Lecture 1 & 2: Integumentary System

maturation phase of wound healing

-Scab sloughs off -Epidermis normal thickness -Collagen is more organized -Fibroblasts decrease and blood vessels stabilize -Fibrosis--> type of scar

Pacinian corpuscles 1.Where are they located? 2. Which portion is myelinated and which is unmyelinated? 3. Function?

1. They're located in the reticular dermis and hypodermis 2. The nerve ending surrounded by the capsule structure is myelinated. But after entering the capsule, it becomes unmyelinated and instead surrounded by Schwann cells. 3. It is used for pressure and vibration

Dermal Papillae

A fingerlike projection of the dermis that may contain blood capillaries or Meissner corpuscles (of touch) -Extend into the epidermal layer

Stratum Lucidum

A layer of the epidermis found only in the thick skin of the fingers, palms, and soles -Keratinization process I well advanced --> differentiated

Hypodermis

Also called a subcutaneous layer, this is a layer of *fat (adipose tissue) located under the reticular layers of the. It helps to insulate the body, store energy, and protects underlying muscles and other structures. -Thicker in individuals in colder climates -Hair follicles, glands, and mechanoreceptors extend into this layer

arrector pili muscle

An involuntary smooth muscle fiber attached to the underside & base of the hair follicle

How is melanin produced?

By oxidation of TYROSINE to 3,4-dihydroxyohenyalanine (DOPA) and transformation of DOPA into melanin.

Hypertrophic Scar

Can occur during healing process when collagen production greatly exceeds collagen lysis. will be raised, but remain within borders of original injury

Reticular Layer 1. What type of collagen is present?

Deeper layer of the dermis that supplies the skin with oxygen and nutrients. Dense irregular connective tissue 1. Type I mainly and elastic fibers

Acantholysis

Dissolution of the intercellular bridges of the prickle cell layer of the epithelium (loss of cohesions between keratinocytes) -Pemphigus Vulgaris

Acanthosis

Epidermal hyperplasia (stratum spinosum) -Acanthosis nigricans

Proliferative phase of wound healing

Growth of epithelial tissue at random and continued growth of blood vessels

Node of Bizzozero

In the stratum spinous, a slight thickening of the desmosomes

Dermis

Inner layer of skin composed of loose connective tissue and dense irregular connective tissue. -Gives strength and elasticity to skin -Contains smooth muscle cells that move the hairs

Birbeck granules on EM

Langerhans cells

Squamous Cell Carcinoma

Malignant tumor of the keratinocytes in the epidermis -Formed from already differentiated cells -Exposure to UV with DNA damage (inactivation of p53) -Hyperkerstosis (more cells) and parakeratosis (cells in outer layer that contain nuclei) -More common in fair skin in head and neck region

Hyperkeratosis

Overgrowth (hyperplasia) of horny layer (corneum) of the epidermis -Psoriasis

Parakeratosis

Retention of nuclei in stratum corneum -Psoriasis

Langerhans cells 1. What kind of connections are present? 2. Where do they originate from? 3. What special reaction are they involved in?

Special macrophages that serve as antigen-presenting cells (APC) in the skin. CONTACT DEMATITIS 1. NO desmosomesal junctions 2. Common lymphoid progenitor (CLP) 3. Delayed-type hypersensitivity reactions

First Degree Burn

Superficial burns through only the epidermis (partial thickness) and will heal spontaneously; sunburn

Basal Cell Carcinoma

The most common type of skin cancer -Caused by IV light -Dark nuclei with poorly defined cytoplasm -Periphery cells have palisaded appearance while central cells are more randomly arranged -Invades dermis and deeper structures -No usually malignant

Keloid Scar

can occur during healing process when collagen production greatly exceeds collagen lysis. extends beyond original boundaries of an injury and damages healthy tissues.

cytocrine secretion

process in which melanin is passed from the melanocyte to nearby keratinocytes

Phenomelanin

reddish-yellow pigment

Epidermal Wound Healing

-Abrasion or minor burn -Basal cells break from basement membrane and migrate across the wound -Contact inhibition with other cells stops migration -Epidermal growth factor stimulates cell division via basal stem cells -Full thickness of epidermis results from further cell division *no breaking of basement membrane

Keratinization

-Cells lose their organelles, cytoplasm, and nuclei -More tonofilaments are formed and then arranged into fibrils by filaggrin -Desmosomes are broken apart when reaches the corneum layer -Total epidermal turnover time is about 47 days

Keratinocytes 1. How are they attached to each other? 2. How are they attached to the basal lamina? 3. What is special about their cell death?

-The most abundant epidermal cells, they function mainly to produce keratin. 1. Attached to each other via desmosomes 2. Attached to the basal lamina via hemidesmosomes 3. They are sloughed off the stratum corneum which is regulated by proteolytic activity on the desmosomes

Melanocytes 1. Where are they derived from? 2. Where are they found? 3. What kind of connections are present?

