BSCI201- Exam #2

Skin and accessory skin structures

What are the two divisions of the integumentary system?

Skin

What is the largest organ OF the body?

Liver

What is the largest organ IN the body?

Thin

Any part of the skin except the palm/soles = ____ skin

0.5; 4.0

The thickness of skin varies from ___mm in THIN skin to ___mm in THICK skin.

Palms and the soles

What parts of the body is covered by thick skin?

Epidermis; dermis

Skin is composed of the superficial ____ and the deeper ____.

Skin appendages

Accessory skin structures = ________ ________

Accessory structures of the skin

Sweat (sudoriferous) glands, sebaceous ( oil) glands, hair/hair follicles, and nails are all…

Stratum Corneum, Stratum Lucidum, Stratum Granulosum, Stratum Spinosum, Stratum Basale

What are the strata of the epidermis in order from superficial to deep?

Stratum Lucidum

What strata of the epidermis is only present in thick skin?

Stratum Basale

What is the deepest strata of the epidermis?

Stratum Corneum

What is the superficial strata of the epidermis?

Stratum Granulosum

What strata of the epidermis contains granules?

Stratum Spinosum

What strata of the epidermis contains tonofilaments?

Stratum corneum, stratum granulosum, stratum spinosum, and stratum basale

What are the four strata of the epidermis in thin skin?

Merkel cells

At the epidermal-dermal junction associate with free nerve endings to form Merkel Discs, which act as Touch receptors.

Melanocytes

Produce the pigment melanin contained in melanosomes. When you go out into the sun, these cells make extra melanin to protect you from getting burned by the sun's ultraviolet, or UV, rays = tanning.

Keratinocytes

Are mitotically active producing cells for the superficial layers hence, the stratum basale is also known as the stratum Germinativum.

Stratum Basale

The deepest stratum. A single layer of cells including Keratinocytes, Melanocytes, Merkel cells. Acts as the germinal layer for new skin cells.

Melanin

Acts as a chemical shield to protect the nuclei of the keratinocytes from the harmful effects of UV radiation in sunlight. Gives skin its color.

Melanosomes

Accumulate on the superficial surface of the keratinocytes in the stratum basale.

Albinism

Genetic condition in which melanin is not synthesized.

Due to the lack of melanin which protects the skin from UV radiation.

Why are albinos more susceptible to developing skin cancers?

Stratum Spinosum

Several layers of cells that are connected by desmosomes, contain intermediate filaments called tonofilaments, and have Langerhan cells that act as macrophages to engulf and digest pathogens.

Desmosomes

Hold cells together which cause the cells to appear “spiny” during histological preparation.

Tonofilaments

Composed of keratin and resist tension placed on the skin.

Langerhans’ cells

Epidermal dendritic cells – in the stratum spinosum act as macrophages (because the epidermis is avascular, macrophages are not present in the epidermis) to engulf and digest pathogens via phagocytosis.

Stratum Granulosum

Composed of 3-5 layers of cells. Cells contain 2 types of granules called Lamellated granules and keratohyaline granules.

Lamellated granules

Membrane-bound organelles found in keratinocytes of the epidermis, specifically within the stratum granulosum that contain Glycolipids.

Glycolipids

What are the lipids that make the epidermis water-proof?

Keratohyaline granules

Contain the tough, insoluble protein, Keratin, which makes the epidermis tough and abrasive- resistant.

Stratum Lucidum

Thin, translucent layer of dead cells that thickens the epidermis and is present only in thick skin – palms, soles.

Stratum Corneum

Superficial layer of the epidermis, composed of 20-30 layers of dead, flat cells. Include cornification and this layer is replaced every three to four weeks.

Cornification

Dead cells are impregnated with glycolipids and keratin to provide a tough, durable, water-proof “coat”.

Dermis

Consists of the superficial papillary layer and the deep reticular layer.

Papillary layer of the dermis

Composed of areolar CT. The surface has peg-like projections called dermal papillae – house blood capillaries, nerve endings, and Meissner’s corpuscles which act as touch receptors.

Dermal Paillae

House blood capillaries, nerve endings, and Meissner’s corpuscles which act as touch receptors.

Dermal Ridges

In thick skin, the surface of the papillae are supported by mounds called ____ ____ which form impressions on the epidermal surface called the epidermal ridges.

Epidermal Ridges

Friction ridges – increase friction and enhance gripping. Genetically determined and unique to an individual and is therefore the basis for finger-printing.

Reticular layer of the dermis

Deeper layer accounting for 80% of the dermis. Composed of dense irregular CT and contains the touch receptors for deep pressure called Pacinian corpuscles. It includes cleavage lines which are areas with less collagen bundles.

Pacinian corpuscles

Located in the reticular layer of the dermis and they respond to deep pressure placed on the skin.

Cleavage (tension) lines

Areas of the reticular layer with less collagen bundles.

Parallel

Incisions made _____ to the cleavage lines gape less, lower infection rate and therefore heal faster with less scar formation.

Across

Incisions made _____ cleavage lines gape, higher infection rate and therefore take longer to heal with less scar formation.

Striae

Stretch Marks - are a type of skin scarring that appear as lines, stripes, or bands on the skin.

Merkel Discs

Epidermal-dermal junctions; act as light touch. Is the functional unit, consisting of the Merkel cell combined with an associated afferent nerve ending.

Meissener’s Corpuscles

In the papillary layer of the dermis and act as touch receptors. Rapidly adapting, specialized mechanoreceptors located in the hairless skin, particularly in the fingertips, lips, and palms.

