Integumentary System Flashcards

1
Q

Skins consists of what two distinct regions?

A
  1. Epidermis- superficial region

Keratinized stratified squamous epithelial tissue

  1. Dermis- underlies epidermis

Loose areolar and dense irregular connective tissue

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2
Q

What are the five layers of the epidermis?

A

1) Stratum corneum: 20-30 rows of dead, flat, enucleate keratinized membranous sacs.

Protects from abrasion and penetration, protects deeper cells from environment and water loss, barrier against biological, physical, and chemical assaults

2) Stratum lucidum: Only in thick skin. A few rows of flat, dead keratinocytes. Thin, translucent band superficial to the stratum granulosum.

3) Stratum granulosum: Thin, four to six layers. Cells above this layer die. Cytoplasm full of lamellar granules (release lipids; their water resistant glycolipids slow water loss) and keratoyhalin granules (form keratin in upper layers).

4) Stratum spinosum: Several layers thick, several layers of keratinocytes unified by desmosomes.

5) Stratum basale: Single row of stem cells, actively mitotic (produce daughter cells). One cell journeys from basal layer to surface (takes 25-45 days, dies as it reaches surface) and one remains in basal layer as a stem cell.

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3
Q

Keratinocytes

A

-Most cells of epidermis

-Produce fibrous protein keratin

-Tightly connected by desmosomes

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4
Q

Melanocytes

A

-Located at stratum basale

-Produce pigment melanin, which protects keratinocyte nucleus from the UV damage

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5
Q

Dendritic (Langerhan) cells

A

-Located in the stratum spinosum

-Macrophages- key activators of the immune system

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6
Q

Tactile (Merkel) cells

A

-Located at stratum basale

-Sensory touch receptors

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7
Q

Compare and contrast the possible variations in the layers of the epidermis.

A

Thick skin
* 5 layers in epidermis
– Has stratum lucidum
* Found in palms of hands and soles
of feet
* Epidermis is 0.4–0.6 mm thick
* No hair follicles or sebaceous
glands

Thin skin
* 4 layers in epidermis
– No stratum lucidum
* Covers most of body
* Epidermis is 0.075–0.150 mm thick

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8
Q

Is the epidermis vascular or avascular?

A

Avascular

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9
Q

Describe the dermis

A

-Strong, flexible connective tissue

-Fibroblasts, macrophages, and occasionally mast cells and white blood cells

-Fibers in matrix bind body together. “Hide” used to make leather

Contains:
– nerve fibers
– blood and lymphatic vessels
– epidermal hair follicles
– oil and sweat glands

  • Two layers
    – Papillary
    – Reticular
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10
Q

Papillary layer of the dermis

A
  • Superficial layer
  • Loose areolar connective tissue
  • Dermal papillae
    – Superficial peg-like projections
    – Connect to epidermal ridges
    – Most contain capillary loops
    – Some contain Meissner’s corpuscles (touch receptors)
    – Some contain free nerve endings (pain receptors)
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11
Q

Reticular layer of the dermis

A

-80% of the dermis
-Dense irregular fibrous connective tissue

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12
Q

Why do we have fingerprints?

A

They are formed from large folds and valleys of both dermis and epidermis. They are found in the fingers, palms, soles, and toes.

They enhance gripping ability and contribute to sense and touch.

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13
Q

Lines of cleavage

A

Most collagen and elastic fibers are parallel to skin surface

– Externally invisible
– Important to surgeons
– Incisions parallel to cleavage lines gap less and heal more readily

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14
Q

What are the functions of skin?

A

-Protection

-Prevention of water loss and gain

-Temperature regulation

-Metabolic regulation

-Sensory regulation

-Secretion

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15
Q

The skin is selectively permeable with chemical, physical, and biological barriers

A

Chemical barriers:

Skin secretions
– Sebum and defensins kill bacteria
– Low pH retards bacterial multiplication
– Melanin- defense against UV radiation damage

Physical barriers:

The outermost layer of the epidermis is composed of flat, dead cells surrounded by lipids

  • Limited penetration of skin:
  • Lipid-soluble substances
  • Plant oleoresins (e.g., Poison ivy)
  • Salts of heavy metals (e.g., Mercury)
  • Some drugs
  • Drug agents

Biological barriers:

– Dendritic cells of epidermis
* Phagocytize pathogens and cancer cells
* Present foreign antigens to white blood cells

– Macrophages of dermis
* Similar functions

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16
Q

Subcutaneous layer

A

Superficial fascia deep to skin

– Not part of integument, but shares some functions

– Mostly adipose tissue that absorbs shock & insulates

– Anchors skin to underlying structures – mostly muscles

– Vascular networks make for good drug delivery

  • Injections
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17
Q

What are the derivatives of the epidermis?

