Path 1- Integument 1

kelseyfmeyer's version from 2015-04-16 19:02

Lecture 1

Question Answer
what are the layers of skin, from outside to in?(1) Stratum corneum (2) Stratum granulosum (3) Stratum spinosum (4) Stratum basale
describe the Stratum corneumcomposed of corneocytes (keratinized cells) and forms the protective outer barrier
describe the Stratum granulosumcells contain keratohyalin granules
describe the Stratum spinosumpolyhedral-shaped cells with desmosomal attachments which are visible histologically as intercellular bridges
describe the stratum basaleIt is the germinal layer, single layer of cuboidal cells resting on the basement membrane, and these basal cells are interspersed with specialized cells: melanocytes, Langerhans cells, merkel cells
what cell is the layers of the epidermis composed of?keratinocytes
where do keratinocytes originate from? how/where do they differentiate? what is their fate?originate from germinal cells in stratum basale, they differentiate more and more as they move upwards towards the surface. They are eventually all shed from the stratum corneum
*What is the typical transit time of a single keratinocyte?approximately one month
what three things is the basement membrane zone composed of?(1) hemidesmosomes of the basal cells (2) lamina lucida composed of plasma membrane and anchoring filaments (3) lamina densa composed Type IV collagen
what do desmosomes do?Desmosomes provide intercellular adhesion between keratinocytes
what do Hemidesmosomes do? provide attachment of the epidermis to the basement membrane
what is the dermis composed of?Composed of collagen and elastin fibers embedded in glycosaminoglycan ground substance
what is the purpose of the dermis?Provides support for epidermis, adnexa, vessels, and nerves
what are the two types of nerves supplying the skin? examples?(1) MOTOR (efferent, autonomic) neurons, for arrector pili mm, endocrine sweat glands, and arteriolar sm mm. (2) Sensory (efferent) for free nerve endings (pain),Meissner’s corpuscles(light touch), and Pacinian corpuscles (deeper pressure)
what is/explain the subcutisaka hypodermis, aka panniculus. Attaches the dermis to underlying musculoskeletal system. Made of adipose, and collagenous and elastic fibers
what is the "adenexa" ?it's the hair follicles and associated glands in the skin
how does hair grow? ExplainHair grows in CYCLES, there are 4 of them: Anagen - growth period, Catagen - transition period, Telogen - resting period, Exogen - shedding period (ACTE)
what is Anagen? growth period of hair cycle
what is Catagen?transition period of hair cycle
what is Telogen?resting period of hair cycle
what is Exogen? shedding period of hair cycle
what are three things hair growth is affected by?(1) photoperiod (2) nutrition (3) health status
explain how hairgrowth is affected by photoperiodthe hypothalamus, pituitary, and pineal gland secrete the trophic hormones (growth stimulating hormones): melatonin, gonadal, thyroid, adrenal hormones
what are the two sweat glands?(1) apocrine (duct opens into hair follicle “epitrichial glands” undergo apocrine secretion (by membrane budding) ) (2) eccrine (duct opens directly onto skin surface, “atrichial glands” undergo merocrine secretion (by exocytosis) )
explain a sebaceous glandduct opens into deeper area of hair shaft, secretions condition and lubricate the hair shaft, undergo holocrine secretion (by membrane rupture)
