Week 35 / Skin 1

Question 1

What are the components of the integumentary System? [8]

Answer 1

Skin

Hair

Glands

Oils

Dermis

Epidermis

Subcutaneous

Sensors

Question 1

What are the functions of the integumentary System?
[6]

Answer 1

Regulates body temperature

Stores blood

Protects body from external environment

Detects cutaneous sensations

Excretes and absorbs substances

Synthesizes vitamin D

Question 2

What is the skin?

Answer 2

A sheetlike organ that covers the body and acts as a barrier
between the internal and external environment

Question 3

What are the two primary layers that comprise the skin, and what are their characteristics?

Answer 3

Answer:
The two primary layers of the skin are:

Epidermis: The superficial, thinner layer.

Dermis: The deep, thicker laye

Question 4

What is the difference between thin and thick skin in terms of distribution, epidermal thickness, and features?
[Think skin
Distribution

stratum lucidum.

strata spinosum and corneum.

epidermal ridges.

hair follicles, glands

sweat glands and sensory receptors
]

[Thick skin
Distribution

stratum lucidum.

strata spinosum and corneum.

epidermal ridges.

hair follicles, glands

sweat glands and sensory receptors
]

Answer 4

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.

Question 5

What are the 4 major cell types found in the epidermis, and their functions?

Answer 5

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.

Question 6

What are the different layers of the epidermis, and their key characteristics?

Answer 6

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.

Question 7

What is involved in the regeneration of the skin?
[4]

Answer 7

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.

Question 8

What is the function of the Dermoepidermal Junction (DEJ)?
[what do they join?]
[what does it provide support to ?]

Answer 8

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.

Question 9

What are the functions of the epidermis? [6]

Answer 9

1. Skin repair
2. Prevents fluid loss
3. UV protection
4. Produces Vitamin D3
5. Prevents damage abrasion
6. Innate immune barrier

Question 10

What are the two layers of the dermis?

Answer 10

The dermis consists of two layers:

Papillary layer

Reticular layer

Question 11

Question 2:
What is the function of the papillary layer in the dermis?
[what does it contain?]
[what are the two functions ?]

Answer 11

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 12

Question 3:
What is the function of the reticular layer in the dermis?
[what is it made of?]
[what is the function?]

Answer 12

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.

Question 13

What is the role of the dermal layer in relation to hair?

Answer 13

Answer 1:
The dermal layer anchors hairs in place.

Question 13

Question 2:
What are the arrector pili muscles?

Answer 13

Answer 2:
Arrector pili muscles are small involuntary muscles attached to hair follicles.

Question 14

Question 3:
What happens when the arrector pili muscles contract?

Answer 14

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.

Question 15

Where are somatic sensory receptors located?

Answer 15

Answer 1:
Somatic sensory receptors are located in the dermis of all skin areas.

Question 16

Question 2:
What is the function of somatic sensory receptors in the skin?

Answer 16

Answer 2:
Somatic sensory receptors permit the skin to serve as a sense organ and transmit sensations to the brain.

Question 17

Question 3:
What sensations do the sensory receptors in the dermis transmit?

Answer 17

Answer 3:
The sensory receptors in the dermis transmit sensations of pain, pressure, touch, and temperature.

Question 18

What is the inner most layer of the skin?

Answer 18

Answer 1:
The innermost layer of the skin is the hypodermis (also called the subcutaneous layer).

Question 19

Question 2:
What does the hypodermis contain?

Answer 19

Answer 2:
The hypodermis contains fat and nutrients.

Question 20

Question 3:
What is the function of the hypodermis?

Answer 20

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 21

Question 4:
What is the common use of the hypodermis in medical procedures?

Answer 21

Answer 4:
The hypodermis is the site for hypodermic needles or subcutaneous injections.

Question 22

Where are melanocytes located?

Answer 22

Answer 1:
Melanocytes are located in the stratum basale of the epidermis.

Question 23

Question 2: What causes skin color variation?

Answer 23

Answer 2: Skin color variation is caused by the amount and type of melanin pigment produced by melanocytes.

Question 24

Question 3: What are the two types of melanin and their associated colors?

Answer 24

Answer 3: The two types of melanin are: Eumelanin – Brown to dark brown Pheomelanin – Red to orange

Question 25

Question 4: What is the function of melanin?

Answer 25

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 26

Question 5: How is melanin produced and released?

Answer 26

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.

Question 27

What causes albinism?

Answer 27

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.

Question 28

How do individuals with albinism appear?

Answer 28

Answer 2: Individuals with albinism tend to appear white or very pale due to the lack of melanin in their skin and hair.

Question 29

What are the sun-related risks for individuals with albinism?

Answer 29

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.

Question 30

How is Vitamin D synthesized in the body?

Answer 30

Answer 1: Vitamin D is synthesized in the skin through the activation of a precursor molecule by ultraviolet (UV) rays in sunlight.

Question 31

How much UV light exposure is required for Vitamin D synthesis?

Answer 31

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 32

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 32

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.

Question 32

Why might people living in colder, northern climates need Vitamin D supplements?

Answer 32

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.

Question 33

What role does Vitamin D play in the body?

Answer 33

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 34

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 34

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 35

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 35

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.