Chapter 5: The Integumentary System

Question 1

Define integumentary system and explain functions

Answer 1

Skin, hair, oil, and sweat glands, nails, and sensory receptors

Functions: Regulate body temp, store blood, protect body from external environment, detect cutaneous sensations, excrete and absorb substances, synthesize vitamin D

Question 2

What are the 2 components of the cutaneous memebnae?

Answer 2

aka skin consists of:

Epidermis: superficial thinner portion
Dermis: deeper connective tissue

Question 3

Define the SubQ layer

Answer 3

aka hypodermis

Not a part of the skin but is anchored to the dermis and attaches to the connective tissue

Question 4

_______ corpuscles in the subQ and sometimes dermis are sensitive to pressure

Answer 4

lamellated

aka pacinian corpuscle

Question 5

The epidermis has 4 principle types of cells, describe them:

Keratinocytes
Melanocyte
Intraepidermal macrophages (langerhans cell)
Tactile epithelial cells

Answer 5

Keratinocytes (90%): arranged in 4-5 layers and produce keratin that helps protect the skin

Melanocyte (8%): develop from the ectoderm of a developing embryo and produce melanin which contributes to skin colour and absorbed UV light

Intraepidermal macrophages: arise from red bone marrow and participate in immune responses

Tactile epithelial cells: located in the deepest layer where they contact a sensory nuron called a tactile or Merkel disk

Question 6

Thin vs. Thick skin

Answer 6

Thin skin is regions of the epidermis that has 4 strata (layers):
- straum basale, stratum spinosum, stratum granulosm, and stratum corneum

Thick skin is where friction is greatest and has 4 layers:
- all same layers +stratum lucidium

Question 7

List & describe the layers of the epidermis (from deepest to most superficial)

Answer 7

Basale: single row of keratinocytes that include scattered kertain intermediate filaments (tonofilaments) which are tough and protect from injury

Spinosium: 8-10 layers of keratinocytes that increasingly become flattened the more superficial they are; provides strength and flexibility

Granulosum: 3-5 flattened layers of keratinocytes undergoing apoptosis; has keratohyalin (darkly staining granules) that assembled monofilaments into keratin; also have lamellar granules acting as sealant against water/particles

Lucidum (thick skin): 4-6 layers of flattened, dead keratinocytes that overlap like scales to prevent injury from friction (it is a thickening of the stratum corneum)

Corneum: 25-30 layers of flattened dead keratinocytes that are extremely thin and flat; constant exposure to friction results in a callus

Question 8

As cells move from one epidermal layer to the next, they accumulate more and more keratin, a process called _________

Answer 8

keratinization

The whole process from basale to the surface and then being sloughed off takes about 4-6 weeks

Question 9

What is psoriasis?

Answer 9

A skin disorder in which keratinocytes divide and more more quickly than normal and shred prematurely in as little as 7-10 days

They are abnormal keratin which forms flaky scales on the skin

Question 10

The dermis can be subdivided into two portions. List and describe them:

Answer 10

Papillary region (superficial): consists of areolar connective tissue with thin collagen and fine elastic fibres; contains dermal ridged that house blood capillaries capillary loops), corpsucles of touch (tactile nerve endings), and free nerve endings (initiate sensation of temp, pain, itch, etc.)

Reticular region (deep): consists of dense irregular connective tissue with bundles of thick collagen and some coarse elastic fibers. Provides skin with extensibility and elasticity

Question 11

What are epidermal ridges? When are they produced?

Answer 11

Produced during 3rd month of fetal development and they create a strong bond between epidermis and dermis at areas of high mechanical stress (Ex. found in the creases of a palm)

Sweat glands that open on the top of these ridges form fingerprints/footprints

Question 11

What are epidermal ridges? When are they produced?

Answer 11

Produced during 3rd month of fetal development and they create a strong bond between epidermis and dermis at areas of high mechanical stress (Ex. found in the creases of a palm)

Sweat glands that open on the top of these ridges form fingerprints/footprints

Question 12

What causes differences in skin colour? How about a mole?

Answer 12

Skin colour is due to the amount of pigment the melanocytes produce (not the overall number) - phenomelannnin (yellow to red) and eumelanin (brown to black)

A mole occurs when a patch of melanin accumulates and becomes raised due a localized overgrowth

Question 13

_______ is a yellow-orange pigment that gives egg yolks/carrots their colour. Eating a lot of these foods can turn your skin orange

Answer 13

Carotene

Question 14

Describe albinism and vitiligo

Answer 14

Albinism is the inherited inability of an individual to produce melanin, albinos have melanocytes that are unable to synthesize tyrosinase

Vitiligo is the partial or complete loss of melanocytes that produces irregular white spots - may be related to an autoimmune dysfunction

Question 15

Skin colour can be used as a diagnostic tool - what do the following terms mean:

Cynotic
Jaundice
Erythema
Pallor

Answer 15

Cynotic: blue (lack of oxygen)

Jaundice: yellow (liver disease)

Erythema: redness (ergorement of capillaries - skin injury)

Pallor: pale (shock/anemia)

Question 16

What is the function of hair?

Answer 16

Guards scale from injury/sun rays (limited protection)
Decreases heat loss
Protect eyes from foreign particles
Sensing light touch

Question 17

Describe the following structures of hair anatomy:

Shaft 
Root
Follicle 
Bulb 
Matrix
Hair root plexus

Answer 17

Shaft: superficial portion that projects above surface

Root: potion deep to the shaft that penetrates into the dermis; comprised of medulla, middle, and cuticle

Follicle: surrounds the root

Bulb: base of each folic that contains a germinal layer of cells called the hair matrix - responsible for growth/production of hair

Hair root plexus: dendrites that surround each follicle to generate nerve poles if hair shafts are moved

Question 18

Describe the 3 layers of the hair root:

Answer 18

Medulla (inner): 2-3 irregular shade cells that contain pigment granules that determines hair colour

Middle cortex: forms major part of shaft

Cuticle (outer): consist of thin, flat cells that are heavily keratinized

Question 19

When under psychological or emotional stress the smooth muscle called the ___________ contracts causing goosebumps

Answer 19

arrestor pilli

Question 20

What are the 3 stages of hair growth?

