A & P chapter 5

Cerumen

earwax, the yellowish substance secreted by the glands in the auditory canal of the external ear

Fourth degree

even more severe, affecting the underlying muscle and bone.

Tactile discs

extend from the dermis into the epidermis where they connect to Merkel cells and monitor the chemical secretions from these cells which produce tactile stimuli.

Third degree

fully extends into the epidermis and dermis, destroying the tissue and affecting the nerve endings and sensory function.

Second degree

goes deeper and affects both the epidermis and a portion of the dermis

Free nerve endings

numerous unencapsulated nerve endings for pain and temperature detection

Squamous cell carcinoma

originates in the stratum spinosum layer and like basal cell carcinoma, it rarely metastasizes.

First degree

superficial burn that affects only the epidermis.

Strata of the Epidermis

stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum

skin

*1.* The ___________, or simply integument, accounts for approximately *16%* of your total body weight. *2.* The ________ surface, 1.5 - 2.0 m2, is constantly worn away, attacked by micro-organisms, irradiated by sunlight, and exposed to environmental chemicals.Most accessible but often least appreciated organ system.

Doctors often give their patients the following ABCDE mnemonic to help with the diagnosis of early-stage melanoma. If you observe a mole on your body displaying these signs, consult a doctor.

*A*symmetry - the two sides are not symmetrical *B*orders - the edges are irregular in shape *C*olor - the color is varied shades of brown or black *D*iameter - it is larger than 6 mm (0.24 in) *E*volving - its shape has change

Accessory Structures:

*a.* Nerve fibers and corpuscles *b.* Hair follicles, hair shafts, and arrector pili muscles *c.* Oil glands and sweat glands *d.* Arteries, veins, and lymph vessels forming the *cutaneous* *network*

Cutaneous membrane:

*a.* The *epidermis*, our outermost layer, consists of stratified squamous epithelium. *b.* The *dermis* consists of a papillary layer of areolar tissue and a reticular layer of dense irregular connective tissue.

Stratum Granulosum

- Consists of 3 - 5 cell layers where the keratinocytes appearance begins to change. The name _____________ means "grainy layer". - These cells become flattened, the plasma membrane becomes thickened, less permeable, and the organelles deteriorate. - By the time the cells reach this layer, most have stopped dividing and have started making large amounts of *keratin* and *keratinohyalin* stored in numerous visible granules. - Beyond this layer, there is no nutrient availability.

Stratum Spinosum

- Consists of approximately 8 - 10 layers of keratinocytes bound together by *desmosomes* and microfilaments of pre-keratin. - The name stratum spinosum, which means "spiny layer", refers to the fact that the cells look like miniature pincushions in standard histological sections. - Large numbers of *dendritic cells* are found in this layer. These are specialized cells (sometimes called Langerhans cells) that participate in the immune response by stimulating a defense mechanism against 1) microorganisms that manage to penetrate the superficial layers of the epidermis and 2) superficial skin cancers.

sweat glands

- Eccrine sweat glands - Apocrine sweat glands - Mammary glands - Ceruminous glands

Stratum Lucidum

- In the thick skin of the palms and soles, a ____________ separates the stratum corneum from deeper layers. -The cells of this layer are flattened, densely packed, largely devoid of organelles, and filled with the proteins *eleiden*. - By the time they reach the_____________ , the cells are dead and undergoing dehydration.

Parts of the nail

- Nail body - Nail bed - Nail root - Hyponychium - Eponychium - Lunula

Stratum Corneum

- Outermost layer of keratinocytes (sometimes called the "horny layer"). - A broad zone of 15 - 30 layers of keratinized cells that accounts for up to three-quarters of the epidermal thickness. - Keratinization is the formation of protective, superficial layers of cells filled with keratin. - The dead cells in each layer of the stratum corneum remain tightly interconnected by desmosomes. It takes 7 to 10 days for a cell to move from the stratum basale to the stratum corneum. The dead cells generally remain in the exposed stratum corneum for an additional two weeks before they are shed or washed away. - Glycolipids in this layer provide a waterproofing quality to the epidermis.

