The integumentary system

What is the integumentary system made up of and what is it called?

• The integumentary system is made up of the skin and several accessory organs

• Also called the cutaneous membrane or the integument

What four tissue types comprise the integumentary system?

Connective, epithelial, muscle, and nervous

What is the largest organ of the body?

The integumentary

What are the functions of skin?

• Protection

• Temperature maintenance

• Synthesis and storage of nutrients

• Sensory reception

• Excretion and secretion

How does the skin protect the body?

• Covers underlying tissues and organs from impacts, chemicals and infections

• Prevents loss of body fluids

How does the skin maintain temperature?

• Regulates heat exchange with the environment

How does the skin synthesize and store nutrients?

• Epidermis synthesizes vitamin D, a steroid building block for a hormone that aids in calcium uptake

• The dermis stores large reserves of lipids (fats) in adipose tissue

How does the skin receive sensations?

• Receptors in the skin detect touch, pressure, pain, and temperature stimuli and relay information to the nervous system

How does the skin excrete and secrete?

• Integument glands excrete water, salts and organic wastes

define homeostasis

tendency for physiological systems to stabilize internal conditions

Describe the epidermis

• Outer, thinner region

• Composed of 5 layers, or strata

What are the 5 strata layers of the epidermis?

(listed from deepest to most superficial)

• Stratum Germinativum (or Stratum Basale) BALL

• Stratum Spinosum SOFT

• Stratum Granulosum GREY

• Stratum Lucidum LIKES

• Stratum Corneum CAT

Describe the stratum germinativum (stratum Basale)

• Just superficial to the dermis

• Form epidermal ridges and dermal papillae where the epidermis and dermis meet

• Layer of new cell generation

• New cells replace old cells as they shed from the epithelial surface

• Contains melanocytes, which synthesize melanin.

-Melanin gives brown, yellow-brown, or black pigment to the epidermis

• Contains sensory nerves

-Free nerve endings – detect pain and temperature

-Tactile cells (Merkel cells) – touch sensations

Describe the stratum spinosum

Layer of continual divide of epithelial cells

Describe the stratum granulosum

• Cells stop dividing in this layer and begin producing the protein, keratin

• Keratin – Extremely durable and water-resistant protein; basic structure of hair, nails, and calluses

Describe the stratum lucidum

• Thick layers of flattened densely packed, keratin-filled cells

• Thick layers on palms and soles of feet

Describe stratum corneum

• Most superficial layer

• 15-30 layers of flattened and dead epithelial cells that are keratinized (hardened)

• Serves as a mechanical barrier against microbes

• Cells are so tightly connected, they shed in large groups or sheets

Describe the dermis

• Lies beneath the epidermis

• Has 2 layers

• Contains vasculature, nerve fibers, and epidermal accessory organs (hair follicles and glands)

What are the two layers within the epidermis?

• Papillary layer – loose connective tissue that nourishes and supports the epidermis

• Reticular layer – mesh-like network of dense, irregular connective tissue

-Contains elastic fibers which allow for flexibility and collagen fibers which limit flexibility to prevent tissue damage

Describe the hypodermis

• Also called the subcutaneous layer, and lies beneath the dermis

• Important in stabilizing the position of the skin relative to the underlying tissues (bones, muscles, organs)

• Composed of loose connective tissue and many fat cells (adipose or subcutaneous fat)

• Energy reserves

• Insulation

• Shock absorber

Describe the accessory structure hair

• On all parts of the body except palms of the hands, soles of the feet, lips, and portions of external genital organs

• Nonliving structures produced by hair follicles in the dermis

Describe hair follicles and their components

• Formed from epidermal cells

• Cells become keratinized as they are pushed out

• Hair root – portion of hair within the follicle

• Hair shaft – portion of hair that extends beyond the surface of the skin

Describe sebaceous glands

• Also called oil glands which secrete oily lipids (called sebum) into hair follicles and onto the surrounding skin

• Lubricates the hair and skin and inhibits the growth of bacteria

Describe sweat glands

2 different types

• Merocrine – secrete directly onto the surface of the skin

• Apocrine – secrete through a hair follicle

Describe the arrector pili muscle

small smooth muscle that extends the hair and squeezes sebum out of the sebaceous glands

What are nails and their components?

• Formed from specialized, densely-compacted, keratinized epithelial cells

• Nail bed – area of epidermis covered by the nail

• Nail root – site of nail growth

• Cuticle (eponychium) – fold of stratum corneum that extends partially over the nail root

Define burn

To oxidize or be oxidized by fire or equivalent means, creating a tissue reaction or injury

What is the rule oof nines used for?

to determine the extent of a burn to the human body

Describe a 1st degree burn

• Only epidermis is affected

• Pink or red skin

• No blisters or swelling

• No tissue destruction

Describe a 2nd degree burn

• Acute inflammation with blistering

• Extends into the dermis

• Red tissue discoloration

• No charring and no major tissue destruction

• Hair may be singed

Describe a 3rd degree burn

• Destruction of entire thickness of skin

• Usually expansion and splitting of tissue

Describe a 4th degree burn

• Charring

-Black, crumbling tissue

-Partially missing tissue

-Very discolored (black)

-Very dehydrated

• Complete incineration of skin and underlying tissue

• Muscle greatly affected

• Expansion and splitting of lesser charred areas