Flashcards in Lecture 3: Integument And Barriers To Infection Deck (65):
Where is thick skin found?
Palms and soles
Thick skin is composed of ______ layers, lacks _______, and may be characterized by fingerprints
Where is thin skin found?
Everywhere on the body except the palms and soles
Thin skin is made up of _____ layers, contains _____ and _______ glands, and contains hair follicles
Thin skin is made up of 4 layers, while thick skin is made up of 5. Which layer is missing from thin skin?
The surfaces of palms and soles have _________ ________ with intervening furrows.
Each ridge follows the outline of an underlying ___________ _________
There is a tight interface at the _________ ___________ junction via hemidesmosomes
What are the 5 layers of the epidermis that are found in thick skin?
The epidermis is composed of what 4 additional cell types?
Which one has immune function?
Langerhans cells (immune function)
The stratum basale layer of skin is mitotically __________.
Skin is replaced every ____-____ days.
It is a single layer of _____________ or low __________ cells bound to more apical ____________ via desmosomes
Cuboidal; columnar; keratinocytes
Psoriasis is a skin condition resulting from the overproliferation in which skin layer?
The stratum spinosum layer contains polyhedral ______________ that produce ___________, which aggregates to form ______________.
This layer thickens with pressure to produce corns and calluses.
The stratum spinosum + the stratum basale = __________ layer.
Keratinocytes; cytokeratin; tonofilaments
In the stratum granulosum, cells become progressively more flattened and contain ___________. It is 3-5 layers thick, cells have a distinct __________ and it is where terminal differentiation begins.
What type of granules, present in stratum granulosum, are basophilic and non-membrane bound?
What type of granules, found in stratum granulosum, are lipid-rich and function as a barrier to foreign material and water loss?
What layer of the epidermis consists of a translucent band of cells that do not contain organelles or nuclei?
The stratum lucidum is a translucent band of cells without organelles or nuclei, but it does contain densely packed _______ filaments
True or false: the stratum lucidum is mitotically active
Why does it make sense that the stratum lucidum does not contain nucleated cells?
The nucleus is lost after the granulosum layer because lucidum is no longer mitotically active. The nucleus would take up valuable space that is needed in order to pack more keratin into the cells
Stratum ________ consists of multiple layers of cells filled with mature keratin.
__________ are fully keratinized cells that are continuously shed.
In thick skin, this layer is made up of ____-____ layers.
In thin skin, this layer is made up of _____-_____ layers.
The stratum corneum is typically the second thickest layer of the epidermis, while ___________ is the first
Melanocytes originate in the _____ ______ and are visible from the 8th embryonic week.
They are the ____ cells to arrive in the epidermis.
The cell body is located in the stratum _______. Cytoplasmic extensions of one melanocyte establish contact with about 36 ____________, forming an epidermal-melanin unit.
True or false: melanocytes and keratinocytes are associated to each other via desmosomes
___________ cells derive from a bone marrow cell precursor and are present in the embryonic skin 4-5 weeks after the arrival of the melanocytes
Langerhans cells are found in the stratum of _______ (spinosum and basale).
A langerhans cell is a peripheral __________ cell of the immune system that migrates to a local LN to present Ags to _____ cells to initiate responses to foreign antigens
Merkel cells derive from the ______ _______.
They appear in _________ and _________ epidermis at about 8-12 weeks gestation.
They are tactile mechanoreceptors but may also have a ___________ function.
Merkel cells are associated with the ______ _______.
Their cytoplasm contains ________.
A small _____ _____ is connected to a myelinated axon. Myelin is lacking on the short axon segment penetrating the basal lamina of the epidermis.
Keratinocytes are responsible for making keratin and __________ granules.
They form the ________ in stratum corneum.
They also house the pigment protein __________.
What protects nuclei from UV radiation?
Melanin (pigment protein)
Once melanocytes produce melanin, where is it transfered?
What disease may result from overproliferation of melanocytes?
Melanin production increases in sun-exposed areas because the enzyme _____________is UV sensitive.
