ANP W7 Integumentary System

What are the 2 primary layers of the skin? Describe each.

1. Epidermis → outer most portion; stratified squamous epithelial cells; avascular

2. Dermis → CT layer; vascular; has nerves and glands

How is the epidermis nourished?

By the capillaries in the dermis

What does a pink flush indicate? What does cyanosis indicate?

increased blood volume or increased bloody oxygen

Cyanosis = low blood oxygen; blueish gray skin colour

The dermis is composed of what kind of connective tissue?

Dense irregular CT → collagen and elastic fibres

What is a sudoriferous gland?

sweat gland - located in dermis layer

What are the 4 functions of the dermis layer of the skin?

1. protection

2. nourishment of epidermis

3. skin elasticity

4. sensory perception

What is the subcutaneous layer? Fx?

Hypodermis

• composed of Areolar and adipose tissue

• vascularized and has nerves

• thickness varies

Fx:

• Connects skin to underlying muscle

• insulation

• temperature regulation

• sensory perception

Why is there no clear boundary between the hypodermis and the dermis?

Continuous bundles of elastic fibers connect them together

Accessory structures of the skin help protect it and give it more functions. What are 3 accessory structures of the skin?

1. Glands → sebaceous oil glands and sudoriferous (sweat) glands

2. Hair

3. Nails

Describe Sebaceous glands. Location, fx? What does it secrete?

• Sac like gland associated with hair follicles

• found every where except on palm of hands and soles of feet

• secretes sebum → oily substance that lubricates skin and hair and prevents drying

• **produces the Vernix caseosa a greasy white substance covering the fetus during the last trimester

What is the Meibomian gland?

Meibomian gland is a type of oil gland that helps lubricate the eyes.

What are the 2 types of sudoriferous glands? Describe each.

1. Eccrine glands

• Widely distributed; most numerous on palms, soles, forehead

• Secrete watery sweat (mainly water + salts) for thermoregulation

• Open directly onto skin surface

2. Apocrine glands

• Found in armpit, groin, areola of breast

• Open into hair follicles

• Become active at puberty; can produce odor when decomposed by skin bacteria

• Secrete thicker, milky fluid (water, salts, proteins, lipids)

Describe sudoriferous gland. Fx?

Coiled-tube like gland that directly opens up to the skin or to a hair follicle. It is located in the dermis and hypodermis

fx:

• body thermoregulation

• eliminate wastes (salts)

What are some modified sudoriferous glands?

1. Ceruminous gland in the ear canal producing ear wax (cerumen)

2. Ciliary glands on the edge of eyelids

3. Mammary glands in breast

What is lanugo?

soft hair of fetus and newborns

What is the name of the involuntary smooth muscle that causes hair to stand up straight?

Arrector pili → also stimulates secretion of sebum

The hair follicle is a sheath of …?

Epithelial and connective tissue

What is the crescent-shaped area nearest the root on a nail called?

Lunula

What are the 4 major functions of the Integumentary System?

1. Protection - the body’s first line of defense

2. Protection against dehydration (drying)

3. Temperature Regulation

4. Collect sensory information

How does the skin act as the first line of defense to protect the body? (4)

1. An intact skin is a barrier against infection by microbes

2. Sloughing (shedding) of old, dead, surface skin removes pathogens

3. Protection against UV rays (melanin)

4. Sweat has some microbial characteristics

   • Defense against bacterial toxins and some harmful environ chemicals

How does the skin protect against dehydration? (2)

1. prevents excess water loss by evaporation

2. Keratin and sebum help to waterproof the skin and keep it moist and supple

How does the skin regulate body temperature? (3 mechanisms)

1. Regulation of sweat secretion

2. Regulation of blood flow near body surface

3. Shivering causes contraction of the arrector pili muscle → raised hair traps warm air near the skin

What type of senses is the skin able to detect? What type of nerve/receptor is responsible for each?

1. Pain → free nerve ending

2. Temperature → free nerve ending

3. Light touch and deep pressure → sensory receptor

4. Heat and Cold → thermoreceptor

What contributes to the colour of skin?

1. Melanin → degree of brown pigment in the skin

2. Hemoglobin → blood in the surface of blood vessels (pallor =pale, flush=pink, cyanosis=blue)

Define Carotenoderma.

A skin discolouration where excess carotene in the blood gives the skin a yellow/orange colour.

• carotene pigment obtained from vegetables

What pigment causes the skin to turn yellow when someone has Jaundice?

Bile pigments

Jaundice reflects impaired liver function, gall bladder problems abd or excess hemolysis (RBC death)

What are 4 conditions that Jaundice may be a symptom of?

1. Tumour pressing on bile duct

2. Virus that causes inflammation of liver (hepatitis)

3. Blood disease → RBC rapidly destroyed

4. Immaturity of liver (inability to process bilirubin)

How does the skin repair itself? (wound healing)

Wound healing only happens in areas with actively dividing cells. It beings after blood has clotted with an inflammatory response.

• stem cells produce new tissue cells and BV

• collagen produced by fibroblasts close the wound

• arger injuries require more extensive growth which can lead to scars(cicatrix) and keloids

What 4 factors affect healing?

1. nutrition

2. blood supply

3. infection

4. age

What are the 4 classifications of burns? Describe each briefly.

1. First degree superficial

   • surface of epidermis only; minimal pain

   • skin is red and dry

2. Second degree superficial partial thickness

   • burn reached deep into the epidermis and part of the dermis

   • red, blistered painful

   • heals without scarring

3. Second degree deep partial thickness

   • burn through epidermis and dermis

   • tissue blistered, weeping, or dry if sweat glands damaged

   • less painful than superficial burns because of nerve damage

4. Third degree full thickness

   • burn through all layers of skin + some hypodermis; may include damage to muscle and bone

   • may require surgery, loss in digits or limbs

Of these 3 types of skin cancer, list them from most to least common.

1. Basal Cell carcinoma

2. Squamous cell carcinoma

3. Melanoma

**remember carcinoma is cancer of the epithelial tissue

What is Impetigo?

Bacterial infection of the skin caused by staphylococcal or streptococcal infection

What are 2 examples of a viral infection of the skin?

1. warts

2. herpes simplex virus

What is tinea?

a fungal infection of the skin

Define Dermatitis

general inflammation of the skin

Urticaria and eczema are exampels of what kind of disorder of the skin?

Acute inflammatory disorder

Describe Lupus erythematosus

• Autoimmune disease of connective tissue

• characterized by rough, raised, violent tinted papules on face/scalp only

Describe systemic sclerosis/scleroderma.

• Unknown etiology; may be autoimmune disease of vessels and CT

• thickening and tightening of skin

• severe cases: impaired function, lack of facial expression

Describe Psoriasis

• Chronic inflammatory condition with unknown cause; could be autoimmune or genetic

• characterized by silvery scales

Describe Dermatographia

“Allergy to touching self”

Dermatographia is a skin condition where light scratching or pressure causes raised, red, itchy welts.

• Also called “skin writing”

• Caused by histamine release from mast cells in the skin

• Usually harmless and often temporary

Define these types of Lesions: Macule, Papule, Pustule

Macule - flat and discoloured

Papule - small firm, raised lesion → large papule is a nodule

Pustule - pus filled lesion; infected vesicle

Define these types of Lesions: Vesicle, Plaque, Cicatrix and Keloid.

Vesicle - bulla/blister or small fluid filled sac

Plaque - Large, slightly elevated, flat surfaced legion often topped by scales.

Cicatrix - scar

Keloid - raised, irregular, tumour-like masses of collagen resulting from excess scar tissue formation