1
Q
Introduction
A
- The organs of the integumentary system include the skin and its accessory structures including hair, nails, and glands, as well as blood vessels, muscles and nerves.
- Note that all 4 of the basic tissue types are well-represented in this organ system: Epithelium in the hair, nails, and the epidermis of the skin; the dermis contains C.T.; muscle is found attached to the hair follicles, and in the substance of arteries and veins; nerves provide an abundance of sensation.
2
Q
Integumentary System
A
The Integument is an organ system comprised of many organs such as hair and multiple types
of glands.
3
Q
Integumentary System
A
- The integument can also be thought of as a cutaneous membrane that covers the outer surface of the body.
- It is the largest organ by surface area and weight.
- Its area is about 2 square meters (22 square feet) and weighs 4.5–5kg (10–11 lb), about 16% of body weight.
- It is 0.5–4 mm thick, thinnest on the eyelids, thickest on the heels.
- We lose almost a kg of skin epithelium a year that becomes a major part of household “dust”.
- It is the largest organ by surface area and weight.
4
Q
Functions of the Skin
A
- Besides protection, the skin contributes to:
- Regulation of body temperature
- Sensory perceptions
- Synthesis of vitamin D
- Emotional expression
- It also serves as an important reservoir of blood.
5
Q
Structures of the Skin
A
- The skin has 3 major layers:
- The outer, thinner layer is called the epidermis and consists of epithelial tissue.
- The inner, thicker layer is called the dermis and consists of C.T.
- The subcutaneous (subQ) layer (also called the hypodermis) is located underneath the dermis.
- It is a loose areolar/adipose C.T. that attaches the skin to the underlying tissues and organs.
6
Q
Structures of the Skin
A
7
Q
Dermatologists
A
Dermatologist are doctors who treat disorders of all layers of the integumentary system
8
Q
The Epidermis
A
- The epidermis is composed of keratinized stratified squamous epithelium which contains four major types of cells:
- Keratinocytes
- Melanocytes
- Langerhans cells
- Merkel cells
9
Q
Epidermis
Keratinocytes
A
make up 90% of the cells. They produce keratin - a tough fibrous protein that provides protection.
10
Q
Epidermis
Melanocytes
A
produce the pigment melanin that protects against damage by ultraviolet radiation.
11
Q
Epidermis
**Langerhans cells **
A
are macrophages that originated in the red bone marrow. They are involved in the immune responses.
12
Q
Layers of epidermis
A
- The epidermis is composed of four layers in thin skin, and five layers in thick skin.
- Stratum basale
- stratum spinosum
- stratum granulosum
- stratum lucidum
- stratum corneum
13
Q
Epidermis
**stratum basale **
A
or stratum germinativum is always the bottom (deepest) layer. Continuous cell division occurs here and produces all the other layers.
14
Q
Epidermis
**stratum spinosum **
A
is a layer of 8–10 keratinocytes
The non-dividing cells of the 3rd layer (stratum granulosum) are filled with granules of keratin.
15
Q
epidermis
stratum lucidum
A
is the 4th layer but is only present in thick skin (the skin of the fingertips, palms, and soles).
16
Q
Epidermis
**stratum corneum **
A
- is always outermost, composed of approximately 20 layers of flat cell-remnants that are like “bags of turtle wax” (dead keratinocytes with no cellular organelles filled with only keratin protein.)
- They are continuously shed and replaced by cells from deeper strata.
17
Q
Epidermis
Keratinization
A
- is the process of replacing viable cells in the stratum basale with more and more of the waxy keratin protein as cells move from the deepest layer to the surface layer.
- Constant friction can stimulate the process and produce a callus (an even thicker buildup of keratinocytes in the stratum corneum).
- Dandruff is an excess of keratinized cells shed from the scalp.
18
Q
Epidermis
**Thin (hairy) skin **
A
covers all body regions except the palms, palmar surfaces of digits, and soles.
19
Q
Epidermis
Thick (hairless)
skin
A
covers the palms, palmar surfaces of digits, and soles.
20
Q
The Epidermis
Skin Pigments
A
- Melanin is produced by melanocytes in the stratum basale
- Eumelanin (brown to black)
- Pheomelanin (yellow to red)
- Freckles are clusters of concentrated melanin triggered by exposure to sunlight.
- Having more freckles is a genetic trait.
