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?
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Ch. 5 The Integumentary System
Martini, Nath, Bartholomew11th EditionFundamentals of Anatomy & PhysiologyISBN: 9780136874089
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Table of contents
- Ch. 1 An Introduction to Anatomy and Physiology26
- Ch. 2 The Chemical Level of Organization34
- Ch. 3 The Cellular Level of Organization30
- Ch. 4 The Tissue Level of Organization24
- Ch. 5 The Integumentary System17
- Ch. 6 Bones and Bone Structure36
- Ch. 7 The Axial Skeleton11
- Ch. 8 The Appendicular Skeleton17
- Ch. 9 Joints13
- Ch. 10 Muscle Tissue12
- Ch. 11 The Muscular System28
- Ch. 12 Nervous Tissue18
- Ch. 13 The Spinal Cord, Spinal Nerves, and Spinal Reflexes22
- Ch. 14 The Brain and Cranial Nerves20
- Ch. 15 Sensory Pathways and the Somatic Nervous System17
- Ch. 16 The Autonomic Nervous System and Higher-Order Functions30
- Ch. 17 The Special Senses16
- Ch. 18 The Endocrine System20
- Ch. 19 Blood31
- Ch. 20 The Heart31
- Ch. 21 Blood Vessels and Circulation29
- Ch. 22 The Lymphatic System and Immunity31
- Ch. 23 The Respiratory System12
- Ch. 24 The Digestive System18
- Ch. 26 The Urinary System31
- Ch. 27 Fluids & Electrolytes32
- Ch. 28 The Reproductive System12
- Ch. 29 Development and Inheritance23
Martini, Nath, Bartholomew11th EditionFundamentals of Anatomy & PhysiologyISBN: 9780136874089Not the one you use?Change textbook
Chapter 5, Problem 21
In clinical practice, drugs can be delivered by diffusion across the skin. This delivery method is called transdermal administration. Why are fat-soluble drugs more suitable for transdermal administration than drugs that are water soluble?
Verified step by step guidance1
Understand the structure of the skin, focusing on the outermost layer called the stratum corneum, which is composed mainly of dead skin cells embedded in a lipid (fat) matrix.
Recognize that the stratum corneum acts as a barrier to substances trying to penetrate the skin, and its lipid-rich nature makes it more permeable to fat-soluble (lipophilic) substances than to water-soluble (hydrophilic) substances.
Explain that fat-soluble drugs can dissolve in the lipid matrix of the stratum corneum, allowing them to diffuse more easily through this barrier and reach deeper layers of the skin and eventually the bloodstream.
Contrast this with water-soluble drugs, which have difficulty passing through the lipid-rich stratum corneum because they do not dissolve well in lipids, limiting their ability to penetrate the skin effectively.
Conclude that the lipophilicity of fat-soluble drugs enhances their transdermal absorption, making them more suitable for delivery via the skin compared to water-soluble drugs.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Transdermal Drug Delivery
Transdermal drug delivery involves administering medication through the skin to enter the bloodstream. This method bypasses the digestive system and provides controlled, sustained release of drugs. The skin's outer layer, the stratum corneum, acts as a barrier that drugs must penetrate to be effective.
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Skin Structure and Barrier Function
The skin's outermost layer, the stratum corneum, is composed mainly of lipids and dead cells, creating a hydrophobic barrier. This lipid-rich environment favors the passage of fat-soluble substances, while water-soluble drugs have difficulty crossing due to their inability to dissolve in lipids.
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Solubility and Drug Permeability
Drug solubility affects its ability to penetrate biological membranes. Fat-soluble (lipophilic) drugs dissolve well in the lipid layers of the skin, enhancing absorption. In contrast, water-soluble drugs struggle to cross the lipid barrier, making fat-soluble drugs more suitable for transdermal delivery.
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Related Practice
Textbook Question
Why is it important for a surgeon to choose—when possible—an incision pattern according to the skin's tension lines?
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Textbook Question
The fibrous protein that is responsible for the strength and water resistance of the skin surface is
(a) Collagen
(b) Eleidin
(c) Keratin
(d) Elastin
(e) Keratohyalin
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Textbook Question
List the four phases in the regeneration of the skin after an injury.
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Textbook Question
What widespread effects does epidermal growth factor (EGF) have on the integument?
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Textbook Question
What two major layers constitute the dermis, and what components are in each layer?
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