Skin Test

What are the primary functions of the skin?

Protection of internal tissues, immune defense, prevention of dehydration, temperature regulation, sensory reception, waste disposal, and vitamin D production.

What role do Langerhans cells play in the skin?

They arise from bone marrow, migrate to the epidermis, ingest foreign substances, and activate the immune system as antigen presenting cells.

How does the skin protect against infection?

The skin acts as a physical barrier with tightly packed cells, and the low pH of the acid mantle slows bacterial reproduction.

What mechanisms does the skin use to regulate body temperature?

Sweating and blood vessel dilation cool the body when hot; shivering and blood vessel constriction retain heat when cold.

What is the role of melanin in the skin?

Melanin, produced by melanocytes, absorbs UV rays, preventing DNA mutations and contributing to skin color.

What are the layers of the skin?

The skin consists of two main layers: the epidermis and the dermis, separated by the basement membrane.

What is the stratum basale?

The deepest layer of the epidermis, nourished by blood vessels in the dermis, where active mitosis occurs.

What is the function of the papillary layer of the dermis?

It contains areolar connective tissue, small blood vessels, and allows immune cells to check for bacteria.

What is the reticular layer of the dermis composed of?

Dense fibrous connective tissue that provides strength, resiliency, and hydration to the skin.

What are Meissner's corpuscles?

Specialized nerve endings in the dermal papillae that respond to light touch.

What is the function of sebaceous glands?

They secrete sebum to keep skin and hair soft, pliable, and waterproof, and are associated with hair follicles.

What distinguishes merocrine glands from apocrine glands?

Merocrine glands secrete sweat directly onto the skin surface and function throughout life, while apocrine glands secrete into hair follicles and are activated at puberty.

What are the characteristics of first-degree burns?

They affect only the epidermis, cause redness and mild pain, and typically heal within a few days to two weeks.

What happens during the healing of deep cuts?

Inflammation occurs, followed by blood clotting, scab formation, fibroblast infiltration, and eventual scab fall-off.

What is the role of the hypodermis?

It acts as insulation, contains major blood vessels, and anchors the skin to underlying structures.

What is keratinization?

The process by which skin cells in the hair follicle mature and accumulate keratin, eventually forming the hair shaft.

What is the function of nails?

Nails protect the ends of digits and assist in manipulation.

How does the skin help in waste disposal?

The skin disposes of waste materials through sweat.

What is the significance of the acid mantle?

The acid mantle is a chemical barrier that slows bacterial reproduction on the skin.

What is the role of the arrector pili muscle?

It causes hair to stand on end (goosebumps) in response to cold or fear.

What is the process of skin cell replacement?

Skin cells slough off and are replaced approximately every four weeks.

What are the two types of sweat glands?

Merocrine (eccrine) glands and apocrine glands.

What is the role of collagen fibers in the dermis?

Collagen fibers provide strength and prevent scrapes from penetrating the dermis.

What is the function of the stratum corneum?

It is the outermost layer of the epidermis, composed of dead epithelial cells filled with keratin.

What is the significance of the lunula in nails?

The lunula is the active mitosis area (nail matrix) where new nail cells are produced.

How does the skin help in the regulation of vitamin d

Regulates levels of clacium and phosphates in the bones which prevents rickets (softening of bone deformity)

Substances that can penetrate the skin

Lipid soluable substances (O2, CO2), Oleoresins of plants ( poison ivy and oak), Organic Solvents which dissolve lipid cells ( acetone and paint thinner), salts of heavy metals (lead and mercury), selected drugs (nicotine)

what causes wrinkles

the boundary between the epidermis and dermis being uneven because the epidermis projects inwards and the dermis has papillae between the ridges of the epidermis

what is the stratum spinosm

Many layers of cells with centrally located nuclei and large centrally located nuclei and developing fibers of keratin

what is the stratum granulosm

composed of 3-5 layers of cells with flattened grandular cells filled with keratin granules and a shriveled nuclei

What is the stratum corneum?

outermost layer made of dead epithelial cells filled with keratin

what is stratum lucidem

a translucent layer of cells with an additional layer for thickened skin found on the soles and palms

Order of Stratums from Front to deep

1. Corneum

2. Lucindum

3. Granulosm

4. Spinosm

5. Basale

What happens in an injury

rate of cell division will increase in the stratum basale

what layer determines skin color

epidermis

how does the epidermis determine skin color?

