Skin Structure & Function Year 1

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Questions and Answers

What is the approximate percentage of body weight that the skin accounts for?

15-20%

5-10%

20-25%

10-15% (correct)

What is the main component of the epidermis?

Keratinocytes (correct)

Connective tissue

Nerve endings

Blood vessels

What is the process by which cells in the epidermis change from one cell type to another?

Stratification

Differentiation (correct)

Cell migration

Cell division

Which layer of the skin contains blood vessels and nerves?

Dermis Signup and view all the answers

What is the approximate surface area of skin in the average adult?

2 m2 Signup and view all the answers

What is the main function of the hypodermis layer?

To provide insulation and energy supply Signup and view all the answers

What is the primary function of eccrine sweat glands?

Regulating body temperature through sweat Signup and view all the answers

What is the purpose of erector pili muscles?

To cause 'goosebumps' through muscle contraction Signup and view all the answers

What type of secretion do apocrine glands produce?

Protein-rich and oily secretion Signup and view all the answers

What type of epithelium is the epidermis composed of?

Specialised stratified squamous epithelium Signup and view all the answers

What is the function of sebaceous glands?

To secrete sebum onto hair Signup and view all the answers

Which layer of the epidermis is responsible for the symmetrical/asymmetrical cell divisions?

Basal layer Signup and view all the answers

What type of proteins are secreted by keratinocytes in the granular layer?

Filaggrin and loricrin proteins Signup and view all the answers

What is the function of melanocytes in the epidermis?

To protect against UV radiation and ROS Signup and view all the answers

What type of junctions connect keratinocytes to one another in the epidermis?

Desmosomes Signup and view all the answers

What is the primary function of the papillary dermis?

To provide flexible but tough support for the epidermis Signup and view all the answers

Which type of cells are highly represented in the skin and play a crucial role in adaptive immunity?

T-lymphocytes Signup and view all the answers

What is the primary role of Merkel cells in the skin?

To transmit sensory information Signup and view all the answers

During wound healing, which cell type plays a critical role?

Fibroblasts Signup and view all the answers

The dermis is separated from the epidermis by which structure?

Basement membrane Signup and view all the answers

What is the range of wavelengths of UVB radiation that acts on the epidermis?

290-320 nm Signup and view all the answers

What is the effect of UVA radiation on the skin?

It penetrates deeper and affects both dermis and epidermis Signup and view all the answers

What is the most common type of skin cancer?

Non-melanoma skin cancer (NMSC) Signup and view all the answers

What is the term for non-invasive skin cancer?

In situ Signup and view all the answers

Why are incidence rates of non-melanoma skin cancers known to be under-estimated?

Due to variations in policies and practices in diagnosis and treatment Signup and view all the answers

What is the location where non-melanoma skin cancers originate most frequently?

Sun-exposed areas of the skin Signup and view all the answers

What is the effect of UV radiation on melanocytes?

It damages melanocytes Signup and view all the answers

What type of skin cancer is responsible for 20% of malignancies in white populations?

Non-melanoma skin cancer (NMSC) Signup and view all the answers

What is the term for invasive skin cancer?

Invasive SCC Signup and view all the answers

What is the wavelength range of UVA radiation?

320-400 nm Signup and view all the answers

What is the importance of observation in identifying skin lesions?

To identify the shape and surroundings of the lesion Signup and view all the answers

What is the primary concern in dental management of patients with skin conditions?

Early referral and sensitive treatment Signup and view all the answers

Why is skin structure important to understand?

To understand the effects of dermatological drugs on oral health Signup and view all the answers

What is a notable observation in the incidence of SCC in England?

Higher incidence in the south west Signup and view all the answers

What is the main aim of understanding skin structure and function?

To describe normal human skin and its role in homeostasis Signup and view all the answers

What is the primary function of cutaneous receptors?

To detect changes in environmental temperature Signup and view all the answers

Which structure in the skin is responsible for immune response?

