Lecture Slides 4 - Integumentary System

What structures does the integumentary system include?

Skin, hair, nails, and glands

What are the three main functions of the integumentary system?

Protection, sensation, and regulation

What is the largest organ system in the body?

Skin and its accessory structures

What are the two main layers of the skin?

The epidermis and the dermis

How many layers does the epidermis have?

Four to five layers

How many layers does the dermis have?

Two layers (papillary and reticular)

What connects the skin to underlying fascia?

The hypodermis

What is the hypodermis composed of?

Loose, areolar, and adipose connective tissue

How does skin provide a defense function?

Sweat glands produce dermcidin, a protein with antibiotic properties

How does skin provide protection?

Acts as a shield against environmental hazards, prevents water loss, and blocks harmful microorganisms

What sensory structures does the skin contain?

Nerve structures that detect touch, temperature, and pain, concentrated in areas like fingertips

How much sweat can the skin produce per hour during vigorous activity?

Up to 1.5 L per hour

How does the skin help with thermoregulation?

Through sweating and dilation/constriction of dermal blood vessels

What happens to dermal blood vessels to release heat?

They dilate (vasodilation)

What happens to dermal blood vessels to retain heat?

They constrict (vasoconstriction)

What is the metabolic function of the skin?

UV radiation from sunlight synthesizes vitamin D in the skin, essential for bone health and immune function

What is the epidermis composed of?

Keratinized, stratified squamous epithelium

Is the epidermis vascular or avascular?

Avascular (lacks blood vessels)

List the five layers of the epidermis from deepest to most superficial.

Stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum

What is the deepest layer of the epidermis, where new cells are generated?

Stratum basale

What is the stratum basale also known as?

The basement membrane (basal layer)

What cell types are found in the stratum basale?

Basal cells (cuboidal stem cells), Merkel cells, and melanocytes

What is the role of the stratum basale?

Skin regeneration

What does the stratum basale interact with in the dermis?

The dermal papillae

What layer provides strength and flexibility via a multilayer of keratinocytes with a spiny appearance?

Stratum spinosum

What cell junctions are found in the stratum spinosum?

Desmosomes

What do stratum spinosum cells synthesize?

Keratin and water-repellent glycolipid

What immune cells are found in the stratum spinosum?

Dendritic cells

What layer has a grainy appearance and is where keratin production ramps up?

Stratum granulosum

How many layers of keratinocytes are in the stratum granulosum?

3-5 layers

What happens to the nucleus and organelles in the stratum granulosum?

They disintegrate and the cells die

Which epidermal layer is only present in thick skin (palms and soles)?

Stratum lucidum

What substance in the stratum lucidum creates its clear appearance and water barrier?

Eleidin

What is the most superficial layer of the epidermis?

Stratum corneum

How many layers of keratinocytes make up the stratum corneum?

15-30 layers

How often is the stratum corneum entirely replaced?

About every 4 weeks

What are the two layers of the dermis?

Papillary layer and reticular layer

What type of connective tissue makes up the papillary layer?

Loose, areolar connective tissue

What cells are present in the papillary layer?

Fibroblasts, adipocytes, phagocytes, and small blood vessels

What are dermal papillae?

Projections of the papillary layer into the stratum basale of the epidermis

What sensory receptors in the papillary layer sense light touch?

Meissner corpuscles (tactile corpuscles)

What type of connective tissue makes up the reticular layer?

Dense irregular connective tissue

What are the properties of the reticular layer?

Rich vascularization and sensory nerve supply, elastic fibers for elasticity, collagen fibers for structure, tensile strength, and hydration

What is the hypodermis also known as?

The subcutaneous layer

What are the functions of the hypodermis?

Fat storage, insulation, and cushioning

What three pigments influence skin color?

Melanin, carotene, and hemoglobin

Where is melanin produced and how is it transferred to keratinocytes?

Produced by melanocytes in the stratum basale and transferred via melanosomes

What are the two types of melanin?

Eumelanin (black and brown pigment) and pheomelanin (red pigment)

What stimulates melanin production, leading to tanning?

Sun exposure

What does melanin shield DNA from?

UV damage

Where is carotene found and what is it converted into?

Found in vegetables like carrots; converted into vitamin A

What can excessive carotene intake cause?

Yellowish-orange skin

What does hemoglobin do in red blood cells?

Carries oxygen

What causes ashen (white) skin?

