Exam 2 Study Guide
Chapter 13: Skin, Hair, and Nails
Vocabulary:
Hypopigmentation: the lightening of skin (or hair/eyes) due to reduced melanin
Hyperpigmentation: when skin patches darken due to excess melanin
Erythema: skin redness caused by dilated blood vessels (often a sign of inflammation, infection,
sunburn, irritation, or allergic reactions, manifesting as a rash that can be itchy, painful, or
present as target-like lesions with treatment focusing on the underlying cause like infections or
allergies)
Pallor: an unhealthy pale appearance
Jaundice: medical condition with yellowing of the skin or whites of the eyes, arising from
excess of the pigment bilirubin and typically caused by obstruction of the bile duct, by liver
disease, or by excessive breakdown of red blood cells
Cyanosis: a bluish or purplish skin discoloration, most visible on lips, gums, nail beds, and
earlobes, caused by a lack of oxygen in the blood due to severe lung or heart conditions, airway
problems, or poor circulation
Seborrhea: a common skin condition causing greasy, flaky, red patches with white scales, often
on the scalp (dandruff), face (around nose, eyebrows, ears, eyelids), chest, and skin folds
Xerosis: a common condition where skin becomes rough, flaky, itchy, and tight due to a lack of
moisture
Pruritus: itchy skin, a sensation that prompts scratching and can range from mild to severe
Vitiligo: a chronic autoimmune skin condition causing loss of skin color in patches, resulting
from the immune system destroying melanocytes (Pigment-producing cells)
SKIN
● The skin is the largest organ system in the body
○ Covers about 20 square feet of surface area in the average adult
○ Guards the body from environmental stresses and adapts to its environmental
influences
○ Protects the body from injuries, germs, and dirts
○ It also helps the body to adjust to temperature
● Layers of the skin:
○ Epidermis (outer layer): thin but tough
■ Top layer, acts like a shield to protect the body
■ Completely replaced every 4 weeks; the inner stratum basale or basal cell
layer forms new skin cells
■ Their main ingredient is the tough, fibrous protein keratin
■ The melanocytes interspersed along this layer produce the pigment
melanin, which gives brown tones to the skin and hair
■ It’s cells are bound tightly together into sheers that form a rugged
protective barrier
, ■ From the basal layer the new cells migrate up and flatten into the outer
stratum corneum or horny cell layer. This consists of dead keratinized cells
that are interwoven and closely packed
■ Skin color is derived three sources: (1) mainly from the brown pigment
melanin, (2) from the yellow-orange tones of the pigment carotene, and
(3) from the red-purple tones of blood in the underlying vascular bed
○ Dermis (middle layer):
■ The inner supportive layer consisting mostly of connective tissue or,
collagen which allows the skin to stretch and resist tearing
■ Gives support and has blood vessels, sweat glands, nerves, hair follicles
○ Subcutaneous (bottom layer):
■ Made of fat (adipose tissue)
■ Tissue stores fat for energy, provides insulation for temperature control,
and aids in protection by its soft cushioning
HAIR
● Is made of keratin-a tough protein
○ The shaft is the visible part; the root is under the skin, embedded in the follicle
○ At the root the bulb matrix is the expanded area, where new hair cells grow
● People have two types of hair. Fine, faint vellus hair covers most of the body (except the
palms and soles, the dorsa of the distal parts of the fingers, the umbilicus, the glans pens,
and inside the labia)
● The other type is terminal hair, the darker, thicker hair that grows on the scalp and
eyebrows and, after puberty, on the axillae, the pubic area, and the face and chest in the
male
● Hair growth cycle:
○ Grows in cycles: a time of growth and a time of rest
○ Each hair grows on its own schedule, so while some are growing, others are
resting
○ Tiny muscles called arrector pili are attached to hair follicles
■ They contract when you’re cold or emotional, making your hair stand up-
what we call “goosebumps”
SEBACEOUS & SWEAT GLANDS
● Sebaceous glands:
○ The skin’s natural oil makers
○ Makes an oily substance called sebum-lubricates the skin and hair
■ Secreted through the hair follicles
○ Sebum oils and lubricates the skin and hair and forms an emulsion with water that
helps keep water in the skin
○ Found everywhere on the body except the palms and soles, they are most
abundant in the scalp, forehead, face, and chin
, ● Sweat glands: two types
○ 1. Eccrine:
■ produce sweat (mature in the two-month-old infant)
■ Coiled tubules that open directly onto the skin surface and produce a dilute
saline solution called sweat
○ 2. Apocrine:
■ Produce thick, milky secretion and open into the hair follicles
■ become active during puberty, secretion occurs with emotional and sexual
stimulation
■ Bacterial flora residing on the skin surface react with apocrine sweat to
produce a characteristic musky body odor
NAILS
● Hard plates of keratin on dorsal edges of fingers and toes
● Lunula-white, semilunar area at the proximal end of the nail.
