Integumentary System

What are the five main functions of the integumentary system?

Protection, temperature regulation, elimination, synthesizing vitamin D, and sensation

How does the skin provide protection?

It protects deeper tissues from mechanical, chemical, bacterial, UV, and thermal damage

How does the integumentary system regulate temperature?

Through heat loss or retention controlled by the nervous system

What substances are eliminated by the skin?

Urea and uric acid through perspiration

How does the skin synthesize vitamin D?

By converting modified cholesterol molecules using sunlight

What sensory inputs can the skin detect?

Heat, cold, touch, pressure, and pain

What structures are part of the integumentary system?

Skin, hair, nails, sebaceous glands, and sweat glands

What are the two main tissue layers of the skin?

Epidermis and dermis

What type of cells make up the epidermis?

Stratified squamous epithelial cells that can become keratinized

What type of tissue is found in the dermis?

Dense connective tissue

What is the function of the papillary layer of the dermis?

Provides nutrients, supports sensory perception and temperature regulation

What structures are found in the papillary layer?

Capillaries, lymph vessels, sensory neurons, and loose connective tissue

What is the function of the reticular layer of the dermis?

Contains blood vessels, sweat glands, oil glands, and deep pressure receptors

What are Pacinian corpuscles?

Deep pressure receptors found in the reticular layer of the dermis

What role do collagen fibers play in the dermis?

Provide toughness and attract water to keep the skin hydrated

What function do elastic fibers serve in the dermis?

Give skin elasticity, which decreases with age

How do dermal blood vessels regulate body temperature?

By dilating or constricting to either release or retain heat

What is the role of nerves in the dermis?

Transmit environmental stimuli to the central nervous system

Is the epidermis vascular or avascular?

Avascular — it has no blood supply of its own

What are keratinocytes?

Cells that produce keratin, making the epidermis tough and protective

What is the stratum basale?

The deepest layer of the epidermis, nourished by the dermis

What occurs in the stratum basale?

Cell division and production of new skin cells

Where is the stratum spinosum located?

Between the stratum basale and stratum granulosum

What is the stratum granulosum known for?

Flattening cells that become increasingly filled with keratin

Where is the stratum lucidum found?

In thick, hairless areas like the palms and soles

What is the stratum corneum?

The outermost and thickest layer of the epidermis

What are cornified cells?

Shingle-like dead cells filled with keratin

Why is keratin important in the skin?

It protects deeper cells from environmental harm

What is melanin?

A pigment ranging from yellow to black that protects skin from UV damage

Where is melanin produced?

In melanocytes located in the stratum basale

What are melanosomes?

Granules that transfer melanin from melanocytes to keratinocytes

What are hairs made of?

Flexible epithelial structures produced by hair follicles

What is the root of a hair?

The part enclosed in the follicle

What is the shaft of a hair?

The part that projects above the skin surface

How is hair formed?

By division of stratum basale cells in the hair bulb

What are the layers of a hair?

Medulla (core), cortex, and cuticle

What is the function of the cuticle in hair?

Provides strength and keeps hair layers compact

What gives hair its color?

Melanin produced by melanocytes in the hair bulb

What are hair follicles composed of?

Epidermal and dermal sheaths

What does the epidermal sheath do?

Forms the hair and is made of epithelial tissue

What does the dermal sheath do?

Supplies blood vessels and is made of connective tissue

What is the papilla of the hair?

The structure that provides blood to the hair bulb matrix

What are nail folds?

Skin folds overlapping the sides of the nail

What is the cuticle of the nail?

The thick proximal nail fold

What forms the nail bed?

The stratum basale under the nail

What is the nail matrix responsible for?

Nail growth

Why do nails appear pink?

Due to blood supply in the underlying dermis

What is the lunula?

The white crescent-shaped area over the nail matrix

What type of glands are cutaneous glands?

Exocrine glands that release products through ducts

What are the two types of cutaneous glands?

Sebaceous (oil) glands and sweat glands

Where are sebaceous glands found?

All over the body except palms and soles

What is the function of sebum?

Lubricates skin, prevents brittle hair, and kills bacteria

What are the two types of sweat glands?

Eccrine and apocrine

Where are eccrine glands found?

All over the body

What do eccrine glands secrete?

Sweat made of water, salts, vitamin C, waste, and lactic acid

What is the role of eccrine sweat glands?

Help regulate body temperature

Where are apocrine glands found?

In the armpits (axillary) and genital areas

What do apocrine glands secrete?

Fatty acids and proteins

When do apocrine glands become active?

At puberty, influenced by androgens