9: Vitamins and Minerals II

1. 
2. Buy Print CopyDonate

• 
• Alice Callahan, Heather Leonard, & Tamberly Powell
• Lane Community College via OpenOregon

Learning Objectives

After completing this unit, you should be able to:

1. Define bone and discuss the process of bone formation, modeling, and remodeling across the lifecycle.
2. Define osteoporosis, identify risk factors for development, and explain how osteoporosis can be prevented.
3. Describe the functions of calcium in the body, how calcium homeostasis is regulated, food sources of calcium, and effects of calcium deficiency and toxicity.
4. Briefly describe the functions of phosphorus, magnesium, and fluoride in bone health and beyond, their food sources, and effects of deficiency and toxicity.
5. Describe the synthesis, metabolism, and functions of vitamin D, as well as food sources and effects of deficiency and toxicity of vitamin D.
6. Describe the role of B vitamins and minerals in energy metabolism, as well as food sources and the effects of deficiency and toxicity.
7. Describe the specific functions of folate and vitamin B12, as well as food sources and effects of deficiency and toxicity of folate and B12.
8. Describe the role of blood, as well as the more specific functions, food sources, and effects of deficiency and toxicity for iron and vitamin K.

Xerophthalmia

 Xerophthalmia 

Xerophthalmia is an eye condition caused by severe vitamin A deficiency. It is characterized by dryness of the eyes, leading to night blindness and other vision problems. 

Causes: 

• Vitamin A deficiency, primarily due to inadequate dietary intake or malabsorption 

Symptoms: 

• Dry eyes
• Night blindness (difficulty seeing in dim light)
• Bitot's spots (foamy white patches on the conjunctiva, the clear membrane covering the white part of the eye)
Corneal ulcers (in severe cases) 

Progression: 

Xerophthalmia progresses in stages: 

Night blindness: The earliest symptom. 
Conjunctival xerosis: Dryness of the conjunctiva, causing it to appear red and wrinkled. 
Bitot's spots: Formation of white patches on the conjunctiva. 
Keratomalacia: Softening and melting of the cornea, which can lead to permanent blindness. 

Treatment:

Vitamin A supplementation (usually in the form of oral capsules or injections) 
In severe cases, eye drops or ointments to lubricate the eyes 

Prevention: 

Consume a diet rich in vitamin A-containing foods, such as fruits (mangoes, apricots), vegetables (carrots, sweet potatoes), and animal products (eggs, liver) 
Take vitamin A supplements if recommended by a healthcare professional 

Additional Information:

Xerophthalmia is more common in developing countries where vitamin A deficiency is prevalent.
It is a preventable condition.
Early diagnosis and treatment are crucial to prevent permanent vision loss. 

• Xerophthalmia: Symptoms, Causes & Treatment - Cleveland Clinic

  What is xerophthalmia? Xerophthalmia is pronounced "zeer-of-thal-mee-uh” or “zeer-op-thal-mee-uh.” The Greek root words literally ...

  

  Cleveland Clinic
• Xerophthalmia - Wikipedia

  In xerophthalmia, Bitot's spots occur after conjunctival xerosis. Xerophthalmia caused by a severe vitamin A deficiency is describ...

  

  Wikipedia
• Xerophthalmia - Wikipedia

  Xerophthalmia (from Ancient Greek xērós (ξηρός) meaning "dry" and ophthalmos (οφθαλμός) meaning "eye") is a medical condition in w...

  

  Wikipedia
• Show all

This is for informational purposes only. For medical advice or diagnosis, consult a professional. Generative AI is experimental.

Rhodopsin

 Rhodopsin 

Rhodopsin is a light-sensitive protein found in the retina of the eye. It plays a crucial role in vision, particularly in low-light conditions. 

Structure and Function: 

• Rhodopsin is a G protein-coupled receptor (GPCR). 
• It consists of a protein component called opsin and a small molecule called 11-cis-retinal. 
• In the presence of light, 11-cis-retinal isomerizes to all-trans-retinal, which triggers a conformational change in rhodopsin. 
• This change activates a cascade of events that ultimately leads to the generation of an electrical signal in the brain, allowing us to perceive light. 

Location and Role in Vision: 

Rhodopsin is primarily located in the rod cells of the retina, which are specialized for night vision. 
It enables the eye to detect extremely low levels of light and provides monochromatic (black and white) vision in dim conditions. 

Other Facts: 

Rhodopsin is also known as "visual purple" due to its reddish-purple color. 
It is essential for vitamin A metabolism, as 11-cis-retinal is derived from vitamin A. 
Mutations in the rhodopsin gene can lead to night blindness and other eye disorders. 

Summary:

Rhodopsin is a vital light-sensitive protein that enables vision in low light conditions. It is located in the rod cells of the retina and plays a key role in the transduction of light into electrical signals that are processed by the brain.