● The cuticle protects the nail matrix
FUNCTION OF THE SKIN
● The skin is a washable, waterproof, and rugged covering that has protective and adaptive
properties:
○ Protection from the environment: skin minimizes injury from physical, chemical,
thermal, and light-wave sources
○ Prevents penetration: skin is a defense barrier that stops invasion of
microorganisms and loss of water and electrolytes from within the body
○ Perception: skin is a vast sensory surface holding the neurosensory and
end-organs for touch, pain, temperature, and pressure
○ Fluid balance: about 500 mL of fluid are lost daily by insensible perspiration,
and additional loss may occur as visible sweat
○ Temperature regulation: skin allows heat dissipation through sweat glands and
heat storage through subcutaneous insulation
○ Identification: People identify one another by unique combinations of facial
characteristics, hair, skin color, and even fingerprints
○ Communication: emotions are expressed in the sign language of the face and
body posture. Vascular mechanisms such as blushing or blanching also signal
emotional states
○ Wound repair: Skin allows cell replacement of surface wounds
○ Absorption and excretion: Skin allows limited excretion of some metabolic
wastes, by-products of cellular decomposition such as minerals, sugars, amino
acids, cholesterol, uric acid, and urea
○ Production of vitamin D: The skin is the surface on which ultraviolet (UV) light
converts cholesterol into vitamin D
Chapter 13: Skin, Hair, and Nails
Vocabulary:
Hypopigmentation: the lightening of skin (or hair/eyes) due to reduced melanin
Hyperpigmentation: when skin patches darken due to excess melanin
Erythema: skin redness caused by dilated blood vessels (often a sign of inflammation, infection,
sunburn, irritation, or allergic reactions, manifesting as a rash that can be itchy, painful, or
present as target-like lesions with treatment focusing on the underlying cause like infections or
allergies)
Pallor: an unhealthy pale appearance
Jaundice: medical condition with yellowing of the skin or whites of the eyes, arising from
excess of the pigment bilirubin and typically caused by obstruction of the bile duct, by liver
disease, or by excessive breakdown of red blood cells
Cyanosis: a bluish or purplish skin discoloration, most visible on lips, gums, nail beds, and
earlobes, caused by a lack of oxygen in the blood due to severe lung or heart conditions, airway
problems, or poor circulation
Seborrhea: a common skin condition causing greasy, flaky, red patches with white scales, often
on the scalp (dandruff), face (around nose, eyebrows, ears, eyelids), chest, and skin folds
Xerosis: a common condition where skin becomes rough, flaky, itchy, and tight due to a lack of
moisture
Pruritus: itchy skin, a sensation that prompts scratching and can range from mild to severe
Vitiligo: a chronic autoimmune skin condition causing loss of skin color in patches, resulting
from the immune system destroying melanocytes (Pigment-producing cells)
SKIN
● The skin is the largest organ system in the body
○ Covers about 20 square feet of surface area in the average adult
○ Guards the body from environmental stresses and adapts to its environmental
influences
○ Protects the body from injuries, germs, and dirts
○ It also helps the body to adjust to temperature
● Layers of the skin:
○ Epidermis (outer layer): thin but tough
■ Top layer, acts like a shield to protect the body
■ Completely replaced every 4 weeks; the inner stratum basale or basal cell
layer forms new skin cells
■ Their main ingredient is the tough, fibrous protein keratin
■ The melanocytes interspersed along this layer produce the pigment
melanin, which gives brown tones to the skin and hair
■ It’s cells are bound tightly together into sheers that form a rugged
protective barrier
, ■ From the basal layer the new cells migrate up and flatten into the outer
stratum corneum or horny cell layer. This consists of dead keratinized cells
that are interwoven and closely packed
