Week 35 / Skin 1 Flashcards
What are the components of the integumentary System?
Skin
Hair
Glands
Oils
Dermis
Epidermis
Subcutaneous
Sensors
What are the functions of the integumentary System?
Regulates body temperature
Stores blood
Protects body from external environment
Detects cutaneous sensations
Excretes and absorbs substances
Synthesizes vitamin D
What is the skin?
A sheetlike organ that covers the body and acts as a barrier
between the internal and external environment
What are the two primary layers that comprise the skin, and what are their characteristics?
Answer:
The two primary layers of the skin are:
Epidermis: The superficial, thinner layer.
Dermis: The deep, thicker laye
What is the difference between thin and thick skin in terms of distribution, epidermal thickness, and features?
Answer:
Thin Skin:
Distribution: Covers most of the body, except for the palms, fingertips, soles of the feet, and plantar surfaces of toes.
Epidermal Thickness: 0.10-0.15 mm (0.004-0.006 in.).
Features:
Lacks stratum lucidum.
Thinner strata spinosum and corneum.
Lacks epidermal ridges.
Has hair follicles, arrector muscles of the hair, and sebaceous glands.
Has sweat glands and sensory receptors, but they are sparser.
Thick Skin:
Distribution: Found in areas subject to friction, such as palms, soles, and plantar surfaces of toes.
Epidermal Thickness: 0.6-4.5 mm (0.024-0.18 in.), mostly due to a thicker stratum corneum.
Features:
Contains stratum lucidum.
Thicker strata spinosum and corneum.
Well-developed and more numerous epidermal ridges.
Lacks hair follicles and arrector muscles of the hair.
Contains more numerous sweat glands and sensory receptors.
What are the 4 major cell types found in the epidermis, and their functions?
Answer:
Keratinocytes (85% of epidermal cells)
Function: Produce keratin, a tough fibrous protein that provides strength and waterproofing to the skin.
Melanocytes (8% of epidermal cells)
Function: Produce melanin, the pigment responsible for skin color and protection against UV radiation.
Dendritic Cells (5% of epidermis)
Function: Play a role in the immune response, protecting the body from infections by identifying and attacking foreign pathogens.
Tactile Epithelial Cells (Merkel Cells) (2% of epidermal cells)
Function: Function as sensory receptors for touch, providing the sense of pressure and texture.
What are the different layers of the epidermis, and their key characteristics?
Answer:
Stratum Corneum
Characteristics: Several layers of dead, flakelike cells (corneocytes), mainly composed of dense networks of keratin fibers and cemented by glycophospholipids. This layer forms a tough, waterproof barrier. It is the keratinized layer.
Stratum Lucidum
Characteristics: A few layers of squamous cells filled with eleidin, a keratin precursor, giving the layer a translucent appearance. This layer is not visible in thin skin.
Stratum Granulosum
Characteristics: 2-5 layers of dying, somewhat flattened cells filled with dark keratohyalin granules and multilayered bodies of glycophospholipids. The nuclei disappear in this layer.
Stratum Spinosum
Characteristics: 8-10 layers of cells that are connected by desmosomes, giving the cells a spiny appearance.
Stratum Basale
Characteristics: A single layer of mostly columnar cells capable of mitotic division. All cells of the superficial layers are derived from this layer. It includes keratinocytes and some melanocytes.
What is involved in the regeneration of the skin?
Answer:
Turnover Time and Regeneration Time: These terms describe the period needed for a population of cells to mature and reproduce.
Keratinocyte Replacement: As surface cells in the stratum corneum are lost, new keratinocytes are formed through mitotic activity. The rate of new cell formation must match the rate at which old keratinized cells flake off, maintaining the epidermis’ constant thickness.
Cell-Signaling Proteins:
Epidermal Growth Factor (EGF): Plays a role in regulating the regeneration and repair of the epidermis.
Growth Hormone (GH): Has a growth-promoting effect on epidermal cells.
What is the function of the Dermoepidermal Junction (DEJ)?
Answer:
The epidermis and dermis are joined by the dermoepidermal junction (DEJ).
The DEJ is a unique kind of basement membrane (BM) containing a special polysaccharide gel that cements the superficial epidermis to the dermis.
The junction “glues” the two layers together and provides mechanical support for the epidermis, which is attached to its upper surface.
What are the functions of the epidermis?
- Skin repair
- Prevents fluid loss
- UV protection
- Produces Vitamin D3
- Prevents damage abrasion
- Innate immune barrier
What are the two layers of the dermis?
The dermis consists of two layers:
Papillary layer
Reticular layer
Question 2:
What is the function of the papillary layer in the dermis?
Answer 2:
The papillary layer contains loose fibrous connective tissue elements and a fine network of thin collagenous and elastic fibres.
Dermal papillae increase the surface area of the dermoepidermal junction (DEJ), which helps bind the skin layers together and can form dermal ridges, such as fingerprints.
It also provides sensory information to the skin through touch sensors.
Question 3:
What is the function of the reticular layer in the dermis?
Answer 3:
The reticular layer is made up of dense collagenous fibres that provide strength and toughness to the skin.
It also contains elastic fibres, which make the skin stretchable and elastic.
What is the role of the dermal layer in relation to hair?
Answer 1:
The dermal layer anchors hairs in place.
Question 2:
What are the arrector pili muscles?
Answer 2:
Arrector pili muscles are small involuntary muscles attached to hair follicles.
Question 3:
What happens when the arrector pili muscles contract?
Answer 3:
When the arrector pili muscles contract, the hair stands on end or becomes upright, which is responsible for the phenomenon of goosebumps. This is typically caused by extreme fright or cold.
