Integumentary System Flashcards
1
Q
What is the integumentary system?
A
A complex set of organs consisting of the skin and its appendages (sweat and oil glands, hairs, and nails) that serves several functions, mostly protective.
2
Q
What are the two layers of the skin?
A
The epidermis and dermis.
3
Q
What is subcutaneous tissue?
A
The layer of tissue beneath the dermis that is mostly made up of fat and connective tissue.
4
Q
What are some functions of the skin and its derivatives?
A
Mostly protective functions, such as regulating body temperature, protecting against physical and chemical damage, and preventing water loss.
5
Q
What causes skin color?
A
The amount and type of melanin produced by melanocytes in the epidermis.
6
Q
What are sweat and sebaceous glands?
A
Sweat glands produce sweat to regulate body temperature, while sebaceous glands produce oil to lubricate and waterproof the skin and hair.
7
Q
What are some developmental aspects of the integumentary system?
A
Changes in skin thickness, elasticity, and pigmentation occur with aging, and skin cancer risk increases with prolonged sun exposure.
8
Q
What are some things that can go wrong with the integumentary system?
A
Skin conditions such as acne, eczema, and psoriasis, as well as skin cancer and infections.
9
Q
What are some functions of the skin?
A
Regulating body temperature, protecting against physical and chemical damage, and preventing water loss.
10
Q
What is the subcutaneous tissue?
A
The layer of tissue just deep to the skin, consisting mostly of adipose tissue with some areolar connective tissue, that anchors the skin to underlying structures and acts as a shock absorber and insulator.
11
Q
What are the functions of the subcutaneous tissue?
A
To anchor the skin to underlying structures, act as a shock absorber and insulator, and protect the body by allowing the skin to slide relatively freely over those structures.
12
Q
What is the skin’s total surface area and how much does it weigh in the average adult?
A
The skin’s total surface area is 2.2 square meters, and it accounts for about 7% of total body weight in the average adult.
13
Q
What are the two distinct layers of the skin?
A
The epidermis, composed of epithelial cells and the outermost protective shield of the body, and the underlying dermis, making up the bulk of the skin and composed mostly of dense connective tissue.
14
Q
Which layer of the skin is vascularized?
A
Only the dermis is vascularized. Nutrients reach the epidermis by diffusing through the tissue fluid from blood vessels in the dermis.
15
Q
What are some of the appendages of the skin?
A
Eccrine sweat gland, arrector pili muscle, sebaceous (oil) gland, hair follicle, hair root.
16
Q
What are some of the nervous structures in the skin?
A
Sensory nerve fiber with free nerve endings, lamellar corpuscle, hair follicle receptor (root hair plexus).
17
Q
What is the function of the dermal vascular plexus?
A
To supply blood to the skin and help regulate body temperature.
18
Q
What is the purpose of the Check Your Understanding section?
A
To test the reader’s comprehension of the material presented in the chapter.
19
Q
Name the four types of cells found in the epidermis.
A
Keratinocytes, melanocytes, dendritic cells, and tactile epithelial cells.
20
Q
What is the chief role of keratinocytes?
A
To produce keratin, the fibrous protein that helps give the epidermis its protective properties.
21
Q
What is the most common type of cell found in the epidermis?
A
Keratinocytes.
22
Q
What is the function of melanocytes?
A
To produce melanin, the pigment that gives color to the skin and protects it from UV radiation.
23
Q
What are the major layers of the epidermis?
A
Stratum basale, stratum spinosum, stratum granulosum, and stratum corneum.
24
Q
What is the deepest layer of the epidermis?
A
Stratum basale.
25
What is the most superficial layer of the epidermis?
Stratum corneum.
26
What is the function of dendritic cells in the epidermis?
To help the immune system recognize and respond to pathogens.
27
What is the function of tactile epithelial cells in the epidermis?
To detect touch sensations.
28
What is the fibrous protein produced by keratinocytes?
Keratin.
29
What are keratinocytes and how are they tied together?
Keratinocytes are epithelial cells that produce keratin and are tied together by desmosomes for strength and, in some layers, by tight junctions to hinder movement of water between cells.
30
Where do keratinocytes arise from and what stimulates their growth?
Keratinocytes arise in the deepest part of the epidermis from a cell layer called the stratum basale. They undergo almost continuous mitosis in response to epidermal growth factor, a peptide produced by various cells throughout the body.
31
What happens to keratinocytes as they move towards the skin surface?
As keratinocytes move towards the skin surface, they make keratin that eventually fills them. By the time they approach the skin surface, they are dead, scale-like flat sacs completely filled with keratin.
32
What are melanocytes and what is their function?
Melanocytes are epithelial cells that synthesize the pigment melanin. They are found in the deepest layer of the epidermis and transfer melanin to nearby keratinocytes, forming a pigment shield that protects the nucleus from the damaging effects of ultraviolet (UV) radiation in sunlight.
33
What are dendritic cells and what is their function?
Dendritic cells are star-shaped cells that ingest foreign substances and are key activators of our immune system. They arise from bone marrow and migrate to the epidermis, extending their processes among the surrounding keratinocytes to form a more or less continuous network.
34
What are tactile epithelial cells and what is their function?
Tactile epithelial cells, also called Merkel cells, are present at the epidermal-dermal junction and are intimately associated with a disclike sensory nerve ending. The combination functions as a sensory receptor for touch.
35
What are the layers of the epidermis in thick skin and what are their functions?
In thick skin, the layers of the epidermis from deep to superficial are stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, and stratum corneum. These layers contain stem cells, keratinocytes, melanocytes, dendritic cells, and tactile epithelial cells, and are responsible for producing and protecting the skin.
36
What are the layers of the epidermis in thin skin and how do they differ from thick skin?
In thin skin, the stratum lucidum appears to be absent and the other strata are thinner than in thick skin. Thin skin covers the rest of the body and is less subject to abrasion than thick skin.
37
What is the stratum basale and what is its function?
The stratum basale is the deepest epidermal layer, also called the stratum germinativum. It consists of a single row of stem cells representing the youngest keratinocytes, which undergo almost continuous mitosis. Each time one of these basal cells divides, one daughter cell is pushed into the cell layer just above to begin its specialization into a mature keratinocyte, while the other daughter cell remains in the basal layer to continue the process of producing new keratinocytes.