- Nevi (“birthmarks” or moles) are chronic lesions of the skin – they are, by definition, benign.
- Malignant melanoma is a cancer of melanocytes.
- Vitiligo is a chronic disorder that causes depigmentation patches in the skin. The precise pathogenesis, or cause, is not known, but is most likely a combination of
genetic factors coupled with a disorder of the immune system (autoimmune disease). - Albinism is a congenital disorder characterized by the complete or partial absence of pigment in the skin, hair, and eyes due to a defect of an enzyme involved in the production of melanin.
21
Q
The Dermis
A
is composed of connective tissue containing collagen and elastic fibers.
22
Q
The Dermis
**papillary region **
A
lies just below the epidermis and consists of areolar connective tissue containing thin collagen and elastic fibers, dermal papillae (including capillary loops), corpuscles of touch and free nerve endings.
23
Q
The Dermis:
**reticular region **
A
- consists of dense irregular connective tissue containing collagen and elastic fibers, adipose cells, hair follicles, nerves, sebaceous (oil) glands, and sudoriferous (sweat) glands.
- Tears or excessive stretching in this region cause stretch marks (also called striae).
24
Q
The Dermis
A
- Lines of cleavage are “tension lines” in the skin that indicate the predominant direction of underlying collagen fibers.
- Plastic surgeons make their incisions parallel to the normal cleavage lines in order to minimize scarring.
- Epidermal ridges reflect contours of the underlying dermal papillae and form the basis for fingerprints (and footprints)
- Function to increase firmness of grip by increasing friction
25
Subcutaneous Layer
* is also called the hypodermis, and it attaches the skin to underlying tissues and organs.
* It contains blood vessels and nerves in transit to the more superficial layers.
* It also contains lamellated (pacinian) corpuscles that detect external pressure applied to the skin.
26
Benefits of Multiple Layers
* Multiple layers in the skin allow for specialization.
* Adapted to fast turn-over, the epidermis resists damage and offers protection to underlying tissues.
* The dermis provides temperature stability and prevents dehydration, and yet is capable of limited healing.
* The subcutaneous tissues insulate,store fat, and anchor the skin.
27
Sensory Receptors
* The skin contains different types of sensory receptors to differentiate between the different tactile (“touch”) sensations.
* Light touch, pressure, vibration, itch and tickle
28
Sensory Receptors
* These sensory receptors are found in different layers:
* Superficially:
* Merkel discs, free nerve endings (detect many stimuli), Meissner corpuscles, and hair root plexuses
* Deep
* Pacinian corpuscles
29
**Hair**
* Hair is associated with the word “pili”.
* It is present on most surfaces except the palms, anterior surfaces of fingers, and the soles of the feet.
* It is composed of dead, keratinized epidermal cells.
* Genetics determines thickness and distribution.
* Hair helps with touch sensations and protects the body against the harmful effects of the sun and against heat loss.
30
**Hair**
* The parts of a hair include:
* The shaft (above the skin surface)
* The follicle (below the level of the skin)
* A root that penetrates into the dermis includes:
* An epithelial root sheath
* A dermal root sheath
31
**Hair**
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32
**Hair Type and Color**
* Types of hairs
* Lanugo – fine, nonpigmented, downy hairs that cover the body of the fetus
* Vellus hairs – short, fine, pale hairs barely visible to the naked eye
* Terminal hairs – long, coarse,heavily pigmented hairs
* Hair color is determined by the amount and type of melanin.
33
**Sebaceous (oil) glands **
* are connected to hair follicles.
* They secrete an oily substance called sebum which does 2 important things:
* Prevents dehydration of hair and skin
* Inhibits growth of certain bacteria
34
Skin Glands:
**Eccrine sweat glands **
* are the most numerous. They secrete a watery solution (600 ml per day) that helps to cool the body and eliminates small amounts of waste.
* Both are simple coiled tubular glands
35
Skin Glands:
Apocrine sweat glands
* are located mainly in the skin of the axilla, groin, areolae, and bearded facial regions of adult males. They secrete a slightly viscous sweat.
* Both are simple, coiled tubular glands.
36
Skin Glands
**Eccrine sweat glands **
* release sweat in response to an emotional stress such as fear or embarrassment. This type of sweating is referred to as emotional sweating or a “cold sweat”.
37
skin Glands
**The secretory portion of apocrine sweat glands **
* is located mostly in the subcutaneous layer, and the excretory duct opens into hair follicles, with sweat secreted during emotional stress and sexual excitement.