The *dermis lies* between the epidermis and hypodermis. The dermis consists of two layers:

- Papillary layer - Reticular layer

Stratum Basale

- The deepest epidermal layer consisting of a single row of *basal* *cells*, or germinative cells, that are undergoing rapid mitotic divisions. These cells are sometimes called stem cells because their mitotic divisions replace the more superficial keratinocytes that are lost or shed at the surface. Basal cells are cuboidal in shape while keratinocytes are squamous shaped cells. - *Hemidesmosomes* attach the cells of this layer to the basal lamina that separates the epidermis from the areolar tissue of the adjacent papillary layer of the dermis. - Approximately 10 - 25% of cells in this layer are *melanocytes* which produce *melanin*, a brown, yellowish-brown, or black skin pigment. - In hairless skin, specialized cells called *merkel cells* exist in small numbers. These cells are sensitive to touch and when compressed, they release chemicals that stimulate sensory nerve endings.

Sebaceous glands

- oil glands - Simple alveolar glands that are found all over the body except on the palms and the soles. Sebaceous follicles secrete onto skin surfaces located on the face, back, chest, nipples, and external genitalia. - Contractions of the arrector pili muscles squeeze the ________ and force the sebum (a mixture of triglycerides, cholesterol, proteins, and electrolytes) into the hair follicle and onto the surface of the skin. - These glands are the *holocrine* type, the cells fill up with oil then bust (lysis). - *Sebum* is secreted into a *hair* *follicle*, or occasionally a pore, or follicle, on the skin surface. Sebum softens and lubricates hair and surrounding skin and also has anti-bacterial properties. - Sebaceous glands tend to be inactive in childhood.

arrector pili muscle

Associated with each hair follicle is a bundle of smooth muscle cells called an _____________. These muscles will contract and cause hairs to stand up or become erect.

hair bulb

Hair production begins at the base of the hair follicle. Here a mass of epithelial cells forms a cap, called the _________ that surrounds a smaller *hair papilla*, a peg of connective tissue containing capillaries and nerves.

sympathetic nervous system

If the body becomes excessively warm due to high temperatures, vigorous activity or a combination of the two, sweat glands will be stimulated by the _____________ to produce large amounts of sweat. When the sweat evaporates from the skin surface, the body is cooled as body heat is dissipated. In addition, arterioles of the skin dilate so that more warm blood can come to the surface to radiate heat away from vital internal organs.

flushed

If those vessels are dilated, the red tones become much more pronounced. For example, your skin becomes ____________ and red when your body temperature rises because the superficial blood vessels dilate so that the skin can act like a radiator and lose heat.

hair matrix

Immediately above the hair papilla and within the hair bulb, is the____________. The __________ is a clump of rapidly dividing basal cells that produce the hair.

Melanoma

In contrast, _____________ is the least common form of skin cancer but is extremely dangerous. In this condition cancerous melanocytes within the stratum basale grow rapidly and metastasize through the lymphatic system. The outlook for long-term survival is in many cases determined by how early the condition is diagnosed. If the cancer is detected early, while it is still localized, the affected area can be surgically removed, and the 5-year survival rate is 99 percent. If the condition is not detected until extensive metastasis has occurred, the 5-year survival rate drops to 14%.

stratum basale and stratum spinosum

In individuals with pale skin, this transfer occurs in the _________________, and the cells of more superficial layers lose their pigmentation. In dark-skinned individuals, the melanosomes are larger, and the transfer may occur in the stratum granulosum as well; thus skin pigmentation is darker and more persistent.

avascular

Like all other epithelia, the epidermis lacks local blood vessels, that is, they are __________ . Epidermal cells rely of the diffusion of nutrients and oxygen from capillaries within the dermis. As a result the cells with the highest metabolic demand are closest to the underlying dermis.

Thermoregulation

Maintenance of normal body temperature through either insulation or evaporative cooling, as needed.

hypodermis

The ____________ (also known as the subcutaneous layer or superficial fascia) separates the integument from the fascia around the deeper organs. The _______________ is composed of loose connective tissues like adipose and areolar connective tissue. Note this layer is NOT part of the integument.

hypodermis separates

The _____________ the dermis of the skin from deeper structures. - It stabilizes the position of skin in relation to underlying tissues (such as skeletal muscles or other organs) while permitting independent movement. - Because it is often dominated by adipose tissue, the hypodermis also represents an important site for 1) insulation, 2) cushioning, and 3) the storage of energy reserves. - At puberty men accumulate subcutaneous fat at the neck, on the arms, along the lower back, and over the buttock. In contrast, women accumulate subcutaneous fat at the breasts, buttocks, hips, and thighs. In both genders, there are almost no fat cells on the back of the hands and feet but distressingly large numbers in the abdominal regions (resulting in the "potbelly"). - The borders between the hypodermis and dermis are sometimes hard to distinguish.