what are two examples of pathogens which can penetrate skinhookworm larvae, Schistosoma
two examples of Dermatophytes which colonize the stratum corneum and cornified structures such as hair and clawsMicrosporum canis, Trichophyton mentagrophytes
example of a pathogen which infects skin via penetrating trauma such as puncture wounds?clostridium tetani
pathogens which penetrate through hair follicle openings/pores?Demodex, Staphylococcus
what is furunculosis? why does this happen?ruptured follicle or gland leading to a bacterial infection
what could cause a bacterial embolism?Erysipelothrix rhusiopathiae
which pathogen uses migration along nerves from infected ganglia as a portal entry into the skin?hervesvirus\
which layer is the most important barrier against infection and fluid loss?stratum corneum
what do Keratinocytes do?produce keratin filaments, desmosomes, and hemidesmosomes that provide structural integrity
*what are the 6 components of the innate immune system?Stratum corneum barrier, Macrophages and dendritic cells, Phagocytes, Endothelial cells, Coagulation system, and compliment cascade
explain how the Stratum corneum barrier affects the innate immunity of the skinprevents pathogen adherence, normal flora prevents pathogen colonization, contains antimicrobial peptides and fatty acids
how do Macrophages and dendritic cells work as a part of the innate immunity of the skin?they have pathogen recognition receptors (PRRs) Initiates toll signalling pathway, and Promotes expression of pro-inflammatory mediators (cytokines, chemokines, adhesion molecules)
how do endothelial cells contribute to the innate immunity of the skin?express adhesion molecules and trigger kinin, coagulation, and complement systems which facilitates influx of plasma proteins and migration of leukocytes to sites of injury and infection
what kinda things does the Complement cascade do for the skin's innate immunity?recruits inflammatory cells (C5a), causes mast cell degranulation (C3a, C5a), opsonizes pathogens (C3b, C4b), and kills some pathogens (MAC)
*what are the 6 components of the adaptive immune system of the skin?Langerhans cells, CD8 T cells(cytotoxic T lymphocytes), CD4 TH1, CD4 TH2, Endothelial cells, Keratinocytes
how do langerhans cells contribute to the adaptive immune system of the skin?They produce pro-inflammatory cytokines, they present antigen to naive T lymphocytes in lymph nodes, and they present antigen to sensitized T lymphocytes at site of infection/injury
what do CD8 T cells do in the adaptive immunity of the skin?(cytotoxic lymphocytes) kill virus-infected cells and neoplastic cells
what do CD4 TH1 cells do in the adaptive immunity of the skin?activate macrophages (IFN-γ) to eliminate intracellular bacteria
what do CD4 TH2 cells do in the adaptive immunity of the skin?activate B cells, mast cells, and eosinophils (IL-4, IL-5, IL-13) to produce immunoglobulins and eliminate extracellular pathogens
how do Endothelial cells play a role in the ADAPTIVE immune system of the skin?express adhesion molecules and bind activated leukocytes for extravasation and migration to sites of injury and infection
how do Keratinocytes play a role in the adaptive immune system of the skin?produce cytokines and growth factors which modulate adaptive immune responses