38
What is the stratum granulosum and what is its function?
The thin stratum granulosum consists of one to five cell layers in which keratinocyte appearance changes drastically, and the process of keratinization begins. These cells flatten, their nuclei and organelles begin to disintegrate, and they accumulate two types of granules: keratohyaline granules that help to form keratin in the upper layers, and lamellar granules that contain a water-resistant glycolipid that is secreted into the extracellular space. Together with tight junctions, the glycolipid plays a major part in slowing water loss across the epidermis.
39
Name the layers of the epidermis from superficial to deep that a rusty nail would pierce when stepping on it barefoot.
The layers of the epidermis that a rusty nail would pierce from superficial to deep are the stratum corneum, stratum lucidum (if present), stratum granulosum, stratum spinosum, and stratum basale.
40
What is the major function of the stratum basale?
The major function of the stratum basale is to produce new keratinocytes to replace the ones shed from the surface of the skin.
41
Why are the desmosomes and tight junctions connecting the keratinocytes so important?
The desmosomes and tight junctions connecting the keratinocytes are important because they help to hold the cells together and provide strength and stability to the epidermis.
42
What problems might be caused if the dead cells of the stratum corneum did not shed from the body and continued to accumulate?
If the dead cells of the stratum corneum did not shed from the body and continued to accumulate, it could cause dry, flaky skin, clogged pores, and potentially lead to skin infections.
43
What are cleavage lines in the skin?
Separations between underlying collagen fiber bundles in the reticular dermis that tend to run longitudinally in the skin of the limbs and in circular patterns around the neck and trunk.
44
Why are cleavage lines important to surgeons?
When an incision is made parallel to these lines, the skin gapes less and heals more readily.
45
What is the function of collagen fibers in the dermis?
They give skin strength and resiliency that prevent minor jabs and scrapes from penetrating the dermis.
46
What is the function of elastic fibers in the dermis?
They provide the stretch-recoil properties of skin.
47
What are flexure lines in the skin?
Dermal folds that occur at or near joints, where the dermis is tightly secured to deeper structures.
48
Where are flexure lines visible in the body?
On the wrists, fingers, soles, and toes.
49
What are friction ridges in the skin?
Skin ridges that may enhance our ability to grip certain kinds of surfaces and contribute to our sense of touch by enhancing vibrations detected by the large lamellar corpuscles (receptors) in the dermis.
50
What is the function of sweat pores along the crests of friction ridges?
They leave identifying films of sweat called fingerprints on almost anything we touch.
51
What is the reticular dermis?
The deeper layer of the dermis that accounts for about 80% of the thickness of the dermis and is coarse, dense irregular connective tissue.
52
What is the extracellular matrix of the reticular dermis composed of?
Thick bundles of interlacing collagen fibers.
53
What is the dermal vascular plexus?
The network of blood vessels that nourishes the reticular dermis and lies between this layer and the subcutaneous tissue.
54
What are striae?
Silvery white scars that result from extreme stretching of the skin, such as during pregnancy, that can tear the dermis.
55
What is melanin?
A polymer made of an amino acid called tyrosine that determines skin color.
56
What is the enzyme responsible for melanin synthesis?
Tyrosinase.
57
How does prolonged sun exposure affect skin color?
It causes a substantial melanin buildup, which helps protect the DNA of skin cells from UV radiation by absorbing the rays and dissipating the energy as heat. In all but the darkest-skinned people, this defensive response causes skin to darken visibly (tanning occurs).
58
What is carotene and where is it found in the body?
A yellow to orange pigment found in certain plant products such as carrots. It tends to accumulate in the stratum corneum and in the fat of the subcutaneous tissue.
59
What is the role of hemoglobin in determining skin color?
The pinkish hue of fair skin reflects the crimson color of the oxygenated pigment hemoglobin (he9mo-glo0bin) in the red blood cells circulating through the dermal capillaries. Because light-skinned people have only small amounts of melanin in their skin, the epidermis is nearly transparent and allows hemoglobin’s color to show through.
60
What are freckles and pigmented nevi?
Local accumulations of melanin.
61
What is cyanosis and what does it indicate?
Blueness of the skin due to poorly oxygenated hemoglobin, which can be a sign of respiratory or cardiovascular problems.
62
Name three alterations in skin color and their possible causes.
Pallor (emotional stress, low blood pressure, anemia), erythema (blushing, fever, inflammation, allergy), jaundice (liver disorder)
63
What are bruises and how do their color, size, and shape help in forensic medicine?
Bruises are areas of skin discoloration caused by blood leaking from damaged blood vessels. The color, size, and shape of bruises can help determine the timing and severity of an injury in forensic medicine.
64
What are the skin appendages and their functions?
Hair and hair follicles (sense insects, guard against physical trauma, heat loss, and sunlight), nails (protect fingertips and toes), sweat glands (regulate body temperature), sebaceous glands (secrete oil to lubricate and waterproof skin).
65
What is the structure of a hair and what is it made of?
Hairs are flexible strands produced by hair follicles and consist largely of dead, keratinized cells. They are made of hard keratin which is tougher and more durable than the soft keratin found in typical epidermal cells.
66
What is the main function of hair in humans?
To sense insects on the skin before they bite or sting us. Hair on the scalp guards the head against physical trauma, heat loss, and sunlight. Eyelashes shield the eyes, and nose hairs filter large particles like lint and insects from the air we inhale.
67
What are the three concentric layers of a hair?
The medulla, cortex, and cuticle.
68
What is the medulla of a hair?
The central core of a hair consisting of large cells and air spaces. It is the only part of the hair that contains soft keratin and is absent in fine hairs.
69
What are the chief regions of a hair?
The root, which is embedded in the skin, and the shaft, which projects above the skin's surface.
70
What determines the shape of a hair?
The shape of the hair shaft. If it is flat and ribbonlike, the hair is kinky. If it is oval, the hair is silky and wavy. If it is perfectly round, the hair is straight and tends to be coarse.
71
What is the arrector pili?
A small band of smooth muscle attached to the follicle that causes the hair to stand upright when contracted, producing goosebumps.
72
What is the sebaceous gland?
A gland that secretes an oily substance called sebum, which lubricates the hair and skin.
