Chapter 5 Flashcards
(49 cards)
1
Q
What does the Integumentary system include?
A
Includes: skin and derivatives; hair, glands, sensory structures, nails
Protects the body as a whole from external environment
2
Q
What is the largest organ in the body?
A
Skin is the largest organ of the body (surface area and weight) -Measures ~1.2 – 2.2 m2 - Weighs ~4.5 – 6.5kg - Accounts for ~ 7% of body mass
3
Q
Functions of the Skin (1-3)
A
- Thermoregulation via negative feedback
- Dermal blood vessel dilation (cooling) and vasoconstriction (warming)
- Increased/decreased sweat gland secretions (500mL/day up to 12L/day) - Protection – chemical, physical, and biological barrier
- Stratified, keratinized epithelium with lipids provide mechanical and waterproof
barrier
- Oil secretions (sebum) moisturizes and controls bacteria
- Melanin protects from UV-rays - Cutaneous Sensations
- Exteroreceptors – respond to stimuli from outside body
- Meissner’s corpuscles (tacticle) – in dermal papillae – soft touch
- Pacinian corpuscles (lamellar) – in deeper dermis or hypodermis – deep pressure
- Sense touch, pain, vibration, pressure, temperature, tickling, and itch
- Can signal damage to tissue, but can also be exploited for pleasure, relaxation, etc.
4
Q
Functions of the skin continued (4-7)
A
- Excretion and Absorption
- Sweat secretion (water, salts, heat, and waste products)
- Excretes small amounts of nitrogen containing wastes
- Absorbs heavy metals and fat soluble molecules - dangerous - Synthesis of vitamin D
- modified cholesterol molecules in skin are converted into vitamin D by sunlight
- Vit. D is required for uptake of calcium from digestive tract - Blood reservoir
- Skin blood vessels store up to 5% of the body’s volume - Immunity
- Epidermis contains Langerhan’s cells – self-presenting dendritic cells
- Part of immune system – will study later
5
Q
Skin integument
A
Consists of two major regions:
- Epidermis: Outermost superficial surface
- Dermis: Vascularized middle region
Hypodermis: Deepest region (subcutaneous) superficial fascia
- Not part of the skin
- Many adipocytes, pressure receptors, and blood vessels that supply the skin
- Functions in anchoring the skin, protection, insulation, energy storage
6
Q
Epidermal cells 4 types:
A
Consists of keratinized, stratified, squamous epithelium consisting of four distinct cell types.
- Keratinocytes
- Melanocytes
- Langerhans cells/ Dendritic cells
- Merkel cells
7
Q
- Keratinocytes (epidermal cell)
A
- 90% of epidermal cells
- produce and fill with keratin – fibrous protein that protects the skin from heat, microbes, and chemicals
8
Q
- Melanocytes (epidermal cells)
A
- produce the brown pigment melanin
- slender projections transfer melanin to keratinocytes
- protects keratinocytes from harmful UV-rays
9
Q
- Langerhans cells/ Dendritic cells (epidermal cells)
A
- arise from bone marrow and migrate to epidermis
- epidermal macrophages that activate immunity
10
Q
- Merkel cells (epidermal cells)
A
- in deepest layer of epidermis attached to keratinocytes by desmosomes
- functions at touch receptors in association with sensory nerve endings
11
Q
Epidermal layers 4-5
A
Consists of five to four layers depending on friction:
- Stratum basale (Basal layer) (stratum germinativum)
- Stratum Spinosum (Prickly layer)
- Stratum Granulosum (Granular layer)
- Stratum Lucidum (Clear layer)
- Stratum Corneum (Horny layer)
12
Q
- Stratum basale (Basal layer) Epidermal layer
A
Deepest epidermal layer
- Consists of a single layer of keratinocytes
- Rapid cell division
- Keratinocytes, melanocytes, and Merkel cells located here
13
Q
- Stratum Spinosum (Prickly layer) Epidermal layer
A
- 8-10 rows of tightly packed cells
- Web-like system of intermediate filaments attached to desmosomes –
strength and flexibility - Langerhans’ cells and melanin granules located here
14
Q
- Stratum Granulosum (Granular layer) Epidermal layer
A
- 3-5 rows of flattened keratinocytes
- Different colour because keratinization occurs
- Keratohyaline granules deposit thickened keratin
- Lamellated granules release lipids = waterproof = death
15
Q
- Stratum Lucidum (Clear layer) Epidermal layer
A
- Found in the thick skin of the hands and feet – absent everywhere else
- 3-5 layers of clear flat dead cells
- Lacks hair follicles and sebaceous glands
16
Q
- Stratum Corneum (Horny layer) Epidermal layer
A
- 25–30 rows of flat dead cells completely filled with keratin
- Continuously shed microbial, mechanical, and water-repellant barrier.
