorbs photons, it activates a G-protein called transducin, which subsequently activates phosphodiesterase. This enzyme reduces the levels of cyclic GMP (cGMP), leading to the closure of ion channels and hyperpolarization of the photoreceptor cell, ultimately resulting in a change in neurotransmitter release.

Outcome of Phototransduction

The outcome of the phototransduction cascade is the conversion of light into an electrical signal that can be processed by the brain. This process leads to the hyperpolarization of photoreceptor cells, reducing the release of neurotransmitters and signaling to bipolar cells. This change in signaling is crucial for visual perception, allowing the brain to interpret light intensity and color.