Flashcards in Chapter 5 Integumentary System Deck (60)
Skin aka the cutaneous membrane has which 2 main components, and what are they made of?
1. Epidermis: superficial layer made of keratinized stratified squamous epithelia resting on its basement membrane.
2. Dermis: Deep to epidermis. Consists of loose connective tissue and dense irregular connective tissue.
what are the accessory structures embedded in the cutaneous layer?
1. sweat glands: produce sweat.
2. sebaceous glands: produce oil (holocrine)
5. sensory receptors
6. arrector pili muscles: small bands of smooth muscle that attach to hairs in dermis.
Is the epidermis vasuclar? What percentage of cells in epidermis are dead?
Is the hypodermis, aka superficial fascia, part of the skin? Where is it located, and what is its function? What is is made of?
hypodermis aka superficial fascia, is deep to the dermis. It is not part of the skin. It anchors the skin to the muscle and bone. It is made of loose connective and adipose tissue.
What are the functions of the integumentary system?
5. Vitamin D synthesis
What does the skin provide protection against?
1. mechanical trauma
2. pathogens: immune cells are scattered throughout skin, and sebaceous glands secrete oil.
3. environment; against UV, and water from entering the skin.
what is the acid mantle?
the secretions of the sebaceous glands give the skin a slight acid Ph.
how does the skin provide sensation? what is sensation?
it houses many sensory receptors that convey changes in the internal/external environment to the nervous system. This conveyance is sensation. This helps us detect harmful stimuli like hot, cold, and help avoid tissue damage.
The maintenance of a stable internal body temperature through negative feedback loops.
What is the sequence of events that occur when the body temp rises above the normal range.
1. stimulus: temperature rises due to varying circumstances.
2. thermoreceptors detect the change.
3. Hypothalamus in brain receives the info.
4. Effectors respond by sweating and widening blood vessels. In cold conditions, blood vessels constrict.
5. Homeostasis is returned and negative feedback stops the effectors.
although other organs primarily perform this function, the skin excretes lactic acid, urea, and metals through sweat.
Explain vitamin D synthesis. Is Vitamin D a hormone?
Vitamin D is a hormone synthesized by the skin when its precursor molecule, which resides in the epidermis is exposed to UV. The molecule then converts to cholecalciferol which enters the blood and is modified by the liver and kidneys to become calcitrol, the active form which is required by the small intestine to absorb calcium ions.
why is the absorption of calcium ions critical?
they're important for nerve function, muscle contraction, building and maintaining bone.
What percentage of the skin is made of Keratinocytes? What are the 2 features that make skin strong?
1. keratin makes the skin hard
2. linking desmosomes
What are the 5 structural layers of the epidermis?
1. stratum basale: deepest layer. Single layer of stem cells that appear cuboidal. Produce the precursor to vitamin D. Highly mitotic.
2. stratum spinosum: next layer out, thickest layer. Spinousum b/c cells appear spiky. Highly mitotic and help produce viatmin D
3. Stratum Granulosum: Middle 3-5 layers of cells. Prominent cytoplasmic granules made of either keratin bundles or lipid substance. Hydrophobic nature of lipid substance is important for skin's waterproof ability.
4. Stratum Lucidum: narrow layer of clear, dead keratinocytes found only in thick skin..
5. Stratum Corneum: outermost layer consisting of several layers of dead flattened keratinocytes. These cells are sloughed off as the connecting desmosomes are lost.
How many days does it take skin cells to migrate from the stratum basale to being sloughed off as stratum corneum?
Acronym for remembering the epidermal strata
BSGLC: brilliant studying gives loads of confidence.
Other cell types in the epidermis
1. Dendritic cells, aka langerhan cells. They are phagocytes of the immune system found in the stratum spinosum.
2. Merkel cells: scattered throughout the stratum basale. They are tiny sensory receptors that detect light touch, shape and texture. Found is fingertips, lips, and base of hairs.
3. Melanocytes: located in stratum basale produce melanin.
Differences btw thick and thin skin
1. Thick skin: epidermis is width of paper towel. Contains all 5 epidermal strata and very thick stratum corneum. Lacks hair follicles, but contains numerous sweat glands.
2. Thin skin: epidermis is width of a sheet of printer paper. Lacks stratum lucidum (has only 4 layers of epidermal stratum). All other layers are much thinner. Has a lot of hairs, sebaceous and sweat glands.
What are the 2 layers of dermal tissue
*The 2 layers are actually 2 different types of connective tissue*
1. Papillary Layer: Most superficial layer of dermis. Thin layer. Composed of loose connective tissue.
2. Reticular Layer: Deeper and thicker composed of dense irregular connective tissue.
What are the functions of the dermis?
1. Houses blood supply for epidermis
2. Contains sensory receptors
3. Anchors epidermis in place
What anchors the epidermis to the dermis?
special collagen fibers at the dermal epidermal layer extend from dermis into epidermal basement membrane.
Describe dermal papillea, and what is the function of its capillary loops?
The papillae are tiny projections found at the surface of the dermal layer where it comes into contact with the epidermis. The projections contain capillaries arranged in loops that extend upwards. These loops serve the function of allowing oxygen and nutrient to diffuse into the ECM which feeds the epidermis.
Where are meissner corpuscles found and what is their purpose?
They are found in the papillary layer in higher concentration in areas of sensitivity like the lips, face, fingertips, and external genitalia. Their purpose is providing tactile sensation. They are tactile corpuscles.
What is the purpose of the reticular layer of the dermis and what is it composed of?
It separates the dermis from the hypodermis. it is made of dense irregular connective tissue with many collagen fibers and elastic fibers.
What is the function of the collagen bundles in the reticular layer?
They strengthen the dermis and and prevent injuries from reaching deeper layers of tissue. *There are many more many more collagen fibers in the reticular layer than the papillary layer.
What is the function of the elastic fibers in the reticular layer?
enable the dermis to return to its original shape and size after stretching. If the elastic fibers tear, then stretch marks ensue.
Why are proteoglycans present in the reticular layer?
proteoglycans draw water into the ground substance, which hydrates skin and makes it firm.
To what sensations do lamellated (Pancinean) corpuscles respond? Where are they located? What else is embedded here?
They respond to pressure and vibration. They are embedded in the reticular layer as well as blood vessels, sweat and sebaceous glands, and hair.