It is responsible for converting ___________ to ___________, which is then polymerized into melanin
Tyrosine --> DOPA (dihydroxyphenylalanine)
Langerhans cells are APCs that provide defense against pathogens. They develop in the bone marrow from a ________ precursor.
They are typically identified in the stratum _________ by their _____ cytoplasm with ______ processes.
Spinosum; pale; long
True or false: Merkel cells are more numerous in thin skin
False; more numerous in thick skin
The dermis is composed of CT of ____________ origin.
It contains _________ and _________ layers, as well as skin appendages, vasculature, and sensory nerve endings.
Describe the papillary layer of the dermis
Superficial layer of loose CT
Contains Meissner corpuscles (sensation) and dermal papilla
Describe the reticular layer of the dermis
Deep layer of dense irregular CT (type I collagen) with elastic fibers
More fibers and fewer cells
Are hair follicles epidermally derived or dermally derived structures?
Epidermally derived, but the follicles do extend down into the dermis
Between the papillary and reticular layers of the dermis lies the __________ ___________, consisting of capillary branches that provide a source of nutrients.
Within the reticular layer is the ___________ _________ with larger vasculature and lymphatics.
The hypodermis is loose, subcutaneous tissue containing adipocytes. What is the primary function?
Binds skin to underlying organs
Why might a surgeon recommend that their patient lose weight prior to undergoing surgery?
Fatty tissue present in the hypodermis has an extensive vascular supply, and could increase the risk of bleeding during a procedure
What is the simplest sensory receptor?
Free nerve endings
Free nerve endings are made up of numerous _________ fibers positioned along the __________-________ junction.
They relay modalities such as temperature, touch, itching, and ______
_________ ________ are elliptical-shaped, encapsulated touch receptors that detect light touch or low-frequency stimuli.
Meissner Corpuscles are located in dermal ________, partially surrounded by _________.
They are numerous in ___________, palms, and soles.
________ _________ are large oval structures that detect coarse touch, vibration, or pressure.
They are found deep in the __________ dermis or hypodermis.
An outer CT capsule surrounds 15-50 thin concentric layers, and movement/pressure leads to a nerve impulse
What is the primary example of merocrine glands?
[note that merocrine = eccrine; and apocrine glands can also be sweat glands]
How do merocrine glands release their contents?
Via exocytosis at apical ends
What is the primary example of holocrine glands?
How do holocrine glands release their contents?
Disintegration of the cell with contents becoming the secreted product
What type of glands are mammary glands?
How do apocrine glands secrete their product?
Via membrane-enclosed vesicles at the apical end
The acinus of sweat (sudoriferous) glands is characterized by ____________ _______ epithelium.
____________ cells surround the acinus and expel the secretions
The duct of sweat (sudoriferous) glands is characterized by _________ _________ epithelium (as opposed to acinus simple cuboidal).
The ducts are typically _______ staining.
Sebaceous glands are abundant on the face and scalp, and are often associated with the hair follicle.
They produce a lipid mixure called ________, via ___________ secretion.
They typically have a single duct made up of _________ ________ __________ epithelium.
Simple branched acinar
What is the purpose of the sebum produced by sebacous glands?
It is a waxy mix of triglycerides and cholesterol responsible for lubricating, softening, and waterproofing the skin
What is the difference between eccrine and apocrine sweat glands in terms of their distribution?
Eccrine sweat glands are found extensively throughout the skin
Apocrine glands are restricted to the dermis of the axilla, circumanal region, and areola
What type of sweat glands produces sweat for thermoregulation?
What type of sweat gland is under adrenergic regulation and responds to hormones?
Describe the sweat components of eccrine glands
Water, salt, ammonia, uric acid, and mucinogen granules
Describe apocrine secretions
Milky sweat secretion
Odorless until it mixes with bacteria
Hair follicles are epidermal derivatives. What two structures are they typically directly associated with?
Arrector pili muscles
What are the 3 general components of hair
What are the 3 components of the hair shaft itself?
Medulla = core of hair shaft
Cortex = middle layer
Cuticle = outer layer
What is the difference between vellus and terminal hair?
Vellus hair is thin and found diffusely around the body. Terminal hair is thicker and is typically generated in certain areas in response to androgenic hormones during puberty (males have more)