Ch 6-Integumentary System (Exam 2) Flashcards
What is melanin
Natural substance that gives color to skin, hair, eyes
What does subcutaneous mean
Under the skin
What is the largest organ in the body?
Skin- 15-16% of body weight
What is the top layer of the skin?
Epidermis
What is the epidermis and dermis separated by?
Basement membrane
What is the epidermis nourished by? (Since it is avascular)
Diffusion from capillaries of the papillary layer of the dermis
What is the epidermis composed of
Cells arranged into stratified layers
What are the cells of the epidermis?
-stem cells
-keratinocytes
-melanocytes
-dendritic cells
What are stem cells
-undifferentiated cells that give rise to keratinocytes
-in the deepest layer of the epidermis
What is the deepest layer of the epidermis?
Stratum basale
What are keratinocytes?
Cells of the epidermis that produce keratin (great majority of epidermal cells)
What are melanocytes?
-occur only in the stratum basale
-synthesize pigment melanin that shields DNA from ultraviolet radiation
What are dendritic cells?
Macrophages originating in bone marrow that guard against pathogens
What is the only layer of the epidermis to undergo cell division?
Stratum basale
What are the layers of the epidermis?
(BSGLC)
-Stratum basale
-stratum spinosum
-stratum granulosum (granular layer)
-stratum lucidum (clear layer)
-stratum corneum (horny layer)
Stratum spinosum
made up of multiple layers of cells that are held together by desmosomes
Stratum granulosum (granular layer)
-contains keratohyalin
-contains lysosomal enzymes
-contains granules
-nucleus and other organelles degenerate and cells die
Stratum lucidum (clear layer)
-thin, clear zone. Found only in palms and soles
-dead cells filled with keratin precursor called eleidin
Stratum corneum
-most superficial and consists of cornified cells
-outermost layer of the skin
Layers of the epidermis in order (bottom to top)
1.Stratum basale (deepest layer)
2. Stratum spinosum
3. Stratum granulosum
4. Stratum lucidum
5. Stratum corneum (outermost layer of skin)
How long does it take for epidermal cells to form in the stratum basale and migrate to the skin surface?
30-40 days
What percent of cells in the stratum basale enter mitosis daily?
10%-12%
Does the dermis continually shed and regenerate itself?
No
Which layer plays a critical role in temperature regulation?
Dermis
Dermis (true skin) qualities
-storage site for water and electrolytes
-sensory receptors for pain, itch, tickle, pressure, touch, and temperature
What is inside of the dermis?
Hair follicles, sweat and sebaceous glands, blood vessels, and muscle fibers
What are the layers of the dermis?
-papillary layer
-reticular layer
Papillary layer of the dermis
-composed of dermal papillae that project into the epidermis
-forms unique pattern that gives individual fingerprints
Reticular layer of the dermis
-contains connective tissue that makes the skin tough yet stretchable
-deeper layer of dermis, thicker and less cellular
Decrease blood flow to skin leads to what
Pale
Increased blood flow to skin leads to what
Flush (erythema)
Albinism
Hair is white, skin is pale, irises of eyes are pink. Caused by lack of melanin production
Bronzing
Skin appears golden brown, copper, or bronze in color. Caused by Addison disease
Erythema
Skin appears abnormally red. Caused by increased blood flow
Hematoma
A bruise is observable through the skin
Jaundice
Skin and whites of the eyes appear yellow. Caused by elevated levels of bilirubin in the blood
Pallor
Skin appears ashen, pale due to decreased blood flow to the skin
What are the functions of the skin?
-protection
-sensation
-excretion
-vitamin D synthesis
-immune function
-homeostasis of body temperature
Hyperthermia
Abnormally high body temperature. Sweating and vasodilation
Hypothermia
Abnormally low body temperature. Shivering and vasoconstriction
Is the hypodermis part of the skin?
No
Types of cells in the hypodermis
-fibroblasts
-adipose cells
-macrophages
What does the Hypodermis consist of
Consists of loose connective tissue with collagen and elastic fibers
Hypodermis and fat
Contains about half of the body’s fat. Functions as: energy source, insulation, padding
Where on the body is hair located?
Over the entire body except palms of hands and soles of feet and a few other small areas
What causes hair color?
Varying amounts and types of melanin
Arrector pili
Smooth muscle. Muscle contraction causes hair to “stand on end”
Sebaceous glands and function
Groups of specialized epithelial cells. Secretes sebum. Keeps hair soft, pliable, and waterproof
Eccrine glands and function
Abundant sweat glands with odorless secretion. Used to lower body temperature and eliminate wastes
(Small)
Apocrine sweat glands and function
Sweat glands with secretions that develop odors. Wets skin during pain, fear, emotional upset, and sexual arousal
Ceruminous glands
Secrete earwax
Mammary glands
Secrete milk
What are the most numerous sweat glands?
Eccrine glands
When do apocrine glands begin to function?
At puberty
Where are apocrine glands found?
Armpit, areola of breast, and around anus (large)
What is the function of cerumen?
Protect area from dehydration; excess secretions can cause blockage of ear canal and loss of hearing