73
What is the hair bulb?
The expanded base of the hair follicle that contains the hair matrix, which produces new hair cells.
74
What is the hair matrix?
The actively dividing area of the hair bulb that produces new hair cells.
75
What is the glassy membrane?
A thickened, clear layer of the follicle wall that surrounds the hair bulb.
76
What is the melanocyte?
A cell in the hair bulb that produces pigment, giving hair its color.
77
What is the follicle wall?
The connective tissue sheath that surrounds the hair follicle.
78
What is the peripheral connective tissue sheath?
The fibrous sheath that surrounds the follicle wall.
79
What is the external root sheath?
The downward continuation of the epidermis that surrounds the follicle.
80
What is the internal root sheath?
The layer of epithelial tissue that surrounds the hair root and the lower part of the shaft.
81
What is the subcutaneous adipose tissue?
The layer of fat cells beneath the skin that provides insulation and padding.
82
What are the muscle cells called that raise hair on the skin?
Arrector pili.
83
What is the function of arrector pili muscle cells?
To raise hair on the skin.
84
What is the location of arrector pili muscle cells?
In the skin.
85
What is the other name for arrector pili muscle cells?
Raiser of hair.
86
What is the pronunciation of arrector pili?
ah-rek-tor pi-lye.
87
What is the arrector pili?
A tiny muscle attached to the base of a hair follicle in mammals.
88
What is the function of the arrector pili?
To contract and make the hair stand up, causing 'goosebumps' on the skin.
89
At what angle does the arrector pili approach the skin surface?
At a slight angle.
90
What are goose bumps?
Small bumps that appear on the skin in response to cold temperatures or fear.
91
What causes goose bumps?
The contraction of small muscles at the base of each hair on the skin, which causes the hair to stand up and create a bump.
92
What is the purpose of goose bumps?
In animals, it can be a response to fear or aggression, making the animal appear larger and more intimidating. In humans, it is a vestigial response that has lost its original purpose.
93
What is the scientific term for goose bumps?
Piloerection.
94
What other factors can cause goose bumps?
Strong emotions, such as nostalgia or awe, can also cause goose bumps.
95
What is the evolutionary purpose of goose bumps?
In animals, it can be a response to fear or aggression, making the animal appear larger and more intimidating. In humans, it is a vestigial response that has lost its original purpose.
96
What is the advantage of retaining heat for animals?
It helps them stay warm in cold environments.
97
How do animals protect themselves from cold environments?
By retaining heat.
98
What kind of animals stay warmer due to their fur?
Furry animals.
99
What is the function of fur in furry animals?
To help them stay warm.
100
What is the benefit of staying warm for animals?
It helps them survive in cold environments.
101
What is the name of the phenomenon where an animal's hair stands on end?
Piloerection.
102
What is the purpose of piloerection in animals?
To make the animal look larger and more formidable.
103
Which part of the body is affected by piloerection in animals?
Hair or fur.
104
Which animals exhibit piloerection?
Many mammals, including cats, dogs, and humans.
105
What is another name for piloerection in humans?
Goosebumps or goose flesh.
106
What is sebum?
Sebum is an oily substance secreted by the sebaceous glands in the skin.
107
What is the function of sebum?
The function of sebum is to moisturize and protect the skin and hair.
108
Where is sebum produced?
Sebum is produced by the sebaceous glands in the skin.
109
What is the role of sebum in the skin?
Sebum helps to lubricate the skin surface.
110
How does sebum act as a skin lubricant?
Sebum is secreted onto the skin surface where it acts as a lubricant.
111
What is terminal hair?
Terminal hair is a type of hair that is thick, long, and pigmented. It is the hair that grows on the scalp, lashes, and eyebrows.
112
What is vellus hair?
Vellus hair is a type of hair that is short, fine, and unpigmented. It is the hair that covers most of the body.
113
What is the difference between terminal hair and vellus hair?
Terminal hair is thicker, longer, and pigmented, while vellus hair is shorter, finer, and unpigmented.
114
Where is terminal hair found?
Terminal hair is found on the scalp, lashes, and eyebrows.
115
What is the color of terminal hair?
Terminal hair may be darker in color.
116
What is the difference between scalp hair and body hair?
Scalp hair is terminal hair, while body hair is mostly vellus hair.
117
What is the texture of terminal hair?
Terminal hair is thick in texture.
118
What are terminal hairs?
Thick, long, and pigmented hairs that grow in certain areas of the body.
119
When do terminal hairs appear in the body?
At puberty.
120
Where do terminal hairs appear at puberty?
In the axillary and pubic regions.
121
What is the difference between terminal and vellus hairs?
Terminal hairs are thicker, longer, and more pigmented than vellus hairs, which are shorter, finer, and less pigmented.
122
What is the role of androgens in the growth of terminal hairs?
Androgens stimulate the growth of terminal hairs in certain areas of the body, such as the axillary and pubic regions.
123
What are the other areas of the body where terminal hairs may grow?
Terminal hairs may also grow on the face, chest, and legs in males, and on the face and lower abdomen in females.
124
What is the function of terminal hairs in the axillary and pubic regions?
Terminal hairs in these regions may help to reduce friction and chafing, and may also play a role in pheromone signaling.
125
What are androgens?
Male sex hormones.
126
What are the effects of androgens?
Stimulating effects.
127
Which gender has higher levels of androgens?
Males.
128
What is the role of androgens in male development?
They play a crucial role in male development.
129
What is the primary androgen in males?
Testosterone.
130
What are the secondary sexual characteristics that androgens help develop in males?
Facial hair, deep voice, and muscle mass.
131
What is the medical condition caused by low levels of androgens in males?
Hypogonadism.
132
What is the medical condition caused by high levels of androgens in females?
Polycystic ovary syndrome (PCOS).
133
What is the cortex?
A bulky layer surrounding the medulla.
134
What is the location of the cortex?
Around the medulla.
135
What is the function of the cortex?
The cortex is responsible for processing and integrating sensory information, as well as for initiating voluntary motor movements.
136
What is the relationship between the cortex and the medulla?
The cortex surrounds the medulla.
137
What is the outermost cuticle made of?
A single layer of cells.
138
What is the purpose of hair conditioners?
