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A&P Fall > Chapter 5: The Integument System > Flashcards

Chapter 5: The Integument System Flashcards

1
Q

What is the integument system and what is it composed of?

A

Covers entire outer surface of body

Includes skin, hair, nails, various glands, & sensory receptors

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2
Q

Functions of Skin - 5

A

Is the largest organ of the body by surface area and weight

Has several functions:
	1. Protects the body against:
		- dehydration (keratin layer)
		- impact & friction injuries
		- mold & bacterial invasion
		- UV light damage (melanin  
            production)
2. Acts as a receptor organ for 
   sensory input

   3. Regulates body temp (capillary 
  network & sweat glands)

4. Secretes some wastes  urea, 
  salts, & water

5. Synthesizes vitamin D from  
  cholesterol molecules under 
  action of sunlight
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3
Q

Skin Layers

A

Composed of 2 layers:
• Outer, thinner layer called the epidermis
> Blood vessles directly in the dermis but not in the epidermis
> No direct blood supply to the epidermis
• Inner, thicker layer called the dermis
•Subcutaneous layer
> Also called hypodermis
> Located underneath the dermis

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4
Q

Epidermis

  • Characteristics
  • List four major types of cell
  • List five cell layers
A 
Characteristics:
• Composed of keratinized stratified squamous epithelium
• Contains four major types of cells
   1) Keratinocytes 
   2) Melanocytes 
   3) Langerhans cells
   4) Merkel cells
• Contains five cell layers
   1) Stratum basale
   2) Stratum spinosum
   3) Stratum granulosum
   4) Stratum lucidum 
   5) Stratum corneum 
Keratinized = thick layer of dead cells on the top
Stratified = more than one layer 
Squamous = flat type of cell
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5
Q

Keratinocytes - Epidermal cell types

A
  • (90%)
  • Produce keratin (fibrous protein)
  • Protect skin & underlying tissues from heat, microbes, & chemicals
  • Surface cells die & only contain keratin
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6
Q

Melanocytes - Epidermal cell types

A
  • (8%)
  • Spider-shaped epithelial cells
  • Secrete & transfer the pigment melanin to keratinocytes
  • Found near basal surface & their cell projections extend between keratinocytes
  • Melanocytes – shield the skin cells from UV light. Increase in sun make more of these which gives you a tan. The tan fades as the cells regenerate/flake off
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7
Q

Langerhans cells - Epidermal cell types

A
  • (or intraepidermal cells)
  • Arise from red bone marrow & migrate to epidermis
  • Involved in immune responses
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8
Q

Merkel cells - Epidermal cell types

A
  • (or Tactile cells)
  • Least numerous
  • Contact sensory neurons & function in touch sensations
  • Located deep in epidermis
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9
Q

Stratum basale - Epidermal cell layers

A
  • (or stratum germinativum)
  • Deepest layer, attached to dermis by wavy border
  • Single row of cuboidal/columnar keratinocytes
  • Cells divide by mitosis
  • Contains melanocytes & Merkel cells
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10
Q

Stratum spinosum - Epidermal cell layers

A
  • 8 to 10 layers of irregular-shaped keratinocytes
  • Cells contain many keratin filaments
  • Contains Langerhans cells & projections of melanocytes
  • The cells are attached to one another very strongly
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11
Q

Stratum granulosum - Epidermal cell layers

A
  • 3 to 5 layers of flattened keratinocytes; nucleus & organelles disintegrate
  • Cells contain keratohyalin (protein) & lamellated granules
  • Lamellated granules release a lipid-rich, water repellent secretion
  • Transition layer between living cells below & dead cells above
  • Starting to die bc epidermis is avascular so it’s getting farther from blood supply
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12
Q

Stratum lucidum - Epidermal cell layers

A
  • Present only in thick skin (fingertips, palms, & soles)
  • Consists of 3-5 layers of clear, flat, dead keratinocytes
  • Missing in thin skin like eyelinds
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13
Q

Stratum corneum - Epidermal cell layers

A
  • 25 to 30 layers of flat, dead keratinocytes containing keratin
  • Lamellar secretion (lipids) between the cells waterproofs this layer
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14
Q

Dermis

-2 regoins/layers

A

• Connective tissue with fibroblasts, adipocytes, macrophages, mast cells, & embedded with fibers
• Contains blood vessels, hair follicles, glands, & nerves
•Layers/Regions
1) Papillary region
2) Reticular region

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15
Q

Papillary region - Dermis Layer

A
  • Upper 1/5 of dermis
    • Has dermal papillae at junction with epidermis
    • These papillae contain capillaries, free nerve endings and Meissner’s corpuscles
    • fingertips are caused by the wavy boarders and they’re for giving texture to help with grip
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16
Q

Meissner’s corpuscles

A

nerves that sence light touch, found in dermis

17
Q

Reticular region - Dermis Layer

A
  • Lower portion of dermis
  • Collagen fibers give skin strength & resiliency, & bind water to keep skin hydrated
  • Elastic fibers provide stretch-recoil properties
  • Stretch marks can appear if the skin is stretched too much
  • Contains Pacinian corpuscles
18
Q

