Integumentary System

• skin or cutis

- external covering of the body,

comprising the skin, hair, feathers,

scales, nails, glands, etc.

• L. intergumentum- “a covering”

Function:Frog Skin• Protection from

mechanical and chemical injury and invasion of microorganisms

• Reception of environmental stimuli (pain, pressure and temperature)

• Respiration• Movement of nutrients

and gas

Human Skin:• Protection from

mechanical and chemical injury, invasion of microorganisms and UV light

• Regulation of body temperature

• Excretion of waste materials

• Thin, slippery and moist

• Darker on dorsal side

• Skin color varies

a. environment

b. distribution of

pigment cells (chromatophores)

• Chromatophores

3 kinds of pigments:

a. melanophores (black brown pigment)

b. guanophores (white)

c. lipophores (reddish )

xanthophores (yellow pigment)

2 layers of the frog skin 1. Epidermis

- stratified squamous epithelium

- divided into 2 layers:

a. stratum corneum

- outermost layer

- squamous cells

- shed off

b. stratum germinativum

- inner to s. corneum

- columnar cells

- mitosis

- stratum Malpighi

- chromatophores

2. Dermis - Made up connective tissue - Composed of 2 regions a. stratum spongiosum - loose connective tissue, blood vessels, pigment cells and glands 2 types of glands 1. Mucous glands - smaller, more numerous - Mucus - Moist and slimy - Prevents drying up 2. poison gland - larger, fewer- produce substances to that can be mildly irritating to very toxic

depending on the species - protection against enemies

b. stratum compactum

- dense connective tissue

- smooth muscle fibers

Organ System: Human Skin

• Body’s largest

organ

• Two layers

– Upper epidermis

– Lower dermis

• Lies atop a layer of

hypodermis Sweat gland

Epidermis

• Stratified squamous epithelium

• Grows from bottom upward

• Most abundant cells are keratin-

producing keratinocytes

• Melanocytes produce the brown

pigment melanin

Dermis

• Dense connective

tissue with many elastin

and collagen fibers

• Includes blood vessels,

lymph vessels, and

receptor endings of

sensory nerves and

glands

Sebaceous Glands

• Secretions lubricate and soften hair and

skin; also kill many surface bacteria

• Acne occurs when bacteria infect oil gland

ducts

Sweat/Sudoriferous Glands

• Composition of sweat

– 99% water, with dissolved salts, trace of

ammonia (waste product)