To smooth out the rough surface of hair.
139
What is the benefit of using hair conditioners?
It makes hair easier to comb and manage.
140
What is the main ingredient in most hair conditioners?
Emollients, such as silicone or oils.
141
What is the difference between a regular conditioner and a leave-in conditioner?
A regular conditioner is rinsed out after a few minutes, while a leave-in conditioner is not rinsed out and is left on the hair.
142
How often should you use hair conditioner?
It depends on your hair type and condition, but generally 2-3 times a week is recommended.
143
Can hair conditioner repair damaged hair?
No, it cannot repair damaged hair, but it can help to prevent further damage and make hair appear healthier.
144
Is it necessary to use hair conditioner every time you wash your hair?
No, it is not necessary to use hair conditioner every time you wash your hair, but it can be beneficial for some hair types to use it regularly.
145
What is the most heavily keratinized part of the hair?
The hair shaft.
146
What is the function of keratin in the hair shaft?
To provide strength.
147
What is the composition of the hair shaft?
Keratinized cells.
148
What is the function of the hair shaft?
To protect the inner layers of the hair and provide structural support.
149
What is the difference between the hair shaft and the hair root?
The hair shaft is the visible part of the hair, while the hair root is located beneath the skin surface.
150
What is the role of melanin in the hair shaft?
To provide color to the hair.
151
What is the function of sebaceous glands in relation to the hair shaft?
To secrete oils that lubricate and protect the hair shaft.
152
What is the role of the hair cuticle?
To protect the inner layers of the hair shaft from damage.
153
What are split ends?
Split ends are the frayed and damaged tips of hair strands.
154
What causes split ends?
Split ends are caused by damage to the hair's cuticle layer, often due to heat styling, chemical treatments, or rough handling.
155
What is the cortex of hair?
The cortex is the middle layer of the hair shaft, responsible for providing strength and elasticity to the hair.
156
What is the medulla of hair?
The medulla is the innermost layer of the hair shaft, consisting of soft keratin cells.
157
How do split ends form?
Split ends form when damage to the hair's cuticle layer causes the cortex and medulla to fray, resulting in split and damaged hair tips.
158
What is melanin?
Melanin is a pigment that gives color to the skin, hair, and eyes.
159
What is the function of melanin in hair?
Melanin provides color to the hair.
160
What happens when melanin production decreases in hair?
When melanin production decreases in hair, hair turns gray or white.
161
What causes the decrease in melanin production in hair?
The decrease in melanin production in hair is a natural part of the aging process.
162
Can stress cause hair to turn gray?
There is some evidence to suggest that stress may contribute to premature graying of hair.
163
Is there a way to reverse gray hair?
There is currently no way to reverse gray hair.
164
What is the difference between gray hair and white hair?
Gray hair still has some melanin, while white hair has no melanin at all.
165
Can hair turn gray overnight?
No, hair cannot turn gray overnight. It is a gradual process.
166
What is a hair follicle?
A knot of sensory nerve endings.
167
What is the function of a hair follicle?
To produce hair.
168
Where are hair follicles found in the body?
All over the body except for the palms of the hands and soles of the feet.
169
What are the three main parts of a hair follicle?
The bulb, the root, and the shaft.
170
What is the role of the bulb in a hair follicle?
It nourishes and supports the hair.
171
What is the role of the root in a hair follicle?
It anchors the hair to the skin.
172
What is the role of the shaft in a hair follicle?
It is the visible part of the hair that extends above the skin.
173
What is the function of our hairs?
To act as sensitive touch receptors.
174
What is a hair papilla?
A dermal papilla located at the base of a hair follicle.
175
Where is a hair papilla located?
At the base of a hair follicle.
176
What is the function of a hair papilla?
To nourish and support the growth of hair.
177
What is the structure of a hair papilla?
It is a small, nipple-like projection of the dermis that contains blood vessels and connective tissue.
178
What happens if a hair papilla is damaged?
Hair growth may be affected or stopped completely.
179
What is the importance of a hair papilla?
It is essential for the growth and maintenance of hair follicles.
180
What is the composition of a hair papilla?
It contains blood vessels, nerves, and connective tissue.
181
What are the two components of the wall of a hair follicle?
A dermal component and an epidermal component.
182
What is the peripheral connective tissue sheath?
It is a fibrous sheath that surrounds the axon of a peripheral nerve.
183
What is the function of the peripheral connective tissue sheath?
It provides support and protection to the axon and helps to maintain its structural integrity.
184
What is the composition of the peripheral connective tissue sheath?
It is composed of several layers of connective tissue, including endoneurium, perineurium, and epineurium.
185
What is endoneurium?
It is the innermost layer of the peripheral connective tissue sheath that surrounds individual axons.
186
What is perineurium?
It is the middle layer of the peripheral connective tissue sheath that surrounds bundles of axons called fascicles.
187
What is epineurium?
It is the outermost layer of the peripheral connective tissue sheath that surrounds the entire nerve and provides a pathway for blood vessels and lymphatics.
188
What is the origin of the connective tissue sheath?
It is derived from the dermis.
189
What does the connective tissue sheath form?
It forms a protective covering around nerves and blood vessels.
190
What is the outermost layer of the follicle wall called?
The external layer or outer sheath.
191
What is the basement membrane of the follicle epithelium?
The essence of the follicle epithelium.
192
What is the function of the basement membrane in the follicle epithelium?
To provide structural support and act as a barrier between the epithelium and underlying connective tissue.
193
What is the location of the basement membrane in the follicle epithelium?
It is located at the base of the follicle epithelium.
194
What is the epithelial root sheath?
The epithelial root sheath is a structure that surrounds the root of a hair follicle.
195
What is the origin of the epithelial root sheath?
The epithelial root sheath is derived from the embryonic ectoderm.
196
What is the function of the epithelial root sheath?
The epithelial root sheath plays a role in hair follicle development and maintenance.
197
What are the components of the epithelial root sheath?
The epithelial root sheath is composed of several layers of epithelial cells, including the outer root sheath, inner root sheath, and Huxley's layer.
198
What is the outer root sheath?
The outer root sheath is the outermost layer of the epithelial root sheath and is continuous with the epidermis.
199
What is the inner root sheath?
