THe integumentary System

what is the significance of the integumentary system

it plays a vital role beyond appearance, providing protections and maintaining homeostasis essential for overall health

epidermis layer

the epidermis is the outer epithelial layer of the skin

dermis layer

the dermis is a connective tissue layer housing blood vessels, nerves, and accessory structures

hypodermis layer

the hypodermis is a subcutaneous layer of loose connective and fatty tissue providing insulation and cushioning

structure of the epidermis

keratinized stratified squamous epithelium, composed of four or five layers depending on location

is the epidermis vascular or avascular

avascular

think skin characteristics

think skin consists of four layers of the epidermis

thick skin characteristics

thick skin consists of five layers, including the stratum lucidum and is found on palms and soles

layers of the epidermis (list outermost to deepest)

stratum corneum

stratum lucidum (and thick skin)

stratum granulosum

stratum spinosum

stratum basale

(remember: Can Llamas Get Some Bamboo)

keratinocytes

in epidermis; produce keratin, the main structural protein

melanocytes

in epidermis; produce melanin pigment for UV protection and skin color

merkel cells

in epidermis; sensory receptors for touch, abundant in hands and feet

langerhans cells

in epidermis; are immune cells that engulf bacteria and foreign particles

stratum basale

deepest epidermal layer

composed of mainly basal stem cells undergoing mitosis to produce keratinocytes

constrains melanocytes for pigmentation

contains merkel cells that stimulate sensory nerves for touch

basal stem cells are actively dividing to replenish keratinocytes

stratum spinosum

layer provides strength through desmosomes that interlock keratinocytes

contains 8-10 layers of keratinocytes beginning keratinocytes synthesis and producing water-repelling glycolipids

langerhans calls here function as macrophages to defend against microbes

stratum granulosum

composed of 3-5 layers of flattened cells with thickened membranes

produce large amounts of keratin

nuclei and organelles disintegrate as cells die, forming the basis for upper epidermal layers as accessory structures

stratum lucidum and thick skin

lucidum is a think translucent layer found only in thick skin areas such as palms and soles

consists of dead, flattened keratinocytes desnely packed with eleidein

provides additional protection in high-friction areas

stratum corneum

outermost epidermal layer, composed of 15-30 layers of dead keratinized cells

forms a tough, dry barrier that prevents dehydration and microbial invasion

shells are regularly shed and replaced approximately every four weeks

what is the dermis structural role, sensory function and components

provided structural strength and elasticity

houses sensory receptors

contains blood vessels, nerves, hair follicles, sweat glands, and sebaceous glands

papillary layer of dermis

superficial dermal layer made of loose areolar connective tissue

contains fibroblasts, adipocytes, small blood vessels, phagocytes, lymphatic capillaries, and nerve fibers

meissner corpuscle in the papillary layer are responsible for light touch sensation

dermal papillae project into the epidermis strengthening the connection

small blood vessels are present in the papillary layer supporting its function

reticular layer of dermis

thicker, deeper dermal layer composed of dense irregular connective tissue

rich in collagen and elastin fibers, it provides tensile strength and elasticity

well vascularized with abundant sensory and sympathetic nerve supply

subcutaneous layer- hypodermis

lies beneath the dermis, composed of loose connective tissue and adipose tissue

includes fat storage, insulation to prevent heat loss, and cushioning to protect underlying muscles and bones

connects skin to underlying fascia

melanin production, UV protection, and skin color variation

melanocytes in the stratum basale produce melanin, transferred to keratinocytes via melanosomes

melanin protects epidermal cells from UV radiation and determines hair and skin color

darker skin repulses from higher production of melanin

what are the types of melanin and their color

eumelanin- black/brown

pheomelanin- red

albinism

genetic disorder causing little or no melanin production, resulting in pale skin, increased UV sensitivity, and vision issues

vitiligo

autoimmune-related loss of melanocyte function in patches, causing depigmentation

what does the hair follicle anatomy include and what’s their function

• internal root sheath- surrounds the hair root and is derived from the basal cells of the hair matrix

• external root sheath- an extension of the epidermis that encloses the hair root

• hair matrix- responsible for production hair cells

• hair papilla- connective tissue at the follicle base containing blood capillaries and nerves

• arrector pilli muscle- causes hair to stand in response to stimuli

hair growth cycle

1- anagen phase: active growth period lasting 2-7 years where basale cells divide rapidly in the hair matrix

2- cartagen phase: short transition period of 2-3 weeks marking the end of active growth

3- telogen phase: resting phase lasting 2-4 months after which a new anagen phase begins

marisol structure and growth

• protects the fingertips and toes from mechanical distress

• composed of densely packed dead karatinocytes forming the nail body

• grows continuously from the nail matrix located at the nail root

eccrine sweat glands

• widespread across the skin and produce hypotonic, watery sweat

• primarily for thermoregulation (regulating body temp.) and excreting waste

• released directly on the skin surface

apocrine sweat glands

• larger and located in hair-rich areas like armpits and genital regions

• secrete a thicker sweat into hair follicles contains organic compounds decomposed by bacteria

• causes body odor

• also assist in waste excretion and temp regulation

sebaceous glands and sebum

• sebaceous glands are oil-producing associated mostly with hair follicles

• glands secrete sebum, a lipid mixture that lubricates and waterproofs the skin and hair

• sebum has antibacterial properties

• increases at puberty contributing to skin oilliness

functions of the integumentary system

• protection- against microbes, chemicals, UV radiation, and dehydration

• sensory detection- touch, temp, pain, and vibration; pecinan detect vibration, meissner respond to light touch, merkel cells sense pressure

• thermoregulation- through sweating and blood vessel adjustment

• vitamin D synthesis- essential for calcium absorption and bone health

• fat storage- stored in hypodermis for insulation and cushioning

aging effects on the skin

• thinning epidermis from reduces cell division

• decreased skin elasticity leading to wrinkles and sagging

• paler skin and lower immunity to reduced melanocyte acitivity

• would healing slows

• impaired thermoregulation and skin lubrication

basal cell carcinoma skin cancer

• most common skin cancer

• appears as uneven patches

squamous cell carcinoma

• second most common type of skin cancer

• lesions commonly appear on the scalp, ears, and hands

melanoma

• fatal due to high metastic potential

• develops from moles

eczema

chronic inflammatory skin condition characterized by dry, itchy, red patches that may flake or bleed

acne

results from clogged sebaceous glands, primarily during puberty due to hormonal changes increasing sebum production

how are first, second, and third degree burns classified?

• first affects only the epidermis

• second affects the epidermis and part of dermis

• third destroy the full thickness of skin and nerve ending (all of dermis)