* Much of body odor is due to apocrine sweat.
38
skin Glands
**Ceruminous glands **
* are modified sweat glands located in the ear canal.
* Along with nearby sebaceous glands, they are involved in producing a waxy secretion called cerumen (earwax) which provides a sticky barrier that prevents entry of foreign bodies into the ear canal.
39
**Nails**
* Nails are composed of hard, keratinized epidermal cells located over the dorsal surfaces of the ends of fingers and toes.
* Nail structures include:
* Free edge
* Transparent nail body (plate)
* with a whitish lunula at its base
* Nail root embedded in a fold of skin
40
Maintaining Homeostasis
Skin damage sets in motion a sequence of events that repairs the skin to its normal (or near-normal) structure and function.
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41
Wound Healing
Two kinds of wound-healing processes can occur, depending on the depth of the injury.
1. Epidermal wound healing
2. Deep woundhealing
42
Epidermal wound healing
* occurs following superficial wounds that affect only the epidermis.
* Return to normal function is the rule.
43
Deep wound healing
* occurs when an injury extends to the dermis and subcutaneous layer.
* Loss of some function and development of scar tissue is the rule.
44
Wound Healing
We will observe similar attempts at homeostasis in all the organ systems we study for the remainder of the year.
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45
Burns
* is tissue damage caused by excessive heat, electricity, radioactivity, or corrosive chemicals that denature (break down) the proteins in the skin cells.
* Burns destroy some of the skin's important contributions to homeostasis—protection against microbial invasion and desiccation, and thermoregulation.
* Burns are graded according to their severity.
46
Epidermis
**Merkel cells**
function in the sensation of touch along with the other adjacent tactile discs (receptors).
47
A first-degree burn
involves only the epidermis
It is characterized by mild pain and erythema (redness) but no blisters and skin functions remain intact.
48
A second-degree burn
* destroys the epidermis and part of the dermis - some skin functions are lost.
* A second-degree burn Redness, blister formation, edema, and pain result.
49
third-degree burn
* is a full-thickness burn (destroys the epidermis, dermis, and subcutaneous layer).
* Most skin functions are lost, and the region is numb because sensory nerve endings have been destroyed.
50
Development of the Integumentary System
* The epidermis develops from the ectoderm.
* Nails, hair, and skin glands are epidermal derivatives.
* The dermis develops from the mesoderm.
51
Aging
* The integumentary system changes with age:
* Wrinkles develop.
* Dehydration and cracking occurs.
* Sweat production increases.
* An increase in the numbers of functional melanocytes results in gray hair and atypical skin pigmentation.
* Subcutaneous fat is lost, and there is a general decrease in skin thickness.
* Nails may also become more brittle.
52
Aging
* With age, there is also an increased susceptibility to pathological conditions (as demonstrated by this decubitus ulcer).
* These type of pressure ulcers (“bed sores”) are an all-to-common occurrence in nursing homes.
53
The two parts of the dermis are the \_\_\_\_\_\_\_and the papillary regions.
## Footnote
a. lamellated
b. dermal
c. reticular
d. subcutaneous
c. reticular
54
The alternate name for the stratum basale, the stratum \_\_\_\_\_\_\_\_\_\_, suggests its role in forming new cells.
## Footnote
a. spinosum
b. granulosum
c. germinativum
e. lucidum
c. germinativum
55
The epidermal layer that is found in thick skin but not in thin skin is the \_\_\_\_\_\_\_\_\_\_\_
## Footnote
a. stratum lucidum
b. stratum basale
c. stratum spinosum
d. stratum corneum
a. stratum lucidum
56
Which is not true about eccrine/merocrine sweat glands?
a. They begin to function at puberty
b. They are found throughout the body
c. Their excretory duct terminate at the surface of the epidermis
d. They regulate body temperature
a. They begin to function at puberty
57
Which of the following is true concerning the skin and the production of vitamin D?
## Footnote
a. Vitamin D is manufactured on the skin
b. Synthesis of vitamin D requires activation of a precursor molecule called calcium
c. The role of calcitriol is to convert calcium to vitamin D.
d. Calcitriol is the active form of vitamin D and is necessary for the absorption of gastrointestinal calcium
d. Calcitriol is the active form of vitamin D and is necessary for the absorption of gastrointestinal calcium
58
Although they appear in the dermis, hair follicles are derived from the epidermis
## Footnote
True
False
True
59
Which occurs as the integumentary system ages?