The inner root sheath is the layer of the epithelial root sheath that surrounds the hair shaft and is composed of three layers: Henle's layer, Huxley's layer, and the cuticle.
200
What is Huxley's layer?
Huxley's layer is a layer of the inner root sheath that is located between Henle's layer and the cuticle.
201
What is the cuticle?
The cuticle is the innermost layer of the inner root sheath and is in direct contact with the hair shaft.
202
What is the internal root sheath?
The internal root sheath is a part of the hair follicle that surrounds the hair shaft.
203
What is the origin of the internal root sheath?
The internal root sheath is derived from the matrix cells.
204
What are matrix cells?
Matrix cells are undifferentiated cells located at the base of the hair follicle that give rise to the hair shaft and its associated structures.
205
What is the function of the internal root sheath?
The internal root sheath provides structural support and protection to the growing hair shaft.
206
What are the different layers of the internal root sheath?
The internal root sheath is composed of three layers: the cuticle, the Huxley layer, and the Henle layer.
207
What is the cuticle layer of the internal root sheath?
The cuticle layer is the outermost layer of the internal root sheath and is composed of flat, overlapping cells that provide a protective barrier.
208
What is the Huxley layer of the internal root sheath?
The Huxley layer is the middle layer of the internal root sheath and is composed of several layers of flattened cells.
209
What is the Henle layer of the internal root sheath?
The Henle layer is the innermost layer of the internal root sheath and is composed of a single layer of cuboidal cells.
210
What is the reason for hair growth?
Hair grows because cells in the bulb of the follicle divide.
211
What is the average rate of hair growth per week?
2 mm.
212
Does the rate of hair growth vary?
Yes.
213
By what factors can the rate of hair growth vary?
Age, gender, genetics, health, and environmental factors.
214
What are some environmental factors that can affect hair growth?
Climate, stress, and nutrition.
215
What is the scientific name for hair loss?
Alopecia.
216
What is the most common cause of hair loss?
Androgenetic alopecia (male or female pattern baldness).
217
What is the medical term for male pattern baldness?
Androgenetic alopecia.
218
What is the medical term for female pattern baldness?
Female pattern hair loss or androgenetic alopecia.
219
What is the average number of hairs on the human scalp?
Around 100,000 to 150,000 hairs.
220
What happens during the active phase of hair growth?
The newly growing hair pushes out the old hair.
221
What is the active phase of hair growth called?
Anagen phase.
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What is the name of the old hair that is pushed out during the active phase of hair growth?
Club hair.
223
What is the duration of the active phase of hair growth?
2-7 years.
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What happens during the resting phase of hair growth?
Hair follicles shrink and hair growth stops.
225
What is the resting phase of hair growth called?
Telogen phase.
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What is the duration of the resting phase of hair growth?
2-4 months.
227
What happens during the shedding phase of hair growth?
Old hair falls out and new hair growth begins.
228
What is the shedding phase of hair growth called?
Exogen phase.
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At what age does hair grow the fastest?
During the teen years.
230
What are the ideal conditions for hair growth?
Healthy diet, good sleep, and low stress levels.
231
What are the factors that affect hair growth?
Age, genetics, hormones, and health status.
232
What is the average rate of hair growth per month?
About half an inch (1.25 cm).
233
What is the purpose of hair?
To protect the skin and regulate body temperature.
234
What is the lifespan of a hair strand?
2-7 years.
235
What is the scientific name for hair loss?
Alopecia.
236
What are some common causes of hair loss?
Genetics, aging, hormonal changes, medical conditions, and certain medications.
237
What are some ways to promote hair growth?
Eating a balanced diet, taking supplements, reducing stress, and avoiding damaging hair practices.
238
What are the possible causes of hair growth stimulation?
Ovarian or adrenal gland disorders.
239
What are the less common causes of hair growth stimulation?
Ovarian or adrenal gland disorders.
240
Which glands can cause hair growth stimulation?
Ovarian or adrenal glands.
241
What are the medical conditions that can cause hair growth stimulation?
Ovarian or adrenal gland disorders.
242
What are the hormonal disorders that can cause hair growth stimulation?
Ovarian or adrenal gland disorders.
243
What are the organs that can cause hair growth stimulation?
Ovaries or adrenal glands.
244
What can tumors secrete?
Tumors can secrete androgens.
245
What is the effect of androgens secretion by tumors?
It can lead to various clinical conditions.
246
Do all tumors secrete androgens?
No, not all tumors secrete androgens.
247
What are the clinical conditions that can be caused by androgens secretion by tumors?
It depends on the type and location of the tumor.
248
Is androgen secretion by tumors a common occurrence?
It is not very common, but it can happen in some cases.
249
Can androgen secretion by tumors be treated?
Yes, it can be treated depending on the underlying cause and the severity of the condition.
250
What is the medical term for the condition caused by androgen secretion by tumors?
It depends on the type and location of the tumor.
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Is androgen secretion by tumors only seen in men?
No, it can occur in both men and women.
252
12. Why is having your hair cut painless?
Hair cutting is painless because hair is composed of dead cells that lack nerves.
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13. What are the names of the parts of the hair labeled a and c? What are the names of structures b and d and what is the function of each of these structures?
a - hair shaft, c - hair follicle, b - arrector pili muscle, d - sebaceous gland. The arrector pili muscle is responsible for making the hair stand up when we are cold or frightened. The sebaceous gland produces sebum, an oily substance that lubricates the hair and skin.
254
14. DRAW Draw a cross section of a hair shaft and label its three concentric regions.
Answer not provided in the given text.
255
What are sweat glands?
Sweat glands are also called sudoriferous glands and are distributed over the entire skin surface except the nipples and parts of the external genitalia. Their number is staggering—up to 3 million per person.
256
How many types of sweat glands are there?
There are two types of sweat glands: eccrine and apocrine.
257
What is the difference between eccrine and apocrine sweat glands?
Eccrine sweat glands are far more numerous than apocrine sweat glands and are particularly abundant on the palms, soles of the feet, and forehead. Each is a simple, coiled, tubular gland. The secretory part lies coiled in the dermis, and the duct extends to open in a funnel-shaped pore at the skin surface. Apocrine sweat glands are found mainly in the skin of the axilla, groin, areolae, and bearded facial regions of adult males. The secretory part of the gland lies in the superficial dermis or hypodermis, and the duct usually empties into a hair follicle.