-cells that produce melanin for pigmentation 1.Neural crest derived 2.Found in the BASAL layer (stratum basale) 3. Hemidesmosomes connect them to the basal lamina. NO desmosomes

sebaceous gland

-oil-secreting gland in the dermis that is associated with hair follicles -Simple branded acinar -Secretory portion in located in the dermis -Product is clear sebum -Holocrine secretion

Inflammatory phase of wound healing

1. Blood clot formed 2. Vasodilation and increased neutrophils and macrophages 3. Mesenchymal cells develop into fibroblasts

migratory phase of deep wound healing

1. Clot dehydrates and becomes a scab. 2. Fibroblasts begin making scar tissue (collagen and glycoprotein) 3. Damaged blood vessels begin to grow. *granulation of tissue --> needed to remove stitches

Free Nerve Endings 1.Where does it terminate? 2. Is myelin present? Connective tissue? 3. Function? 4. How does it surround hair follicles?

1. Most numerous and ends in the stratum granulosum 2. There is NO myelin or connective tissue present 3. The function is for fine touch, heat, and cold - low frequency pain such as a paper cut, tickle, or itch -sensitive to hair movement 4.Attaches to the outer root sheath Mechanoreceptor

Deep Wound Healing (4 steps)

1. inflammatory phase 2. migratory phase 3. proliferative phase 4. maturation phase *breaking of the basement membrane

What are the five layers of the epidermis?

1. stratum corneum 2. stratum lucidum (thick skin only!) 3. stratum granulosum 4. stratum spinosum 5. stratum basale

Ruffini corpuscles 1. Function? 2. Myelinated or unmyelinated? 3. Structure?

1. stretch or torque 2&3. They are encapsulated with connective tissue. Collagen surrounds capsule and can pass through. A single myelin fiber enters the capsule, causes it to lose its sheath. Then it branches (arborization) of fine axonal endings. These axonal endings are what respond to the stretching torque!

Meisner's corpuscles 1. Function? 2. Where are they located? 3. Myelinated or unmyelinated? 4. What is special about the Schwann cell distribution?

1.They perceive light touch, very low frequency stimuli 2.Just below the epidermal surface in the dermal papillae 3. The nerve endings are unmyelinated at the end of a myelinated nerve fiber 4. The Schwann cells are very irregular and randomly distributed

Second Degree Burn

A burn marked by pain, blistering, and superficial destruction of dermis with edema and hyperemia of the tissues beneath the burn. -Epidermis and DERMIS (partial thickness) -Water barrier is disrupted (do not break blister) -heals spontaneously

stratum granulosum

A layer of the epidermis that marks the transition between the deeper, metabolically active strata and the dead cells of the more superficial strata (cells that are about to die) -Most superficial non keritanized -Contains conspicuous granules.... --Keratochylain Granules--> cystine and histidine rich proteins which are precursors for filaggrin (responsible for aggregating the keratin filaments within the cornfield cells- gives cell strength) -Lamellar bodies --> water barrier

Pemphigus vulgaris

Autoimmune disorder impacting the epidermis and mucosal epithelium -Antibodies target cadherins and desmoplakins, DESMOSOMES -Atrophy of the prickle layer (spinosum) -Blisters are easy to rupture -Nikolsky's sign (separation of epidermis caused by rubbing of the skin)

Bullous pemphigoid

BULLOw the BM --> autoantibodies against hemidesmosomes (damage) --> eosinophils release proteases that degrade the hemidesmosomes -Separation of the epithelium from the dermis -Large blisters that DO NOT rupture easily

Albinism

Congenital hereditary condition characterized by partial or total lack of pigment in the skin, hair, and eyes - Lack of TYROSINASE (cannot break tyrosine because lack of the enzyme so there is a lack of melanin production) -Autosomal recessive

Merkel cells 1. What kinds of connections are present?

Detect touch sensations where perception is acute (finger tips) 1. Desmosomes -Contains keratin filaments -Nucleus is lobed and the cytoplasm contains neurosecretory granules

Hair Follicle 1. Thick or thin skin? 2. What are the three segments? 3. Where is the matrix located for hair formation?

Invagination of the epithelium that extends into the hypodermis -Pilosebaceous organ 1.Thin skin only 2. infundibulum, isthmus, inferior segment 3. In the bulb. Melanocyte stem cells are also found there.

How do melanocytes dictate skin color?

It is determined by the amount of melanin present and the type -Lighter skinned people have INCREASED melanin degradation

Malignant Melanoma

Most serious form of skin cancer; often characterized by black or dark brown patches on the skin that may appear uneven in texture, jagged, or raised. IN THE STRATUM BASALE -Exposure to sun light A --> asymmetry B --> borders C --> color D --> diameter E --> evolving

Epidermis

Outer layer of skin consisting of stratified squamous keratinized epithelium.

