Epithelial Flashcards
Integumentaty system is composed of what?
skin, hair, nails
What is the largest organ in the body?
Skin
What layers make up skin?
Epidermis, dermis, and hypodermis
What does the integumentary do?
Absorbs ultraviolet light to make Vitamin D which is used for bone development
Protects internal organs from extreme temperature changes and pathogenic microorganisms
Has sensory receptors and glands used for protection of skin and internal tissues
What is the next line of defense if the skin barrier is broken and foreign objects or microorganisms enter?
The lymphatic system is responsible for mounting an attack
Merkel’s cells and Meissner’s corpuscles
Mechanoreceptors that detect mechanical sensory information in the form of light touch and vibration
Nociceptors
detect pain such as from a pin prick
Pancinian corpuscles
detect mechanical sensory information of pressure applied to the skin
Thermoreceptors
detect hot and cold
What are sensory organs
These are organs embedded in the skin that relay information to the brain.
The brain interprets that information and determines the appropriate response
Exocrine glands
can be categorized by shape and size
most glands in the body are multicellular glands which are set within epithelial tissue and release their contents through ducts onto the surface.
Sebaceous glands
oil glands that produce sebum
sebum helps keep the hair and skin from drying out and inhibits the growth of harmful microorganisms
Sweat glands
sudoriferous glands
produce sweat in almost every part of the skin
the secretory portion is deep within the dermis layer of the skin
the duct expands all the way through the dermis, through the epidermis to release its contents on the external surface
Perspiration
the release of sweat from sudoriferous glands is called perspiration.
Perspiration helps regulate the body temperature through a process called thermoregulation by releasing heat from the body
Epidermis
The outermost layer of skin
made of stratified squamous epithelium - stratified means layers and squamous means flat
Avascular - does not have a direct blood supply
receives it nutrients from the basement membrane (basal lamina)
Gases, nutirents, etc. from the blood supply in the dermis diffuse across the basement membrane into the epidermis
What are the four distinct layers of the epidermis?
Superficial to deep
stratum corneum, stratum granulosum, stratum spinosum, stratum basale
The stratum basale is firmly adhered to basement membrane
Gases, nutrients, etc. from the blood supply in the dermis diffuse across the basement membrane to the epidermis
Stratum basale
the cells of this layer are constantly dividing to rebuild the skin
As the cells divide they are pushed towards the external surface until they are dead and slough off (are removed through friction or washing)
The most superficial layer of the epidermis is dead, because it is far away from the blood and nutrient supply of the basement membrane
How long does it take for new cells from the stratum basale to reach the surface?
30 days for a single cell to move from the stratum basale to the stratum corneum.
Cells remain on the stratum corneum for another two weeks until they are sloughed off
Epidermal ridges
the stratum basale forms epidermal ridges (grooves) that are unique to each person and constant throughout a person’s lifetime.
The projections extend all the way through the epidermis and form a distinct pattern called fingerprints
What are some cells present in the epidermis?
keratinocytes, langerhans cells, fibroblasts, melanocytes, and Merkel cells
Melanocytes
produce a pigment called melanin which absorb ultraviolet waves and determines skin color
Langerhans cells
involved in the body’s immune response.
Act as a first line of defense for the body, helping to identify microorganisms before they reach the bloodstream
Merkel cells
a type of sensory receptor that respond to light touch
Keratinocytes
produce a tough substance called keratin
cells within the epidermis undergo keratinization which protects the exposed surface of the skin
Fibroblast cells
produce collagen which help adhere the cells of the epidermis to each other and give the skin elasticity
What glands are also found in the dermis?
Sweat, oil, and sensory organs are also found within the dermis.
What are the two sensory organs found in the dermis?
Meissner Corpuscles and pacinian corpuscles
How can the dermis be used to detect dehydration?
The dermis has a higher water content compared to the epidermis
If a person is dehydrated they will have less water in their dermal layer of the skin.
You can test for dehydration by pinching the skin on the back of the skin on the back of the hand. One indicator of dehydration is when the skin does not recoil back to its normal shape but instead stays pinched
What are the two regions that comprise the dermis
superficial papillary region and deeper reticular region
both regions/layers contain collagen and elastic fibers which enable the skin to be stretched within certain limits to prevent damage to underlying tissue
What region of the dermis contains the main blood supply for the skin?
