CH. 5 The Integumentary System | L.O

Pictures of Epiderms & Dermis

What tissue type is the epidermis (superficial) composed of?

Keratinized stratified squamous epithelium

What are the 4 cell types of the of the epidermis?

Keratinocytes, Melanocytes, Tactile epithelial cells, Dendritic cells

Location of Keratinocytes?

Stratum spinosum and corneum

Description of Keratinocytes

• Produces KERATIN

• Abundant cell type in epiderms

• Arise from deepest layer, dead at skins surface

Location of Melanocytes?

Stratum basale

Description of Melanocytes

• Manufactures and secretes pigment (melanin)

• Transfers melanin to nearby keratinocytes

Location of Tacticle epithelial cells?

Stratum basale

Description of Tactile epithelial cells

• Attached to sensory nerve endings to function as a touch receptor

Location of Dendritic cells?

Stratum spinosum

Description of Dendritic cells

• Act as the sentinels of the immune system

  • Presents antigens to T-Cells

What tissue type is the dermis (deep) composed of?

Dense irregular connective tissue

Name and describe the 5 primary functions of the skin.

• Protection (protection of bumps, chemicals, water loss, UV, abrasion, etc)

• Body temperature regulation (maintaining body temp. and regulating heat loss through capillary networks and sweat glands)

• Excretion (removal and waste of bodily fluid through sweat)

• Production of Vitamin D (epidermal cells use UV radiation to synthesize Vitamin D)

• Sensory Reception (contains sense organs associated with nerve endings)

What are the 5 layers of the epidermis? (Deep to Superficial)

• Stratum basale

• Stratum spinosum

• Stratum granulosum

• Stratum lucidum

• Stratum corneum

Describe the structure and function of each layer.

1) Stratum basale

• Deepest layer and is attached to underlying dermis

• Cells are activiely dividing

• Contains tactile epithelial cells and melanocytes

2) Stratum spinosum

• Spiny layer

• Contains keratinocytes (with thick bundles of intermediate filaments
  - among them are dendritic cells

3) Stratum granulosum

• Consists 8-10 layers of keratinocytes

• Contains Keratohyaline granules and Lamellar granules

• Cells are flattened with deteriorating organelles

4) Stratum lucidum

• Occurs only in thick skin

• Located in the palms of hands and soles of feet

• Composed of a few, flat dead keratinocytes

5) Stratum corneum (horny layer)

• Superficial and external layer

• Layers thick of dead keratinocytes

• Protects skin against abrasion and penetration

• Cells are shed regularly

What are the 2 layers of the dermis?

• Papillary dermis

• Reticular dermis

Describe the structure and function of each layer.

1) Papillary dermis

• Superficial, and makes up 20% of the dermis

• Aerolar C.T containing thin collagen and elastic fibers

• Includes dermal papillae

• Increases surface area for exchange of gases, nutrients, and wastes

2) Reticular Dermis

• Deeper, and makes up 80% of the dermis

• Dense irregular C.T

• Has cleavage and flexure lines

• Rich nerve supply

• 2 massive vascular plexuses
  - dermal plexus
  - subpapillary plexus

Describe the structure and function of the hypodermis.

• Deep to the skin (Also known as the superficial fascia)

• Contains aerolar and adipose C.T

• Anchors skin

• Insulates the body

Describe the factors that contribute to skin color

3 Pigments:

1) Melanin

• Most important pigment

• Passes from melanocytes to keratinocytes in the stratum basale of the epidermis

• Difference in skin color results from the amount and type of melanin produced
  

2) Carotene

• Yellow-orange pigment from carrots and tomatoes
  

3) Hemoglobin

• Crimson color of oxygenated blood is due to this

Describe the structure of nails.

• Made up of dead, keratinized cells filled with hard keratin

• Rests on nail bed of epidermis

• At the root, the nail bed thickens into nail matrix (actively growing part of the nail)

What are the parts of a hair? Explain the function of each part

Root

• Embedded in the skin

Shaft

• Projects above the skin’s surface

• Medulla - central core; contains large cells and air spaces

• Cortex - surrounds the medulla; layers of flattened cells; most heavily keratinized (provides strength)

• Cuticle - outermost layer; single layer of overlapping cells (provides protection)

What are the parts of a hair follicle? Explain the function of each part.

1. Hair follicle - extends from epidermal surface into dermis; structure that surrounds and produces the hair

2. Hair bulb - deep, expanded end of the follicle; site of active cell division that produces/grows the hair

3. Dermal papilla - projection at the base of the hair bulb; contains blood vessels that nourish the growing hair

4. Hair follicle receptor (root plexus) - knot of sensory nerves wrapped around the hair bulb; detects hair movement and touch

5. Arrector pili muscle - bundle of smooth muscle attached to the follicle; contracts to make hair stand erect (causes goosebumps)

6. Sebaceous (oil) gland - attached to the hair follicle; produces sebum (oil) to lubricate the hair and skin

Describe the structure and function of oil glands

Oil glands (sebaceous glands)

• Occurs everywhere around the body except palm and soles

• Secretes sebum (oily substance)

Functions of sebum

• Collects dirt

• Helps slow water loss across skin

• Helps kill bacteria

What are the 2 type of sweat glands?

• Eccrine glands

• Apocrine glands

Compare eccrine and apocrine glands.

Eccrine glands

• Produces true sweat

• 99% water with some salt

• Contrains traces of metabolic waste

Apocrine glands

• Confined to axillary, anal, and geniteal areas

• Produces sweat + fatty substances + proteins

• Involved with sexual signaling, attractiveness, mate selection

Describe the layers involved in first-, second-, and third-degree burns, along with the symptoms, and explain why serious burns are life-threatening.

1st Degree Burn

• Upper epidermis is damaged

2nd Degree Burn

• Epidermis and superficial region of dermis is also damaged
  - Blisters appear
  - Skin heals with little scarring

3rd Degree Burn

• Consumes entire thickness of the skin (Both epidermis and dermis are affected)
  - Burned area appears white, red, or blackened
  - Graft is needed

Serious burns are life-threatening because it can lead to a catastrophic loss of body fluids

• Can lead to fatal circulatory shock

• After the initial crisis, infection becomes the main threat
  - Pathogens can easily pass through the skin

• Rule of Nines help estimate the extent of the burn

Identify the cell type involved and the degree of malignancy in the three types of skin cancer.

3 types of Skin Cancer

• Basal cell carcinoma 
  - Stratum basal cells proliferate, invading the dermis and subcutaneous tissue
  - Least Malignant and most common
  - Full cure after removal

• Squamous cell carcinoma
  - Arises from keratinocytes of stratum spinosum
  - Grows rapidly and metastasizes if not removed

• Melanoma
  - A cancer of melanocytes
  - MOST DANGEROUS due to it being very invasive in nature