258
What is the function of sweat glands?
Sweat glands help control body temperature.
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What are sebaceous glands?
Sebaceous glands secrete sebum.
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Where are sebaceous glands found?
Sebaceous glands are found all over the skin except for the palms and soles of the feet.
261
What is the function of sebum?
Sebum helps keep the skin and hair soft, pliable, and waterproof.
262
What are eccrine glands?
They are sweat glands that lie closer to the skin surface and their ducts empty directly onto the skin surface.
263
What are apocrine glands?
They are modified sweat glands that lie deeper in the dermis or subcutaneous tissue, and their ducts empty into hair follicles.
264
What is the difference between eccrine and apocrine secretion?
Eccrine secretion is a hypotonic filtrate of the blood that is released directly onto the skin surface, while apocrine secretion contains fatty substances and proteins, and is released into hair follicles.
265
What is the function of eccrine glands?
Their major function is to prevent the body from overheating by producing sweat.
266
What is the function of apocrine glands?
Their precise function is not yet known, but they may be the human equivalent of other animals' sexual scent glands.
267
What are ceruminous glands?
They are modified apocrine glands found in the lining of the ear canal, and they produce earwax (cerumen).
268
What is the composition of eccrine gland secretion?
It is 99% water, with some salts (mostly sodium chloride), traces of metabolic wastes (urea, uric acid, and ammonia), and a microbe-killing peptide called dermcidin.
269
What is the composition of apocrine gland secretion?
It contains the same basic components as true sweat, plus fatty substances and proteins.
270
What is the method of secretion for eccrine glands?
They release their product by exocytosis (merocrine secretion).
271
What is the method of secretion for apocrine glands?
They release their product by exocytosis (merocrine secretion).
272
Name at least five functions of the skin.
The skin performs a variety of functions, including protection, body temperature regulation, cutaneous sensation, metabolic functions, blood reservoir, and excretion.
273
What are the three types of barriers provided by the skin?
The skin constitutes at least three types of barriers: chemical, physical, and biological.
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What are the chemical barriers provided by the skin?
Chemical barriers include skin secretions and melanin. Skin secretions have a low pH that retards bacterial multiplication, and bactericidal substances in sebum kill many bacteria outright. Skin cells also secrete natural antibiotics called defensins that literally punch holes in bacteria. Melanin provides a chemical pigment shield to prevent UV damage to skin cells.
275
What are the physical barriers provided by the skin?
The continuity of skin and the hardness of its keratinized cells provide physical barriers. The stratum corneum, which has been compared to bricks and mortar, is the outstanding barrier capacity of the skin.
276
What are the biological barriers provided by the skin?
Biological barriers include dendritic cells, macrophages, and DNA. Dendritic cells and macrophages are immune cells that help to prevent infection. DNA absorbs UV radiation and converts it to harmless heat.
277
What are sebaceous glands and what is their function?
Sebaceous glands are simple branched alveolar glands that secrete an oily substance called sebum. Sebum softens and lubricates the hair and skin, prevents hair from becoming brittle, and slows water loss from the skin. It also has bactericidal action and increases its activity during puberty under the influence of male sex hormones.
278
What is acne and what causes it?
Acne is an active inflammation of the sebaceous glands accompanied by 'pimples' (pustules or cysts), whiteheads, or blackheads on the skin. It is associated with infection by Propionibacterium acne and can range from mild to severe, leading to permanent scarring.
279
What is seborrhea and what causes it?
Seborrhea is overactive sebaceous glands that cause 'fast-flowing sebum,' known as 'cradle cap' in infants. It begins on the scalp as pink, raised lesions that gradually become yellow to brown and begin to slough off oily scales.
280
What are biological barriers in the skin?
Dendritic cells in the epidermis and macrophages in the dermis.
281
What is the function of dendritic cells in the skin?
They patrol beneath the skin's surface, engulfing any foreign invaders that have penetrated the epidermis, and trigger an immune response.
282
What is the function of dermal macrophages in the skin?
They dispose of viruses and bacteria that manage to penetrate the epidermis and can initiate an immune response.
283
How does the body regulate its temperature?
By sweating, which dissipates body heat and efficiently cools the body, preventing overheating.
284
What are the cutaneous sensory receptors in the skin?
Tactile (Meissner's) corpuscles, tactile epithelial cells, lamellar (Pacinian) corpuscles, hair follicle receptors, and free nerve endings.
285
What is the metabolic function of the skin?
The skin converts modified cholesterol molecules to a vitamin D precursor when sunlight bombards the skin, which plays various roles in calcium metabolism. The epidermis also makes chemical conversions that supplement those of the liver.
286
What substances can penetrate the skin?
Lipid-soluble substances, such as oxygen, carbon dioxide, fat-soluble vitamins (A, D, E, and K), and steroids (estrogens), oleoresins of certain plants, organic solvents, salts of heavy metals, selected drugs, and drug agents called penetration enhancers that help ferry other drugs into the body.
287
What are the water-resistant glycolipids of the epidermis?
They block most diffusion of water and water-soluble substances between cells, preventing both their loss from and entry into the body through the skin.
288
What are the dangers of organic solvents and heavy metals penetrating the skin?
They can be lethal and result in kidney shutdown, brain damage, anemia, and neurological defects. These substances should never be handled with bare hands.
289
What are the most common skin disorders?
Bacterial, viral, or yeast infections.
290
What is the most common type of cancer?
Skin cancer.
291
What is the most important risk factor for skin cancer?
Exposure to UV radiation in sunlight and tanning beds.
292
What are the three major forms of skin cancer?
Basal cell carcinoma, squamous cell carcinoma, and melanoma.
293
What is basal cell carcinoma?
The least malignant and most common form of skin cancer that accounts for nearly 80% of cases. It occurs on sun-exposed areas of the face and appears as shiny, dome-shaped nodules that later develop a central ulcer with a pearly, beaded edge.
294
What is squamous cell carcinoma?
The second most common skin cancer that arises from the keratinocytes of the stratum spinosum. The lesion appears as a scaly reddened papule that arises most often on the head and hands. It tends to grow rapidly and metastasize if not removed.
295
What is melanoma?