Langerhans cells Signup and view all the answers

What happens to the dermis as we age?

It becomes thinner and less compact Signup and view all the answers

What is the main impact of reduced sweat gland activity in older adults?

Reduced ability to regulate body temperature Signup and view all the answers

What happens to the subcutaneous fat layer as we age?

It decreases in proportion to body weight Signup and view all the answers

What is the primary function of the skin in the human body?

Maintenance of homeostasis Signup and view all the answers

What is the name of the process by which cells in the epidermis change from one cell type to another?

Differentiation Signup and view all the answers

What is the approximate surface area of skin in the average adult?

2 m2 Signup and view all the answers

What is the main significance of understanding skin structure and function in dental management of patients with skin conditions?

To understand the impact of skin conditions on oral health Signup and view all the answers

What is the importance of observation in identifying skin lesions?

To identify skin conditions Signup and view all the answers

What is the primary function of the lipids produced by keratinocytes in the granular layer?

To retain water in the skin Signup and view all the answers

What is the approximate percentage of cells in the epidermis that are keratinocytes?

90-95% Signup and view all the answers

What is the term for the proteins secreted by keratinocytes in the granular layer, including filaggrin and loricrin?

Envelope proteins Signup and view all the answers

What is the purpose of the desmosome junctions in the epidermis?

To connect keratinocytes to one another Signup and view all the answers

What is the function of the basal layer of the epidermis?

To house the stem cell population and facilitate cell division Signup and view all the answers

What is the primary function of the hypodermis layer?

Insulation and energy supply Signup and view all the answers

What type of secretion do sebaceous glands produce?

Fatty mixture Signup and view all the answers

What type of glands are typically found in the areolae of the breast, axillae, and genital regions?

Apocrine glands Signup and view all the answers

What stimulates the secretion of sebum by sebaceous glands?

Androgens Signup and view all the answers

What is the function of erector pili muscles?

To cause 'goosebumps' Signup and view all the answers

What is the primary function of cutaneous receptors?

To detect changes in environmental temperature Signup and view all the answers

What is a significant change that occurs in the skin as we age?

Reduced sebaceous gland activity Signup and view all the answers

What is the primary function of the hypodermis layer?

To store fat and attach skin to underlying tissue Signup and view all the answers

What is the importance of understanding skin structure and function in dental management of patients with skin conditions?

To provide sensitive treatment and understand the effect of dermatological drugs on oral health Signup and view all the answers

Why are incidence rates of non-melanoma skin cancers known to be under-estimated?

Due to lack of registration of subsequent cases in some countries Signup and view all the answers

What is the effect of reduced sweat gland activity in older adults?

Reduced ability to lose heat Signup and view all the answers

What is the result of changes in fat distribution as we age?

Increased fat in the thighs, waist, and abdomen Signup and view all the answers

What are the 5 S's used to describe a skin lesion?

Size, Shape, Surface, Surroundings, Site Signup and view all the answers

What is the notable observation in the incidence of SCC in England?

Higher incidence in the south west Signup and view all the answers

Why is early referral important in dental management of patients with skin conditions?

For identification and quick treatment Signup and view all the answers

Which type of UV radiation penetrates deeper into the skin?

UVA Signup and view all the answers

What percentage of malignancies in white populations is attributed to non-melanoma skin cancers?

20% Signup and view all the answers

What is the most common location for non-melanoma skin cancers to originate?

Sun-exposed areas of the skin Signup and view all the answers

What is the name of the non-invasive skin cancer that is also known as in situ?

Bowen's disease Signup and view all the answers

What is the reason for the underestimation of non-melanoma skin cancer incidence rates?

Policies for recording NMSC vary Signup and view all the answers

Which layer of the skin contains melanocytes, keratinocytes, and proteolytic enzymes?

Epidermis Signup and view all the answers

What is the effect of UVB radiation on the skin?

It acts preferentially on the epidermis, causing damage to melanocytes and keratinocytes Signup and view all the answers

What is the term for the process of skin cancer progression from in situ to invasive?