epidermis thins

The ______________ as germinative cell activity declines, and the connections between the epidermis and dermis weakens, making older people more prone to injury, skin tears, and skin infections.

dermis becomes thinner

The __________________ and has fewer elastic fibers, making the integument weaker and less resilient. The results - sagging and wrinkling - are most pronounced in body regions with the most sun exposure.

metabolic activity in the skin decreases

The _____________________ as well. Synthesis of calcitriol (vitamin D3) decreases leading to muscle weakness and brittle bones.

hemoglobin

The blood supply affects skin color because blood contains red blood cells filled with the red pigment ____________.

keratinocytes

The cells in all of the layers of the epidermis, except the stratum basale, are called ___________. A ___________is a cell that manufactures and stores the protein *keratin*. *Keratin* is an intracellular fibrous protein that gives hair, nails, and skin their hardness and water-resistant properties.

PIGMENATION

The color of one's skin is genetically programmed. However, increased_________, or tanning, can result in response to ultraviolet radiation. Skin color is influenced by the presence of pigments in the epidermis: 1. Melanin 2. Carotene

epidermal ridges

The deeper layers of the epidermis form _______________ which extend into the dermis and are adjacent to the dermal projections called *dermal papillae* that project upward to the epidermis. These ridges and papillae are significant because they greatly increase the surface area for attachment, firmly binding the epidermis to the dermis.

strata

The epidermis is formed of several layers called ___________. Note that the terms "thick" and "thin" refer to the relative thickness of the epidermis, not the integument as a whole.

75%

The human body has about 2.5 million hairs and ___________ of them are on the general body surface and not on the head.

basal cell carcinoma (BCC)

The most common form of skin cancer is ______________. This is a cancer that originates in basal cells of the stratum basale, due to mutations caused by overexposure to the UV light. Metastasis virtually never occurs in ______________, and most people survive these cancers.

dendritic cells decreases

The number of ______________ to about half the levels seen at maturity. This reduction in cells may decrease sensitivity of the immune response and further encourage skin damage and infection.

dermal papillae

The patterns of the _________ in the thick skin on the surface of the fingertips produce fingerprints, which have been used to identify individuals in criminal investigations for more than a century

melanin production

The skin covering most areas of the body has about 1000 melanocytes per square millimeter. Differences in skin pigmentation among individuals do not reflect different numbers of melanocytes but instead different levels of _____________.

functions of integumentary system: Protection:

The skin protects the rest of the body from the basic elements of nature such as abrasion (by the various strata), and UV sunlight (by *melanin*). It acts as a protective barrier against water loss, due to the presence of layers of *keratin* and glycolipids in the stratum corneum. It also is the first line of defense against abrasive activity due to contact with grit, microbes, or harmful chemicals. Sweat from sweat glands deters microbes from over-colonizing the skin surface by generating *dermicidin*, which has antibiotic properties.

hair color

Variations in ___________ reflect differences in hair structure and variation in the pigment produced by melanocytes at the hair papilla. Different forms of melanin give a dark brown, yellow-brown, or red color to the hair. As pigment production decreases with age, hair color lightens. White hair results from the combination of a lack of pigment and the presence of air bubbles in the medulla of the hair shaft.

body temperatures drop

When _________________, the arterioles constrict to minimize heat loss, particularly in the ends of the digits and tip of the nose. This reduced circulation can result in the skin taking on a whitish hue. Although the temperature of the skin drops as a result, passive heat loss is prevented, and internal organs and structures remain warm.

capillaries

When bound to oxygen, hemoglobin is bright red, giving ___________ in the dermis a reddish tint that is most apparent in light-skinned individuals.

cyanosis

When the blood flow decreases, oxygen levels in the tissues decline, and under these conditions hemoglobin releases oxygen and turns a much darker red. Seen from the surface the skin takes on a bluish color. This coloration is called ______________. In individuals of any skin color, cyanosis is most obvious in areas of very thin skin (lips and under the fingernails).

declining levels of sex hormones

With ___________________, differences in secondary sexual characteristics with respect to hair distribution and body-fat distribution begin to fade. As a consequence, people age 90 - 100 of both sexes tend to look alike.

Nail body

_______ consists of dead, tightly compressed keratinocytes packed with keratin. The _________ is the portion of the nail to which polish might be applied.

Nail root

_______ the epidermal fold not visible from the surface and anchors the nail body into the underlying tissues; the deepest portion of the __________ lies very close to the bone of the fingertip

Nail bed

_______ the nail body covers an area of the epidermis that contains rapidly dividing cells that divide to replace the cells that are lost.

