2. Integumentary System Flashcards
What are the two main layers of the skin?
Epidermis and dermis.
What lies beneath the dermis?
The hypodermis (subcutaneous layer).
What type of tissue composes the epidermis?
Keratinized, stratified squamous epithelium.
How many layers are in thin skin?
Four: stratum basale, stratum spinosum, stratum granulosum, stratum corneum.
What additional layer is found in thick skin?
Stratum lucidum.
Where is thick skin found?
Palms of the hands and soles of the feet.
What does the dermis contain?
Blood and lymph vessels, nerves, hair follicles, sweat glands.
What are the two layers of the dermis?
Papillary layer and reticular layer.
What tissue is found in the papillary layer?
Loose areolar connective tissue.
What structures are in the papillary layer?
Capillaries, nerve endings, Meissner corpuscles, phagocytes.
What tissue is found in the reticular layer?
Dense irregular connective tissue.
What fibers are present in the reticular layer?
Collagen and elastin fibers.
What is the hypodermis composed of?
Loose connective and adipose tissue.
What is the function of the hypodermis?
Insulation, fat storage, and cushioning.
What are the three main pigments affecting skin color?
Melanin, carotene, and hemoglobin.
What cells produce melanin?
Melanocytes.
What are the two types of melanin?
Eumelanin (black/brown) and pheomelanin (red).
What stimulates melanin production?
Exposure to UV radiation.
What causes a tan?
Increased melanin in keratinocytes due to sun exposure.
What is the role of melanin?
Protects DNA from UV damage and prevents folic acid breakdown.
How does too much melanin affect health?
It can interfere with vitamin D production.
What is carotene?
A yellow-orange pigment stored in the dermis and subcutaneous layer.
What is hemoglobin’s role in skin color?
Oxygenated hemoglobin gives light skin a red or pink hue.
What are the main functions of the skin?
Protection, thermoregulation, sensation, excretion, vitamin D synthesis.
How does the skin protect the body?
Acts as a barrier to water loss, microbes, UV rays, and abrasions.
What compound in sweat deters microbial growth?
Dermicidin.
How does the skin help regulate temperature?
Through sweat production and blood vessel dilation/constriction.
What is insensible perspiration?
Sweat loss of about 500 mL/day that isn’t noticeable.
How much can sweat production increase during activity?
Up to 0.7–1.5 liters per hour.
What happens to dermal vessels in hot conditions?
They dilate to release heat.
What happens to dermal vessels in cold conditions?
They constrict to conserve heat.
What sensory structures are found in skin?
Meissner corpuscles, Pacinian corpuscles, Merkel cells, free nerve endings.
What is the function of Meissner corpuscles?
Detect light touch.
What is the function of Pacinian corpuscles?
Detect vibration.
How does skin excrete waste?
Via sweat containing water, salts, ammonia, and urea.
How is vitamin D synthesized in the skin?
UV rays trigger production of cholecalciferol from cholesterol.
What does vitamin D do?
Aids in calcium absorption and supports immune function.
What can vitamin D deficiency cause?
Rickets in children and osteomalacia in adults.
What are the four main types of cells in the epidermis?
Keratinocytes, melanocytes, Langerhans cells, Merkel cells.
What is the function of keratinocytes?
They manufacture and store the protein keratin.
What percentage of epidermal cells are keratinocytes?
Approximately 90%.
What is keratin?
A fibrous protein that gives hair, nails, and skin their hardness and water resistance.
What is the role of melanocytes?
Produce melanin granules to absorb UV radiation and contribute to skin color.
What is the function of Langerhans cells?
Part of the immune system; they recognize and destroy microbes.
What do Merkel cells do?
Act as touch receptors by stimulating sensory nerves.
What are the five layers of the epidermis from superficial to deep?
Stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, stratum basale.
Which layer is only found in thick skin?
Stratum lucidum.
Where is thick skin located?
Palms of the hands and soles of the feet.
What is the stratum corneum?
The outermost layer composed of dead, keratinized cells.
What is the main function of the stratum corneum?
Prevents microbial penetration and dehydration.
What is the stratum lucidum composed of?
Dead, flattened keratinocytes packed with eleidin.
What is eleidin?
A clear protein found in the stratum lucidum derived from keratohyalin.
What gives the stratum granulosum its grainy appearance?
Keratohyalin and keratin accumulation.
What happens to cells in the stratum granulosum?
They flatten, thicken, lose organelles, and start dying.
What structures connect cells in the stratum spinosum?
Desmosomes.
What is the function of desmosomes?
They form strong, interlocking cell junctions.
What immune cells are found in the stratum spinosum?
Langerhans cells.
What cells are found in the stratum basale?
Basal cells, Merkel cells, and melanocytes.
What are basal cells?
Cuboidal stem cells that produce keratinocytes.
What structure anchors the stratum basale to the dermis?
