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.
What are skin markings, and where are they best seen?
small visible lines in the epidermis created by interactions between the epidermis and dermis. Best seen in the palmar surface of the hands and the plantar surface of the feet.
What are dermal ridges?
Found in areas where the dermal papillae are more prominent (like the palms and soles of feet) thick collagen fibers. This structure indents the overlying epidermis creating epidermal ridges. Enhances gripping ability. The sweat excreted on dermal ridges makes fingerprints.
How is skin color determined? And where is this substance produced?
by various amounts of the orange-red to black protein pigment melanin, is produced by melanocytes in the stratum basale of the epidermis.
The reticular layer is also associated with which types of skin markings?
Tension, aka cleavage lines, and flexure lines.
The special vesicle in which the enzymatic reaction that produces melanin is?
What is the primary function of melanin?
to protect the DNA of neighboring keratinocytes from UV induced mutations that cause cancer. A secondary function of melanin is it decreases the synthesis of vitamin D in response to UV radiation because too much vitamin D can lead to kidney failure. This is why climates with less sun have whiter skin than climates with more sun.
What is the immediate response to UV radiation? What is the secondary response?
1.immediate: oxidize the melanin already formed within the keratinocytes, which causes the melanin to darken.
2. secondary: UV radiation damages the DNA of the melanocytes, which increases the production of more melanin (about 72 hours later).
what is a freckle?
what is a mole/nevus?
1. an area of increased pigmentation resulting from an increase of melanin production in a concentrated spot.
2. a local proliferation of melanocytes.
What is carotene, and where is it found?
a yellow-orange lipid soluble pigment that accumulates, and is slightly visible in the stratum corneum of thick skin.
What is hemoglobin, and how does it affect skin color?
hemoglobin is an iron containing protein that binds to and transports oxygen through the body in the blood. It is responsible for blood's red color because it oxidizes iron when in contact with oxygen. It can be seen through the epidermis of fair skinned people, giving the skin a faint pinkish hue.. In areas of thinner skin, like the lips, the pink color appears darker.
What is erythema, and why does it happen?
when a person becomes more red because of increased blood flow through the dermis. Reasons for this are is a person is exercising and the body needs to cool off, or at the site of an injury, like a broken bone.
What is pallor, and why does it happen?
when the skin becomes white due to lack of blood flow to an area. Reasons for this include the body trying to conserve heat.
What is cyanosis, and why does it happen?
cyanosis is when a person turns bluish due to low levels of hemoglobin binding to oxygen. A person with cyanosis needs immediate med attn.
Hair grows between 1 - 1.5cm /month, but varies between individuals. Describe the growth phase, and the resting phase.
1. Mitosis occurs within the cells of the matrix in the root. As cells divide, the cells above them are pushed away from the blood supply, keratinize and die (much like the epidermis). Lasts from 1 month in eyelashes to 6 years in the scalp.
2. During the resting phase, the cells stop dividing and start to die. The follicle shortens and the hair is pushed up to the surface of the follicle, which remains dormant for 1 to several months. The hair may fall out, or be pushed out when a new one comes in.
Name and describe the 3 types of hair.
1. Laguno: a fetus is covered in this. It is non-pigmented, and falls out around the time of birth, and is replaced by one of the following...
2. Terminal hair: thicker, coarser, and pigmented. Found on scalp, and around eyes
3. Vellus hair: thinner, and non-pigmented. Found all over the body. After puberty, much of the vellus hair is replaced by terminal hair (about 90% for males, and 35% for females).
What produces hair color?
melanin in the matrix by melanocytes. Blond has little melanin, whereas black has a lot. Red is special, containing iron. As we age, we produce less melanin, so hair turns grey or white.
What are nails made of? What is the most visible component? Now name each other structure of the nail.
Nails are made of stratified squamous epithelia full of hard keratin. The most visible part is the nail plate, which rests on the nail bed. The nail plate is divided into the nail body, and the nail root (under the skin). This is where the nail matrix actively divides new cells.
name the folded regions of skin around the nail.
proximal nail fold, medial nail fold, and lateral nail fold. They reinforce the nail.
Nails do not contain melanocytes so are mostly translucent except at a region called the...
lunula (the 1/2 moon shaped region close to the nail root). Represents an accumulation of keratin.
What are the functions of nails?
1. protect the finger and toe tips from trauma. Nails can be used as tools, enabling better gripping when picking things up.
The skin contains two basic types of glands both derived from epithelial cells in the epidermis but located deeper in the dermis. What are they?
1. Sweat glands
2. Sebaceous glands
What are the 4 types of sweat glands and what is their function?
1. Eccrine: most prevalent. Found in dermis, sweat exits through a sweat pore. Primary function is thermoregulation
2. Apocrine: Found in axillae, anus, and areola. Large glands that release protein-rich secretion into hair follicles. Can stink when bacteria comes in contact. Influenced by sex hormones after puberty.
3. Ceruminous: modified apocrine glands that release earwax into ears. Function is to lubricate tympanic membrane and trap incoming particles.
4. Mammary glands: highly specialized. Produce a sweat product, milk.
Sebaceous glands empty into a hair follicle or a small pore that makes and secretes...
Where are sebaceous glands located? And what body parts lack them?
most numerous in face and scalp, but found everywhere in the body except the palms and soles.
Describe the composition and release of sebum. What does sebum contain?
it is a waxy, oily mixture that contains lipids. It is excreted by holocrine secretion. For this reason it contains cell fragments and debris. it inhibits the growth of certain bacteria.
What is a wound? What is a burn?
A wound is defined as any disruption in the skin’s integrity and include the following more specific injuries: lacerations or cuts, burns, and skin cancers. A burn is a wound caused by heat, extreme cold, electricity, chemicals, or radiation.
Explain the rule of nines and why its used
The rule of nines divides the body into 11 different regions each equaling 9% of the surface of the body plus the genital area equaling 1%. This rule is important because it is used to predict the complications associated with the burn, the patients level of dehydration, and their prognosis.
Describe the three levels of burns
1. first degree: only epidermis is damaged. No blisters. May be red and painful. no Dr. needed.
2. Second degree: partial thickness. Involve epidermis, and part or all of the dermis. Very painful, blistering, scarring. Dr. usually needed.
3. Third degree: Full thickness burns. Involve epidermis, dermis, hypodermis, and maybe more. Loss of tissue. Possible grafting needed. Dehydration is a danger.
Where does basal cell carcinoma arise from? Describe its appearance
most common type of skin cancer, arises from the keratinocytes of the stratum basale. It looks like a nodule with a crater in the middle. Easy to resolve w/ surgery.
Where does squamous cell carcinoma arise from? What does it look like?
second most common type of skin cancer. Arises from the keratinocytes of the stratum spinosum. Looks like scaly plaques that bleed. Found mainly on head and neck. More likely to metastasize than basal, but still possible to manage by removal.