Albinism

________ a genetic disorder that affects (completely or partially) the coloring of skin, hair, and eyes. The defect is primarily due to the inability of melanocytes to produce melanin. Individuals with ___________ tend to appear white or very pale due to the lack of melanin in their skin and hair.

Lunula

_________ a pale crescent shaped area near the root where the dermal blood vessels are obscured; may not be present in all nails.

Eponychium

_________ a portion of stratum corneum of the nail root that extends over the exposed nail; more commonly called the cuticle.

Reticular layer

_________ consists of an interwoven meshwork of *dense irregular* *connective tissue* containing both collagen and elastic fibers. - Bundles of collagen fibers extend superficially to blend into those of the papillary layer and deeply to blend with the hypodermis. - The collagen fibers provide strength while the elastic fibers provide flexibility. - This layer restricts the spread of pathogens, stores lipid reserves, attaches skin to deeper tissues, possesses sensory receptors (like pacinian corpuscles), and contains blood vessels for temperature regulation.

Acne

_________ is a skin disturbance that typically occurs on areas of the skin that are rich in sebaceous glands (face and back). It is most common along with the onset of puberty due to associated hormonal changes, but can also occur in infants and continue into adulthood. Hormones, such as androgens, stimulate the release of sebum. An overproduction and accumulation of sebum along with keratin can block hair follicles. This plug is initially white. The sebum, when oxidized by exposure to air, turns black. __________results from infection by ___________-causing bacteria, which can lead to redness and potential scarring due to the natural wound healing process

Hair shaft

_________ is the portion of the hair that extends through the follicle and protrudes above the skin line.

Ceruminous glands

__________ Modified sweat glands that line the external ear canal and secrete a sticky, bitter substance called *cerumen*.

Mammary glands

__________ Specialized sweat gland that secretes *milk*.

Melanocytes

__________ are located within the stratum basale, squeezed between or deep to the keratinocytes. Melanocytes manufacture melanin from the amino acid *tyrosine*, and package it in intracellular vesicles called *melanosomes*.

Cuticle

__________ forms the surface of the hair. Composed of *hard keratin*.

Eczema

__________ is an allergic reaction that manifests as dry, itchy patches of skin that resemble rashes. It may be accompanied by swelling of the skin, flaking, and in severe cases, bleeding. Many who suffer from ___________ have antibodies against dust mites in their blood, but the link between ___________ and allergy to dust mites has not been proven. Symptoms are usually managed with moisturizers, corticosteroid creams, and immunosuppressants.

Vitiligo

__________ the melanocytes in certain areas lose their ability to produce melanin, possibly due to an autoimmune reaction. This leads to a loss of color in patches. Neither albinism nor ________ directly affects the lifespan of an individual.

Nails

__________ thick sheets of keratinized epidermal cells. _________ protect the exposed dorsal surfaces of the tips of the fingers and toes. They also help limit distortion of the digits whey they are subjected to mechanical stress. The cells producing the _________can be affected by conditions that alter body metabolism, so changes in the shape, structure, or appearance of the ________ can provide useful diagnostic information.

Cleavage Lines

__________ within the dermis, the collagen and elastin fibers are arranged in parallel bundles oriented to resist the forces applied to the skin during normal movements. The resulting pattern of fiber bundles establishes the lines of cleavage. These lines are clinically significant: a cut parallel to a cleavage line will usually remain closed and heal with little scarring whereas a cut at a right angle to a cleavage line will be pulled open as movement occurs and result in greater scarring.

Eccrine sweat glands

___________ (also called merocrine sweat glands) are highly coiled glands that lie deep in the dermis of the palms, soles of the feet, and forehead. - ___________ secretions, commonly called *sweat*, are a hypotonic filtrate of the blood composed mostly of water (90%) and release by exocytosis. - Once secreted by *exocytosis* (*merocrine*), the sweat travels via a duct to the surface of the skin where it opens into a funnel-shaped pore. - Normal pH of sweat is between 4 and 6.

Cortex

___________ an intermediate layer of cells deep to the cuticle. Contains thick layers of *hard keratin*, which give hairs their stiffness.

Melanocyte activity declines

___________ and in light skinned individuals, the skin becomes pale. With less melanin in the skin, people become more sensitive to sun exposure and more likely to experience sunburn.

