CHAPTER 6- INTEGUMENTARY SYSTEM Flashcards

the integumentary system is an organ system consisting of the Skin and Accessory structures:

• Hair
• Nails
• Skin glands (sweat & sebaceous)

1. protecting the body from invasion by micro-organisms, chemicals and other environmental factors
2. preventing dehydration
3. acting as a sensory organ; regulating body temperature and electrolyte balance
4. synthesis of Vitamin D

true

false

cutaneous membrane

2 Layers

epithelial tissue overlying connective tissue

Epidermis

Dermis

1. stratum corneum
2. stratum lucidum
3. stratum granulosum
4. stratum spinosum
5. stratum basale

1. Papillary layer
2. Reticular layer

• outer layer of the skin
• composed of epithelial cells
• outermost protective shield of the body
• avascular
• gets nutrients through the diffusion of tissue fluid from blood vessels in the dermis
• stratified squamous epithelium

• inner layer of skin
• makes up the bulk of the skin
• tough thick layer, composed of mostly dense connective tissue
• contains collagenous and elastic fibers
• only the dermis is vascularized

The dermis is connective tissue, which is vascular, so its cells are better nourished than those of the epidermis, which is avascular epithelium.

Hypodermis or superficial fascia

The Hypodermis is not a part of the skin, but it shares some of the skin's protective functions.

• consists of mostly adipose tissue
• contains some areolar connective tissue
• acts as a shock absorber
• acts as an insulator that reduces heat
• contains blood vessels that supply skin

Hypodermis

1. The Palms
2. The Fingertips
3. The Soles of Feet

true

true

• Clear-thin translucent layer just above the stratum granulosum
• consists of a few rows of flat, dead keratinocytes
• through electron microscope, its cells are identical to those at the bottom of the next layer- stratum cormeum

• horny layer
• outermost epidermal layer- 20-30 cells layers thick
• keratin and proteins accumulated inside the plasma membrane and function to protect the skin against abrasion and penetration
• nearly waterproof because of the glycolipid between its cells
• cells shed regularly- dandruff from scalp and flakes of dry skin

• thin layer
• consists of 1-5 layers
• keratinocytes appearance change drastically; process of keratinization begins

The cells of the Stratum Granulosum accumulate dense basophilic keratohyalin granules. These granules contain glycolipids, which along with desmosomal connections, help to form a waterproof barrier that functions to prevent fluid loss from the body.

• The keratohyalin granules help to form keratin in the upper layers.
• The lamellar granules contain a water-resistant glycolipid that is secreted into the extracellular space. Tight junctions & the glycolipid play a major part in slowing water loss across the epidermis.

The Stratum Spinosum (or spinous layer/prickle cell layer) is
a layer of the epidermis found between the Stratum
Granulosum and stratum Basale. This layer is composed
of polyhedral keratinocytes. These are joined together with
desmosomes. Scattered among the keratinocytes are
dendritic cells, which are most abundant in this epidermal
layer.

The Stratum Spinosum is several cell layers thick.
This layer gets its name from the many spine-like
extensions of its keratinocytes as seen under a
microscope.

• The Stratum Basale, the deepest epidermal layer (Stratum Germinativum)
• The many mitotic nuclei seen in this layer reflect the
  rapid division of these cells.
• A single row of cuboidal or columnar cells that divide
  and grow; this layer also includes melanocytes

The cells in the Stratum Basale divide and grow, whereas the cells in the Stratum Corneum are dead and keratinized.

Papillary Dermis layer

The subcutaneous layer contains areolar connective tissue and adipose tissue.

• The epidermis is composed of stratified squamous epithelium.
• The dermis has connective tissue, smooth muscle tissue, and nervous tissue.

The subcutaneous layer conserves heat and has major blood vessels that supply the skin.

• keratinocytes
• melanocytes,
• dendritic cells
• tactile epithelial cells

The chief role of keratinocytes ("keratin cells") is
to produce keratin, the fibrous protein that helps
give the epidermis its protective properties.

