INTEGUMENTARY
SYSTEM
Skin, hair, nails, and glands
What does it mean?
• Integere (Latin)- “to cover”
• Dermato and cutis (Greek and Latin)- “skin”
• Epi- (Greek)- “upon” or “above”
Why do we need it? overview
• Largest organ
• Retains moisture
• Sensory receptors for:
– pain,
– Heat
– Touch
• Excretes salts
• Excretes small amounts
of waste
• Stores blood
• Regulates body temp.
• 2 main parts
– Epidermis and dermis
• Under the dermis is the hypodermis
(supericial fascia- subcutaneous tissue)
– It acts a foundation not truly part of the skin
Epidermis
• Surface skin
– 1st line of defense against infection
– Contains no blood vessels
– Layers and layers of epithelial cells
• Melanocytes
– ¼ of stratum basale is made of these
– Synthesize a pale yellow to black pigment called
melanin
– Cytocrine secretion- melanin is secreted into
keratinocytes
• Melanin- skin color and protection against uv rays
• Keratinocytes
– majority of stratum basale
– Primary epithelial cell of skin
More about the epidermis
• Carotene- in stratum
corneum and fatty layers
beneath the skin
– Produces yellowish hue
common with Asian
ancestry
• Hemoglobin- cause for
pinkish color of Caucasian
skin
– Less melanin, more
hemoglobin
• Albinos- no melanin in
skin at all
• Ridges and groovesincrease friction to grasp
other objects
– Ex. Loops and whorls
(fingerprints, palm prints,
footprints)
The Dermis
• Also known as the
corium
• Thicker and more
fibrous than the dermis
• 2 layers
• Fibrolasts- connective
tissue develops
• Macrophages- engulf
wastes and foreign
microorganisms
• Adipose tissue
• Thinnest over eyelids
and male sex organs
• Thicker on back than
stomach
• Thickest on palms of
hands and soles of feet
Papillary Layer
• Top (outer) layer
• Soft
• Elastic, reticular fibers that enter the epidermis
– Brings blood and nerve endings closer
• Papillae are finger-like projections- loops of
capillaries to increase the surface area of dermis
and anchor epidermis
nerve endings sensitive to
soft touch.
– In some papillae
Reticular Layer
• Rete- net (Latin)
• Dense, irregular connective tissue
– Interlacing bundles of collagenous and elastic
fibers
• Strong resistant layer
• Gives skin strength, extensibility, ad elasticity
• Oil glands (seaceous glands), sweat glands, fat
cells, and larger blood vessels are in this layer
Hair
• Follicles embedded in the epidermis and extend
to the dermis angle hair growth (curly or
straight).
• Follicle bases are expanded (called bulbs) reach
nerve endings
• Epithelial cells in the bulb divide to create the
hair shaft
• Hair pigment: melanin
– Gives hair its color
– Gray and white hair grow when melanin levels
decrease and air pockets form
• sebaceous gland- sebum is produced (cholesterol,
fats, and other substances)
– Keeps hair soft, pliable, and waterproof
• Hair has 3 layers
– Medulla
• Central core
• Cells contain eleidin separated by air spaces
• Fine hair- minimal/ nonexistent
– Cortex
• Major part of hair shaft
– Several layers
– Flattened cells
• Elongated pigment-bearing cells in dark hair
• Air pockets in white hair
– Cuticle
• Single layer, overlapping cells with free end pointing up
• Strengthens and compacts the inner layers
• Split ends
– Abrasion wears away the end of the shaft, exposes the medulla and
cortex to create the horrid split end
Sweat? Gross…or is it?
• 2 types of sweat glands
(sudoriferous)
– Coiled tubules in the dermis
– Eccrine glands-all over body
• Watery (99%), salty secretion known as
sweat
• Passes through the epidermis to skin’s
surface and opens to a sweat pore
• Controlled by the sympathetic nervous
system
– Apocrine sweat glands
• Under the armpits and groin area,
associated with hair follicles
• Same components as eccrine and is
odorless
– Bacteria breaks down apocrine sweat’s
fatty acids and proteins
» Creates the odor accompanying
post exercise
Connection to the Nervous System
• 4 receptors are involved in the sensation of touch
• 2 primary temperature receptors
• Dermis has neuromuscular spindles
(proprioceptors)
– Transmit information to the spinal cord and brain about
the lengths and tensions of muscles
• Provides awareness about the body’s position
– Spindles help in muscle coordination and muscle action
efficiency
– Jess check with Hans but I think he covers this in his
presentation!!!!!!
Touch
• Free nerve endings- dendrites are primarily pain
receptors
– Sometimes touch, temperature, and muscles
– Fibers swell at the end in response
– Disc-shaped (merkel discs) endings- light-touch
receptors in deep layers of epidermis
• Meissner’s corpuscles- light-touch
mechanoreceptors in dermal papillae
– Egg-shaped capsules of connective tissue around a
spiraled end of a dendrite
– Great amounts in lips and fingertips
– Sense quick touch, not sustained
• Pacinian corpuscles- deep-pressure
mechanoreceptor
– Dendrites surrounded by layers of connective tissue
– Respond to deep/firm pressure or vibration
– Visible to the naked eye- 2 millimeters long
• Hair nerve endings
– Respond to change in hair position
– Bare dendrites
TEMPERATURE
• End-bulbs of Krause (Krause’s corpuscles)
– Activate below 68 degrees F
– Bulbous capsule surrounds the dendrite
– Commonly found throughout the body in the dermis and
lips, tongue, and conjunctiva of the eyes
• Brushes of Ruffini (Ruffini cylinders/Ruffini’s
Corpuscles)
– Respond between 77 degrees and 113 degrees F
– Found in dermis and subcutaneous tissue
– Dendrite endings in flattened capsules
– There are less then end-bulbs and are deeper in the
tissue
• Human body is less sensitive to heat than to cold