Skin Biology and Drug Delivery Mechanisms

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Questions and Answers

What is transdermal administration and how does it facilitate drug delivery?

Topical application of creams that do not enter the bloodstream.

Use of a patch to deliver drugs through the skin to the bloodstream. (correct)

Oral ingestion of drugs for systemic circulation.

Direct injection of drugs into the blood.

How does vasoconstriction contribute to temperature regulation in the body?

By narrowing blood vessels to reduce heat loss from the body. (correct)

By allowing more heat to escape through sweat glands.

By increasing blood flow to the skin to enhance heat loss.

By promoting the evaporation of sweat to cool the body.

What role do epidermal dendritic cells play in the immune function of the skin?

They initiate a response against pathogens and attack skin cancer cells. (correct)

They regulate the temperature of the skin to enhance immune response.

They serve as a barrier to prevent all types of pathogens.

They produce antibodies to neutralize infectious agents.

What types of stimuli are detected by sensory receptors in the skin?

Touch, pressure, and other external environmental stimuli. Signup and view all the answers

Which statement describes the waterproof nature of the skin?

The skin allows selective absorption of certain water-soluble substances. Signup and view all the answers

Which areas of the body typically lack hair?

Palms of the hands and the soles of the feet Signup and view all the answers

What primarily determines differences in hair density?

Texture and pigmentation of the hair Signup and view all the answers

Which part of the hair structure is responsible for growth?

Hair bulb Signup and view all the answers

What is the function of the arrector pili muscle?

To cause hair to stand on end Signup and view all the answers

What is the significance of the hair papilla?

It provides nutrients to the hair bulb. Signup and view all the answers

Which part of the nail appears lighter in color, due to the lack of underlying capillaries?

Free edge of the nail Signup and view all the answers

What primarily composes nails and hair?

Dead keratinocytes Signup and view all the answers

Which of the following disorders is characterized by a nail that grows into the surrounding skin?

Ingrown nails Signup and view all the answers

What condition is indicated by the presence of Beau's lines on the nails?

Chronic malnutrition Signup and view all the answers

What is the likely cause of yellow nail syndrome?

Respiratory disease Signup and view all the answers

What symptom is typically associated with nail clubbing?

Enlargement of the fingertip Signup and view all the answers

What is the primary purpose of botulinum toxin type A (Botox) in cosmetic treatments?

To temporarily block nerve impulses to muscles Signup and view all the answers

During which weeks of development do fingernails begin to form?

Between weeks 10 and 12 Signup and view all the answers

What contributes to the appearance of creases and wrinkles in aging skin?

Loss of elasticity in elastic fibers Signup and view all the answers

What is the role of the periderm during fetal development?

To serve as a covering layer and eventually slough off Signup and view all the answers

Which factor does NOT contribute to slower skin repair processes in older adults?

Increased elasticity of collagen fibers Signup and view all the answers

What distinguishes apocrine sweat glands from merocrine sweat glands regarding their duct structure?

Apocrine glands have a duct with a larger lumen that conveys secretions into a hair follicle. Signup and view all the answers

Which mechanism is responsible for the secretion of sweat from merocrine sweat glands?

Contraction of myoepithelial cells stimulated by the nervous system. Signup and view all the answers

Where are the coiled, tubular secretory portions of sweat glands located?

In the reticular layer of the dermis. Signup and view all the answers

What effect does activation of the autonomic nervous system have on sweat glands?

It enhances secretion due to stimulation of myoepithelial cell contraction. Signup and view all the answers

During secretion, how do sebaceous gland cells release their oily secretion?

By rupturing and being destroyed in the process. Signup and view all the answers

Which primary characteristic differentiates merocrine sweat glands from apocrine sweat glands in terms of their function?

Merocrine glands are associated with regulating body temperature. Signup and view all the answers

What is the physiological role of myoepithelial cells in sweat glands?

To facilitate the expulsion of secretions from the glands. Signup and view all the answers

How does the opening of a merocrine sweat gland duct on the epidermal surface appear?

As a sweat pore. Signup and view all the answers

What is the primary function of lanugo hair in fetal development?

To serve as a precursor to terminal hair post-birth Signup and view all the answers

What distinguishes terminal hair from vellus hair?

Terminal hair is generally coarser and pigmented Signup and view all the answers

Which layer of hair is responsible for its mechanical strength?