Hair Cuticle

Outermost layer of hair; consisting of a single, overlapping layer of transparent, scale-like cells that look like shingles on a roof.

Papillary Layer 1. what type of collagen is present? 2. Vascular or Avascular? 3. What special corpuscle is found here?

Outermost layer of the dermis, directly underneath the epidermis. Loose connective tissue 1. Collagen type I and II and elastic fibers 2. Vascular- contains bloods vessels 3. Meissener Corpuscle

Nail

Outgrowth of the skin, composed of keratin, at the end of each finger and toe -Helps with grip and gives protection -Nail matrix and hypoysium -DO NOT extend into the dermis

Pemphigus vulgaris vs bullous pemphigoid

PV: Autoantibodies against desmogliein (Desmosomes) Blisters are FLACCID, intraepidermal, Nikolsky's sign is positive, INVOLVEMENT OF MUCOUS MEMBRANES BP: Autoantibodies against hemidesmosomes glycoprotein antigens in the basement membrane Blisters are TENSE, subepidermal, Nikolsky's sign in negative, NO INVOLVEMENT OF MUCOUS MEMBRANES

Eumelanin

Pigement produced by melanocytes that result in darker hair, skin, and freckles

Rete Ridges (Epidermal Ridges)

Projections that provide the "stick" that anchors layers of the skin together, preventing them from sliding back and forth. - Areas with increased stress will have deeper epidermal ridges

eccrine sweat glands 1.How do the clear cells stain and why? 2.What is special about the dark cells? 3. What are myoepithelial cells?

Secreting glands, are far more numerous and are abundant on palms, soles of feet and forehead. Each is a simple, coiled, tubular gland. Ducts connect to pores. -Moves into the dermis -Merocrine secretion (secretion into a vesicle) 1. They stain with PAS because they are rich in glycogen 2. Dark cells have an abundance of RER and secretory granules 3. Myoepithelial cells are the basal aspect of the secretory segment, assist with expulsion

Stratum Spinosum (Prickly Layer)

Several cell layers thick, cells contain a weblike system of intermediate prekeratin filaments attached to desmosomes. Keratinocytes appear to have spines and are scattered among abundant melanin granules and Langerhans' cells. -Cells gradually lose their cytoplasm and organelles and become flattened moving close to the surface

Stratum Basale (basal layer) 1. What special corpuscle is present? 2. What types of cell junctions are present?

The deepest layer of the epidermis consisting of stem cells capable of undergoing cell division to form new cells (can differentiate) -Cells are mitotically active (Stratum germinativum- keratinocyte stem cells) 1. Merkel cells 2. Basal Lamina- hemidesmosomes cell to cell- desmosomes

thick skin vs thin skin

Thick skin- covers palms, soles fingers and toes thickness is due to the dead cells (stratum corneum). has seat glands but no hair follicles or sebaceous (oil) glands) Thin skin- all over body, thin stratum corneum, has hair follicles, sebaceous glands and sweat glands.

Vitiligo

White patches on the skin caused by the destruction of melanocytes associated with autoimmune disorders (normal production --> destruction) -Steroid therapy offered -Skin grafts, micropigmentation, melanocyte transplant

Tonofilaments

a bundle of protein filaments (Keratin) that extend from one side of the cell to the other in the stratum spinosum.

Third Degree Burn

a burn involving all layers of the skin; characterized by the destruction of the epidermis and dermis, with damage or destruction of subcutaneous tissue (Full thickness) -Water barrier is disrupted -Blood vessel destroyed -Does NOT heal spontaneously -Fluid loss is extensive

internal root sheath

a covering of epithelium produced by the matrix that surrounds the root of the hair

appocrine glands 1. Where is the secretory portion located at? 2.What is the mode of secretion? What is something special that they secrete? 3.How do these differ from eccrine glands?

a sweat gland that secretes a viscous fluid into a hair follicle (as in the armpit or groin), is lined with a single layer of usually columnar cells with eosinophilic cytoplasm, and typically does not become active until puberty -Coiled tubular 1. The secretory portion is located in the dermis and sometimes the hypodermis 2. The mode of secretion is via merocrine and they secrete pheromones 3. These glands are more viscous, less clear, and have a larger lumen compared to apocrine

Psoriasis

chronic, recurrent inflammatory disorder marked by itchy, scaly, red plaques (erythematous) covered by silvery gray scales -Parakeratosis retention of the nuclei in stratum corneum (nuclei aren't supposed to be exposed --> the pain aspect) -Moving through keratinization too quickly (increased proliferation)

Stratum Corneum

the most superficial layer of the epidermis consisting of dead cells (dead keratinized ells) -No organelles or nuclei -Deeper portion contains the water barrier -Abrupt transition to granulosum... nuclei or none

medulla of hair

the spongy anterior core of hair that gives it flexibilty; appears as a canal in the middle of the shaft.