17
Q
Dermis: Composed of…
Cell types…
A
- Composed of strong and flexible connective tissue
fibers (collagen and elastin) - Cell types include: fibroblasts, macrophages, and
occasionally mast cells and white blood cells
18
Q
Two types of Dermis
- Papillary
- Reticular
A
- Areolar connective tissue with collagen, elastin,
and blood cells
- Dermal papillae project up into the epidermis
creating friction ridges – finger grips
- Dermal papillae contain capillary loops,
Meissner’s Corpuscles (touch), and free nerve
endings sensitive to pain, itch, tickle, heat and
cold
- Areolar connective tissue with collagen, elastin,
- Accounts for 80% of the thickness of dermis
- Also contains adipose tissue, hair follicles,
sebaceous glands and sweat duct
- Consists of dense irregular connective tissue:
- Collagen fibers provide strength and resiliency
- Elastin fibers provide stretch – recoil abilities
- Accounts for 80% of the thickness of dermis
19
Q
What are the three skin colour pigment types?
A
- Melanin
- Carotene
- Hemoglobin
20
Q
- Melanin: pigment type
A
- Located in epidermis
- Melanocyte number is same in different races but amount of pigment they produce is different
- Freckles and liver spots are accumulation of melanin
- UV light increases melanin production
- Melanin granules then protect nuclei of keratinocytes in stratum basale from UV-light
21
Q
- Carotene: pigment type
A
- Yellowish-orange pigment
- Precursor to Vitamin A – needed for vision
- Carotene + melanin = yellowish tint
- Found in stratum corneum
22
Q
- Hemoglobin: pigment type
A
- Caucasians have translucent epidermis due to little melanin
- Skin appears pink to red
- Colour depends on amount and quality of blood movement through dermis
- No oxygen results in blue skin
23
Q
Sweat/ Sudoriferous Glands
A
Four different types: all secrete by exocytosis
- Eccrine/merocrine sweat glands
- Apocrine sweat glands
- Ceruminous glands
- Mammary glands
24
Q
- Eccrine/merocrine sweat glands
A
- Found in palms, soles of the feet, and
forehead - Simple coiled tubular glands that open on
skin - Prevent overheating
25
2. Apocrine sweat glands
- Found in axillary and anogenital areas
- Reacts with bacteria on skin – body
odour
- Believed to be the equivalent of animal
sex scent glands
26
3. Ceruminous glands (sweat gland)
- Modified apocrine glands in external ear
| canal that secrete cerumen (wax)
27
4. Mammary glands (sweat gland)
- Specialized sweat glands that secrete milk
| - Studied later in female reproduction
28
Sebaceous Glands
- Simple alveolar glands found all over the body
- Open on skin or within hair follicle
- Secrete an oily secretion called sebum
- Softens and waterproofs skin when stimulated
by hormones
- Blackheads – accumulation of sebum
- Black because of built up melanin and oxidized oil
- Acne and pimples – inflammation due to
bacteria feeding on sebum in follicles
29
Hair: What is it, shaft, root, contains?