The most dangerous form of skin cancer that arises from the melanocytes. It is often characterized by a change in the size, shape, or color of a mole or other pigmented skin lesion.
296
What is the function of collagenase?
To aid the natural turnover of collagen and deter wrinkles.
297
What is the dermal vascular supply?
An extensive network of blood vessels in the dermis that can hold about 5% of the body's entire blood volume.
298
How does the body eliminate nitrogen-containing wastes?
Through sweat, although most such wastes are excreted in urine.
299
What is the effector that causes blood vessel dilation or constriction when blood vessels in the dermis constrict or dilate to help maintain body temperature?
Smooth muscle tissue.
300
Define third-degree burns.
Third-degree burns are full-thickness burns that involve the entire thickness of the skin, and the burned area appears gray-white, cherry red, or blackened, and initially there is little or no edema. Since the nerve endings have been destroyed, the burned area is not painful.
301
What is the recommended treatment for third-degree burns?
Skin grafting is advised.
302
What are the critical conditions for burns?
Burns are considered critical if any of the following conditions exist: over 25% of the body has second-degree burns, over 10% of the body has third-degree burns, or there are third-degree burns of the face, hands, or feet.
303
How is the percentage of body surface burned estimated in adults?
The percentage of body surface burned is estimated using the rule of nines, which divides the body into 11 areas, each accounting for 9% of total body area, plus an additional area surrounding the genitals accounting for 1% of body surface area.
304
What is melanoma?
Melanoma is cancer of melanocytes, and it is the most dangerous skin cancer because it is highly metastatic and resistant to chemotherapy.
305
What is the key to surviving melanoma?
The key to surviving melanoma is early detection.
306
What is the ABCD rule for recognizing melanoma?
The ABCD rule for recognizing melanoma is: Asymmetry, Border irregularity, Color, and Diameter.
307
What is the immediate threat to life resulting from severe burns?
The immediate threat to life resulting from severe burns is a catastrophic loss of body fluids containing proteins and electrolytes, which leads to dehydration and electrolyte imbalance, and then renal failure and circulatory shock.
308
How are burns classified according to their severity?
Burns are classified according to their severity (depth) as first-, second-, or third-degree burns.
309
What are the symptoms of first-degree burns?
Symptoms of first-degree burns include localized redness, swelling, and pain.
310
What are the symptoms of second-degree burns?
Symptoms of second-degree burns mimic those of first-degree burns, but blisters also appear. The burned area is red and painful, but skin regeneration occurs with little or no scarring within three to four weeks if care is taken to prevent infection.
311
What is the difference between partial-thickness and full-thickness burns?
First- and second-degree burns are considered partial-thickness burns, while third-degree burns are full-thickness burns.
312
What is the major problem with skin grafts?
Extensive scar tissue often forms, which can limit mobility at joints and other critical areas.
313
What is synthetic skin and how is it used?
Synthetic skin is a silicone 'epidermis' bound to a spongy 'dermal' layer composed of collagen and ground cartilage, which can be applied to the debrided area. In time, the patient's own dermal tissue absorbs and replaces the artificial one. Then the silicone sheet is peeled off and replaced with a network of epidermal cells cultured from the patient's own skin.
314
What is three-dimensional bio-printing and how is it used in skin grafts?
Three-dimensional bio-printing is used to create skin grafts that can be used as alternatives to a patient's own skin. This tissue engineering technology makes use of a bio ink comprising a combination of keratinocytes, fibroblasts, pericytes, and endothelial cells to construct a multilayered skin graft. The advantage of using this technology is that it produces a functional epidermis and vascularized dermis, which improve the chances of graft survival and integration with the patient's own tissue.
315
What is the main threat to burn patients after the initial crisis has passed?
Infection, with sepsis (widespread bacterial infection) being the leading cause of death in burn victims.
316
What is the rule of nines used for in burn treatment?
The rule of nines is used to estimate the extent and severity of burns. Surface area values for the anterior body surface are indicated on the human figure, and total surface area (anterior and posterior body surfaces) for each body region is indicated to the right of the figure.
317
Why are burns to the anterior head and face often more serious than those to the body trunk, despite representing only a small percentage of the body surface?
Burns to the anterior head and face are often more serious than those to the body trunk because they can impair breathing, vision, and communication, and can also cause disfigurement.
318
What is vernix caseosa and what is its function?
Vernix caseosa is a white, cheesy-looking substance produced by the sebaceous glands that protects the fetus's skin within the water-filled amnion.
319
What are milia and when do they disappear?
Milia are small white spots that appear on the newborn's skin due to accumulations in the sebaceous glands on the forehead and nose. They normally disappear by the third week after birth.
320
What is the relationship between the integumentary system and the skeletal system?
The skin protects bones and synthesizes a vitamin D precursor needed for normal calcium absorption and deposit of bone salts, which make bones hard. The skeletal system provides support for the skin.
321
What is the relationship between the integumentary system and the muscular system?
The skin protects muscles. Active muscles generate large amounts of heat, which increases blood flow to the skin and may activate sweat glands in the skin.
322
What is the relationship between the integumentary system and the nervous system?
The skin protects nervous system organs. Cutaneous sensory receptors for touch, pressure, pain, and temperature are located in the skin. The nervous system regulates the diameter of blood vessels in the skin, activates sweat glands, contributes to thermoregulation, interprets cutaneous sensation, and activates arrector pili muscles.
323
What is the relationship between the integumentary system and the endocrine system?
The skin protects endocrine organs. It converts some hormones to their active forms and synthesizes a vitamin D precursor. Androgens produced by the endocrine system activate apocrine and sebaceous glands and are involved in regulating hair growth.
324
What is the relationship between the integumentary system and the cardiovascular system?
The skin protects cardiovascular organs, prevents fluid loss from the body, and serves as a blood reservoir. The cardiovascular system transports oxygen and nutrients to the skin and removes wastes from the skin. It provides substances needed by skin glands to make their secretions.
325
What is the relationship between the integumentary system and the lymphatic system/immunity?
The skin protects lymphatic organs, prevents pathogen invasion, and dendritic cells and macrophages help activate the immune system. The lymphatic system prevents edema by picking up excessive leaked fluid, and the immune system protects skin cells.
