Integumentary System

What are the six basic functions of the skin?

Protection, temperature regulation, excretion of urea, vitamin D synthesis, immunity, and sensory reception.

What are the six things skin protects against?

Mechanical damage, chemical damage, thermal damage, bacteria, UV radiation, and desiccation.

What are skin derivatives?

Sweat glands, oil glands, hair, and nails.

How does skin regulate temperature?

Sweat glands release sweat, and blood vessels in the dermis help control heat loss.

What waste product does skin excrete?

Urea.

Where is most urea produced?

In the liver during protein and amino acid breakdown.

What is the function of vitamin D3?

It helps the body store calcium and phosphorus and helps prevent bone diseases such as rickets.

What is vitamin D3 also called?

Cholecalciferol.

How is vitamin D3 activated?

The liver converts cholecalciferol into calcidiol, and the kidneys convert calcidiol into calcitriol, the active form.

What sensations can skin detect?

Touch, heat, pain, and pressure.

What are the two main regions of the skin?

Epidermis and dermis.

What type of tissue makes up the epidermis?

Keratinized stratified squamous epithelium.

What type of tissue makes up the dermis?

Fibrous connective tissue.

What is the hypodermis?

Subcutaneous tissue beneath the skin containing adipose tissue.

What are the functions of the hypodermis?

Anchors skin to underlying muscle, absorbs shock, stores fat, and provides insulation.

What are the two main epidermal cell types covered in the slides?

Keratinocytes and melanocytes.

What are keratinocytes?

Epidermal cells that produce keratin, a fibrous protein.

Where does keratinocyte growth begin?

In the deepest epidermal layer, the stratum basale.

What happens to keratinocytes as they grow?

New cells push older cells upward until they become flattened, dead cells at the surface.

What are melanocytes?

Cells that produce melanin, a pigment that can be yellow, brown, or black.

What is melanin's function?

It helps shield DNA in nearby keratinocytes from UV radiation.

How do keratinocytes receive melanin?

They take up melanin granules produced by nearby melanocytes.

What is the stratum corneum?

The outermost epidermal layer, made of dead, flattened, shingle-like cells.

What are the functions of the stratum corneum?

Protects against abrasion, penetration, and water loss.

How thick is the stratum corneum according to the slides?

About 20–30 cells thick.

Where is the stratum corneum especially thick?

On the palms of the hands and soles of the feet.

What helps make the stratum corneum water-resistant?

Keratin and glycolipids between cells.

What is the stratum lucidum?

The clear layer of the epidermis, associated with thick skin.

What is the stratum granulosum?

The granular epidermal layer where cells become flatter and fill with keratin.

What is the stratum spinosum?

The prickly epidermal layer containing thick bundles of pre-keratin.

What is the stratum basale?

The deepest epidermal layer containing rapidly dividing stem cells.

What is another name for the stratum basale?

The basal layer.

What is another name for the stratum spinosum?

The prickly layer.

What is another name for the stratum granulosum?

The granular layer.

What is another name for the stratum lucidum?

The clear layer.

What is another name for the stratum corneum?

The horny layer.

What supplies nutrients to the stratum basale?

The dermis.

What is the dermis made of?

Strong, flexible connective tissue with a semifluid matrix containing collagen and elastic fibers.

What structures are found in the dermis?

Nerve fibers, blood vessels, lymph vessels, hair follicles, oil glands, and sweat glands.

What cells are found in the dermis?

Fibroblasts, macrophages, mast cells, and white blood cells.

What are mast cells?

Immune cells that participate in inflammatory and allergic reactions.

What happens when mast cells are irritated?

They release their contents into surrounding tissue.

What is histamine?

A chemical released during immune responses that helps cause inflammation and increases blood flow.

What effects can histamine cause?

It can contribute to itching, sneezing, coughing, tearing, smooth muscle contraction, and capillary dilation.

What are fibroblasts?

Connective tissue cells that synthesize extracellular matrix and collagen.

What are the functions of fibroblasts?

They provide structural support for tissues and play an important role in wound healing.

What are macrophages?

Immune cells that engulf and destroy bacteria and other harmful organisms.

How do macrophages help initiate inflammation?

They release signaling molecules called cytokines that activate other cells.