A

-Nails

-Hair

-Exocrine glands

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18
Q

Nails

A

-Scalelike modifications of epidermis
-Protective cover for distal, dorsal
surface of fingers and toes
-Contain hard keratin
-Nail matrix

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19
Q

Hair

A

-Dead cells of hard keratin

Functions include
– Protection
– Heat retention
– Sensory perception
– Visual identification

20
Q

What are the three kinds of hair?

A
  1. Lanugo: downy hair on fetuses that occurs in the second trimester
  2. Vellus: pale, fine body hair of children and adult females
  3. Terminal: Coarse, long hair
21
Q

Know the parts of hair

A

(Label)

22
Q

What hair pigment is in red hair?

A

Trichosideran

23
Q

What causes hair to go gray?

A

Decreased melanin and air bubbles in the shaft

24
Q

Apocrine sweat glands

A

Distributed in axillary, anal, areolar, and pubic regions. Produce viscous, complex secretion (sweat, fatty substances, and protein, vicous–milky color, odorless until bacterial function); secretion influenced by hormones.

25
Q

Merocrine sweat glands

A

Distributed throughout the body, except external genitalia, nipples, and lips. Especially prominent on palms, soles, and forehead.

Provides non viscous, watery secretion (sweat); controlled by nervous system, antibacterial protection, function in thermoregulation and secretion; flush surface of epidermis.

26
Q

What is another word for sweat glands?

A

Sudoriferous glands

27
Q

Holocene (Sebaceous) glands

A
  • Widely distributed
  • Not in thick skin of palms and soles
  • Most develop from hair follicles and secrete into hair follicles

Function: Secrete sebum
* Oily holocrine secretion
* Bactericidal
* Softens hair and skin

Relatively inactive until puberty.

28
Q

Ceruminous glands

A

lining of external ear canal; secrete cerumen (ear wax)

29
Q

Mammary glands

A

secrete milk

30
Q

Integument Repair and Regeneration

A

Necessary when barriers are penetrated

  • Cells must divide and migrate
  • Occurs in two major ways:
    1. Regeneration
  • Same kind of tissue replaces destroyed tissue
  • Original function restored
  1. Fibrosis
    * Connective tissue replaces destroyed tissue
    * Original function lost
31
Q

What are the steps of tissue repair?

A

1) cut blood vessels bleed into the wound

2) blood clot forms, and leukocytes clean wound

3) blood vessels regrow, and granulation tissue forms

4) epithelium tissue regenerates, connective tissue fibrosis occurs

32
Q

Regenerative capacity in different tissue types

A

Well regenerative capacity:
-epithelial
-bone
-areolar connective tissue
-dense irregular connective tissue
-blood-forming tissue

Moderate:
-smooth muscle
-dense regular connective tissue

Poor:
-skeletal muscle
-cartilage

Virtually none:
-cardiac muscle
-nervous tissue of brain and
spinal cord

33
Q

Keratinocytes in the epidermis are usually present for about ____ weeks.

A

4

34
Q

The dermal papillae interlock with deep projections of the epidermis called

A

epidermal ridges

35
Q

Nerve fibers in the dermis are _______ dispersed

A

extensively

36
Q

As a person ages, the production of ___________ glands in the skin decreases resulting in dry skin.

A

sebaceous

37
Q

During the fetal period, the ______ is eventually sloughed off, and these sloughed off cells mix with ______ secreted by the sebaceous glands.

A

periderm, sebum

38
Q

Fingernails and toenails start to form in the ______ week of development.

A

tenth

39
Q

Sebum begins to form in sebaceous glands during the ______ period.

A

fetal

40
Q

Migration of a keratinocyte from the stratum basale to the stratum corneum takes about _____ weeks.

A

2

41
Q

Nerve fibers in the skin help control

A

blood flow
gland secretion rates

42
Q

Which best describes the differences between sensible and insensible perspirations produced by sweat glands in the skin?

A

Insensible is in the form of water vapor and cannot be seen while sensible contains water and salts and can be seen.

43
Q

Late in the fetal period, the mammary gland develops an external epidermal depression called the _______.

A

mammary pit

44
Q

In what layers does keratinization begin and end?

A

stratum granulosum

stratum corneum? (dead and anucleate)

45
Q

The epidermis is derived from the ________ and the dermis is derived from the _________.

A

ectoderm

mesoderm