Invasion Signup and view all the answers

What is the significance of understanding skin structure and function in dental management of patients with skin conditions?

It is crucial for providing appropriate care and treatment Signup and view all the answers

Why are policies for recording non-melanoma skin cancers varied?

Due to differences in diagnosis and treatment practices Signup and view all the answers

What is the main function of Merkel cells in the skin?

To release neurotransmitters through small membrane-bound vesicles Signup and view all the answers

Which type of connective tissue is the reticular dermis comprised of?

Dense irregular connective tissue Signup and view all the answers

What is the primary cell type found in the dermis?

Fibroblast Signup and view all the answers

What is the approximate thickness of the dermis?

1-4mm Signup and view all the answers

What type of immune cells are highly represented in the skin?

T-lymphocytes Signup and view all the answers

What is the primary function of hemidesmosomes in the epidermis?

To connect the epidermis to the basement membrane Signup and view all the answers

What is the significance of the granular layer in the epidermis?

It is where keratinocytes undergo terminal differentiation Signup and view all the answers

Which of the following cell types is NOT found in the epidermis?

Fibroblasts Signup and view all the answers

What is the function of integrin-α6 in the epidermis?

To anchor the epidermis to the basement membrane Signup and view all the answers

What is the significance of the basal layer in the epidermis?

It is the site of stem cell division and proliferation Signup and view all the answers

Which type of sweat glands do not involve sebaceous glands?

Eccrine Signup and view all the answers

What stimulates the secretion of sebum by sebaceous glands in puberty?

Androgens Signup and view all the answers

Which type of glands produce oily and protein-rich secretions that become malodorous when in contact with commensal bacteria on the skin?

Apocrine glands Signup and view all the answers

What is the primary function of the hypodermis layer?

Insulation and energy supply Signup and view all the answers

Which muscles are stimulated by the sympathetic branch of the autonomic system, causing the skin to appear with 'goosebumps'?

Erector pili muscles Signup and view all the answers

What is the approximate surface area of skin that is influenced by the homeostatic role of the skin?

almost 2 m2 Signup and view all the answers

What is the primary function of the skin in the human body?

To protect the body from mechanical damage Signup and view all the answers

Which layer of the skin is composed primarily of keratinocytes?

Epidermis Signup and view all the answers

What is the process by which cells in the epidermis change from one cell type to another?

Differentiation Signup and view all the answers

What is the significance of understanding skin structure and function in dental management of patients with skin conditions?

It is crucial for the early referral of patients with skin conditions Signup and view all the answers

What is the role of Merkel cells in the skin?

To release neurotransmitters through membrane-bound vesicles Signup and view all the answers

Which type of connective tissue provides flexible but tough support for the epidermis?

Loose areolar connective tissue Signup and view all the answers

What is the estimated ratio of T-lymphocytes in the skin compared to total blood circulation in healthy individuals?

2:1 Signup and view all the answers

What is the primary cell type found in the dermis?

Fibroblast Signup and view all the answers

What is the approximate thickness of the dermis?

1-4 mm Signup and view all the answers

What is the primary response of cutaneous receptors to environmental temperature changes?

Stimulation of cutaneous receptors Signup and view all the answers

What is the primary effect of aging on the skin's ability to regulate body temperature?

Reduced ability to lose heat Signup and view all the answers

What is the primary reason for the decrease in skin thickness with aging?

Loss of collagen and elastin fibers Signup and view all the answers

What is the primary change in fat distribution with aging?

Redistribution of fat from face, hands, and feet to thighs, waist, and abdomen Signup and view all the answers

What is the primary effect of aging on the skin's ability to heal wounds?

Slower wound healing Signup and view all the answers

What is the primary concern in dental management of patients with skin conditions?

Risk of oral health complications Signup and view all the answers

What is the significance of the '5 S's' in skin lesion diagnosis?