What are the two layers of the dermis?

Papillary layer and reticular layer.

Where is the papillary layer located?

In the upper part of the dermis.

What are dermal papillae?

Peg-like projections in the papillary layer.

What structures are found in dermal papillae?

Capillary loops, free nerve endings, and touch receptors called Meissner's corpuscles.

What are Meissner's corpuscles?

Touch receptors located in the papillary layer.

How do dermal ridges improve gripping?

They increase friction on the fingers and feet.

What creates fingerprints?

Friction ridge patterns in the skin.

Where is the reticular layer located?

It is the deeper layer of the dermis.

What type of tissue makes up the reticular layer?

Dense, fibrous connective tissue.

What structures are found in the reticular layer?

Blood vessels, sweat glands, oil glands, pressure receptors, and white blood cells.

What are Pacinian corpuscles?

Pressure receptors found in the deeper dermis.

What are cleavage lines?

Lines formed by bundles of collagen fibers that indicate the direction of tension in the skin.

How do cleavage lines affect incisions?

Incisions parallel to cleavage lines tend to heal more readily.

What is the function of collagen in the skin?

It provides strength and helps bind water to hydrate the skin.

What is the function of elastic fibers?

They allow skin to stretch and recoil.

How does aging affect the skin?

Fewer fibers and less subcutaneous fat cause the skin to lose elasticity and sag or wrinkle.

What causes stretch marks?

Extreme stretching can tear the dermis, leaving white scars.

What is a blister?

A separation between the epidermal and dermal layers.

How do dermal blood vessels help regulate temperature?

They adjust blood flow near the skin's surface to release or conserve heat.

What happens to skin during cooling?

Capillaries fill with heated blood, making the skin red and warm while heat radiates away.

How does the body conserve heat through skin blood flow?

Blood bypasses capillaries near the skin's surface, reducing heat loss.

What causes bedsores?

Restricted blood and oxygen supply causes skin cells to die, leading to ulcers.

How can bedsores be prevented in bedridden patients?

By turning patients regularly to relieve pressure.

Where is tattoo pigment deposited?

In the dermis.

What are the two forms of melanin?

Brown-black and pink-red.

What cells produce melanin?

Melanocytes.

Where is melanin found?

In the deeper layers of the epidermis.

What causes freckles and moles?

Local accumulations of melanin.

What is the function of melanin?

Protects DNA from UV radiation.

What is carotene?

A yellow-orange pigment found in foods such as carrots.

Where does carotene accumulate?

In the stratum corneum and hypodermis.

What does carotene convert into in the body?

Vitamin A.

What contributes to the yellowish skin tone described in the slides for Asians?

Melanin and carotene.

What is hemoglobin's effect on skin color?

It contributes a pinkish hue.

Where does the hemoglobin affecting skin color come from?

Red blood cells in capillaries.

What three influences can cause homeostatic imbalances in the skin?

Internal, external, and environmental influences.

What are examples of internal influences on skin?

Aging and genetics.

What are examples of external influences on skin?

Nutritional deficiencies, physical activity, mental health, and drug and alcohol abuse.

What is an environmental influence on skin?

Exposure to toxins.

What is cyanosis?

A blue skin color caused by poorly oxygenated blood.

What can excessive sun exposure cause?

Leathery skin, rashes, and skin cancer.

What can cause skin redness?

Blushing, fever, allergies, inflammation, and hypertension.

What is pallor?

Abnormally pale skin.

What can cause pallor?

Anemia, low blood pressure, fear, and anger.

What is jaundice?

A yellowish skin color associated with liver disorders and bilirubin buildup.

What causes the yellow color associated with jaundice?

Bilirubin, a bile pigment.

What can cause bronzing of the skin?

Addison's disease and pituitary gland tumors.

What causes bruises?

Blood collecting under the skin.

What are the two types of sweat glands?

Eccrine and apocrine sweat glands.

What do eccrine sweat glands release?

Sweat made mostly of water, along with salts, vitamin C, antibodies, and wastes.

Where are eccrine sweat glands especially abundant?

On the palms, soles of the feet, and forehead.

What is the main function of eccrine sweat?

Evaporative cooling to help regulate body temperature.