2 - APP - Unit 4.1 - Integumentary System Flashcards
Integumentary system - Skin
Main organ of the integumentary system
Aka cutaneous membrane
Sheet-like organ composed of two major layers:
- epidermis
- dermis
Integumentary system - Skin - Epidermis
The thin outermost layer of skin
Integumentary system - Skin - Dermis
The thicker and deeper layer of skin
Integumentary system - Skin - Hypodermis
AKA subcutaneous tissue
Thick layer of loose connective tissue and fat.
Role:
- Supporting the two layer of skin.
- Acts as shock-absorbing pad & helps protect underlying tissues from injury caused by bumps & blows to the body surface
- Fat insulates the body from extreme heat and cold & serves as stored source of energy for the body
Epidermis - Cells
Tightly packed
Arranged in many distinct layers
Epidermis - Stratum germinativum
AKA stratum basale
Cells of the innermost layer / deepest layer of epidermis
Undergo mitosis and reproduce themselves
As they move toward skin surface, new cells increase their ability to provide protection for body tissues that lie below them.
As new cells are being produced in deep layer of epidermis, they move upward through upper layers or “strata” of cells.
Epidermis - Mitosis
A cell makes a complete copy of itself
Epidermis - Keratin
A tough & waterproof protein
Produced by keratinocytes that protect cells in the outer layer of skin.
Replaces cytoplasm as new cells are approaching the surface
Epidermis - Keratinocytes
Cells producing keratin
Epidermis - Melanin
- Dark brown pigment substance giving color to skin
- Produced by melanocytes
- Amount of melanin in skin: mostly genetic information inherited from parents.
- Darker skin: higher concentration of melanin
Epidermis - Melanocytes
Specialized cells producing melanin
Contained in deep layer of epidermis
Epidermis - Stratum corneum
Tough outer layer of epidermis.
Serves as primary barrier between body & environment
Dry dead cells filled with keratin are continually pushed to surface of epidermis (“flaking off” onto surrounding environment)
Dermis
Deeper of the two primary skin layers
Much thicker than epidermis
Composed largely of connective tissue
Cells scattered far appart, separated by 3 types of fibers:
- collagen
- reticulum
- elastin
Appendages of the skin
Hair & nails
Appendages of the skin - Nails
Composed of hard keratinized cells forming continuous sheets
Develop from crescent shaped white area at the base of the nail (=lunula)
Appendages of the skin - Lunula
Crescent shaped white area at the base of the nail
Appendages of the skin - Hair
Composed of hard keratinized cells forming long endless fibres
Each hair develops from a tube-like depression that extends through epidermis and into skin dermal layer
Appendages of the skin - Arrector pili muscles
Associated with hair follicles
Smooth & involuntary muscles attached to the base of a hair shaft
Erect hair shaft when contracting in reaction to cold or emotional stimuli : “goose bumps”
Appendages of the skin - Types of glands
- Sudoriferous - Sweat gland
- Sebaceous - Oil glands
Appendages of the skin - Types of glands - Sudoriferous
Sweat gland
Most numerous
2 groups:
- Eccrine
- Apocrine
Appendages of the skin - Types of glands - Sudoriferous - Eccrine sweat glands
By far the more numerous, important & widespread sweat glands in the body
Quite small
Distributed over the total body surface
Produce a transparent , watery liquid (=perspiration or sweat)
Appendages of the skin - Types of glands - Sudoriferous - Sweat
= transpiration
Transparent , watery liquid produced by sudoriferous eccrine sweat glands
Assists in the elimination of wastes and the maintenance of body temperature
Appendages of the skin - Types of glands - Sudoriferous - Aprocrine sweat glands
Found primarily in: - skin of the armpit - pigmented skin areas around the genitals Larger than eccrine glands Secret thicker, milky secretion
Enlarge and begin to function at puberty.
Appendages of the skin - Types of glands - Sebaceous
Oil glands
Associated with hair follicles
Secrete oil (=sebum) = a lipid substance that lubricate skin and protect it from drying out.
Appendages of the skin - Types of glands - Other skin glands
- Cerominous glands
- Mammary glands
Appendages of the skin - Types of glands - Other skin glands - Cerominous glands
Found within the skin of the ear canal Produce cerumen (=ear wax)
Appendages of the skin - Types of glands - Other skin glands - Mammary glands
Found within the breast tissue
Produce milk
Appendages of the skin - Receptors
In the dermal layer of the skin
Make body act as a sense organ, relaying messages to brain concerning sensations
Appendages of the skin - Receptors - Type of receptors
- Pacinian corpuscles
- Meissner’s corpuscles
- Ruffini’s end organs
- Merkel’s disks
- Free nerve endings (nociceptors)
- Krause’s end bulbs
Appendages of the skin - Receptors - Pacinian corpuscles
Deep receptors
Detecting pressure on the skin surface
Appendages of the skin - Receptors - Meissner’s corpuscles
Located close to the surface of the glabrous (smooth, hairless) skin
Detect sensation of light touch
Appendages of the skin - Glabrous skin
Smooth & hairless skin
Appendages of the skin - Receptors - Ruffini’s end organs
Touch and pressure receptors
In deeper area of hairy portion of skin and in joints
Appendages of the skin - Receptors - Merkel’s disks
Mechanoreceptors In the glabrous skin Discriminative touch (=fine touch - allows to sense and localize touch)
Appendages of the skin - Receptors - Free nerve endings
Nociceptors
Respond to pain
Appendages of the skin - Receptors - Krause’s end bulbs
Detect:
- sensation of touch
- low frequency vibration
- cold
Disorders of the Skin - Massaging
Localized condition:
- Therapeutic massage not contraindicated
- Avoid affected area
Localized touch can irritate skin disorders
Massage contraindicated :
- if skin inflamed
- if contagious condition
- if condition transmissible through contact
- Malignancy - unless supervised by appropriate medical personnel