Spiky-hemisphere shaped Merkel cell associated with a disc-like sensory nerve ending. The combination, called a Merkel or tactile disc, functions as a sensory receptor for touch.

Melanocytes produce the pigment melanin and is found in deepest layer (Stratum Basale) of the epidermis.

Star-shaped dendritic cells arise from bone marrow and
migrate to the epidermis. Also called Langerhans cells, they ingest
foreign substances and are key activators of our immune system.

Vitamin D synthesis

Langerhans cells

True

True

1. Hereditary Factors
2. Environmental Factors
3. Physiological Factors

Protects against water loss, harmful chemicals, mechanical injury, pathogens

This is skin pigment which provides skin color and protects
against the damaging effects of ultraviolet radiation (D N A
damage, fibroblast damage, skin cancer).

Keratinization is the process of hardening, dehydration, and keratin accumulation that occurs in epidermal cells as they
migrate outward.

• Superficial layer
• Areolar connective tissue
• Thinner of the 2 layers
• Location of dermal papillae

• Deeper layer
• Dense irregular connective tissue
• Thicker of 2 layers

Fingerprints

The papillary layer is areolar connective tissue, and the reticular layer is dense irregular connective tissue.
Blood vessels, smooth muscle tissue, and nervous tissue are found in the dermis.

The connective tissues give the dermis toughness and elasticity.

Nervous tissue includes sensory receptors and send signals to the brain and organs.

The smooth muscle tissue can cause wrinkles the skin.

Blood vessels in the dermis supply nutrients to the skin cells.

Cutaneous mechanoreceptors

• Ruffini's end organ (skin stretch)
• End-bulbs of Krause (Cold)
• (Tactile) Meissner’s corpuscle responds to light
  touch and low-frequency vibration.
• (Lamellar) Pacinian Corpuscle responds to deep
  pressure and high-frequency vibration
• Merkel's disc (sustained touch and pressure)
• Free nerve endings- sense painful stimuli (irritating chemicals, extreme heat or cold, and others).

Thermoreceptors

Nociceptors

Chemoreceptors

Nails are the protective coverings on ends of fingers and toes.
• In contrast to soft keratin of the epidermis, nails (like
hairs) contain hard keratin
• 3 parts of a nail:
• Nail plate: overlies nail bed.
• Nail bed: surface of skin, under nail plate.
• Lunula: most active growing region; pale, half-moon-
shaped region at base of nail plate.

The lunula looks white because the epidermis is thicker beneath the matrix, and it blocks the pink color from the blood vessels below.

Nails are hard because (like hair) they contain hard keratin.

Hair is present on all surfaces of skin except palms, soles, lips, nipples, parts of external reproductive organs.

Tube-like depression of epidermal cells from which hair develops; extends into dermis or the subcutaneous layer.

• Hair bulb (dividing cells)
• Hair root
• Hair shaft (dead, epidermal cells)

False

Hair papilla does contain blood vessels to nourish hair

Arrector Pili Muscle is a small band of smooth muscle that connects the hair follicle to the connective tissue of the basement membrane.

Responsible for generating heat when the body is cold, the arrector pili muscles contract all at once, causing the hair to "stand up straight" on the skin. (goosebumps).

Found all over the body except in the thick skin of the palms and soles. They are small on the body trunk and limbs, but quite large on the face, neck, and upper chest. These glands secrete an oily substance called sebum.

Sebum softens and lubricates the hair and skin, prevents hair from becoming brittle, and slows water loss from the skin. Sebum keeps hair soft, pliable, and waterproof.

False

Acne is caused by an excess of sebum which clogs the sebaceous gland.

• Lower body temperature through sweating
• Originate in the deep dermis or subcutaneous layer and abundant on the palms, soles of the feet, neck, and forehead.

The secretion is odorless, but when bacteria on the skin decompose its organic molecules, it takes on a musky and generally unpleasant odor, the basis of body odor.