The reticular region of the dermis contains the main blood supply for the skin
The extensive network of blood vessels supply the skin with its needed nutrients. Branches come off the main arteries to supply nerves and glands, and hair follicles within the skin
Contusion
Is damage to one or more blood vessels. Blood leaks out of the blood vessel into the dermis, creating the color of the bruise. Typically black or blue
Hypodermis
A layer made mostly of fat cells (adipocytes)
Two layers- subcutaneous fat and subcantaneous tissue which blend together
Hypodermis helps anchor the dermis to a layer of fat cells
What does the fat in the hypodermis do?
Helps insulate and regulate body temperature
also helps protect the deeper tissues and organs from injury
subcutaneous injection
means that a medication or vaccination is given in a needle that reaches deep the dermis but superficial to the muscle in the hypodermis layer of the skin
Medication given in the with a subcanteous injection is absorbed by the body more slowly than if given directly into a vein
Dermatone
A region of the skin that is innervated by one sensory nerve
Sensory signals are sent from the skin to the spinal nerve, through the spinal cord, and finally to the brain for processing.
Each region of the skin is innervated by a spinal nerve except the face which is innervated by cranial nerve VII and trigeminal nerve
What are the two parts that make up hair?
The root in the dermis layer and the shaft
The root begins at the hair bulb and has a blood and nervous supply.
The shaft extends through the epidermis to the external surface of the skin.
What is hair made out of?
Hair is made of dead epidermal cells that are converted to keratin, giving the hair a stronger texture compared to skin cells
What is found at the root of each hair follicle?
A sebaceous gland helping to hydrate the hair with oil.
Arrector pili muscle
Each hair follicle is attached to an arrector pili muscle - a smooth muscle that contracts when the body is cold or is experiencing an emotional response
Hormones and hair
hair follicles are found throughout the skin and are susceptible to circulating hormones - for example hair follicles in the armpits, groin, and head change their properties during puberty
What are nails made of?
dead epidermal cells that are converted to
keratin
new cells are converted at the nail root and pushed towards the external surface in the direction of the nail body
Nail body
The visible portion of the nail covering the epidermis in that region called the nail bed
Nail root
is not visible. the stratum corneum of the epidermis extends from the nail root covering the visible portion of the nail, called the cuticle
Lunula
the visible portion of the nail bed near the nail root, which is typically the crescent white shape, and most visible on the thumb.
Tissues
Made up of cells (the smallest unit of life) that are similar in structure and work together to perform a similar function.
Comprised of cells and matrix
Matrix
also called extracellular material
made of ground substance (extracellular fluid), protein, and collagen fibers
When skin is damaged both tissue and matrix need to be repaired
Tissue damage
the body needs to respond quickly to prevent blood loss and microorganisms from entering the blood stream.
healed through a multistep process
Blood platelets
Step one - from the broken blood vessel start to accumulate in the area where the tissue was damaged and form a clot
Clot
secreting a mesh like substance around damaged tissue by platelets to prevent blood loss
Mast cells
after platelets form a clot, mast cells release histamine - a chemical that helps to dilate blood vessels to bring increased blood and nutrients to the injured area
Histamines help initiate a local inflammatory response, which signals other cells in the area to help remove foreign pathogens
Macrophages
A type of white blood cell- work to engulf and destroy disease causing pathogens. Once the dead and foreign cells are removed, the body can begin to replace the damaged cells
Fibroblasts
help to secrete new collagen in the shape of old tissue. The collagen framework supports the tissue matrix in the shape of old cells until new cells are fully developed
Remodeling
The final phase in tissue repair where the tissues matures and the cells begin to take on their original functions.
If a wound is too deep, a scar is formed and some of the original function of the tissue is lost
scar
a overgrowth of fibrous connective tissue that can not be fully replaces by the original tissue
First degree burn
Also called superficial burn. Only damages the epidermis layer
The burned area becomes red, dry, painful without blistering
Mild sunburn is an example
Second degree burn
called partial thickness burns
damage the epidermis and part of the dermis layers of skin
the burn Turns red and forms blisters becoming painful and swollen
the dermis has many sensory organs embedded in it, so damage to the dermis is very painful
third degree burns
also called full thickness burns
damage the epidermis, entire dermis, and may extend slightly into the subcutaneous layer of the skin
the injured skin typically looks white and may even have a charred appearance
The extensive damage to the dermis layer make third degree burns extremely painful
fourth degree burns
damage the epidermis, dermis, hypodermis, and underlying tissue such as muscle or bone
skin grafting
a treatment where healthy skin is taken from a persons own body and grafted on top of damaged area
reduces healing time and prevents infection
How do burns heal?
they heal in the same manner as other skin injuries, however a skin graft may be need if there is severe damage or the burn covers large surface area.