Where are somatic sensory receptors located?
Answer 1:
Somatic sensory receptors are located in the dermis of all skin areas.
Question 2:
What is the function of somatic sensory receptors in the skin?
Answer 2:
Somatic sensory receptors permit the skin to serve as a sense organ and transmit sensations to the brain.
Question 3:
What sensations do the sensory receptors in the dermis transmit?
Answer 3:
The sensory receptors in the dermis transmit sensations of pain, pressure, touch, and temperature.
What is the inner most layer of the skin?
Answer 1:
The innermost layer of the skin is the hypodermis (also called the subcutaneous layer).
Question 2:
What does the hypodermis contain?
Answer 2:
The hypodermis contains fat and nutrients.
Question 3:
What is the function of the hypodermis?
Answer 3:
The hypodermis connects the skin to underlying tissue and forms a connection between the skin and the underlying structures of the body.
Question 4:
What is the common use of the hypodermis in medical procedures?
Answer 4:
The hypodermis is the site for hypodermic needles or subcutaneous injections.
Where are melanocytes located?
Answer 1:
Melanocytes are located in the stratum basale of the epidermis.
Question 2:
What causes skin color variation?
Answer 2:
Skin color variation is caused by the amount and type of melanin pigment produced by melanocytes.
Question 3:
What are the two types of melanin and their associated colors?
Answer 3:
The two types of melanin are:
Eumelanin – Brown to dark brown
Pheomelanin – Red to orange
Question 4:
What is the function of melanin?
Answer 4:
Melanin protects skin cells from UV light by absorbing UV radiation. This helps prevent DNA damage, which can lead to mutations and skin cancer.
Question 5:
How is melanin produced and released?
Answer 5:
Melanin is produced by melanocytes, which convert tyrosine into melanin pigments. These pigments are then stored in melanosomes and released into the skin cells.
What causes albinism?
Answer 1:
Albinism is caused by a rare genetic mutation that impacts the melanin synthesis pathway, leading to an inability of melanocytes to produce melanin.
How do individuals with albinism appear?
Answer 2:
Individuals with albinism tend to appear white or very pale due to the lack of melanin in their skin and hair.
What are the sun-related risks for individuals with albinism?
Answer 3:
Individuals with albinism are more prone to sunburns and skin cancer due to the lack of melanin, which provides protection from UV radiation.
How is Vitamin D synthesized in the body?
Answer 1:
Vitamin D is synthesized in the skin through the activation of a precursor molecule by ultraviolet (UV) rays in sunlight.
How much UV light exposure is required for Vitamin D synthesis?
Answer 2:
A small amount of exposure to UV light, about 10 to 15 minutes at least twice a week, is required for Vitamin D synthesis.
Question 1:
What is the function of the skin in protecting against microorganisms?
Question 2:
How does the skin prevent dehydration?
Question 3:
What role do melanins play in the skin’s function?
Question 4:
How does the skin protect against mechanical trauma?
Question 5:
What is the function of somatic sensory receptors in the skin?
Answer 1:
The skin acts as a mechanical barrier, with a surface film that helps prevent the entry of microorganisms.
Answer 2:
The skin prevents dehydration through the keratin in the epidermis, which acts as a waterproof barrier, reducing water loss.
Answer 3:
Melanins in the skin help protect against ultraviolet radiation by absorbing UV light, preventing damage to deeper layers of the skin.
Answer 4:
The skin provides tissue strength through its structure, helping it resist mechanical trauma like cuts and abrasions.
Answer 5:
Somatic sensory receptors in the skin detect and transmit sensations like pain, heat, cold, pressure, and touch to the brain.
Why might people living in colder, northern climates need Vitamin D supplements?
Answer 3:
People in colder, northern climates may require Vitamin D supplements because there is less sunlight exposure, which reduces their ability to synthesize Vitamin D naturally.
What role does Vitamin D play in the body?
Answer 4:
Vitamin D helps regulate the amount of calcium and phosphate in the body, which is essential for keeping bones, teeth, and muscles healthy.
Question 1:
What causes the orange color in the skin?
Question 2:
What happens when bilirubin accumulates in the skin?
Question 3:
How does the volume of blood in the skin affect its color?
Answer 1:
The orange color in the skin can be caused by beta carotene, found in foods like carrots and sweet potatoes. High consumption of these foods can lead to an orange coloration.
Answer 2:
When bilirubin accumulates in the skin, it can lead to a condition called Jaundice. This occurs due to liver damage, which prevents bilirubin from being fully processed.
Answer 3:
Changes in the volume of blood flowing through skin capillaries can affect skin color. Blood pressure, heat, cardiac problems, stress, infection, and inflammation can cause the skin to appear more reddish due to the presence of hemoglobin in the blood.
Question 6:
How does the skin allow for movement and growth?
Question 7:
What is the role of the skin in vitamin D production?
Question 8:
What substances does the skin excrete?
Question 9:
How does the skin interact with the immune system?
Question 10:
How does the skin regulate body temperature?
Answer 6:
The skin has elastic and recoil properties, allowing for movement and body growth without injury, especially due to the flexibility of the subcutaneous tissue.
Answer 7:
The skin plays an endocrine role by synthesizing vitamin D when exposed to ultraviolet light, activating a precursor compound in the skin.
Answer 8:
The skin excretes water, urea, ammonia, and uric acid through sweat, aiding in waste removal.
Answer 9:
The skin helps destroy microorganisms and interacts with immune system cells, particularly helper T cells, through phagocytic cells and epidermal dendritic cells.
Answer 10:
The skin regulates body temperature through sweat production, blood flow to the skin, and the evaporation of sweat, helping with heat loss or retention.