Hair follicles

___________ are a complex structure composed of epithelial cells and connective tissues that are responsible for the formation of a single hair. The ________ has three regions: the internal root sheath, the external root sheath, and glassy membrane. Hairs are non-living structures composed of keratinocytes.

Moles

___________ are larger masses of melanocytes, and although most are benign, they should be monitored for changes that might indicate the presence of cancer

Root hair plexus

___________ are sensory nerves that surround the hair bulb and give hair the ability to detect touch.

Burns

___________ damage inflicted by intense heat, electricity, radiation or certain chemicals. - First degree - Second degree - Third degree - Fourth degree

Excretion

___________ seepage of salts, water, and organic wastes by integumentary glands.

Melanosomes

___________ travel within the processes of melanocytes and are transferred intact to keratinocytes. The transfer of pigmentation colors the keratinocyte temporarily, until the ____________ are destroyed by fusion with lysosomes.

Carotene

____________ an orange-yellow pigment that normally accumulates in epidermal cells. It is most apparent in cells of the stratum corneum of light-skinned individuals, but it also accumulates in fatty tissues in the deep dermis and hypodermis. ___________- is found in a variety of orange and yellow vegetables (sweet potatoes, carrots, squash).

Sensory

____________ detection of touch, pressure, pain, and temperature stimuli, and the relaying of this information to the nervous system. - Free nerve endings - Tactile discs - Tactile corpuscles (Meissner's corpuscles) - Lamellated corpuscles (Pacinian corpuscles)

Synthesis

____________ of Vitamin D3, a steroid that is subsequently converted to *calcitriol*, a hormone important for normal calcium metabolism. The absence of sun exposure can lead to a lack of vitamin D in the body, leading to a condition called *rickets*, a painful condition in children where the bones are misshapen due to a lack of calcium, causing bow-leggedness. Elderly individuals who suffer from vitamin D deficiency can develop a condition called *osteomalacia*, a softening of the bones.

Hair root

____________ the portion that anchors the hair into the skin

Thick skin

____________ which occurs on the palms of the hands and soles of the feet, possesses five strata. It is about as thick as a standard paper towel (roughly 0.50 mm).

Medulla

____________, or core, consists of cells at the center of the hair matrix filled with *soft keratin*.

Apocrine sweat glands

_____________ are largely confined to the axillary and anogenital areas. - Larger than eccrine sweat glands and release their secretions into hair follicles. - The secretions produced are similar to sweat but they also contain many organic compounds which can be metabolized by bacteria causing it to smell. - ______________ begin functioning at puberty.

Papillary layer

_____________ consists of a highly vascularized loose, *areolar* *connective* tissue with all of the typical cell types within it. - This layer also contains the capillaries, lymphatic vessels, and sensory neurons (called meissner's corpuscles) that supply the surface of the skin. - The __________ gets its name from the dermal papillae that project between the epidermal ridges. - This layer nourishes and supports epidermis.

Storage

_____________ of lipids in adipocytes in the dermis and in adipose tissue in the hypodermis.

Hair follicles stop functioning

______________ or produce thinner, finer hairs. With decreased melanocyte activity, these hairs are gray or white.

Hyponychium

______________ the free edge of the nail composed of a thickened stratum corneum; the distal portion that continues past the nail bed.

Sebaceous gland secretions decreases

______________ with age and the skin becomes dry and often scaly.

Skin cancers

_______________ are the most common types of cancer.

Merocrine sweat glands become less active

_____________________ and with impaired perspiration processes, older people cannot lose hear at fast as younger people. Thus the elder are at greater risk of overheating in warm environments.

A reduction in dermal blood supply

____________________________ cools the skin, which can stimulate thermoreceptors and make a person feel cold even in a warm room. Reduced circulation and sweat gland function lessens their ability to lose body heat, which can cause their body temperature to soar dangerously high.

Thin skin

____________which covers most of the body surface, contains four strata and is about as thick as the wall of a plastic sandwich bag (roughly 0.08 mm).

Melanin

a brown, yellowish-brown, or black pigment produced by melanocytes.

Skin is composed of two major components:

cutaneous membrane and accessory structures

functions of integumentary system

protection, body temperature regulation, cutaneous sensation, metabolic functions, blood reservoir, excretion

Tactile corpuscles (Meissner's corpuscles)

receptors located in the dermal papillae; responsible for the detection of light touch

Lamellated corpuscles (Pacinian corpuscles)

receptors located in the reticular layer of the dermis; responsible for detection of deep pressure and vibration.

parts of hair

shaft, root, follicle, bulb, papilla, matrix