The basement membrane.
What structure increases the strength of the epidermis-dermis connection?
Dermal papillae.
What forms fingerprints?
The interaction of stratum basale and dermal papillae during fetal development.
What are the three main types of skin glands?
Sebaceous glands, sweat glands, and ceruminous glands.
What do sebaceous glands secrete?
Sebum, a lipid mixture that lubricates and waterproofs skin and hair.
What are the functions of sebum?
Keeps the stratum corneum pliable, has antibacterial properties, prevents water loss.
Where are sebaceous glands absent?
Palms of the hands and soles of the feet.
What stimulates sebum secretion?
Hormones, especially active during puberty.
What are the two types of sweat glands?
Eccrine (merocrine) glands and apocrine glands.
Where are eccrine sweat glands most abundant?
Palms, soles, and forehead.
What is the function of eccrine glands?
Produce hypotonic sweat for thermoregulation.
What compound in sweat has antimicrobial properties?
Dermicidin.
Where are apocrine glands located?
Armpits and genital regions.
What do apocrine glands secrete?
Thicker sweat with organic compounds, leading to body odor.
What are ceruminous glands?
Modified apocrine glands in the external ear canal.
What is cerumen composed of?
Secretions of ceruminous and sebaceous glands.
What is the function of cerumen?
Traps particles and protects against infection.
What are the three main regions of a hair?
Shaft, root, and bulb.
Where does hair growth occur?
In the hair bulb.
What are the three layers of the hair shaft?
Medulla (innermost), cortex, cuticle (outermost).
What is the function of the arrector pili muscle?
Contracts in response to cold or fear to raise hair (‘goose bumps’).
What is the hair matrix?
Mitotically active cells around the hair papilla.
What determines hair color?
Melanin produced by melanocytes near the matrix.
What are the phases of hair growth?
Anagen (growth), catagen (transition), telogen (resting).
What happens in the anagen phase?
Rapid cell division at the root pushes the hair out.
How long does the anagen phase last?
2 to 7 years.
What happens during the telogen phase?
Hair is at rest and eventually shed.
What causes hair loss?
More hair is shed than replaced, often due to aging or hormonal changes.
What is the nail composed of?
Dead keratinized epidermal cells.
What is the function of the nail?
Protects finger and toe tips and provides support.
What is the lunula?
Crescent-shaped white area at the base of the nail.
Where does nail growth occur?
In the matrix at the nail root.
What is the hyponychium?
Thickened stratum corneum beneath the free edge of the nail.
What is the eponychium?
Also called the cuticle; the fold at the proximal end of the nail body.
What do sensory receptors in the skin detect?
Touch, pressure, pain, temperature, and stretch.
Where are Meissner’s corpuscles found?
Hairless skin – hands, feet, lips, and genitals.
What do Meissner’s corpuscles detect?
Light touch.
What do Pacinian corpuscles detect?
Pressure and vibration.
What are Merkel discs?
Free nerve endings that detect light, sustained touch.
What are nociceptors?
Free nerve endings that detect pain from various stimuli.
What do Ruffini endings detect?
Stretch.
What is the root hair plexus?
A receptor that detects movement of hair.
What triggers the healing process in the skin?
Damage to the skin structure.
What is the first step in wound healing?
Formation of a blood clot.
What do fibroblasts do during healing?
They secrete collagen and form granulation tissue.
What is the function of macrophages in wound healing?
They engulf foreign matter to prevent infection.
What is inflammation?
The body’s initial response to injury.
What are the cardinal signs of inflammation?
Redness, swelling, pain, and heat (plus loss of function).
What causes redness and heat during inflammation?
Vasodilation and increased blood flow.
What chemical causes vasodilation?
Histamine.
What causes swelling (edema)?
Leakage of fluid and immune cells into tissues.
What do prostaglandins do?
Activate pain receptors.
What is pus composed of?
Dead leukocytes and fluid.
What is granulation tissue?
Delicate new tissue with blood vessels and fibroblasts.
What is a primary union?
Healing of a wound with closely opposed edges.
What is a secondary union?
Healing of a wide or gaping wound involving wound contraction.
What is a keloid?
A raised scar formed from excess collagen deposition.
What is an atrophic scar?
A sunken scar such as from acne or chickenpox.
What causes a bedsore?
Prolonged pressure on bony areas reducing blood flow.
What are stretch marks?
Tears in the dermis from rapid stretching.
What causes a callus?
Repeated mechanical stress increasing skin thickness.
What is a corn?
A callus formed by elliptical motion causing abrasion.
What layer initiates repair in epidermal wounds?
Stratum basale.
What happens in epidermal wound healing?
Basal cells migrate to cover the wound site.
What types of injuries lead to epidermal wound healing?
Minor burns and abrasions.
What are the three phases of deep wound healing?
Inflammatory, proliferation and migration, maturation and remodeling.