Lecture 2 (orange is the yellow must-know stuff)

Question Answer
what is Acanthosis?Diffuse thickening (hyperplasia) of the stratum spinosum (Acantho= “having thorn-like projections”)
what is Acantholysis?Discohesion between keratinocytes leads to breaking apart of epidermis. It's due to a Loss of desmosomal function! Occurs with acantholytic diseases such as pemphigus (Lysis= breaking apart)
what is Spongiosis?Intercellular edema leads to sponge-like appearance of epidermis
what is Ballooning degeneration?Intracellular edema leads to cytoplasmic swelling.... Occurs with injury and infection (esp. viral)
what is Hydropic degeneration?Intracellular edema leads to cytoplasmic swelling. This term is used for basal layer only. Occurs with interface disease such as cutaneous lupus
Regeneration/repair--> blood clotting. when does this start? explain what's going on0-12hr post injury. Blood clot fills the space created by a wound (scab) (the scab provides a temporary protective barrier and provides a matrix for cell migration)
Regeneration/repair--> inflammation. when does this start? what cells are involved?12-24 hrs post injury. recruitment of inflammatory cells: phagocytes( (neutrophils and macrophages)-->engulf pathogens and foreign debris) and Macrophages also secrete collagenases (facilitating tissue debridement and remodelling)
Regeneration/repair--> Re-epithelialization. when does this start? which cells do what?3-7 days post injury!. Keratinocytes migrate and proliferate to cover the wound. Keratinocytes produce proteases in order to dissect between viable and nonviable tissue. All this Re-establishes basement membrane zone
Regeneration/repair--> fibroplasia. when does this start? what cells/things are helping etc?3-7 days post injury. Cytokines and growth factors are released and then FIBROBLASTS begin to perform several tasks: (1) migrate and proliferate to repair wound (2) produce proteolytic enzymes to facilitate migration (3) produce extracellular matrix proteins to form connective tissue
Regeneration/repair--> Angiogenesis. when does this start? what is going on?3-7 days post injury. Injured cells at the wound site release angiogenic factors, and Endothelial progenitor cells (EPCs) migrate to site of injury and proliferate. Endothelial cells form new vessels to re-establish blood flow.
Regeneration/repair--> Wound contraction. when does this start? what is going on?7 days post injury. Fibroblasts produce collagen and contractile microfilaments that link to the dermal matrix. Collagen bundles bind at the wound margins to contract the wound. Inflammation, edema, and vascularity gradually disappear
Regeneration/repair--> Tissue remodelling. when does this start? what is going on?weeks to months post injury. Collagenases and proteases facilitate tissue remodelling to reduce the amount of scar tissue over time.
look at the pic for healing by first or second intentionno pics on exam but wants us to know the concepts of it
what is the hallmark histological feature of healing?granulation tissue
what is granulation tissue made of?Composed of fibroplasia and angiogenesis.
describe the histological appearance of granulation tissueThe histologic appearance of granulation tissue has a latticework array of proliferative capillaries (angiogenesis) oriented perpendicular to proliferative fibroblasts (fibroplasia).
what is "proud flesh"?exuberant granulation tissue (happens in horses most often)
what is Cornification?transformation of squamous epithelial cells into the keratin layers of the stratum corneum, hair, nails
What are the primary (GENETIC) cornification disorders?primary seborrhea of the cocker spaniel (genetic). ichthyosis (genetic)
what are the secondary (ACQUIRED) cornification disorders usually caused by?Occurs as a response to chronic stimuli such as inflammation and trauma OR Nutritional disorders (vitamin A deficiency)
what is Hyperkeratosis? what might his result in?increased thickness of stratum corneum causing flaky skin. Disruption of the stratum corneum can predisposes to infections (bacteria, yeast)
Epidermal hyperplasia is aka? what is the definition and what is it usually a result of?Acanthosis= epidermal hyperplasia= diffuse thickening of the epidermis with increased number of keratinocytes. It is a common response to chronic stimuli (inflammation, trauma)
what is Dyskeratosis? what are some causes of this?it is premature keratinization of epidermal cells. Happens in zinc-responsive dermatosis, actinic keratosis (solar damage), and also occurs with squamous cell carcinoma
Alterations in /Epidermal/ Growth and Differentiation--> apoptosis. When does this usually occur? examples?usually occurs with auto-immune disorders such as lupus erythematosus (basal keratinocytes affected) and erythema multiforme (multiple layers affected)
what is an erosion? what is an ulceration?Erosion= necrosis of superficial epidermis. Ulceration= necrosis of full epidermis and partial dermis.
what is dysplasia (broad def.) examples of when this would occur?dysplasia=abnormal development. Can occur with chronic ulceration and inflammation. It also may proceed malignant transformation such as non-invasive carcinoma (carcinoma in situ)
what is carcinoma in situ?a non-invasive carcinoma (pre malignancy)
what is atrophy of keratinocytes? why/how does this happen? (examples)("Thin skin") decrease in the number and size of keratinocytes. this occurs as a consequence of sublethal cellular injury-- such as: hormone imbalances (e.g. hyperadrenocorticism), partial ischemia, severe malnutrition
what is edema?fluid accumulation BETWEEN cells
what is spongiosis? when does spongiosis usually happen?intercellular edema of the epidermis. spongiosis is common with epidermal inflammation (epidermitis) caused by Staphylococcus sp. or Malassezia sp.
what are the two types of intracellular fluid accumulation?Hydropic degeneration and ballooning degeneration
what is hydropic degeneration? when does it usually occur?(intracellular fluid accumulation) it is keratinocyte swelling limited to the basal keratinocyte layer; occurs with: lupus erythematosus, dermatomyositis, drug eruptions
what is ballooning degeneration? what can cause this to occur?(intracellular fluid accumulation). It is keratinocyte swelling within more superficial layers and is caused by epidermal damage and numerous viruses such as poxviruses, and FMD virus.
what is Acantholysis? What does it result in?disruption of intercellular junctions (desmosomes) between keratinocytes of the epidermis. results in dissociation of keratinocytes and the formation of epidermal vesicles and pustules
what is acantholysis caused by?Caused by immune-mediated injury (Type II cytotoxic hypersensitivity)--> pemphigus (and some skin infections)

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