Integumentary System Flashcards
Integumentary System Overview
Consists of: Skin Hair, nails, glands Sense Receptors (nervous) Muscles
Skin Layers
1- Epidermis
2- Dermis
3- Below skin = hypodermis
Epidermis
- Upper Layer
- Stratified Squamous epithelium
- Avascular
- 4-5 Sub-layers based on cell types:
1) Stratum Basale
2) Stratum Spinosum
3) Stratum Granulosum
4) Stratum Lucidum
5) Stratum Corneum
Stratum Basale
- Single row of cells
- 2 cell types:
1) Keratinocytes (90%) - Undergo mitosis
- Make keratin (tough protein)
- Migrate to surface as new cells produced in basale
2) Melanocytes (10%) - Produce pigment (melanin) for uv light protection (e.g. sunburn, wrinkles and cancer)
Stratum Spinosum
Limited cell division
Stratum Granulosum
Contains dark staining granules
Stratum Lucidum
- Flat, dead cells (too far from blood supply)
- Visible ONLY in thick skin
Stratum Corneum
- 20-30 layers of flat dead cells filled with keratin (tough protein), surrounded by waterproofing glycolipid (prevents water loss)
- Shed and replaced from below
Dermis
- Contains blood vessels, nerves, glands, hair follicles
- 2 sub-layers:
1) Papillary Layer
2) Reticular Layer
Papillary Layer
- Sub-layer of dermis
- Beneath epidermis
- Areolar CT
- Vascular
- Has projection into epidermis = dermal papillae (in thick skin these form dermal ridges = fingerprints)
Reticular Layer
- Sub-layer of dermis
- Most of dermis
- Dense irregular CT
Hypodermis
- NOT part of the skin
- = subcutaneous layer
- = superficial fascia ( Fascia = CT layers that surround and support organs)
- Adipose CT below skin (stores 1/2 of body’s adipose tissue (insulation))
Thin Skin Characteristics
- Lucidum not apparent
- Has hair follicles, sebaceous glands, arrestor pili muscles
Thick Skin Characteristics
- Found on the palm of the hand and sole of the foot
- Lucidum visible (thin clear layer of dead skin cells)
- no hair follicles, sebaceous glands, or arrestor pili muscles
Epidermal Derivatives
- All derived (formed) from the epidermis
- Includes:
1) Hair
2) Nails
3) Skin Exocrine Glands
Hair
- Epidermal Derivate
- All dead cells
- Parts:
1) Root = dead cells below the surface
2) Shaft = above the skin
3) Hair Follicle
Hair Follicle
- surrounds root
- Epithelial root sheath = several epidermal layers extend into the dermis
- Bulb = expanded region at base of root
- Matrix = single layer of cells (from basal cells) - site of hair growth and melanin for hair colour
- Outer CT sheath -> holds follicle in place (formed from the dermis)
- Hair papilla - extends upward beneath matrix (blood supply / formed from dermis)
- Root hair plexus - free nerve ending (touch)
- Sebaceous (oil) gland - opens into follicle
- Arrestor pili muscle (smooth muscle) - causes “shivers”
Nails
- Very heavily keratinized epidermal cells
- Consists of:
1) Nail root (buried in skin)
2) Body (visible portion)
3) Free edge
Skin Exocrine Glands
1) Sebaceous Glands
2) Sudoriferous Glands
3) Ceruminous Glands
4) Mammary Glands
Sebaceous Gland
- Connected mainly to hair follicles
- Secretes sebum (oily - mix of fats, salts, proteins) which softens, lubricates hair and skin, prevents dying out, antibiotic
Sudoriferous Glands
- Sweat glands
- Secretory portions in dermis of thick and thin skin
- Ducts open into skin surface
- Act to:
1) Cool the body
2) Antibiotic (acidic)
3) Remove wastes (ures, etc.)
Ceruminous Glands
- Modified sweat glands
- In ear canal
- Produce ear wax - preventa insects etc from entering
Mammary Glands
- Modified sweat glands
- Produce milk
Cutaneous Sense Receptors
- Receptor = Sensory neuron (part of NS)
- Specialized cel that responds to stimuli (touch, temp., pain)
- 4 major types:
1) Touch Receptors
2) Pressure Receptors
3) Thermoreceptors
4) Nociceptors
Touch Receptor
- Cutaneous sense receptor
-Free nerve endings -> In epidermis
-Root Hair Plexuses
-Meissner’s Corpuscles (in dermal papillae
Carpuscle = connective tissue capsule surrounding nerve ending
Pressure Receptors
- Free nerve endings in dermis
- Pacinian Corpuscles deep in dermis or hyodermis
Thermoreceptors
Free nerve endings for temperature
Nociceptors
- Free nerve endings for pain
- Third degree burns = no pain because nociceptors destroyed