• Wet skin during pain, fear, emotional upset, and sexual arousal
• Near hair follicles in armpit and groin

Ceruminous glands: secrete ear wax - located external acoustic meatus

Mammary glands: s ecrete milk - located in the b reasts

Functions of the skin:

• Protective covering, barrier against harmful substances and microorganisms
• Prevents some water loss
• Contains sensory receptors
• Excretes some wastes
• Helps produce Vitamin D
• Helps regulate body temperature

Methods of heat loss:

• Radiation: Primary method, infrared heat rays escape.
• Conduction: Heat moves from the skin to cooler objects.
• Convection: Heat loss into circulating air currents.
• Evaporation: Sweat changes into a gas, carries heat away.

Setpoint of body temperature is monitored by the Hypothalamus.

When body temperature rises:

• Thermoreceptors signal the hypothalamus.
• Vasodilation of dermal blood vessels.
• Sweat glands are activated.

When body temperature falls:

• Thermoreceptors signal the hypothalamus.
• Vasoconstriction of dermal blood vessels.
• Sweat glands are inactive.
• Muscles contract involuntarily (shivering).

37 degrees Celsius or 98.6 degrees Fahrenheit

Hyperthermia : abnormally high body temperature

• Can occur on hot, humid day, when sweat cannot evaporate.
• When air temperature is high, radiation is less effective.
• Body may gain heat from hotter air.
• Skin becomes dry, person gets weak, dizzy, nauseous, with headache, rapid pulse.

Hypothermia: abnormally low body temperature

• Can result from prolonged exposure to cold, or illness.
• Shivering is involuntary skeletal muscle contraction, caused by hypothalamus.
• Progresses to confusion, lethargy, loss of reflexes and consciousness.
• Without treatment, organs shut down.

• Inflammation is a normal response to injury or stress
• Inflammation is the body’s attempt to restrict spread of infection
• Blood vessels in affected tissues dilate and become more permeable, allowing fluids to leak into the damaged tissues

Inflamed skin may become:

• Reddened
• Swollen
• Warm
• Painful

A deep cut, reaching the dermis or subcutaneous layer, results in blood

vessels breaking; released blood forms a clot.

The first phase of wound healing is Inflammatory Phase

Initial response to injury
• Day 1-4 post injury
• Characterized by heat, pain, redness, swelling
• Platelet aggregation and activation
• Leukocyte (PMNs, macrophages) migration, phagocytosis and mediator release
• Venule dilation
• Lymphatic blockade
• Exudative

The third phase of wound healing is Remodeling Phase

6wks-1 year

• Type III collagen replaced with type I
• Characterized by increase in tensile strength
• Scar flattens

The second phase of wound healing is Proliferative Phase

Day 4-42

• Fibroblast proliferation stimulated by macrophage-released growth factors
• Increased rate of collagen synthesis by fibroblasts

Burns are classified by the extent of tissue damage

Deep, partial-thickness ( second degree ) burn

False

Superficial, partial-thickness (first degree) burn

• Destroys epidermis, dermis, accessory structures.
• Results from prolonged exposure to heat, flames, hot liquids.
• Some healing from margins.
• Often requires skin graft, skin substitutes.

The Rule of Nines

The rule of nines assesses the percentage of burns and is used to help guide treatment decisions including fluid resuscitation, and becomes part of the guidelines to determine transfer to a burn unit.

• Cell cycle slows, skin becomes scaly, age spots appear.
• Epidermis and dermis become thinner.
• Loss of fat in subcutaneous layer; person feels cold.
• Wrinkling, sagging of skin occur.
• Sebaceous glands secrete less oil; skin becomes dry.
• Melanin production slows; hair whitens.
• Hair thins.
• Number of hair follicles decreases.
• Nail growth becomes impaired.
• Sensory receptors decline.
• Body temperature regulation becomes less effective.
• Diminished ability to produce Vitamin D.