Integumentary System Flashcards
What are the two main layers of the skin and what are they made of?
The epidermis (superficial layer of the skin, composed of epithelial tissue) and the dermis (connective tissue)
What is the hypodermis, what is it composed of and what is it function?
The hypodermis is the layer deep to the dermis, it is made of areolar and adipose tissue, and it serves to connect the skin to the underlying fascia.
List the layers of epidermis from superficial to deep
stratum corneum, stratum lucidum (only in hands and soles), stratum granulosum, stratum spinosum, stratum basale
Describe the structure and function of stratum basale
It is the deepest layer of the skin, composed of highly miotic stem cells. It attaches the epidermis to the basal lamina (dermis)
Describe the structure and function of stratum spinosum
Made of keratinocytes attached with desmosomes, provides strength and flexibility to the skin
Describe the structure and function of stratum granulosum
It is made of keratinocytes, and it marks the transition between metabolically active layers and layers of dead cells. A water reppellent scealent forms in this layer.
Describe the structure and function of stratum lucidum
Present only in fingers, palms and soles, it is a thin layer of transparent dead cells
Describe the structure and function of stratum corneum
Composed of dead cells and lamellar granules making it water repellent (increased keratinization). Helps prevention of microbes.
What is a callus?
An increase in depth of the corneum due to abnormal friction.
How many types of cells are contained in the epidermis?
4
What are the principal types of cells in the epidermis?
keratinocytes, melanocytes, Langerhans cells and Merkel cells
Describe keratinocytes, where they are located and their function
They produce the protein keratin, which helps protect the skin from heat, microbes and chemicals. Keratin produces lamellar granules which release a waterproof sealant. They are located in the spinosum and granulosum layers of the skin.
What is keratinazation and how long does it take to occur?
The replacement of a cell contents with the protein keratin, which occurs when cells move to the skin surface over a period of 2 to 4 weeks.
What are melanocytes and where are they located?
Cells that produce melanin, a pigment which contributes to our skin colour and absorbs UV light. They are in the stratum basale layer.
What are Langerhans cells and where are they located?
They are cells that participate in immune response (macrophage) in the stratum spinosum layer.
What are Merkel cells and where are they located?
The Merkel cells touch a sensory structure called a tactile disc and function in the sensation of touch. They are in the stratum basale.
What is the dermis made of and what is its function?
It is the layer underneath the epidermis, it contains two layers of connective tissue containing collagen and elastic fibers, as well as blood, lymph vessels, nerves, etc. It is the core of the integumentary system.
What are the layers of the dermis called ?
The papillary layer and the reticular layer.
What is the connective tissue type of the papillary layer?
Areolar connective tissue (collagen and elastic fibers form a loose mesh)
Describe the papillary layer’s structure
It projects unto the stratum basale to form finger-like dermal papillae.
What structures are included in the papillary layer?
corpuscules of touch (Meissner’s corpuscules) and free nerve endings for sensation of heat, cold, pain, tickle, etc.
What is the reticular layer made of?
Dense irregular connective tissue with bundles of collagen fibers and some elastic fibers
What are epidermal ridges, what it their use and origin?
They come from the underlying contours of the dermis, they increase friction for better grasping ability, and provide the basis for fingerprints and footprints.
What are the three pigments that cause skin color?
Melanin, carotene and hemoglobin.
What are the cellular vesicules transporting melanin into the keratinocytes called?
Melanosomes
What are the three parts of a hair ?
A shaft above the surface of the skin, a root that penetrates the dermis and ends in a hair bulb, and a hair follicle, which consists of two epidermal layers surrounding the root.
What are the parts composing the non-living hair shaft and the living hair root?
The outer cuticle, the inner medulla and the innermost cortex.
What are the different parts of the hair follicle?
The enlarged base called the hair bulb, a hair papilla (brings blood and nutrients), and a hair matrix (miotically active cells)
What are the functions of hair papilla and hair matrix?
Hair papilla has many blood vessels to nourish the growing hair, and the hair matrix contains miotically active cells to produce new hair.
What are the functions of hair?
Protection, thermal insulation, sensing light touch.
What are the skin gland types?
Sebaceous, sudoriferous and ceruminous
What are sebaceous glands, where are they found and what is their function?
They are a type of oil gland, they are mostly connected to hair follicules. They are everywhere in the body except the hands and feet. They produce sebum, which moistens hairs, softens and waterproofs the skin and inhibits bacterial growth.
What are the types of sudoriferous glands?
Ecrine and apocrine sweat glands
What are eccrine sweat glands and where are they located?
They are a type of merocrine glands that produce sweat for thermoregulation through evaporation, and eliminate waste such as urea. They are located everywhere on the body.
What are apocrine sweat glands and where are they located?
They are merocrine sweat glands limited to the skin of the axilla, pubis and areolar, their ducts open into hair follicules.
What are cerumeneous glands and where are they found?
They are modified sudoriferous glands that produce a waxy substance called cerumen. They are found in the external auditory meatus.
Name the functions of the skin
- Thermoregulation
- Protection through physical, chemical and biological barriers
- Cutaneous sensations including: touch, pressure, vibration, tickle, heat, cold, pain
- Excretion and absorption
- Synthesis of vitamin D