Describing skin lesions Signup and view all the answers

Why are incidence rates of non-melanoma skin cancers (NMSC) known to be under-estimated?

Lack of mandatory registration Signup and view all the answers

What is the relevance of understanding skin structure and function in dental management of patients with skin conditions?

To manage skin conditions effectively Signup and view all the answers

What is the association between UV radiation and non-melanoma skin cancers in England?

Higher incidence in the south west Signup and view all the answers

What is the primary effect of UVB radiation on the skin?

Causes the production of proteolytic enzymes Signup and view all the answers

What is the significance of non-melanoma skin cancers in human populations?

Account for 20% of malignancies in white populations Signup and view all the answers

What is the primary reason for under-estimation of non-melanoma skin cancer incidence rates?

Policies for recording non-melanoma skin cancers are varied Signup and view all the answers

What is the primary difference between UVA and UVB radiation?

UVA radiation penetrates deeper into human skin Signup and view all the answers

What is the location where non-melanoma skin cancers originate most frequently?

Sun-exposed areas of the skin Signup and view all the answers

What is the term for the type of skin cancer that is confined to the epidermis?

In situ (Bowen’s disease) Signup and view all the answers

What is the primary challenge in dental management of patients with skin conditions?

Understanding skin structure and function Signup and view all the answers

What is the effect of UVA radiation on the skin?

Exerts a direct effect on both dermis and epidermis Signup and view all the answers

What is the significance of understanding skin structure and function in dental management?

It is essential for managing skin conditions Signup and view all the answers

What is the primary concern in dental management of patients with skin conditions?

Understanding skin structure and function Signup and view all the answers

Study Notes

Structure & Function of Skin

Skin comprises approximately 15% of body weight, weighing over 3 kg in an average adult, and covers nearly 2 m².
The largest organ of the body, skin plays a crucial role in homeostasis, providing protection, sensation, and temperature regulation.

Skin Layers

Epidermis: Primarily made up of keratinocytes, it serves as the outer protective barrier.
Dermis: Mainly consists of connective tissue, providing structural support and strength.

Epidermis Composition

Keratinocytes: Make up over 90% of the epidermis; contain cytokeratin proteins.
Composed of four distinct layers:
- Stratum Corneum: Outer layer with flattened, non-nucleated keratinocytes that protects against trauma and infection.
- Granular Cell Layer: Keratinocytes secrete lipids, forming a barrier that retains moisture.
- Spinous Layer: Contains desmosome junctions that link keratinocytes, creating a spiny appearance.
- Basal Layer: Houses stem cells responsible for high rates of cell division and contributes to skin regeneration.

Non-Keratinocyte Cell Types

Melanocytes: Produce melanin, influencing pigmentation and providing UV protection; present in equal proportions across all races.
Langerhans Cells: Dendritic cells involved in the immune response, located in the mid-layer of the epidermis.
Merkel Cells: Sensory cells associated with nerve fibers, contributing to touch perception.

Dermis Structure

Consists of two layers:
- Papillary Dermis: Comprised of loose areolar connective tissue, providing nutrients to the epidermis.
- Reticular Dermis: Made of dense irregular connective tissue, offering strength and elasticity.

Key Functions of Skin

Barrier Function: Protects against pathogens and physical trauma.
Sensory Reception: Contains specialized receptors that detect touch, pressure, pain, and temperature.
Immune Response: Houses T-lymphocytes and dendritic cells, playing a pivotal role in skin defense.
Temperature Regulation: Adjusts blood flow and sweat production based on environmental conditions.

Accessory Structures

Hair: Provides insulation, sensory input, and protection.
Erector Pili Muscles: Smooth muscles that cause hairs to stand up (goosebumps).
Sebaceous Glands: Secrete sebum for skin moisture and protection, stimulated by androgens.
Sweat Glands: Include apocrine (associated with hair follicles) and eccrine (covering the body) glands, playing roles in thermoregulation.