What is hemostasis?
Formation of a clot to stop blood loss.
What occurs in the inflammatory phase?
Vasodilation, phagocytosis, and clot formation.
What occurs in the proliferation phase?
Epithelial and fibroblast migration, collagen deposition, and angiogenesis.
What is granulation tissue?
New vascular tissue forming under the scab.
What happens in the maturation phase?
Scab falls off, collagen is organized, blood vessels return to normal.
What is fibrosis?
Scar tissue formation that lacks original function.
What causes burns?
Heat, radiation, electricity, or chemicals.
What are the risks of severe burns?
Dehydration, electrolyte imbalance, infection, and organ failure.
What is a first-degree burn?
Superficial burn affecting only the epidermis.
What is a second-degree burn?
Burn affecting the epidermis and part of the dermis.
What is a third-degree burn?
Full-thickness burn affecting both epidermis and dermis, damaging nerves.
What is a fourth-degree burn?
Burn extending to muscle and bone.
Why are third and fourth-degree burns less painful?
Nerve endings are destroyed.
What is the rule of nines?
A method to estimate the surface area affected by a burn.
What causes skin to become thinner and drier with age?
Loss of elasticity and reduced moisture retention.
Why does hair turn gray with age?
Hair follicles produce less melanin.
Why does the face look flabby with age?
Decrease in collagen and elastic fibers, and muscle tone loss.
What causes height to decrease with aging?
Loss of minerals in bones and reduced disc fluid.
What happens to cartilage in joints with age?
It deteriorates and stiffens.
What is atrophy?
Loss of mass in tissues such as muscle, brain, and spinal cord.
How does aging affect nerves?
Nerve impulse transmission slows.
How does aging impact the immune system?
It becomes less efficient, increasing infection risk.
Why is wound healing slower in elderly individuals?
Reduced immune function and cellular regeneration.
What are telomeres and how do they relate to aging?
They are chromosome ends that shorten with each cell division, reducing regeneration.
How does aging affect cell membranes?
It reduces nutrient and waste transport efficiency.
What can promote healthier aging?
Exercise and healthy lifestyle choices.
What is homeostatic imbalance?
Disruption of internal equilibrium in the body.
What are internal causes of homeostatic imbalance?
Genetics and aging.
What are external causes of homeostatic imbalance?
Poor nutrition and vitamin deficiency.
What are environmental causes of homeostatic imbalance?
Temperature extremes and toxin exposure.
Why is vitamin D important?
It supports bone remodeling and has roles in mental and cardiovascular health.
What condition can vitamin D deficiency lead to?
Osteoporosis and mental health issues.
What happens when the body cannot regulate temperature due to environmental extremes?
Hyperthermia or hypothermia may occur.
How does aging impact feedback loops?
It makes them less efficient, increasing disease risk.
How does cardiovascular aging lead to disease?
Weakened cardiac and smooth muscles can cause atherosclerosis and heart attacks.
What is cancer?
A disease where cells grow uncontrollably and invade other tissues.
What is a mutation?
A permanent change in a cell’s DNA.
What is metastasis?
The spread of cancer cells to other parts of the body.
What are carcinomas?
Cancers derived from epithelial cells.
What is basal cell carcinoma?
A cancer of the stratum basale; the most common form of skin cancer.
Where is basal cell carcinoma typically found?
Head, neck, arms, and back—areas with high sun exposure.
What are risk factors for basal cell carcinoma?
UV exposure, radiation, arsenic, tattoos, burns.
What is the typical treatment for basal cell carcinoma?
Surgery, cryosurgery, or topical ointments.
What is squamous cell carcinoma?
A cancer affecting keratinocytes in the stratum spinosum.
Where does squamous cell carcinoma usually appear?
Scalp, ears, and hands.
How is squamous cell carcinoma treated?
Surgery and radiation.
What is melanoma?
A highly metastatic cancer of melanocytes.
What makes melanoma the most dangerous skin cancer?
Its aggressive metastasis and late detection.
What is the ABCDE rule for identifying melanoma?
Asymmetry, Borders, Color, Diameter, Evolving.
What additional signs indicate nodular melanoma?
Elevated, Firm, Growing.
What is eczema?
An allergic reaction that causes dry, itchy patches of skin.
What symptoms are associated with eczema?
Dryness, itching, swelling, flaking, bleeding.
How is eczema treated?
Moisturizers, corticosteroids, immunosuppressants.
What is acne?
A skin condition involving clogged pores and inflammation.
What causes acne?
Excess sebum, keratin accumulation, and bacterial infection.
Which bacterium is associated with acne?
Propionibacterium.
Why does sebum turn black in acne?
Oxidation upon exposure to air.
Why does acne often occur in adolescents?
Hormonal changes increase sebum production.
What parts of the body are most affected by acne?
Face and back—areas rich in sebaceous glands.
