revised integumentary system(comparison bet. man and frog )
TRANSCRIPT
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)