## Footnote
a. The skin's innate immune response becomes less efficient.
b. Production of sweat decreases, which may lead to increased body temperature.
c. Skin thins because subcutaneous adipose tissue decreases.
e. all of these choices
e. all of these choices
60
Which of the following characteristics is associated with malignant melanoma?
## Footnote
a. asymmetry
b. irregular borders
c. diameter larger than a pencil erasure
d. all of these choices
d. all of these choices
61
Which is the correct sequence of phases for deep wound healing?
## Footnote
a. inflammation, proliferation, migration, maturation
b. inflammation, migration, proliferation, maturation
c. proliferation, inflammation, migration, maturation
d. proliferation, migration, inflammation, maturation
b. inflammation, migration, proliferation, maturation
62
Which might be due to a decrease in the amount of oxygen in the blood?
## Footnote
a. jaundice
b. erythema
c. cyanosis
d. albinism
c. cyanosis
63
The epidermal layer that is found in thick skin but not in thin skin is the \_\_\_\_\_\_\_\_.
stratum lucidum
64
The most common sweat glands that release a watery secretion are ________ sweat glands; modified sweat glands in the ear are ________ glands; sweat glands located in the axillae, groin, areolae, and beards of males and that release a slightly viscous, lipid‐rich secretion are ________ sweat glands.
eccrine, ceruminous, apocrine
65
**T or F**
An individual with a dark skin color has more melanocytes than a fair‐skinned person.
False
66
**T or F**
In order to permanently prevent growth of an unwanted hair, you must destroy the hair matrix.
True
67
The layer of the epidermis that contains stem cells undergoing mitosis is the
a. stratum corneum.
b. stratum lucidum.
c. stratum basale.
d. stratum spinosum.
e. stratum granulosum.
c. stratum basale.
68
The substance that helps promote mitosis in epidermal skin cells is
a. keratohyalin.
b. melanin.
c. carotene.
d. collagen.
e. epidermal growth factor.
e. epidermal growth factor.
69
Which of the following is not a function of skin?
a. calcium production
b. vitamin D synthesis
c. protection
d. excretion of wastes
e. temperature regulation
a. calcium production
70
To expose underlying tissues in the bottom of the foot, a foot surgeon must first cut through the skin. Place the following layers in the order that the scalpel would cut. (1) stratum lucidum, (2) stratum corneum, (3) stratum basale, (4) stratum granulosum, (5) stratum spinosum.
a. 3, 5, 4, 1, 2
b. 2, 1, 5, 4, 3
c. 2, 1, 4, 5, 3
d. 1, 3, 5, 4, 2
e. 3, 4, 5, 1, 2
c. 2, 1, 4, 5, 3
71
Aging of the skin can result in
a. an increase in collagen and elastic fibers.
b. a decrease in the activity of sebaceous glands.
c. a thickening of the skin.
d. an increased blood flow to the skin.
e. an increase in toenail growth.
b. a decrease in the activity of sebaceous glands.
72
Which of the following is not true?
a. Albinism is an inherited inability of melanocytes to produce melanin.
b. Striae occurs when the dermis is overstretched to the point of tearing.
c. In order to prevent excessive scarring, surgeons should cut parallel to the lines of cleavage.
d. The papillary layer of the dermis is responsible for fingerprints.
e. Much of the body's fat is located in the dermis of the skin.
73
A patient is brought into the emergency room suffering from a burn. The patient does not feel any pain at the burn site. Using a gentle pull on a hair, the examining physician can remove entire hair follicles from the patient's arm. This patient is suffering from what type of burn?
a. third degree
b. second degree
c. first degree
d. partial thickness
e. localized
a. third degree
74
Which of the following statements are true? (1) Nails are composed of tightly packed, hard, keratinized cells of the epidermis that form a clear, solid covering over the dorsal surface of the terminal end of digits. (2) The free edge of the nail is white due to the absence of capillaries. (3) Nails help us grasp and manipulate small objects. (4) Nails protect the ends of digits from trauma. (5) Nail color is due to a combination of melanin and carotene.
