Integumentary System - AnaPhy Lab Pt. 2 Flashcards
is composed of the skin, or cutaneous membrane, plus its accessory structures: hairs, nails, and glands.
INTEGUMENTARY SYSTEM
the largest and most visible organ of the body
skin
Functions of the Skin
Protection - by forming an impenetrable barrier to infectious agents.
Excretion - Through the excretion of sweat, waste products (including lactic acid and urea) are released onto the skin.
Sensations - Numerous sensory receptors in the skin enable sensations, such as touch, pain, temperature, pressure, and vibration.
Thermoregulation - Blood vessels and sweat glands in the skin enable it to act in thermoregulation by removing excess heat or preventing heat loss.
Synthesis of vitamin D - the skin is the site of the initial steps in the synthesis of vitamin D, which is important for the absorption of calcium from the diet.
The skin is made up of two distinct layers:
- the superficial epidermis
- underlying dermis
A third layer of tissue that lies deep to the dermis
hypodermis
consists of loose connective tissue with many blood vessels and adipose tissue
hypodermis
hypodermis consists of
loose connective tissue with many blood vessels and adipose tissue
is avascular and composed of keratinized, stratified squamous epithelium and contains four distinct cell types
Epidermis
four distinct cell types of the Epidermis
- keratinocytes
- melanocytes
- dendritic (Langerhans) cells
- Merkel (tactile) cells
produce the strong waterproofing protein keratin
keratinocytes
produce the protective pigment melanin
melanocytes
are specialized white blood cells that migrate to the epidermis, where they function as phagocytes
Dendritic (Langerhans) cells
are located at the epidermal–dermal junction and function in light touch reception.
Merkel (tactile) cells
thick skin is located where
only in the palms of the hands and the soles of the feet
thick skin has how many strata/layers?
five
layers of thick skin (from top to bottom)
stratum corneum
stratum lucidum
stratum granulosum
stratum spinosum
stratum basale
thin skin is located where
everywhere else in the body
thin skin contains how many layers?
4
what strata is absent in thin skin?
stratum lucidum
the deepest layer of the epidermis
Stratum Basale
consists of a single layer of cuboidal epithelial cells (keratinocytes) attached to a basement membrane.
Stratum Basale
what cells are present in stratum basale?
keratinocytes and melanocytes
contains 8–10 layers of cells, mostly keratinocytes that have a “spiny” appearance in histological preparations.
Stratum Spinosum
what cells are prominent in stratum spinosum?
keratinocytes, dendritic cells
thin and consists of three to five layers of keratinocytes that undergo a drastic change in appearance as they begin to fill with keratin (a process called keratinization)
Stratum granulosum
the cells flatten and their organelles, including the nucleus, disintegrate; the cells eventually die.
Keratinization
The rods of cells move upward through the skin as new cells form beneath them. As they move up, they’re cut off from their supply of nourishment and start to form a hard protein called keratin
Keratinization
stratum lucidum is found only in the
thick skin of the palms and soles
found only in the thick skin of the palms and soles
stratum lucidum
consists of two to four translucent layers of flat, dead keratinocytes.
stratum lucidum
The most superficial epidermal stratum
Stratum corneum
is the thickest stratum, consisting of 20–30 layers of cells
Stratum corneum
highly vascular
dermis
dermis consists of:
papillary layer and reticular layer
lies immediately deep to the stratum basale and largely consists of loose connective tissue
Papillary Layer
it contains finger-like projections called dermal papillae, many of which contain capillary loops that provide a blood supply to the overlying, avascular epidermis.
Papillary Layer
contain capillary loops that provide a blood supply to the overlying, avascular epidermis.
dermal papillae
are prominent on the hands and feet and form dermal ridges that indent the epidermis and form fingerprints.
dermal papillae
dermal papillae contains
tactile (Meissner) corpuscles
respond to light touch, or free nerve endings, which function as pain or temperature receptors.
Meissner (tactile) corpuscles
the deepest layer of the skin
Reticular Layer
consists largely of dense, irregular connective tissue and accounts for approximately 80% of dermal thickness.
