I 1.1

Question 1

The skin, also known as the _________ (Latin integumentum, covering) or cutaneous layer, covers the external surface of the body and is the largest organ of the body accounting for _____% to _____% of total body weight and, in adults, the skin covers an area of about 2 square meters (22 square feet).

Answer 1

integument; 15% to 20%

Question 2

The skin shows significant regional variation, with the thickest skin being found on the _________ (4.0mm) of the _____ while the thinnest is the delicate skin on the _______ and __________ (0.5mm).

Answer 2

soles; feet; upper and lower eyelids

Question 3

Functions of the skin

Answer 3

• Protection
• Sensory
• Thermoregulator
• Sexual signaling
• Metabolic

Question 4

Skin Structure
Three Main Layers:

Answer 4

• Epidermis
• Dermis
• Subcutis or hypodermis or panniculus

Question 5

Skin Structure
What layer of the skin?
- Composed of keratinized stratified squamous epithelium
- It contains four (4) principal types of cells: Keratinocytes, Melanocytes, Intraepidermal Macrophages, Tactile Epithelial Cells
- Thin Skin: Found in most regions of the body; Has four (4) strata (layers): Stratum basale, Stratum spinosum, Stratum granulosum, Stratum corneum
- Thick Skin: Found in parts of the body where exposure to friction is greatest (fingertips, palms and soles); Has five (5) strata (layers): Stratum basale, Stratum spinosum, Stratum granulosum, Stratum lucidum, Stratum corneum

Answer 5

Epidermis

Question 6

Epidermis: What principal type of cell?
- Constitute about 90% of epidermal cells which are arranged in four or five layers
- Produce the protein keratin (a tough, fibrous protein helps to protect the skin and underlying tissues from abrasions, heat, microbes, and chemicals.
- Produce lamellar granules, which release a water-repellent sealant (minimizes entry and loss of water and inhibits entry of foreign material

Answer 6

Keratinocytes

Question 7

Epidermis: Keratinocytes
- Constitute about ____ % of epidermal cells which are arranged in four or five layers
- Produce the protein _______ (a tough, fibrous protein helps to protect the skin and underlying tissues from abrasions, heat, microbes, and chemicals.
- Produce ________ granules, which release a water-repellent sealant (minimizes entry and loss of water and inhibits entry of foreign material

Answer 7

90; keratin; lamellar

Question 8

Epidermis: What principal type of cell?
- Constitute about 8% of epidermal cells
- Develop from the ectoderm of a developing embryo
- The long, slender projections extend between the keratinocytes and transfer melanin granules to
them
- Melanin: a yellow-red or brown- black pigment that contributes to
skin color and absorbs damaging
ultraviolet (UV) light

Answer 8

Melanocytes

Question 9

Epidermis: Melanocytes
- Constitute about ____% of epidermal cells
- Develop from the ectoderm of a developing embryo
- The long, slender projections
extend between the keratinocytes
and transfer melanin granules to
them
- _____________: a yellow-red or brown-black pigment that contributes to skin color and absorbs damaging
ultraviolet (UV) light

Answer 9

8; Melanin

Question 10

Epidermis: What principal type of cell?
- Also known as Langerhans cells
- Arise from the red bone marrow then migrate to the epidermis
- Participate in immune responses
mounted against microbes invading the skin (help other cells of the immune system recognize an invading microbe and destroy it)
- Easily damaged by UV light

Answer 10

Intraepidermal Macrophages

Question 11

Epidermis: Intraepidermal Macrophages
- Also known as ___________________
- Arise from the ____ bone marrow then migrate to the epidermis
- Participate in immune responses
mounted against microbes invading the skin (help other cells of the immune system recognize an invading microbe and destroy it)
- Easily damaged by UV light

Answer 11

Langerhans cells; red

Question 12

Epidermis: What principal type of cell?
- Also known as Merkel cells
- Least numerous
- Found in the deepest layer of the epidermis coming into contact with a tactile disc/ Merkel disc: flattened process of a sensory neuron
- Detect touch sensations

Answer 12

Tactile Epithelial Cells

Question 13

Epidermis: Tactile Epithelial Cells
- Also known as ______________
- Least numerous
- Found in the ______ layer of the epidermis coming into contact with a tactile disc/ Merkel disc: flattened process of a sensory neuron
- Detect _______ sensations

Answer 13

Merkel cells; deepest; touch