Textbook Question
Explain what happens to dermal blood vessels when heat needs to be conserved (i.e., due to a cold environment).
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Ch. 5 The Integumentary System
Amerman3rd EditionHuman Anatomy & PhysiologyISBN: 9780138247201, 9780138247928, 9780138201814
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Table of contents
- Ch. 1 Introduction to Anatomy and Physiology24
- Ch. 2 The Chemistry of Life37
- Ch. 3 The Cell54
- Ch. 4 Histology46
- Ch. 5 The Integumentary System30
- Ch. 6 Bones and Bone Tissue36
- Ch. 7 The Skeletal System40
- Ch. 8 Articulations19
- Ch. 9 The Muscular System35
- Ch. 10 Muscle Tissue and Physiology29
- Ch. 11 Introduction to the Nervous System and Nervous Tissue28
- Ch. 12 The Central Nervous System41
- Ch. 13 The Peripheral Nervous System41
- Ch. 14 The Autonomic Nervous System and Homeostasis31
- Ch. 15 The Special Senses39
- Ch. 16 The Endocrine System42
- Ch. 17 The Cardiovascular System I: The Heart28
- Ch. 18 The Cardiovascular System II: The Blood Vessels43
- Ch. 19 Blood32
- Ch. 20 The Lymphatic System and Immunity41
- Ch. 21 The Respiratory System27
- Ch. 22 The Digestive System27
- Ch. 23 Metabolism and Nutrition7
- Ch. 24 The Urinary System39
- Ch. 25 Fluid, Electrolyte, and Acid-Base Homeostasis39
- Ch. 26 The Reproductive System10
- Ch. 27 Development and Heredity5
Amerman3rd EditionHuman Anatomy & PhysiologyISBN: 9780138247201, 9780138247928, 9780138201814Not the one you use?Change textbook
Chapter 5, Problem 6
Keratinocytes in the superficial strata of the epidermis die because:
a. They are too far away from the blood supply in the dermis.
b. They are surrounded by a lipid-based substance that makes them more permeable to water.
c. They do not die.
d. No keratinocytes in the epidermis are alive.
Verified step by step guidance1
Understand the structure of the epidermis: The epidermis is the outermost layer of the skin, composed of stratified squamous epithelial cells. It is avascular, meaning it lacks blood vessels, and relies on diffusion from the dermis for nutrients and oxygen.
Identify the role of keratinocytes: Keratinocytes are the primary cell type in the epidermis. They originate in the basal layer (stratum basale) and migrate upward through the layers, undergoing changes as they move toward the surface.
Explain the process of keratinization: As keratinocytes move upward, they produce keratin, a tough, fibrous protein. They also accumulate lipid-based substances that contribute to the skin's barrier function, making the cells less permeable to water and nutrients.
Discuss why keratinocytes die in the superficial layers: Keratinocytes in the upper layers (e.g., stratum corneum) are too far from the blood supply in the dermis to receive adequate nutrients and oxygen via diffusion. This lack of sustenance leads to their death, and they become flattened, dead cells that form the protective outer layer of the skin.
Clarify the correct answer: Based on the explanation, the correct reason for keratinocyte death in the superficial strata is that they are too far away from the blood supply in the dermis, which aligns with option 'a'.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Keratinocyte Function
Keratinocytes are the primary cell type found in the epidermis, responsible for forming a protective barrier. As they move from the deeper layers of the epidermis to the surface, they undergo a process called keratinization, where they produce keratin, a tough protein that helps waterproof the skin. This process is crucial for maintaining skin integrity and preventing water loss.
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Keratinocytes
Epidermal Structure
The epidermis is the outermost layer of the skin, composed of multiple strata of keratinocytes. The superficial strata, or stratum corneum, consist of dead keratinized cells that provide a barrier against environmental damage. These cells are not supplied with blood vessels, which is why they die as they move away from the dermis, where the blood supply is located.
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07:02Other Epidermal Cells
Apoptosis in Keratinocytes
Apoptosis is the process of programmed cell death that occurs in keratinocytes as they reach the surface of the skin. This is a normal part of skin renewal, where older cells are shed to make way for new ones. The lack of nutrients and oxygen at the surface, combined with the accumulation of keratin, leads to the death of these cells, which is essential for maintaining healthy skin turnover.
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04:22Keratinocytes
Related Practice
Textbook Question
Number the strata of thick skin epidermis from deepest (1) to most superficial (5).
____Stratum spinosum
____Stratum corneum
____Stratum basale
____Stratum lucidum
____Stratum granulosum
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Textbook Question
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
Melanocytes account for the bulk of the epidermis.
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Textbook Question
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
Tactile cells produce the pigment melanin.
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Textbook Question
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
Dendritic cells are phagocytes of the immune system that protect the skin and deeper tissues from invasion by pathogens.
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Textbook Question
Nguyen comes to your clinic with a mole that has recently changed in appearance. You examine the mole and note that its borders are irregular, it has a deep blue-black color, and the color is unevenly distributed throughout the mole.
What is your immediate concern? Why?
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