a. 1, 2, and 3
b. 1, 3, and 4
c. 1, 2, 3, and 4
d. 2, 3, and 4
e. 1, 3, and 5
c. 1, 2, 3, and 4
75
Match the following:
\_\_\_ a. produce the protein that helps protect the skin and underlying tissues from light, heat, microbes, and many chemicals
\_\_\_ b. produce a pigment that contributes to skin color and absorbs ultraviolet light
\_\_\_ c. cells that arise from red bone marrow, migrate to the epidermis, and participate in immune responses
\_\_\_ d. cells thought to function in the sensation of touch
\_\_\_ e. located in the dermis, they function in the sensations of warmth, coolness, pain, itching, and tickling
\_\_\_ f. smooth muscles associated with the hair follicles; when contracted, they pull the hair shafts perpendicular to the skin's surface
\_\_\_ g. an abnormal thickening of the epidermis
\_\_\_ h. release a lipid‐rich secretion that functions as a water‐repellent sealant in the stratum granulosum
\_\_\_ i. pressure‐sensitive cells found mostly in the subcutaneous layer
\_\_\_ j. a fatty substance that covers and protects the skin of the fetus from the constant exposure to amniotic fluid
\_\_\_ k. associated with hair follicles, these secrete an oily substance that helps prevent hair from becoming brittle, prevents evaporation of water from the skin's surface, and inhibits the growth of certain bacteria
1. Merkel cells
2. callus
3. keratinocytes
4. Langerhans cells
5. melanocytes
6. free nerve endings
7. sebaceous glands
8. lamellar granules
9. pacinian (lamellated) corpuscles
10. vernix caseosa
11. arrector pili
3 a. produce the protein that helps protect the skin and underlying tissues from light, heat, microbes, and many chemicals
5 b. produce a pigment that contributes to skin color and absorbs ultraviolet light
4 c. cells that arise from red bone marrow, migrate to the epidermis, and participate in immune responses
1 d. cells thought to function in the sensation of touch
6 e. located in the dermis, they function in the sensations of warmth, coolness, pain, itching, and tickling
11 f. smooth muscles associated with the hair follicles; when contracted, they pull the hair shafts perpendicular to the skin's surface
2 g. an abnormal thickening of the epidermis
8 h. release a lipid‐rich secretion that functions as a water‐repellent sealant in the stratum granulosum
9 i. pressure‐sensitive cells found mostly in the subcutaneous layer
10 j. a fatty substance that covers and protects the skin of the fetus from the constant exposure to amniotic fluid
7 k. associated with hair follicles, these secrete an oily substance that helps prevent hair from becoming brittle, prevents evaporation of water from the skin's surface, and inhibits the growth of certain bacteria
76
Match the following:
\_\_\_ a. deep region of the dermis composed primarily of dense irregular connective tissue
\_\_\_ b. composed of keratinized stratified squamous epithelial tissue
\_\_\_ c. not considered part of the skin, it contains areolar and adipose tissues and blood vessels; attaches skin to underlying tissues and organs
\_\_\_ d. superficial region of the dermis; composed of areolar connective tissue
1. subcutaneous layer (hypodermis)
2. papillary region
3. reticular region
4. epidermis
3 a. deep region of the dermis composed primarily of dense irregular connective tissue
4 b. composed of keratinized stratified squamous epithelial tissue
1 c. not considered part of the skin, it contains areolar and adipose tissues and blood vessels; attaches skin to underlying tissues and organs
2 d. superficial region of the dermis; composed of areolar connective tissue
77
Match the following and place the phases of deep wound healing in the correct order:
\_\_\_ a. epithelial cells migrate under scab to bridge the wound; formation of granulation tissue
\_\_\_ b. sloughing of scab; reorganization of collagen fibers; blood vessels return to normal
\_\_\_ c. vasodilation and increased permeability of blood vessels to deliver cells involved in phagocytosis; clot formation
\_\_\_ d. extensive growth of epithelial cells beneath scab; random deposition of collagen fibers; continued growth of blood vessels
1. proliferative phase
2. inflammatory phase
3. maturation phase
4. migratory phase
Match the following and place the phases of deep wound healing in the correct order:
4 a. epithelial cells migrate under scab to bridge the wound; formation of granulation tissue
3 b. sloughing of scab; reorganization of collagen fibers; blood vessels return to normal
2 c. vasodilation and increased permeability of blood vessels to deliver cells involved in phagocytosis; clot formation
1 d. extensive growth of epithelial cells beneath scab; random deposition of collagen fibers; continued growth of blood vessels