Cortex Signup and view all the answers

In which phase of the hair growth cycle does rapid cell division occur?

Anagen Phase Signup and view all the answers

What causes hair to appear gray as a person ages?

Decreased melanin production within hair follicles Signup and view all the answers

What are the two layers of cells that make up the hair follicle?

Connective Tissue Root Sheath and Epithelial Tissue Root Sheath Signup and view all the answers

What type of keratin is primarily found in the medulla of the hair?

Flexible, soft keratin Signup and view all the answers

Which characteristic is NOT true regarding the hair bulb?

It is associated with melanin production Signup and view all the answers

What is the purpose of the root hair plexus associated with hair follicles?

To sense light touch Signup and view all the answers

What happens during the catagen phase of hair growth?

Follicles undergo involution and cell division ceases Signup and view all the answers

Which statement about ceruminous glands is correct?

They secrete a substance that helps trap foreign particles. Signup and view all the answers

What triggers the functional activation of mammary glands?

Interaction between gonadal and pituitary hormones. Signup and view all the answers

Which statement characterizes the fibrosis process during tissue healing?

It results in the formation of scar tissue during healing. Signup and view all the answers

What is the primary role of granulation tissue in wound healing?

To supply nutrients to the regenerating area. Signup and view all the answers

In psoriasis, which immune cells are mainly responsible for the disease's symptoms?

T-lymphocytes attacking keratinocytes. Signup and view all the answers

What is a significant complication during the skin repair process?

Fluid loss and potential infection in the affected area. Signup and view all the answers

Which condition is not a characteristic of the wound healing stages?

Immediate pigmentation restoration post-injury. Signup and view all the answers

What best describes the difference between regeneration and fibrosis?

Regeneration restores tissue functionality, fibrosis results in scar tissue. Signup and view all the answers

In the context of psoriasis, what differentiates plaques from normal skin?

Plaques form due to a halt in the skin cell sloughing-off cycle. Signup and view all the answers

Study Notes

Absorption

Skin can effectively absorb chemicals and drugs, including hormones like estrogen and substances like nicotine.
Transdermal administration involves using adhesive patches for drug delivery, ensuring prolonged contact with the skin.
Absorption occurs as drugs enter blood vessels located in the dermis.

Temperature Regulation

Body temperature regulation is managed through capillary networks and sweat glands in the dermis.
Vasoconstriction reduces blood flow to conserve heat, while vasodilation increases blood flow to release excess heat.

Immune Function

Epidermal dendritic cells initiate immune responses against skin-invading pathogens and target epidermal cancer cells.

Sensory Reception

Numerous sensory nerve endings in the skin detect touch and pressure, involving seven major receptor types for interpreting external stimuli.

Epidermal Derivatives

Nails, hair, and exocrine glands originate from the epidermis and undergo embryological invagination into the dermis.
Nails and hair primarily consist of dead keratinocytes, whereas exocrine glands are made of living epithelial cells.

Nails

Nails are modifications of the stratum corneum that protect fingertips and assist in grasping objects.
Nail structure includes a free edge, nail body, and nail root, with the nail body covering the nail bed, which consists of living cells.

Nail Disorders

Brittle nails often result from environmental exposure and can be alleviated with proper care.
Ingrown nails occur when the nail edge grows into the surrounding skin, potentially leading to infection.
Nail pitting is associated with conditions like psoriasis, exhibiting small holes on the nail surface.
Nail clubbing indicates hypoxia, with the nail tip enlarging and curving around the fingertip over time.
Onychomycosis is a fungal nail infection leading to discoloration and brittleness.
Yellow nail syndrome may signal respiratory issues, characterized by nail growth cessation.
Spoon nails, a sign of iron deficiency, feature a concave nail shape.
Beau's lines indicate interruptions in nail growth due to trauma or illness.
Vertical ridging often appears with age and is typically harmless.

Hair

Hair covers nearly all body areas except palms, soles, and certain other regions.
Hair types include lanugo (fine, unpigmented hair), vellus (short, fine hair), and terminal hair (coarse, pigmented hair).
Three main hair zones are the bulb, root, and shaft; hair structure involves the medulla, cortex, and cuticle.
Hair follicles house tactile receptors for detecting light touch.

Hair Color

Determined by melanin production in the hair matrix; reduced pigment leads to gray or white hair with aging.