A sudden drop in oxygenation

What causes cyanosis (blue skin)?

Prolonged oxygen deficiency

What is vitiligo?

An autoimmune disease that affects patches of skin after birth, appearing as smooth white patches

What is albinism?

A genetic disorder that affects all skin from birth, causing extremely pale skin, hair, and eyes; can affect the eyes

What is hair made of and where does it originate?

A keratinous filament growing out of the epidermis, originating from a hair follicle deep in the dermis

How does hair on the scalp help protect the body?

Protects against sun exposure

What do eyelashes and nasal hair do?

Filter out dust and allergens

What do eyebrows do?

Prevent sweat from entering the eyes

What detects movement around each hair follicle?

A nerve plexus

How does hair help with temperature regulation?

The arrector pili muscle contracts to trap air for insulation, seen as goosebumps

What are the three parts of hair?

Shaft, root, and bulb

What is the hair shaft?

The visible part of hair above the skin

What is the hair root?

Anchors the hair into the skin

What is the hair bulb?

Where hair growth begins

What is the hair follicle?

A complex structure extending from the epidermis into the dermis that houses the hair root and produces hair

What surrounds the hair follicle?

An internal root sheath and an external root sheath

What is the hair growth rate during anagen?

About 0.3 mm per day

How many hairs are lost and replaced per day on average?

50 hairs

What factors affect hair growth?

Hormonal changes, dietary changes, and aging

What determines hair color?

Melanin produced by melanocytes, and its type/concentration

Why does hair turn gray or white with age?

Melanin production decreases

What accessory structures, besides hair, does the skin have?

Nails, sweat glands, and sebaceous glands

Where do skin accessory structures originate and extend to?

Originate from the epidermis and extend through the dermis into the hypodermis

What skin changes occur with aging?

Reduced cell division, blood circulation, and muscle strength

How does aging affect wound healing?

Thinning of the epidermis and dermis leads to slower wound healing

How does aging affect hair, nails, sebum, and sweat?

Hair and nails grow thinner; sebum and sweat production decrease

What causes wrinkles with aging?

Decreased collagen and elastin, weakening of underlying muscles, and reduced moisture retention

What is Basal Cell Carcinoma (BCC)?

The most common, slow-growing skin cancer that rarely metastasizes; appears as a pearly or waxy bump on sun-exposed areas; originates in the stratum basale

How is Basal Cell Carcinoma treated?

Surgical removal, topical medications, or radiation

What is Squamous Cell Carcinoma?

The second most common skin cancer; appears as an open wound with irregular shape, often on the scalp, ears, and hands; originates in the stratum spinosum

How is Squamous Cell Carcinoma treated?

Surgery and radiation

What is Melanoma?

A less common but more dangerous skin cancer that can spread rapidly, arising from melanocytes; appears as irregularly shaped moles or spots with varied colors

How is Melanoma treated?

Surgical removal, chemotherapy, radiation, and targeted therapy

What does the ABCDE check for melanoma stand for?

Asymmetry, Borders (irregular), Color (varied), Diameter (larger than 6 mm), Evolving (changing shape)

What is the cause of acne?

Overactive sebaceous glands leading to clogged pores

What are the symptoms of acne?

Pimples, blackheads, whiteheads, and sometimes cysts

How is acne treated?

Topical treatments, antibiotics, and lifestyle changes

What is the cause of eczema (atopic dermatitis)?

Genetic and environmental factors leading to an overactive immune response

What are the symptoms of eczema?

Red, itchy, and inflamed skin

How is eczema treated?

Moisturizers, corticosteroids, and avoiding triggers

What are the three degrees of burns?

First-degree (superficial), second-degree (partial thickness), third-degree (full thickness)

What are symptoms of burns?

Redness, pain, blistering, and charred skin

How are burns treated?

Cool water, dressings, pain relief, and in severe cases, skin grafts

What causes cuts and lacerations, and how are they treated?

Sharp objects causing skin tears; treated with cleaning, stitches or adhesive strips, and a tetanus shot if needed

What is impetigo?

A contagious bacterial infection causing red sores, treated with antibiotics

What is cellulitis?

A deep bacterial skin infection causing swelling and redness, treated with antibiotics

What does Herpes Simplex Virus (HSV) cause and how is it managed?

Causes cold sores or genital herpes; managed with antiviral medications