■ Skin color is derived three sources: (1) mainly from the brown pigment
melanin, (2) from the yellow-orange tones of the pigment carotene, and
(3) from the red-purple tones of blood in the underlying vascular bed
○ Dermis (middle layer):
■ The inner supportive layer consisting mostly of connective tissue or,
collagen which allows the skin to stretch and resist tearing
■ Gives support and has blood vessels, sweat glands, nerves, hair follicles
○ Subcutaneous (bottom layer):
■ Made of fat (adipose tissue)
■ Tissue stores fat for energy, provides insulation for temperature control,
and aids in protection by its soft cushioning
HAIR
● Is made of keratin-a tough protein
○ The shaft is the visible part; the root is under the skin, embedded in the follicle
○ At the root the bulb matrix is the expanded area, where new hair cells grow
● People have two types of hair. Fine, faint vellus hair covers most of the body (except the
palms and soles, the dorsa of the distal parts of the fingers, the umbilicus, the glans pens,
and inside the labia)
● The other type is terminal hair, the darker, thicker hair that grows on the scalp and
eyebrows and, after puberty, on the axillae, the pubic area, and the face and chest in the
male
● Hair growth cycle:
○ Grows in cycles: a time of growth and a time of rest
○ Each hair grows on its own schedule, so while some are growing, others are
resting
○ Tiny muscles called arrector pili are attached to hair follicles
■ They contract when you’re cold or emotional, making your hair stand up-
what we call “goosebumps”
SEBACEOUS & SWEAT GLANDS
● Sebaceous glands:
○ The skin’s natural oil makers
○ Makes an oily substance called sebum-lubricates the skin and hair
■ Secreted through the hair follicles
○ Sebum oils and lubricates the skin and hair and forms an emulsion with water that
helps keep water in the skin
○ Found everywhere on the body except the palms and soles, they are most
abundant in the scalp, forehead, face, and chin
, ● Sweat glands: two types
○ 1. Eccrine:
■ produce sweat (mature in the two-month-old infant)
■ Coiled tubules that open directly onto the skin surface and produce a dilute
saline solution called sweat
○ 2. Apocrine:
■ Produce thick, milky secretion and open into the hair follicles
■ become active during puberty, secretion occurs with emotional and sexual
stimulation
■ Bacterial flora residing on the skin surface react with apocrine sweat to
produce a characteristic musky body odor
NAILS
● Hard plates of keratin on dorsal edges of fingers and toes
● Lunula-white, semilunar area at the proximal end of the nail.
● The cuticle protects the nail matrix
FUNCTION OF THE SKIN
● The skin is a washable, waterproof, and rugged covering that has protective and adaptive
properties:
○ Protection from the environment: skin minimizes injury from physical, chemical,
thermal, and light-wave sources
○ Prevents penetration: skin is a defense barrier that stops invasion of
microorganisms and loss of water and electrolytes from within the body
○ Perception: skin is a vast sensory surface holding the neurosensory and
end-organs for touch, pain, temperature, and pressure
○ Fluid balance: about 500 mL of fluid are lost daily by insensible perspiration,
and additional loss may occur as visible sweat
○ Temperature regulation: skin allows heat dissipation through sweat glands and
heat storage through subcutaneous insulation
○ Identification: People identify one another by unique combinations of facial
characteristics, hair, skin color, and even fingerprints
○ Communication: emotions are expressed in the sign language of the face and
body posture. Vascular mechanisms such as blushing or blanching also signal
emotional states
○ Wound repair: Skin allows cell replacement of surface wounds
○ Absorption and excretion: Skin allows limited excretion of some metabolic
wastes, by-products of cellular decomposition such as minerals, sugars, amino
acids, cholesterol, uric acid, and urea
○ Production of vitamin D: The skin is the surface on which ultraviolet (UV) light
converts cholesterol into vitamin D
