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