Lesson 2: The Skin (Integumentary System)

• 1. protection
• 2. synthesis of vitamin D
• 3. thermoregulation
• 4. somatosensory perception

• stratum basale or stratum germinativum
•     (new keratinocytes are formed here)
• stratum spinosum
• stratum granulosum
•     (synthesize and store keratohyalin)
• then in hands and feet go to stratum lucidum
•     (here cells are filled with elaidin)
• other parts of body go to stratum corneum
•    (dead keratinocytes filled with keratin)

• hair
• nails
• dermal glands

pigmented areas of the breasts

a tiny bundle of smooth muscle that is attached to each hair follicle

armpits

• arises from cells in the basal layer of the epidermis
• does not spread rapidly
• tends not to metastasize

malignant tumor

a protective coating for the meatus (ear wax)

located in the external auditory meatus (ear canal) and secrete cerumen

as long as the temperature of the body surface exceeds that of the environment, heat can be lost through direct heat flow if the skin is in contact with a cooler object

as long as the temperature of the body surface exceeds that of the environment, heat can be lost to the environment through the air movement across the skin surface if the skin is in contact with a cooler object

temperature of the central thorax, abdomen, and brain

outermost layer of the skin, the stratum corneum

part of the eccrine sweat glands, the coiled portion generates a primary secretion of fluid by secreting NaCl into the gland lumen

• include the sebaceous glands, sudoriferous glands, mammary glands, and ceruminous glands
• arise from the epidermis in the process of embryonic development

• Made up of connective tissue with abundant extracellular fibers of collagen and elastin. Within this layer of skin are:
• hair follicles, sebaceous glands, the ducts of sweat glands, capillaries, and the sensory receptors responsible for sensitivity to pressure and vibration.

part of the eccrine sweat glands, the primary secretion of fluid from the deep-coiled portion passes through this

• type of sudoriferous gland
• most dense in the palms of hands and soles of feet
• produce a dilute solution containing many of the constituents of blood plasma

translucent substance formed from keratohyalin

• stratified squamous epithelium that contains
• keratinocytes, melanocytes, and immunocytes

promotes heat loss from the body surface in which some heat is absorbed by the water in the process of it transformation from a liquid to a gas

• burns that involve mainly damage to the epidermis
• require no special treatment
• typically heal rapidly without scarring

third-degree burn affecting the dermis and subcutaneous tissue

encloses the root of a hair in the skin

sebaceous glands in which the secretions are formed as a product of the breakdown of dead gland cells

• underneath the dermis and is not technically part of the skin
• subcutaneous layer containing loose connective tissue, arterioles, venules, and adipose tissue

provide a first line of defense against invasion by microbes, fungi, and parasites

protein produced by keratinocytes

cells responsible for the wear resistance and waterproof qualities of skin

precursor of keratin

production of milk by the mammary glands during a period of infant nutrition after birth

the crescent shaped region at the base of the nail

• arises from melanocytes in the skin or in pigmented moles
• some forms spread very rapidly and also metastasize freely to other body tissues

• located within the breasts of females
• modified sweat glands that have evolved to produce milk during a period of infant nutrition after birth

located at the base of each hair follicle where the hair grows

pigment in the skin

• produce melanin
• partly responsible for skin color

sudoriferous glands in which part of the secretory cells themselves appears in the secretion

carcinoma spreads to other areas of the body

nails arise from the matrix of stem cells located here at the base of each nail

where the growth of the nail occurs

a pigmented mole

• layer of the dermis, consisting of fingerlike projections that project into the overlying epidermis
• contain an extensive capillary network that supplies the needs of the basal layers of the epidermis
• plays an important role in heat loss from the body core

second degree burns

as long as the temperature of the body surface exceeds that of the environment, heat can be lost to the environment through the transfer by electromagnetic radiation if the skin is in contact with a cooler object

layer in the dermis, largely composed of a network of crisscrossing collagen and elastin fibers that give the skin its elasticity and resilience

holocrine glands that are associated with hair follicles and secrete an oily sebum onto the skin surface

an oily substance secreted by the sebaceous glands onto the skin that reduces the loss of moisture and contains antimicrobial chemicals

these burns involve at least some damage to the dermis

• islands of transplanted skin are created within the burned region, using small flakes of skin removed from unburned body surfaces
• increase the rate of recolonization of new skin cells to the burned area

• arises from cells in the stratum spinosum
• has a higher probability of metastasis

• deepest layer of the skin 
• also called the stratum germinativum

outermost layer of skin, twenty to thirty cells deep, consisting entirely of dead keratinocytes filled with keratin

deepest layer of skin where new keratinocytes are continuously produced from stem cells

• cells begin to synthesize and store keratohyalin here
• layer after stratum spinosum

consists of cells filled with droplets of elaidin

new keratinocytes push upward into this layer above the stratum germinativum

• adipose tissue that protects underlying organs from mechanical shock
• serves a thermal insulation
• contributes to the sex specific body contours of men and women

sweat glands

process that maintains the core body temperature constant within a few tenths of a degree celsius

• also called full thickness burns
• both the dermis and subcutaneous tissue are affected

a steady rate of nerve impulses along sympathetic nerves to superficial blood vessels that maintains some degree of vascular tone in those vessels

vitamin D

keratinocytes

stratum basale

arrector pili

sudoriferous

melanocytes

keratinocytes

collagen and elastin

keratin