Reticular Layer
contains an abundance of collagen fibers (for strength), elastic fibers (for flexibility), and reticular fibers (to form a supporting network for dermal structures).
Reticular Layer
collagen fibers
for strength
elastic fibers
for flexibility
reticular fibers
to form a supporting network for dermal structures
- their multilayered capsule is specialized to
detect pressure and vibrations - are also located in the reticular layer
Lamellated (Pacinian) corpuscles
The accessory structures of the skin include:
- hairs
- nails
- glands
are found all over the body surface—with the exception of the palms, soles, lips, parts of the external genitalia, and nipples.
Hairs
Hairs are ound all over the body surface—with the exception of
the palms, soles, lips, parts of the external genitalia, and nipples
are produced by structures called hair follicles
hair
Hair consists two basic parts:
shaft and root
composed of dead, keratinized epithelial cells and projects from the skin surface
shaft
is enclosed by the hair follicle projecting down into the dermis
root
Hair can be seen to consist of three distinct layers of keratinized cells:
- inner medulla
- middle cortex
- outer cuticle
Hair color is largely determined by the type and amount of
melanin within the cortex.
is formed by layers of epidermal tissue, called the epithelial root sheath, that is surrounded by a dermal root sheath composed of connective tissue.
Hair follicle
bundle of smooth muscle fibers that attaches to the dermal root sheath
Arrector Pili Muscle
causes goosebumps
Arrector Pili Muscle
knob-like base of the hair root
Hair Bulb
hair bulb contains the
matrix/hair matrix
the living, mitotically active part of the hair that adds new hair cells to the base of the hair root
matrix/hair matrix
are connected to the base of the hair bulb.
Sensory receptors
a small projection of dermal tissue from the dermal root sheath that protrudes into the hair bulb
Hair Papilla
hair papilla contains _______________that supply the
growing hair cells with oxygen and nutrients
capillaries
are modifications of the epidermis that protect the dorsal ends of the fingers and toes
Nails
These structures are associated with a nail:
- two nail folds
- eponychium (or cuticle)
- lunula
the folds of skin along either side of the nail body
Two nail folds
the thick fold at the proximal end of the nail
Eponychium (or cuticle)
the white, crescent-shaped region at the base of the nail.
Lunula
rests on a region of the epidermis called the nail bed.
nail body
where the nail body rests
nail bed
The thickened proximal portion of the nail bed
Nail matrix
is responsible for nail growth
Nail matrix
are exocrine glands—glands that release their secretory products onto external or internal body surfaces
Sebaceous Glands
Sebaceous Glands secrete an oily, acidic substance called
_______________ into hair follicles, although some deposit sebum directly onto the skin surface.
sebum
Sebaceous Glands are located
located in skin everywhere except the palms and soles
oily, acidic substance
sebum
acts as a lubricant that keeps the skin and hair soft and moist and deters the growth of infectious agents.
Sebum
consist of a coiled secretory component and a duct composed of simple cuboidal epithelial tissue
Sweat Glands
Two types of glands produce sweat:
eccrine sweat glands and apocrine sweat glands
Eccrine Sweat Glands are distributed
all over the body
they secrete sweat that is primarily water but also contains salts and waste products.
Eccrine Sweat Glands
primary function of eccrine sweat glands is
temperature regulation
confined to the groin, axillae, and the areola around each nipple.
apocrine sweat glands
apocrine sweat glands are confined to the
groin, axillae, and the areola around each nipple
They tend to be larger and deeper in the dermis than eccrine sweat glands, and they have ducts that empty into hair follicles
apocrine sweat glands
activated at puberty
apocrine sweat glands
apocrine sweat glands respond to
pain, emotional stress, and sexual stimulation
Apocrine Sweat Glands secretions also contain proteins. These secretions are odorless, but when released onto the skin they are metabolized by bacteria, producing
body odor
layers of epidermal tissue that forms the hair follicle
epidermal root sheath
