Integumentary System

• Sheet-like membranes of epithelium, connective tissue, and other organs

Types of membranes• Serous - lines body cavities that don’t open

to the outside– Parietal and visceral– secretes serous fluid. What’s the purpose of

serous fluid?– Where would this be found?

• Peritoneum

• Pleura

• pericardium

Types of membranes

• Mucous - lines cavities/tubes that open to the outside– Stratified squamous or simple columnar– secretes mucus. Purpose?– Specific locations?

Types of membranes

• Synovial - lines joint cavities– secretes synovial fluid to lubricate joints– location?

• Cutaneous - skin

Skin

• One of the largest organs

• What are some functions (pg 111)?

• Consists of the epidermis, dermis, hypodermis (subcutaneous)

• What is the difference between a subcutaneous (hypodermic) and a intradermal injection?

Epidermis

• Consists of stratified squamous. What can be said about the blood supply?

• New epidermis is created every 25-45 days

• Stratum basale– Receives the most noursihment– Cell division– ~25% of cells are melanocytes

Epidermis• Stratum Spinosum

– Cell division, how would it compare to the basale?

• Stratum Granulosum– Abundance of granules (glycolipids and keratin)

– What is the purpose of keratin? Glycolipid?

– Loses nourishment

– What does this result in?

– keratinization - the cells fill with keratin protein

– Keratinocytes

Epidermis

• Stratum lucidum– Areas with thick skin possess this layer. Where

would this be? What areas would not possess this layer?

• Stratum corneum - 3/4 of thickness– Functions?– What can be said about the cells here?– Average person sheds ~40 lbs of skin in their

lifetime

Skin Color

• specialized cells (melanocytes) produce the pigment melanin (mainly found in the basale layer)

• melanin ranges from yellow to reddish-brown– absorbs light radiation – Significance?

Skin Color

• Melanocytes possess extensions that transport melanin between epidermal cells

• Cells in stratum basale phagocytize melanin– Causes?

• UV radiation destroys the bodies folic acid reserves

• What other effects does UV radiation have? What layer would be impacted most?

Skin Color• Most people possess the same number of

melanocytes.

• What would cause the differences in skin color?

• Determined by genetics and environment

• How could blood affect skin color?

• Carotene can effect skin color.

• What are freckles?

Dermis

• binds the epidermis to underlying tissues

• Varies in thickness, depending on location

• contains of collagenous and elastic fibers. Significance?

Dermis

• Papillary layer - superficial dermal layer– Looseness of tissue allows cells to move

around.

• Dermal papillae– House capillary loops, pain receptors,

Meissner’s corpuscles– Palms and soles they are arranged in patterns– Significance?

Dermis

• Reticular layer - deepest skin layer– Contains: blood vessels, sweat and sebaceous

glands, and Pacinian corpuscles– Phagocytes also found in this layer

• Collagen and Elastic Fibers– Found throughout dermis– Binds water to keep skin hydrated– Other roles?– What happens as you age?

Subcutaneous Layer (hypodermis)

• no distinct boundary between subcutaneous and dermis

• composed of loose connective and adipose– If it contains adipose tissue, what is a major

function of the hypodermis?

• contains - major blood vessels

Hair • Functions of hair?• hair follicle - group of epidermal cells

inside a dermal sheath• Functions - • nourished by dermal vessels• Pg 118• Where do you think cell division happens? • The hair shaft is completely keratinized.

– How do you think the root differs?

Hair

• Arrector pili muscles attach to the hair follicle.• What happens when they contract?• Hair color

– What causes dark vs blonde vs white hair?

– Another pigment, trichosiderin, is found in red hair

Hair• Hirsutism - excessive hairiness in women

– Results from over production of hormones caused by an ovarian or adrenal gland tumor

• More testosterone production creates more terminal hair in women

Sebaceous Gland

• Typically associated with a hair follicle

• secrete sebum, oily mixture, into hair follicles

• Purpose of sebum?

• These become more active during what period of life?

Sweat glands• Consists of a tiny tube originating from a

ball-shaped coil in the deeper dermis• eccrine glands - most numerous

– function to cool the body

• Sweat consists of water, salts, urea, uric acid, lactic acid

• Sweat is acidic – Significance?

Sweat Glands

• appocrine glands - found in genital and axillary regions– Secretions are odorless, what causes the odor? – When do these become active?– Possible equivalent to sexual sweat glands in other

animals

• Other modified sweat glands are mammary glands and ceruminous glands (ear)

Nails

• Protective coverings• What can be said about the keratinization of

epithelial cells in the skin vs. hair vs. nails?• Cell division happens in the nail matrix• The lunula is the most active growing

region• Cells then slide up to the nail bed • Why do nails have a pinkish color?

Skin disorders• Jaundice• Bed sores• Acne• Whiteheads• Blackheads• Seborrhea• Blister• Rosacea• Shingles• Striae• Warts• Seborrheic keratoses

• Ringworm• Cyanosis• Athlete’s foot• Boils• Cold sores• Contact dermatitis• Impetigo• Psoriasis• Alopecia• Cysts• Lipoma• Eczma• Vitiligo

Skin Cancer• Carcinomas - originating in epithelial cells• What layer?• Basal Cell Carcinoma

– slow growing– typically removed by surgery– caused by prolonged sun exposure– ~80% of skin cancers

Skin Cancer

• melanomas - originating in melanocytes– Associated with preexisting moles– can arise from normal skin or a mole– survival rate is high if removed in horizontal

phase

Melanomas

• ABCD

• Asymmetry

• Border

• Color (several colors)

• Diameter (larger than a pencil eraser

Healing Wounds

• Blood vessels break, which causes?

• What part of blood will trigger these events?

• Cascade of events creates a protein mesh

• How will this help to stop bleeding?

Healing wounds

• What happens to the area around a wound?

• Inflammation– What cells will trigger this response?– Vessels dilate and become more permeable

(plasma and leukocytes)– Benefits of leukocytes?– Release growth factors

Healing Wounds

• Proliferation– Fibroblasts migrate to injured region– What type of tissues do they form? What are

the benefits of this tissue?– Other cells are responsible for reconstructing

blood vessels, nerves, epidermis

Healing Wounds

• Maturation– Could take up to a couple years– The major goal is to increase strength of the

dermis– What cell would be a primary player?