INTEGUMENTARY SYSTEM Flashcards
What type of membrane composes the skin?
- cutaneous membrane
What are the two distinct layers of the skin?
- epithelial tissue overly CT.
- The dermis that is made up of CT
What composes the epidermis?
- Stratified squamous epithelium
What composes the dermis?
- thicker than the epidermis
- Is made up of CT containing collagen a, elastic fibers, and smooth muscle tissue, nervous tissue, and blood/lymphatic vessels
What anchors the epidermis to the dermis?
A basement membrane
Where is the hypo-dermis located?
- beneath the dermis
What is the hypodermic composed of?
- areolar + adipose CT that binds the skin o underlying organs
- Collagen/elastic fibers of the subcutaneous layer are continuous with those of the dermis - and extend in all directions
- Because of this, there are no distinct boundaries between dermis and the hypodermis
What does adipose do in the subcutaneous layer?
-acts to insulate to conserve body heat
What does the subcutaneous layer contain?
- large blood vessels with branches forming a network between the dermis + subcutaneous layer
What are the functions of the skin?
- protective barrier against harmful substances/ microorganisms
- contains sensory receptors
- Helps produce vitamin D
- Helps regulate body temp
Where does mitosis occur in the epidermis?
In the deepest layer - stratum basal
What are keratinocytes?
epidermal cells
What happens when keratinocytes are pushed towards the surface?
- The farther the cells move from the dermal bloods vessels, the poorer nutrients they receive, so they die
What’s keratinization?
- The hardening of keratinocytes
What are the steps in keratinization?
- The cytoplasm fills with strands of tough, fibrous, waterproof keratin proteins.
- They layer and then form a protective non-nucleated outer skin barrier
What is the stratum basal?
- Single row of rapidly dividing cells.
- Deepest layer in the epidermis
What is the stratum spinosum?
- Many layers of cells with centrally located, large, oval nuclei and developing fibers of certain; cells becoming flattened
- Some rare mitotic cycles may occur
What is the stratum granulosum?
Three-five layers of flattened granular cells that contain shrunken fibers of keratin and shriveled nuclei
What is the stratum lucidum?
- only present in thick skin like the palms/soles
- cells appear clear; nuclei, organelles, and cell membranes are no longer visible
Stratum corneum
- Many layers of keratinized, dead epithelial cells that are flattened and non-nucleated
What are the four layers of the epidermis from lowest to highest
- Stratum basale
- Stratum spinosum
- Stratum granulosum
- Stratum lucidum (only in THICK skin)
- Stratum corneum
What are the three things that determine skin pigment?
- hemoglobin: blood pigments in lighter skin can make it appear blue/pinkish
- Melanin: Pigment produced by melanocytes
- Carotene: organa-pinkish pigment from built up food
What three factors affect skin color?
- hereditary
- environmental
- physiological
How does hereditary factors affect skin color?
- all people have the same # of melanocytes but vary in amount of melanin produced
- Varying distribution + size of melanin granules
How does environmental factors affect skin color?
- Oxygenation in blood of dermal vessels
- vasodilation/vasoconstriction of blood vessels
- accumulation of carotene pigment from diet
- diseases such as jaundice
What are dendritic cells?
- Are in the stratum spinosum
- act to protect skin and deeper tissues from pathogen invasion
- engulf microbes within the skin
What are tactile cells?
- scattered among the stratum basale are oval-shaped tactile cells.
- Corresponds with sensory nerve ending
- respond to light touch
What are melanocytes?
- specialized cells in the epidermis
- Produce the pigment melanin from the amino acid tyrosine in organelles called melanosomes
- Prevents mutations of DNA
What are dermal papillae?
- ridges that project separate the epidermis and the dermis
- increase the surface area where epidermal cells receive oxygen/nutrients from dermal capillaries
Where are dermal papillae most abundant?
- hands/feet.
- leaves fingerprints and is used for grasping
What are the two layers of the dermis?
- the papillary layer
- The reticular layer
What is the papillary layer of the dermis composed of?
- composed of areolar CT
What is the reticular layer of the dermis composed of?
- composed of dense irregular CT that consists of tough collagen fibers, and elastic fibers in a gel-like substance.
What are the structures within the dermis?
- contains smooth muscle fibers
- blood vessels that supply the skin and motor nerve cell processes
- sensory receptors, and accessory structures such as nails, hair follicles, sweat glands, and sebaceous glands
What are lines of cleavage?
- lines deep in the dermis formed by orientation of collagen bundles
- incisions across these lines heal more slowly
- incisions along these lines heal quickly
What are pacinian touch receptors?
- sensitive to heavy pressure
What are Meisner’s touch receptors?
- sensitive to light touch
What are nociceptors?
- detect tissue damage
- control blood flow
- control glandular secretions
What is the hypodermic?
- subcutaneous layer
- areolar + adipose CT
- protects underlying structures
- stores energy
- thermal insulation
What are accessory structures?
- hair follicles
- nails
- skin glands
What are the 3 parts of the nail?
- Nail plate
- Nail bed
- Lunula (the half crescent)
What are the functions of hair?
- protection
- heat retention
- facial expression
- sensory reception
- visual identification
- chemical signal dispersal
What produces the nail bed?
- epithelial cells with continuous deeper layers extending into the epidermis of the skin to produce the nail bed
What’s the nail matrix?
- most active growing region.
- cells divid and newly formed cells become heavily keratinized
Where are hair follicles present?
- on all skin surfaces except the palms, soles, lips, nipples and parts of the external reproductive organs
What is a hair follicle
- a group of epidermal stem cells at the base of a tubelike depression
What are the 3 parts of hair?
- hair bulb (dividing cells)
- hair root
- hair shaft (dead epidermal cells)
What nourishes hair cells?
- the epithelial cells are nourished by dermal blood vessels in a projection of connective tissue called the hair papilla
What muscle causes goose bumps?
Arrector pili
What are the four exocrine skin glands?
- Sebaceous
- sudorferous (sweat)
- mammary
- ceruminous
What are the general characteristics of sebaceous glands?
- contains groups of specialized epithelial cells and are usually associated with hair follicles
- they are holocrine glands (they shed the entire cell)
What is sebum?
- globules of a fatty material that accumulate, swelling and bursting the cell
- acne <3
- secreted into hair follicles thru short ducts and keeps the skin soft, pliable and waterproof
What are the general characteristics of sweat glands?
- also called sudoriferous glands
- widespread on skin
- respond throughout life to body temps elevated by environmental heat or physical exercise
What are merocrine sweat glands?
- sweat glands that are abundant on the forehead, neck, and back. They produce sweat on hot days or during exercise.
What are apocrine sweat glands?
- secrete thru ducts to hair follicles, are most numerous in axillary region + groin area
- responds to emotional distress
- develops odor
- secrete by exocytosis
What are ceruminous glands?
- these secrete ear wax
What are mammary glands?
- they secrete milk lol