Answer 20

1. Growth stage - cells of the hair matrix divide and are added and pushed upwards and become keratinized and eventually die
2. Regression stage - cells of the matrix stop dividing the hair follicle shrinks
3. Resting stage - no growth, resting (then growth stage begins)

Question 21

_________ is the partial or complete loss of hair that may occur genetically, due to aging, or due to a disorder/disease

Answer 21

alopecia

Question 22

Differentiate between the following types of hair:

Lanugo
Terminal
Vellus

Answer 22

Lanugo: fine non-pigmented hairs that cover the body of a fetus

Terminal: eventually replace lanugo of eyebrows, armpits, pubic regions, eyelashes, and scalp and are heavily pigmented

Vellus: replace lanugo elsewhere on the body (peach fuzz)

Question 23

The following hair colours contain mainly which type of keratin:

Brown/black
Blonde/red
Grey

Answer 23

Brown/black: eumelanin
Blonde/red: phenomelanin
Grey: lack of melanin production

Question 24

What are the general differences between sebacous, sudiferous, and ceruminous gland?

Answer 24

Sebaceous (oil): secrete oily substances called serum that coats the surface of the hairs and helps them from becoming dry and brittle

Sudiferous (sweat): release sweat/perspiration through pores (2 types)

Ceruminous (ear): produce waxy lubricating secretion called cerumen or earwax

Question 25

Acne is the inflammation of ________ glands

Answer 25

sebaceous

Question 26

What are the 2 different types of sudiferous (sweat glands)? List their functions

Answer 26

Eccrine (most common): coiled tubular

• Functions in thermoregulation (homeostatic regulation of body temp) via thermoregulatory sweating
• sweat can be insensible, sensible, and emotional

Apocrine: simple oiled that have larger ducts and lumens

• simulated during emotional stress/sexual excitement
• sweat appears milky/yellowish

Question 27

What is the difference between insensible & sensible perspiration, and emotional sweating (cold sweat)

Answer 27

Insensible: sweat that evaporates before it is perceived as moisture

Sensible: seat that is exerted in larger amounts and is seen as moisture

Emotional sweating (cold sweat): released in repsonse to emotional stress (both eccrine and apocrine involvement)

Question 28

Nails are plates of highly packed, hard, dead, keratinized epidermal cells. Describe the following components:

Nail body (plate) 
Free edge 
Hyponcychium
Eponychium (cuticle) 
Nail root
Lunula 
Nail matrix

Answer 28

Nail body (plate): visible portion of the nail

Free edge: edge that projects past the finger/toe

Hyponcychium: secures nail to the fingertip

Eponychium (cuticle): stratum corneum of the epidermis

Nail root : portion that is buried in a fold of skin

Lunula: moon shaped white part at bottom nail

Nail matrix: epithelium proximal to the nail root - contains dividing cells which produces new nail cells

Question 29

Describe how the skin contributes to following functions:

Thermoregulation 
Blood reservoir 
Protection 
Cuteanous sensations 
Excretion and absorption 
Synthesis of vitamin D

Answer 29

Thermoregulation : liberates sweat at its surface and adjusts the flow of blood in the dermis depending on temperature

Blood reservoir: carries 8-10% of total blood flow

Protection: prevents damage, dehydration, and shields against UV

Cuteanous sensations: nerve endings throughout the skin that detect sensations

Excretion and absorption

Synthesis of Vit. D: requires activation of a precursor molecule in the skin by UV rays (produce calcitrol, active form of vit. D)

Question 30

Outline the steps involved in epidermal wound healing

Answer 30

Epidermal wound healing is restricting to the epidermis

• Basal cells surrounding the wound break contact with the basement membrane and the cells then enlarge and migrate across the wound
• Once they merge, they stop migrating due to contact inhibition
• As the cells migrate, epidermal growth factor (hormone) stimulates stem cells to divide and replace the ones that have moved into the wound

Question 31

Outline the 4 steps involved in deep wound healing

Answer 31

Inflammatory: blot clot forms in the wound and loosely unites the wound edges

Migratory: clot becomes a scab and the epithelial cells migrate beneath to bridge the wound - tissue following the wound is called granulation tissue

Proliferative: extensive growth of epithelial cells, decomposition by fibroblasts, and continued growth of blood vessels

Maturation: Scab sloughs off and the epidermis returns to normal thickness

Question 32

Would you expect an epidermal wound to bleed?

Answer 32

No - the epidermis is avascular

Question 33

_____ refers to the process of scar tissue formation. What are the 2 different types?

Answer 33

Fibrosis

Hypertrophic: scar remains in the boundaries of original wound
Keloid/cheloid: scar extends beyond the boundaries into normal surrounding areas

Question 34

Outline the details in the following disorders:

Skin cancer
Burn
Pressure ulcer

Answer 34

Skin cancer: ultraviolet radiation (UVA & UVB) affect the health of the skin and are responsible for skin damage
- 3 common types are basal cell carcinoma (tumors arise in stratum basale), squamous cell carinoma (tumors arise in stratum spinosum), and malignant melon (most deadly)

Burn: UVB rays, excessive heat/electricity/chemical that destroys the skins homeostasis

Pressure ulcer (bedsores): caused by deficiency of blood flow to tissues