326
What is the relationship between the integumentary system and the respiratory system?
The skin protects respiratory organs. Hairs in the nose help filter out dust from inhaled air. The respiratory system furnishes oxygen to skin cells and removes carbon dioxide via gas exchange with blood.
327
What is the relationship between the integumentary system and the digestive system?
The skin protects digestive organs, provides vitamin D needed for calcium absorption, and performs some of the same chemical conversions as liver cells. The digestive system provides needed nutrients to the skin.
328
What is the relationship between the integumentary system and the urinary system?
The skin protects urinary organs and excretes salts and some nitrogenous wastes in sweat. The kidneys activate the vitamin D precursor made by keratinocytes and dispose of nitrogenous wastes of skin metabolism.
329
What is the relationship between the integumentary system and the reproductive system?
The skin protects reproductive organs, and cutaneous receptors respond to erotic stimuli. Highly modified sweat glands (mammary glands) produce milk. During pregnancy, the skin stretches to accommodate the growing fetus, and changes in skin pigmentation may occur.
330
What are the effects of aging on the skin?
The rate of epidermal cell replacement slows, the skin thins, and its susceptibility to bruises and other injuries increases. The lubricating substances produced by the skin glands that make young skin so soft become deficient. Skin becomes dry and itchy, although people with naturally oily skin seem to postpone this dryness until later in life. Elastic fibers clump, and collagen fibers become fewer and stiffer. The subcutaneous fat layer diminishes, leading to the intolerance to cold so common in elderly people. Additionally, declining levels of sex hormones result in similar fat distribution in elderly men and women. Decreasing elasticity of the skin, along with the loss of subcutaneous tissue, inevitably leads to wrinkling. Decreasing numbers of melanocytes and dendritic cells enhance the risk and incidence of skin cancer in this age group.
331
What is the best way to slow down skin aging?
Shielding your skin from the sun’s rays of both UVA (aging rays) and UVB (rays that burn) light.
332
What happens to hair during aging?
By age 50, the number of active hair follicles has declined markedly and continues to fall, resulting in hair thinning. Hair loses its luster in old age, and the genes responsible for graying and male pattern baldness become active.
333
What happens to the skin during adolescence?
During adolescence, the skin and hair become oilier as sebaceous glands increase their activity, and acne may appear. Acne generally subsides in early adulthood, and skin reaches its optimal appearance when we reach our 20s and 30s. Thereafter, the skin starts to show the effects of cumulative environmental assaults (abrasion, wind, sun, chemicals). Scaling and various kinds of skin inflammation, or dermatitis (der0mah-ti9tis), become more common.
334
What is dermatology?
The branch of medicine that studies and treats disorders of the skin.
335
What is eczema?
A skin rash characterized by itching, blistering, oozing, and scaling of the skin. A common allergic reaction in children, but also occurs in adults. Frequent causes include allergic reactions to certain foods (fish, eggs, and others) or to inhaled dust or pollen. Treated by methods used for other allergic disorders.
336
What is psoriasis?
A chronic autoimmune condition characterized by raised, reddened epidermal patches covered with silvery scales that itch or burn, crack, and sometimes bleed or become infected. When severe, it may be disfiguring and debilitating. Trauma, infection, hormonal changes, and stress can trigger or exacerbate psoriasis.
337
What is vitiligo?
The most prevalent skin pigmentation disorder, characterized by a loss of melanocytes and uneven dispersal of melanin, resulting in unpigmented skin regions surrounded by normally pigmented areas.
338
What is scleroderma?
An autoimmune disorder characterized by stiff, hardened skin due to abnormal amounts of collagen in the dermis that severely limit joint movements and facial expressions. A classic sign of the disorder is Raynaud’s phenomenon in which the fingers and toes become white and painful because of poor blood flow to those areas.
339
What triggers autoimmune attacks in skin disorders?
Changes, infections, or stress often trigger the autoimmune attacks.
340
What is rosacea?
A chronic skin eruption produced by dilated small blood vessels of the face, particularly the nose and cheeks. Papules and acne-like pustules may or may not occur. More common in women.
341
What determines skin color?
Skin color reflects the amount of pigments (melanin and carotene) in the skin and the oxygenation level of hemoglobin in blood.
342
What are the primary functions of eccrine sweat glands?
Their primary function is thermoregulation.
343
What are the primary functions of apocrine sweat glands?
Their secretion is similar to eccrine secretion, but it also contains proteins and fatty substances on which bacteria thrive. They may function as scent glands.
344
What is the actively growing region of a nail called?
The nail matrix.
345
Which is the most common cause of skin cancer?
Exposure to ultraviolet radiation.
346
What are the types of skin cancer and which one is more dangerous?
Basal cell carcinoma and squamous cell carcinoma are cured if they are removed before metastasis. Melanoma, a cancer of melanocytes, is less common but more dangerous.
347
What are the initial and second threats in severe burns?
The initial threat is loss of protein- and electrolyte-rich body fluids, which may lead to circulatory collapse. The second threat is overwhelming bacterial infection.
348
How can the extent of a burn be evaluated?
By using the rule of nines.
349
What are the three degrees of burns and which one requires grafting for successful recovery?
The severity of burns is indicated by the terms first degree, second degree, and third degree. Third-degree burns are full-thickness burns that require grafting for successful recovery.
350
What are the functions of the skin?
Protection, body temperature regulation, cutaneous sensation, metabolic functions, blood reservoir, and excretion.
351
What are sebaceous glands and what is their function?
Sebaceous glands are simple alveolar glands that produce oily holocrine secretion called sebum. Sebum lubricates the skin and hair, slows water loss from the skin, and acts as a bactericidal agent.
352
What are the epidermal derivatives?
Hair, sweat gland, and sebaceous gland.
353
What is the first threat to life from a massive third-degree burn?
Catastrophic fluid loss.
354
What are the three degrees of burns and how are they distinguished?
First-degree burns involve only the epidermis, second-degree burns involve the epidermis and part of the dermis, and third-degree burns involve the entire thickness of the skin.
355
Why does skin wrinkle and what accelerates the wrinkling process?
Skin wrinkles due to loss of collagen and elastic fibers and subcutaneous fat. Photodamage is a major cause of skin aging and accelerates the wrinkling process.
356