Skin Aging Changes

Thinning epidermis and dermis lead to weaker barrier function and increased fragility.
Reduced sebaceous gland activity and fewer melanocytes result in dry skin and paler complexion.
Loss of collagen and elastin causes sagging and wrinkles.
Changes in fat distribution affect thermoregulation and heat loss.

Skin Cancer Awareness

Non-melanoma skin cancers (NMSC) are common, with various policy challenges in recording incidence.
UV radiation damages skin cells, increasing the risk of skin cancers, particularly in sun-exposed areas.

Importance of Dermatological Knowledge

Early identification and referral for skin conditions are critical for effective management.
Understanding the impact of dermatological drugs on oral health is essential in dental practices.### Sensory Information and Skin Function
Skin contains specialized receptors for fine touch, light touch, pressure, pain, and temperature.
Primary cutaneous nerve branches occur in the hypodermis, with additional branching in the dermis and some free nerve endings in the epidermis.
Activation of skin receptors responds to changes in both environmental and core body temperature, with information processed by the hypothalamus.

Skin undergoes various changes with age, including dryness, thinning of the epidermis, and reduction in sebaceous gland activity.
Decrease in the number of melanocytes leads to a paler skin tone and reduced tolerance to sun exposure.
Healing slows down due to diminished vitamin D production and fewer Langerhans cells.
Thinning dermis, sagging, and wrinkling occur due to collagen and elastin fiber loss and reduced number of active hair follicles.
Changes in subcutaneous fat distribution favor an increase around thighs, waist, and abdomen, while fat in the face, hands, and feet decreases.

Skin Cancer Insights

Registration of Nonmelanoma Skin Cancer (NMSC) is often non-mandatory, leading to variability in reported incidence.
A systematic review indicates a higher incidence of NMSC in the south west of England, correlating with higher UV radiation exposure.
Squamous Cell Carcinoma (SCC) is generally thought to have a higher incidence in males but is more commonly found on the legs in females.

Skin Lesion Assessment

Key aspects for skin lesion description include site, size, shape, surface, edge, and surroundings.
Knowledge of skin conditions is crucial for dental management and requires early referral for identification and treatment.

Structure and Function of Skin

Skin is the largest organ of the body, constituting approximately 15% of body weight, and covers nearly 2 m² in adults.
The epidermis consists primarily of keratinocytes and is composed of four distinct layers: basal, spinous, granular, and corneal.
Dermis serves as a connective tissue framework and is divided into papillary (loose areolar tissue) and reticular (dense irregular tissue) layers.

Accessory Structures of the Skin

Hair follicles, sebaceous glands, and sweat glands are crucial for skin protection and thermoregulation.
Sebaceous glands provide lubrication via sebum, stimulated by androgens and inhibited by estrogen.
Eccrine sweat glands play a major role in thermoregulation, while apocrine glands are associated with hair follicles and become functional during puberty.

Non-Keratinocyte Cells in the Epidermis

Melanocytes produce melanin, which contributes to skin, hair, and eye color, offering protection against UV radiation.
Langerhans cells serve as immune system sentinels within the epidermis, while Merkel cells are involved in sensory functions.

Cell Types and Epidermis Layers

Epidermal layers feature distinct processes of differentiation and turnover, essential for maintaining skin integrity.
Each layer has specific functions crucial for protection, barrier formation, and sensory perception.

UV Radiation and Skin Damage

UV radiation includes UVB (290-320 nm), primarily damaging the epidermis, and UVA (320-400 nm), penetrating deeper and affecting the dermis.
UV exposure leads to cellular damage, contributing to skin aging and cancer development, particularly in sun-exposed areas.

General Health Impact

Understanding the physiological changes in skin with age is critical for effective healthcare and dermatological interventions.
Comprehensive knowledge of skin structure and function assists in recognizing and treating dermatological disorders.

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Description

Learn about the human skin, its role in homeostasis, and the functions of each layer. Understand the main cell types and their functions, as well as the accessory structures of the skin. Test your knowledge of the integumentary system!