Pacinian corpuscles

A
  • further down in skin, specialized for deep pressure touch sensations
  • found in dermis
19
Q

Skin Colour

A
  • Many pigments contribute to skin colour but the most important one is melanin
  • Melanocytes produce melanin
  • The number of melanocytes are about the same in all people but the amount of melanin produced differs
  • Exposure to UV light increases melanin production
  • Melanin absorbs UV radiation
  • Neutralizes free radicals (electrically chanrged atoms that have unpaired electron in outer shell)
  • A mole is a benign localized overgrowth of melanocytes
20
Q

Hair & Hair Follicles

A

Hair (pili) is present on most skin surfaces
Hair shaft protrudes from the skin while the root is embedded in the skin
Eyebrow, eyelash, & nose hairs protect structures from foreign objects
Hairs provide touch sensations in certain areas

21
Q

Hair Shaft & Root Structure

A

• Consists of 3 concentric rings of dead keratinized cells:
> medulla → core of large cells
> cortex → several layers of flattened cells
> cuticle → single layer of cells that overlap onevanother from below
• Hair pigment is made by melanocytes at the base of the
• hair follicle & is transferred to cortex & medulla cells

22
Q

Hair Follicle Structure

A

• The follicle is a tube-like in-pocketing of epidermis that extends into the dermis
• Base of follicle is expanded as hair bulb
• Hair papilla protrudes into hair bulb:
> contains capillaries
> contains layer of cells (matrix)
> matrix cells divide mitotically as hair grows
> cells move upwards & become dead keratinized cells

23
Q

Hair Growth - 3 stages

A

Each hair follicle goes thru a growth cycle which includes:
i) Growth stage → cells of matrix divide
ii) Regression stage → matrix cells stop
dividing
iii) Resting stage → nothing happens

After resting stage, old hair root falls out of follicle and a new hair begins to grow

24
Q

Arrector pili muscle

A
  • This is smooth muscle which attaches to the hair follicle & raises the hair, creates a bump in skin and creates goosebumps
  • Sensory nerve endings around hair bulb
25
Q

Sweat (sudoriferous) glands types

A

1) Merocrine (eccrine) sweat glands

2) Apocrine sweat glands

26
Q

Merocrine (eccrine) sweat glands

A
  • simple coiled tubular glands emptying into a pore (eg. palms, soles, forehead)
  • functional from birth
  • sweat is composed of water, ions, urea, uric acid, ammonia, amino acids, glucose, & lactic acid (pH 4-6)
  • helps to regulate body temperature & has a small role in eliminating wastes
27
Q

Apocrine sweat glands

A
  • Are larger & empty into hair follicles
  • Found in skin of axilla & groin
  • Begin to function at puberty
  • Secretion also contains lipids & proteins

Ceruminous glands are modified apocrine glands found in skin lining the external ear canal
> Secrete sticky earwax (cerumen)
> Helps prevent foreign substances from entering ear

28
Q

Ceruminous glands

A

are modified apocrine glands found in skin lining the external ear canal
> Secrete sticky earwax (cerumen)
> Helps prevent foreign substances from entering ear

29
Q

Sebaceous glands

A
  • Simple branched alveolar glands connected to hair follicles
  • Produce & secrete an oily substance called sebum
  • Sebum softens & lubricates hair & skin
  • Also prevents dehydration of hair and skin
  • Also inhibits growth of certain bacteria on skin
30
Q

Nails

A
  • Are hard, keratinized epidermal cells
  • Deeper layers of epidermis form nail bed under nail
  • Proximal portion of nail bed is nail matrix, responsible for nail growth
  • Matrix layer actively divides and pushes out of the nail bed, grows ~1mm a week
  • Nails function to protect distal phalanx & aid in grasping
31
Q

Nail structures -3

A
  • Free edge extends over digit
  • Nail body is visible portion
  • Nail root embedded in a fold of skin
32
Q

Body Temperature Regulation

A
  • Body temperature is 37 ± 0.5 oC
  • At normal body temp., conditions are optimal for enzymatic activity
  • Body core (organs in skull, thoracic & abdominal cavities) temp. is relatively constant
  • Shell (skin) temp. can fluctuate
33
Q

Vitamin D Synthesis

A
  • Vitamin D is actually a group of closely related compounds
  • Synthesis of vitamin D begins in the skin with the formation of a precursor molecule, cholecalciferol
  • Required to increase calcium absorption from food
34
Q

Vitamin D Synthesis

A

1) Sunlight (uv radation) – >
2) Cholesterol in dermal blood converted to vitamin D precursor – >
3) precursor molecule transported on blood to liver and kidney – >
4) coverted to calcitrol (active vitamin D) – >
5) Vitamine D stimulates absorption of cacium ions from ingested foods in the intestine – >
6) increases blood Ca2+ levels

A&P Fall (17 decks)

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