The Integumentary System: Functions and Aging Vocabulary

Vocabulary flashcards covering skin color factors, protective mechanisms, thermoregulation, vitamin D synthesis, cutaneous sensory receptors, and age-related changes of the integumentary system.

Melanin

A yellow, tan, reddish brown, brown, or black pigment that protects against UV radiation and accumulates in freckles and moles.

How are freckles or moles created?

By accumulation of melanin in one spot

Does number of melaninocytes affect color of skin?

No, differences in skin color are primarily due to the amount and type of melanin produced by melanocytes

Carotene

Is an orange pigment that accumulates in the stratum corneum, dermis, and hypodermis

• used to synthesize Vitamin A for vision.

Hemoglobin (in RBC’s)

A pigment inside red blood cells that changes color during oxygen transport, reflecting changes in dermal blood flow and oxygen content

• Red means lots of oxygen content

• Blue color has less oxygen content

What is hemoglobin?

Hemoglobin is in blood cells carrying oxygen

Bilirubin

A yellow breakdown product of hemoglobin resulting from red blood cell death, which accumulates during liver disease to cause jaundice → eventually turns green

Functions of the skin:

Protects in different ways:

Chemical and Mechanical protection

• Skin Continuity

  • closely-packed cells, tight junctions, desmosomes, multi-layered

• Hardness

  • Keratin

• Prevents water loss and entry

  • Glycolipids

• Melanin

  • UV radiation

• Secretions (sweat, sebum)

  • Acidic (acid mantle)

  • Bactericidal

Acid Mantle

The acidic, bactericidal surface environment of the skin created by sweat and sebum secretions.

Keratin

A hard protein present in the skin that provides mechanical protection and helps prevent water loss and entry.

Glycolipids

Epidermal lipid compounds that act as a barrier to prevent water entry and water loss.

Dendritic cells

Specialized immune cells located within the epidermis that aid in immune defense.

Dermal Macrophages and Leukocytes

Immune cells stationed in the dermis that protect the skin against foreign pathogens and debris.

Insensible Perspiration

Unnoticed, unmeasurable sweat evaporation occurring continuously under baseline conditions at approximately $0.5\text{ L/day}$.

Sensible Perspiration

Visible, heavy sweating secreted by sweat glands in amounts reaching liters per day to promote evaporative body cooling.

Vasodilation

The widening (dilation) of dermal blood vessels, which increases blood flow toward the skin surface to increase heat loss and cool the body.

Vasoconstriction

The narrowing (constricting) of dermal blood vessels, which reduces blood flow near the skin surface to decrease heat loss and warm the body.

Hypothalamus

The region of the brain that dictates body temperature regulation by controlling dermal blood flow and sweat gland secretions.

7-dehydrocholesterol

A precursor molecule in the skin that converts to cholecalciferol (Vitamin $\text{D}_3$) upon exposure to UV light.

Cholecalciferol

Vitamin $\text{D}_3$, synthesized in the skin from 7-dehydrocholesterol under UV exposure prior to modification by the liver and kidneys.

What is vitamin D3 good for?

Activates immune system → prevents you getting sick

Very important for the bones → helps absorb calcium and phosphorus, into the bones

Calcitriol

The active form of Vitamin D produced by liver and kidney modifications, required for intestinal calcium absorption and urinary calcium conservation.

Tactile (Merkel) Discs

Epidermal sensory receptors specialized in detecting light touch sensations.

Tactile (Meissner) Corpuscles

Cutaneous sensory receptors in the skin responsible for detecting fine touch.

Lamellated (Pacinian) Corpuscles

Deep cutaneous sensory receptors responsible for perceiving pressure and vibration sensations.

Bulbous (Ruffini) Corpuscles

Cutaneous sensory receptors that respond to continuous pressure and tissue stretching.

Hair Root Plexus

A hair follicle receptor consisting of nerve endings wrapped around hair follicles to detect hair movement and touch.

Aged skin characteristics

Fibroblasts

Dermal cells that, with advancing age, produce fewer collagen and elastic fibers, resulting in a thinner dermis.

Wrinkles

• Collagen → become fewer, tangle, stiffen and beak apart

• Elastic → they lose elasticity and thicken into clumps

Age-Related Collagen Alterations

Structural changes in dermal collagen fibers during aging, where fibers decrease in number, stiffen, break apart, and tangle.

Age-Related Elastic Fiber Alterations

Degenerative changes in aging skin where elastic fibers lose elasticity and thicken into clumps, leading to wrinkle formation.

Glandular Atrophy

Age-related shrinkage of cutaneous glands, leading to dry and itchy skin, coarse or brittle hair, and impaired heat loss (overheating).

Age-Related Melanocyte Reduction

A decrease in active epidermal melanocytes, causing skin paleness and reduced protection against harmful UV radiation.

Age-Related Vitamin D3 Reduction

A decline in cutaneous Vitamin $\text{D}_3$ synthesis in elderly individuals, contributing to decreased bone density and muscle weakness.

Decreased Dermal Blood Flow

A reduction in blood circulation to aged skin, leading to cold intolerance, impaired temperature regulation, and delayed wound healing.

Subcutaneous Fat Loss

The reduction of hypodermal fat in aging skin, which decreases thermal insulation, causes cold sensitivity, and contributes to skin thinning.

Increased age affects healing. How?

Healing becomes compromised and increase risk of damage, infection, and cancer.

• Fewer melanocytes + dendritic cells

Increased age affects skin thinning. How?

• Decreased collagen + elastic fibers

• Decreased mitosis + subcutaneous fat

• Less fat means less insulation → feel cold

Increased age affects Hair thinning. How?

• Less active hair follicles

• Balding → genetics based

• Gray/white hair → duet to decreased pigment

Why is skin referred to as the Acid Mantle (skin)?

Skin is referred to as the Acid Mantle because it has a slightly acidic pH, which helps protect against pathogens and maintain moisture.

How is sunlight important to bone health?

Sunlight is important to bone health because it stimulates the production of vitamin D in the skin, which is essential for calcium absorption and bone mineralization.

Which alteration in skin color may indicate a liver disorder?

Jaundice, characterized by yellowing of the skin. (accumulation of bilirubin)

What effect would a decrease in oxygenation have on skin color; why?

A decrease in oxygenation can lead to a pale or bluish skin color, known as cyanosis, due to reduced blood flow and oxygen levels in the skin.

Why does your skin appear more red when you exercise?

Your skin appears more red when you exercise due to increased blood flow to the skin's surface, which helps to dissipate heat and regulate body temperature.