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

6. Bones & Skeletal Tissue

Microscopic Anatomy of Bones - Bone Cells

Anatomy & Physiology

6. Bones & Skeletal Tissue

Microscopic Anatomy of Bones - Bone Cells

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3:11 minutes

Problem 29a

Textbook Question

Exposure to optimum amounts of sunlight is necessary for proper bone maintenance and growth in children.
(a) What does sunlight do to promote bone maintenance and growth?

Verified step by step guidance

Sunlight is essential for the synthesis of vitamin D in the skin. When the skin is exposed to ultraviolet (UV) rays from sunlight, a precursor molecule called 7-dehydrocholesterol is converted into cholecalciferol (vitamin D3).

Vitamin D3 is transported to the liver, where it is hydroxylated to form 25-hydroxyvitamin D (calcidiol). This is the inactive storage form of vitamin D.

Calcidiol is further hydroxylated in the kidneys to form the active hormone, 1,25-dihydroxyvitamin D (calcitriol). This active form of vitamin D is crucial for calcium and phosphate homeostasis in the body.

Calcitriol promotes the absorption of calcium and phosphate from the intestines into the bloodstream. These minerals are essential for the mineralization of bone tissue, which strengthens and maintains bones.

Without adequate sunlight exposure, vitamin D synthesis is impaired, leading to reduced calcium absorption and potentially causing conditions like rickets in children, characterized by weak and deformed bones.

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Key Concepts

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

Vitamin D Synthesis

Sunlight exposure is crucial for the synthesis of Vitamin D in the skin. When ultraviolet B (UVB) rays from the sun hit the skin, they convert a cholesterol derivative into Vitamin D3, which is then transformed into its active form in the liver and kidneys. This vitamin plays a vital role in calcium absorption, which is essential for bone health.

Calcium Absorption

Calcium is a critical mineral for bone structure and strength. Vitamin D enhances the intestinal absorption of calcium from the diet, ensuring that sufficient calcium levels are maintained in the bloodstream. Without adequate calcium, bones can become weak and prone to deformities, particularly in growing children.

Bone Remodeling

Bone remodeling is a continuous process where old bone tissue is replaced by new bone tissue. This process is influenced by various factors, including Vitamin D and calcium levels. Adequate sunlight exposure supports this remodeling process, promoting healthy bone density and growth, which is particularly important during childhood when bones are developing rapidly.

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Related Practice

Textbook Question

Noah Beckenstein went to weight-lifting camp in the summer between seventh and eighth grade. He noticed that the camp trainer put tremendous pressure on him and his friends to improve their strength. After an especially vigorous workout, Noah's arm felt extremely sore and weak around the elbow. He went to the camp doctor, who took X rays and then told him that the injury was serious, for the 'end of his upper arm bone was starting to twist off.' What had happened? Could the same thing happen to Noah's 23-year-old sister, Karen, who was also starting a program of weight lifting? Why or why not?

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Textbook Question

Osteocytes residing in lacunae of osteons of healthy compact bone are located quite a distance from the blood vessels in the central canals, yet they are well nourished. How can this be explained?

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Textbook Question

Match the appropriate name with the structure in the figure.

5. Osteocyte

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Textbook Question

Which of the following would you expect to be prominent in osteoclasts?

a. Golgi apparatus

b. Lysosomes

c. Microfilaments

d. Exocytosis

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Textbook Question

Exposure to optimum amounts of sunlight is necessary for proper bone maintenance and growth in children.

(b) If a child lives in an area where exposure to sunlight is rare because of pollution or overcast skies, what can be done to minimize impaired maintenance and growth of bone?

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Textbook Question

The presence of an epiphyseal line indicates:

(a) Epiphyseal growth has ended

(b) Epiphyseal growth is just beginning

(d) The bone is fractured at the location

(e) No particular event

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Textbook Question

The hormones that coordinate the storage, absorption, and excretion of calcium ions are: