Integumentary system Flashcards
The Integumentary system is comprised of what dermal layers?
Epidermis
Dermis
Hypodermis
What are the 6 functions of the integumentary system?
- Prevents dehydration
- Facilitates temp regulation
- Houses cutaneous receptors for environmental sensation
- Active metabolism
- Excretion of wastes
- Continuous with mucosal linings of the oral, anal, urogenital, vestibule of the nostril and palpebral fissure of the eye.
What are the 2 distinct regions all skin is comprised of?
Epidermis
Dermis
The epidermis consists of five strata; from outer to inner:
- stratum corneum
- stratum lucidum
- stratum granulosum
- stratum spinosum
- stratum basale/ germinativum
What is the most abundant cell type in the epidermis?
Keratinocytes
Explain the Stratum Basale (germinativum)
1-2 cells thick
80% are Keratinocytes
20% are Melanocytes
Obtains nutrients from diffusion of plasma out of capillaries in the dermis but not too far away so receives sufficient nourishment.
Explain the Stratum Spinosum
8-20 cells thick
Cells flatten slightly, synthesize proteins (cytokeratin or alpha-keratin)
Nuclei are darkened (pyknosis), early signs of cell death
Explain the Stratum granulosum
Cells mainly dead at this stage
Flattened in appearance
Explain the Stratum lucidum
Translucent band of dead cells
More prominent and thicker in regions of thickened skin such as, palmar and plantar callouses
Explain the Stratum corneum
Outermost layer
Dead cells
Continually sloughed
Keratin and cellular debris combine with lipids to form a tough relatively impermeable layer
What are the 2 layers of the Dermis?
Papillary (outermost next to epidermis)
Reticular (innermost next to the hypodermis)
Explain the Papillary
finger-like papillae that project into the epidermis, forming dermal ridges that increase surface friction/grip and also ‘fingerprints’
What is the hypodermis?
Layer of loose connective tissue separating the dermis from the underlying structures/ tissues especially muscle.
Permits movement of skin without tearing
What are sweat glands important for?
Thermoregulation
_____ are coiled structure that open to the exterior epidermal surface and produce hypotonic watery sweat.
Eccrine glands
Explain Apocrine glands
Affected by sex-steriods and as such are only active following onset of puberty.
Abundant over the surface of dogs, horses, cattle, cats and swine.
‘horse lather’
_____ is a mixture of lipids and cell components because sebaceous cells release _____ through a _____.
Sebum
Sebum
holocrine mechanism
Name some other cutaneous glands:
Anal glands
Anal sacs
Mammary glands
Submental glands
What are the functions of Vitamin D?
Calcium homeostasis (regulation)
Regulation of phosphate in the renal system (kidneys)
An important role in the terminal differentiation of promyelocytes to monocytes (white blood cells)
Vitamin D deficiency affects the immune system, especially T cell-mediated immunity
Excess vitamin D (vitamin D toxicity) suppresses the immune system
Explain Vitamin D synthesis.
Vitamin D3 is produced photochemically in the skin from 7-dehydrocholesterol
This is then converted to cholecalciferol (vitamin D3) in relatively large quantities in the skin.
