3 Veterinary Term: The Integumentary System Flashcards
What does Integument mean?
means covering, and the skin is the outer covering for the body
At does the Integument contain?
glands that secrete several types of fluids.
nerves that carry impulses.
blood vessels that aid in the regulation of temperature.
As a protective membrane over the entire body, the skin guards what?
guards the deeper tissues of the body against excessive loss of water, salts and heat and against invasion of pathogens and their toxins.
What contributes to the skin’s ability to prevent bacterial invasions?
Secretions from the skin that are slightly acidic in nature
What do Specialized cells (LANGERHANS CELLS) do?
react to the presence of antigens and have an immune function.
What two types of glands does the skin contain that produce important secretions?
SEBACEOUS and SWEAT glands
What do SEBACEOUS glands produce?
SEBUM, an oily secretion
What do sweat glands produce?
sweat, a watery secretion
How does sebum and sweat pass through the skin?
pass to the outer edges of the skin through ducts and leave the skin through openings, or PORES
What is the function of sebum?
lubricates the surface of the skin
What is the function of sweat?
cools the body as it evaporates from the skin surface
Nerve fibers under the skin are receptors for what?
sensations such as pain, temperature, pressure and touch
The body’s adjustment to the environment depends on what?
sensory messages relayed to the brain and spinal cord by sensitive nerve endings in the skin.
Different tissues in the skin maintain what?
body temperature (THERMOREGULATION)
Nerve fibers coordinate THERMOREGULATION by?
carrying messages to the skin from heat centers in the brain that are sensitive to increases and decreases in body temperature. Impulses from these fibers cause blood vessels to dilate to bring blood to the surface and cause sweat glands to produce the watery secretion that carries heat away.
What are the three layers of the skin?
Epidermis
Dermis
Subcutaneous layer (HYPODERMIS)
What is the EPIDERMIS?
a thin, cellular membrane layer containing keratin
Outermost layer
What is the DERMIS?
dense, fibrous, connective tissue layer; containing collagen
middle layer
What is the SUBCUTANEOUS LAYER (HYPODERMIS)?
thick fat-containing tissue
innermost layer
What is the epidermis composed of?
SQUAMOUS EPITHELIUM.
Epithelium is the covering of both the internal and the external surfaces of the body.
Describe Squamous epithelium?
cells are flat and scale-like.
In the outer layer of the skin, these cells are arranged in several layers (STRATA) to form STRATIFIED SQUAMOUS EPITHELIUM
What does the epidermis lack?
blood vessels, lymphatic vessels and connective tissue (elastic fibers, cartilage, fat)
What does the epidermis depend on?
dependent on the deeper dermis layer and its rich network of capillaries for nourishment.
Oxygen and nutrients seep out of the capillaries in the dermis, pass through tissue fluid and supply nourishment to the deeper layers of the epidermis.
What is the deepest layer of the epidermis?
BASAL LAYER
Describe the cells of the basal layer?
cells in the basal layer are constantly growing and multiplying and give rise to all the other cells in the epidermis
What happens as the cells of the basal layer divide?
they are pushed upward and away from the blood supply of the dermal layer by a steady stream of younger cells
What is the most superficial layer of the epidermis?
STRATUM CORNEUM
As the cells move toward the STRATUM CORNEUM what happens?
the cells flatten, shrink, lose their nuclei and die, becoming filled with a hard protein material called KERATIN.
The cells are then called HORNY CELLS, reflecting their composition of keratin.
Within 3 to 4 weeks after beginning as a basal cell in the deepest part of the epidermis, the keratinized cell is?
sloughed off from the surface of the skin.
The epidermis is thus constantly renewing itself, cells dying at the same rate at which they are replaced.
What special cells does the basal layer of the epidermis contain?
MELANOCYTES
What do MELANOCYTES form and contain?
a brown-black pigment called MELANIN that is transferred to other epidermal cells and gives color to the skin
The presence of MELANIN in the epidermis is vital for what?
protection against the harmful effects of ultraviolet radiation, which can manifest as skin cancer.
Individuals who are INCAPABLE of forming MELANIN are called?
ALBINO.
Skin and hair are white.
Their pupils (circular opening in the eye) are red because in the absence of pigment in the retina, the tiny blood vessels are visible in the iris (normally pigmented portion) of the eye.
Melanin production increases with what?
exposure to strong ultraviolet light, and this creates a suntan, which is a protective response.
How does one become sunburned?
When the melanin cannot absorb all the UV rays, the skin becomes sunburned and inflamed (redness, swelling and pain).
The dermis is composed of?
blood and lymph vessels, and nerve fibers, as well as the accessory organs of the skin
What are the accessory organs of the skin?
the HAIR FOLLICLES, the sweat glands and sebaceous glands.
How does the dermis support the elaborate system of nerves, vessels and glands?
the dermis contains connective tissue cells and fibers that account for the extensibility and elasticity of the skin.
The dermis is composed of what kind of fibers?
interwoven elastic and COLLAGEN fibers.
What is COLLAGEN?
(COLLA means glue) is a fibrous protein material found in bone, cartilage, tendons and ligaments, as well as in the skin.
It is tough and resistant but also flexible.
Describe collagen in an infant
In the infant, collagen is loose and delicate; it becomes harder as the body ages.
What is the function of collagen?
Collagen fibers support and protect the blood and nerve networks that pass through the dermis.
Collagen diseases affect connective tissues of the body.
The epidermis and dermis are what layers of the skin?
CUTANEOUS layers
The subcutaneous layer (HYPODERMIS) specializes in the formation of what?
Fat
What cells are predominant in the subcutaneous layer and what are their function?
Lipocytes (fat cells)
they manufacture and store large quantities of fat.
The subcutaneous layer of the skin is important functionally because?
important in protection of the deeper tissues of the body, as a heat insulator and for energy storage.
What are the accessory organs of the skin?
Hair
Nails
Sebaceous glands
Sweat glands
What is a hair fiber composed of?
tightly fused meshwork of cells filled with the hard protein called keratin.
Hair growth is similar to what?
the growth of the epidermal layer of the skin.
Deep-lying cells in the hair root produce what?
keratinized cells that move upward through hair follicles (sacs within which each hair fiber grows).
Melanocytes are located where and what do they do?
at the root of the hair follicle
and they donate the melanin pigment to the cells of the hair fiber.
What type of melanin is responsible for red hair?
A type of melanin containing iron
When does hair turn gray?
with advancing age the melanocytes stop producing melanin.
What are the types of hair follicles?
Single (simple) follicle
Compound follicle
Describe a single (simple) hair follicle
one hair emerges from a single opening
found in horse, cattle, pig and sheep (face, ear, distal portion of limbs)
Describe a compound follicle
several hairs emerge from a single opening.
Found in cat, dog, sheep (wool growing areas).
Consists of a long principal (guard) hair and a number of smaller auxiliary (wool) hairs.
What are nails?
are hard keratin plates covering the dorsal surface of the last bone of each toe and finger.
What are nails composed of?
composed of HORNY CELLS that are cemented together tightly and can extend indefinitely unless cut or broken.
How does a nail grow?
A nail grows in thickness and length as a result of division of cells in the region of the nail root, which is at the base (proximal portion) of the nail plate.
What is a CUTICLE?
a narrow band of epidermis (layer of keratin), is at the base and sides of the nail plate.
What is the PARONYCHIUM?
is the soft tissue surrounding the nail border.
What happens during systemic disease?
Nail growth and appearance commonly alter.
For example, grooves in nails may occur with high fevers and serious illness.