Root hair plexus

Wrapped around the base of a hair follicle called the hair bulb and it’s stimulated when the hairs bend; act as touch.

Basale; dermis

Accessory structures of the skin are all derived from the stratum _____ of the epidermis but reside in the ______: where they can get nutrients.

Sweat glands

Also known as sudoriferous glands. Simple (coiled) tubular multicellular exocrine glands. 2 types: Eccrine and Apocrine.

Eccrine sweat glands

3 million of these per person and are abundant in the palms, soles and forehead. They secrete sweat for thermoregulation when body temperature rises. They use the merocrine mode of secretion, hence, they are also known as merocrine sweat glands

Eccrine sweat glands

What are the most abundant sweat glands in the body?

Acid mantle

The combination of acidic pH of sweat and dermicidin on the surface of the skin to retard microbial growth.

A hypotonic filtrate of blood

What type of filtrate is sweat?

About 99%

What percentage of sweat is water?

Why sweating helps cool the body

Since water has a high heat of vaporization, heat from the body is used to evaporate water from surface of skin dropping body temperature back to normal).

Antibodies

What immune component is found in sweat?

Vitamin C

What vitamin is present in sweat?

Sodium chloride (NaCl)

What salt is commonly found in sweat?

Metabolic wastes

What types of wastes are found in sweat?

Dermicidin

What antimicrobial protein is found in sweat?

4-6 (acidic)

What is the typical pH range of sweat?

Apocrine sweat glands

2000 of them located in the anogenital and axillary (armpits) areas and they become active after puberty when they are stimulated by the sex steroid hormones. They secrete a viscous, yellowish fluid onto hair follicles via merocrine mode of secretion. Secretion is associated with body odor hence, these are also known as “ODORIFEROUS” glands.

Ceruminous and mammary glands

What are the two specialized sweat glands?

Ceruminous glands

Specialized sweat glands located in the lining of the external ear canal; they secrete a bitter substance called cerumen (earwax) which prevents entry of foreign objects such as, insects and water, into the ear.

Mammary glands

Specialized sweat glands located in breasts; secrete milk to feed the young.

Sebaceous glands

Also known as Oil glands. Simple (branched) alveolar multicellular exocrine glands that are found all over the body except the palms/soles. They secrete an oily substance called sebum into hair follicles and via pores to the surface of the skin which softens and lubricates hair and skin. They secrete via the holocrine mode of secretion.

Whiteheads

Sebum accumulated in the ducts of the sebaceous glands.

Blackheads

Popped whiteheads that result in oxidation and darkening.

Acne

Inflammation of sebaceous glands caused by bacteria.

Pili

Hairs = ____

Shaft and root

What are the two regions of hair?

Shaft

Region of hair exposed above the skin.

Root

Region below the skin enclosed by the hair follicle.

Shaft and root

What is produced by cells in the matrix inside hair follicles?

Hair matrix

What is this a picture of?

Hirsutism

A common condition in women involving excessive growth of dark, coarse hair in male-pattern areas like the face, chest, and back, typically driven by high androgen levels.

Alopecia

Hair loss, commonly characterized by thinning hair, bald patches, or total hair loss on the scalp or body.

Protection and insulation

What is the function of hair?

Thermoregulation

The biological process by which the body maintains an optimal internal core temperature (roughly or in humans) by balancing heat production and loss.

Nails

Made of tightly packed, hard, keratinized epidermal cells. They consist of a body, a root, lunula, hyponychium, and Eponychium or cuticle.

Nail body

Portion of the nail that is visible.

Free edge

Part of the nail that extends past the distal end of the digit.

Nail root

Portion of the nail buried in a fold of skin.

Lunula

Means little moon- crescent shaped area of the nail (visible part of the nail matrix).

Hyponychium

Secures the nail to the fingertip- thickened stratum corneum.

Enponychium or cuticle

Narrow band of epidermis- growth of nails is in the nail matrix.

Nails

____ are scale-like modification of the epidermis.

Protein; keratin

Fingernails and toenails are composed of dead cells impregnated with a tough protective ____ called ____.

Basal Cell Carcinoma, Squamous Cell Carcinoma, and Melanoma

What are the three main types of skin cancer?

Basal Cell Carcinoma

Involves the proliferation of keratinocytes in the stratum basale. The least malignant and most common type of skin cancer ( 80% ); grows slowly.

Squamous Cell Carcinoma

Involves the cells in the stratum spinosum. Second most common type of skin cancer; grows rapidly.

Melanoma

Proliferation of the melanocytes; most aggressive type of skin cancer, highly metastatic and resistant to chemotherapy; least common.

Burns

Tissue damage by intense heat, radiation, electricity and chemicals such as acids. Classified based on severity.

First-degree burns

Damage is confined to only the epidermis; associated with redness, swelling and pain; heal in 3day without medical intervention. Ex. Sunburn.

Second-degree burns

Damage to the entire epidermis and the papillary layer of the dermis; associated with blisters (fluid collection at the epidermal-dermal junction), swelling, redness and pain; heal in 3-4 weeks if infection is prevented.

Third-degree burns

Damage to the entire skin= damage to the entire epidermis and dermis including all nerve endings hence, the burn site is not painful; subjected to infections and fluid loss; medical intervention involving grafting, fluid, protein and ion replacement are required for healing.

By the percentage of total body surface area (TBSA) damaged

How is the extent of a burn wound measured?

The Rule of Nines

What method is used to estimate the percentage of body surface burned?