Specialized cells in the epidermis called melanocytes produce melanin

How many melanocytes are in each race

the same amount

what determines difference in skin color

the amount of pigment in the melanocytes produce and disperse keratinocytes

what causes freckles

accumulation of melanin in patches

how does the epidermis grow

through a four weeks process where skin cells slough off and are replaced

what is the dermis layer composed of

mostly of irregular dense CT, ET, MT, NT, and blood

dermis layer functions

1. bind epidermis to subcutaneous layer

2. give nutrients to epidermis

what are the two dermal layers

papillary and reticular

what is the papillary layer (dermis) MADE of

Areolar CT with fine interlacing collagen and elastic fibers and numerous small blood vessels

what does the papillary layer (dermis) do?

allow phagocytes and other defensive cells to wander and check for any bacteria that may have breached the skin

what does the dermal papillae CONTAIN

capillary loops, free nerve endings, touch receptors

dermal papillae location

palms and soles of dermal ridges

what is the reticular layer (dermis) made of

dense fibrous CT (80%)

what do the collagen fibers in the reticular layer do

- give skin strength and resiliency

- prevents scrapes from penetrating dermis

- binds with water for hydration

what do the elastic fibers in the reticular layer (dermis) do?

give stretch-recoil properties

what are the specialized nerves in the dermis?

Meissner's Corpuscles and Pacinian Corpuscles

where are the Meissner's Corpuscles

dermal papillae

what stimulates the Meissner's Corpuscles

light touch (fingers, tongue, face, etc)

what stimulates the Pacinian Corpuscles

pressure

where is the Pacinian Corpuscles

deeper in the dermis and hypodermis

where is the subcutaneous (hypodermis) layer

below epidermis and dermis

what is the hypodermis layer made of

- Areolar tissue CT (anchoring fibrous)

- Adipose tissue and microphages

hypodermis layer functions

- insulation

-major blood vessels

- collagenous and elastic fibers of dermis

accessory organs of the skin (epidermal derivatives)

hair follicles, nails, sebaceous glands, skin glands

Where is the root or base of hair follicles located?

In the deep dermis

What process is ongoing at the root of hair follicles?

Keratinization

Where is the hair follicle located?

Throughout the dermis

Where is the hair shaft located?

In the epidermis

What is complete in the hair shaft?

Keratinization

What type of cells are hair follicles made of?

Epithelial cells

What process occurs in the root of hair follicles?

Active mitosis

What happens to cells in the hair follicle?

They mature and accumulate keratin

What are the characteristics of cells in the epidermis related to hair?

They are dead epithelial cells full of keratin, forming the exposed hair or hair shaft

What is the arrector pili muscle in the hair follicles

a bundle of smooth muscle associated with every single hair follicle

what do the arrector pili muscles do

cause hairs to stand on end (when nervous or cold)

function of the nails

protection of digit ends

What are sebaceous glands

Holocrine glands (exocrine)

What do sebaceous glands secrete?

sebum (oil)

what does sebum (sebaceous glands) do?

keep skin and hair soft, pliable, and waterproof

what is acne

hypersecretion of sebum (ducts clog and inflame)

what is seborrhea

hyperproduction of sebum (oil scales)

what are the two types of skin glands

merocrine and apocrine

what is the structure of the merocrine glands

1. coil in deep dermis

2. duct in dermis

3. pore at surface

What is one function of merocrine glands?

Respond to elevated temperature (exercise)

How do merocrine glands help the body?

Prevent overheating

What triggers emotional cold sweats from merocrine glands?

Fright or embarrassment

Do merocrine glands produce odor?

No odor

When do merocrine glands function?

Throughout life

apocrine gland structure

ducts terminate into hair follicles

What do apocrine glands respond to?

Stress and emotions

Are apocrine glands odorless?

Yes

When do apocrine glands begin to function?

At puberty

Where are apocrine glands associated?

With hair follicles, larger and deeper into the hypodermis

what are merocrine glands not associated with

hair follicles

merocrine gland location

forehead

neck

back

apocrine gland location

armpits

groin

what do apocrine glands secret

sweat and fatty oil and cellular debris (proteins)

what do merocrine glands secret

watery, thin sweat (**cold sweats)

what are the modified apocrine glands

ceruminous glands and mammary glands

where are the ceruminous glands

external ear canal

what do ceruminous glands secrete

earwax

what is inflammation

the process that involves blood flow changes and chemical signaling healing the body

epidermal cuts

healed by increased cell division in the stratum basale

What do deep cuts involve that causes inflammation?

Blood vessel damage

What process occurs in deep cuts that leads to blood clotting?

Blood vessel damage