Hair Growth Cycle

Consists of anagen (active growth), catagen (regression), and telogen (resting and shedding), with growth patterns influenced by genetics and location.

Exocrine Glands

Two main types: sweat glands (merocrine and apocrine) and sebaceous glands, aiding thermoregulation and lubrication.
Apocrine glands secrete into hair follicles, while merocrine glands open directly onto the skin surface.

Skin Repair and Regeneration

Skin can repair via regeneration (cell type replacement) or fibrosis (scar tissue formation).
Wound healing includes bleeding, clot formation, granulation tissue development, and epithelial regeneration.
Severity of injuries affects healing time, with deeper wounds taking longer to recover.

Psoriasis

Chronic autoimmune disease marked by skin cell overproduction due to T-lymphocyte attacks, resulting in scaly plaques and potential nail pitting.

Botox and Wrinkles

Botulinum toxin type A (Botox) treats age-related wrinkles by blocking nerve impulses, temporarily relaxing facial muscles responsible for wrinkle formation.### Botox and Its Effects
Effects of Botox are temporary, requiring reapplication approximately every 4 months.
Some individuals may experience adverse effects; excessive use can lead to a "frozen" facial appearance.

Development of the Integument

Integument develops from ectoderm and mesoderm.
By week 7 of development, ectoderm forms squamous epithelium, leading to the periderm and basal layers.
Stratum corneum and friction ridges form by week 21.
Fetal skin is protected by vernix caseosa, composed of sloughed periderm cells and sebum.
Dermis originates from mesoderm, forming mesenchyme during weeks 3-8.
Nails begin to form by week 10; fingernails reach tips by 32 weeks, toenails by 36 weeks.
Hair follicles appear between weeks 9-12 and become recognizable around 20 weeks.
Sweat and sebaceous glands arise from the epidermis at about 20 weeks.

Aging of the Integument

Skin repair slows significantly with age due to decreased stem cell activity.
Older skin is thinner, more susceptible to injury.
Collagen and elastic fibers decrease, leading to wrinkles and reduced resilience.
Environmental factors, particularly UV exposure, accelerate skin aging and can mutate the p53 gene, increasing cancer risk.

Skin Cancer Types

Basal Cell Carcinoma: Most common and least dangerous; originates in stratum basale, usually treated by surgical removal.
Squamous Cell Carcinoma: Can metastasize; lesions arise from keratinocytes and are treated surgically.
Malignant Melanoma: Most aggressive form with high mortality; characterized by changes in moles. Early detection is critical for survival.

ABCDE Rule for Melanoma Detection

A - Asymmetry: Unequal halves.
B - Border: Irregular or blurred edges.
C - Color: Varied colors within the mole.
D - Diameter: Larger than 6 mm or increasing in size.
E - Evolving: Changes in size, shape, or sensation.

Introduction to the Skeletal System

The skeletal system includes bones, cartilage, ligaments, and connective tissues.
Compact Bone: Dense and smooth, making up about 80% of bone mass.
Spongy Bone: Porous, accounting for about 20% of bone mass.

Cartilage in the Skeletal System

Hyaline Cartilage: Present in costal cartilage, articular surfaces, and growth plates; serves as a model for the fetal skeleton.
Fibrocartilage: Provides strength and support; found in intervertebral discs, pubic symphysis, and knee joints.

Bone Functions

Bones offer support, protection for organs, and act as levers for movement.
Hematopoiesis occurs in red bone marrow, producing blood cells.
Bones store minerals (calcium and phosphate) and energy in the form of lipids.

Classification of Bones

Long Bones: Longer than wide; e.g., femur and humerus.
Short Bones: Length nearly equals width; e.g., carpals and tarsals.
Flat Bones: Thin and flat; e.g., skull roof, scapulae, and ribs.
Irregular Bones: Complex shapes; e.g., vertebrae and hip bones.

Gross Anatomy of Bones

Long bones consist of a diaphysis (shaft) and epiphyses (ends).
Vascularization and innervation are essential for bone health and function.

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Description

This quiz explores key concepts in skin biology, including transdermal drug delivery, vasoconstriction's role in temperature regulation, and the functions of epidermal dendritic cells. Additionally, it examines sensory receptors and the waterproof nature of the skin while identifying hairless areas of the body.