```
- Filamentous strands of dead
keratinized cells produced by
hair follicles
- Shaft extends out of follicle
- Root is below the epidermis
- Contains a harder kind of
keratin than what is found in
skin cells
```
30
Hair 3 main layers:
Consists of 3 main layers:
1. Inner medulla
2. Middle cortex
- Pigment granules in dark hair, air in white hair
3. Outer cuticle
- Simple squamous, keratinized for protection
- Hair follicle surrounds root – external and internal root sheaths
31
Hair functions:
1. Protection – from sweat, dust, microbes, insect bites, UV, and trauma
2. Insulation – maintain warmth
3. Sensory – insects. At base of hairs are touch receptors (root hair plexus) that activate when hair is moved
* Hair is found everywhere except palms, soles, lips, nipples, and parts of external genitalia
32
Hair: Root sheath
extends out from epidermal surface into the dermis
33
Hair: Hair bulb
```
at the base anchors follicle to hypodermis and consists of:
- papilla of the hair – blood vessels
- nutrients
- matrix of the bulb – ring of cells
forming germinal layer where
cells grow
```
34
Hair: Root hair plexus
is a knot of sensory nerve endings that is wrapped
around each hair bulb
- Bending stimulates touch
receptors
35
Also associated with hair:
1. Arrector pili – band of smooth muscles that attach hair follicle to superficial dermis which can contract to
pull the hair to a vertical position – ‘goose bumps’ when cold, frightened, or angry
2. Sebaceous glands – produce oil for lubrication
36
Hair grows ~ 2.5 mm/week
Hair colour:
- Melanocytes in the matrix of the hair produce melanin which passes to the cells of the medulla and cortex of root and shaft
- Dark hair – true melanin; Blonde – less melanin with sulfur; Red hair – different type of melanin with iron pigment; genetic
- Gray or white hair – decline in tyrosinase (enzyme that produces melanin); air bubbles form in place of pigment
37
What are Nails:
Two parts of nails:
Fingernails are composed of tightly packed, hard and clear keratinized cells
1. Nail body (visible area)
2. Nail root buried in skin
38
Nails: Hyponychium
thickened stratum corneum that secures free edge of nail at corneum
39
Nails: Eponychium (cuticle)
composed of stratum corneum
40
Nails: Lunule
white crescent at base of nail composed of thick stratum basale
41
Nail facts:
- Site of growth is matrix just like hair follicles
- Epidermal cells under root of nail develop into nail cells and get pushed up
- Grow ~ 1 mm/week
42
Skin cancer: 3 types
- Cause by UV light, chemicals, infections, constant abrasions (bra strap)
- Cancerous cells can metastasize through lymph or blood to other organs – can be fatal
1. Basal cell carcinoma
2. Squamous cell carcinoma
3. Malignant melanoma
43
Basal cell carcinoma: Skin cancer
Cancer of cells in stratum basale
| - Least malignant but most common. Usually on face
44
Squamous cell carcinoma: Skin cancer
Cancer of keratinocytes
- Scalp, ears, hands, and lower lip – look like bumps, warts, reddish pimples, abrasions
- Painless but itchy
45
Malignant melanoma: Skin cancer
```
Cancer of melanocytes
- Most dangerous – most likely to metastasize
- Spontaneously arise or when existing moles transform
- Exhibit ABCDE
A – asymmetrical
B – borders irregular
C – colour varies within mole
D – diameter 5 mm or larger
E – elevated
```
46
Burns:
Damages tissue, denatures proteins, leads to cell death
- Immediate threat: dehydration and electrolyte imbalance, leads to renal shutdown and
circulatory shock
- Burns can be due to: fire, overexposure to sun, dry heat, wet heat (scalding water, steam),
electricity, radiation, extreme cold (frostbite), toxic chemicals
47
1st degree burns:
Epidermal damage only; localized redness, edema (swelling), and pain
48
2nd degree burns:
Epidermal and upper dermal damage; blisters appear
49
3rd degree burns:
```
- Entire thickness of skin damaged;
Gray-white, cherry-red, or black.
- No initial edema or pain (nerve
endings destroyed), skin grafting
usually necessary
- Intense pain as nerves regenerate
through healing process
```
