Integumentary System Flashcards
What are the layers of the skin (external moving inward)?
Epidermis, Dermis, Hypodermis
What are the layers of the Epidermis (external moving internal)?
Stratum Corneum, Stratum Lucidium, Stratum Granulosome, Stratum Spinosum, Stratum Basale
What cells/ functions are unique to the Stratum Basale layer?
Stem Cells (regeneration)
Rapid mitotic cell division which moves outwards,
Skin colour determinants (melanocytes creating variant amounts of melanin)
Merkel Cells
What cells/ functions are unique to the Stratum Spinosum?
Desmosomes found here (aids in cell adhesion between keratinocytes)
Keratinocytes are producing cytokeratin
Langerhans cells found here (immune cells)
When water is lost, the cells are still adhered via desmosomes, and create a spiny appearance
What cells/ functions are unique to the Granulosum?
Keratinocytes have large presence of keratinhyalin granules (profiliggrin (agreggates keratin), involucrin, loricrin)
Releases lamellar bodies which contain lipids that form strong lipid layer (provides ‘water-proofing’)
What cells/ functions are unique to the Stratum Lucidum?
Clear layer- found in palms and feet soles The keratinocytes (which are now dead) are moved up to this layer- and are now clear (no nuclei of organelles).
What cells/ functions are unique to the Stratum Corneum?
Top layer, dead (coroner)
Stacked layers of dead, flat- squamous epithelial cells, the keratinocytes (15-100) which will continually fall off.
Reptiles shed this layer.
What are the layers (and their functions) of the dermis (external to internal)?
Papillary Dermis- Thin loose, connective tissue (so things can move around and change shape), blood vessels (capillaries), nerve endings (Ruffini endings and Krause end bulbs- for perception of touch/pain), arrector pili muscle (smooth muscle that involuntarily controls hair erection), thin interlacing collagen
Reticular Dermis-Thick, dense connective tissue (so things are anchored down), glands found here which secrete contents into papillary layer, hair follicles are found here, some vessels and nerves
What tissue types are in the layers of the skin?
Epidermis - Epithelial
Dermis- Connective Tissue
Hypodermis- Connective Tissue and Adipose Tissue
What are found in the hypodermis?
Contains subcutaneous fat which absorbs shock, and insulates tissue
How does a nail grow?
Nail root is attached to the epidermis, keratincoytes move outwards from the stratum basale to form the nail.
How does hair grow?
Hair grows from follicle in reticular dermis from stratified squamous epithelial cells filled with keratin, and also surrounded by keratin.
Hair ‘standing up’ is controlled by involuntary smooth muscle found in papillary dermis called Arrector Pili Muscle
What are the 3 types and body locations of glands?
Holocrine gland- face, chest, and back
Apocrine Gland- Armpits, groin, and around nipples
Eccrine (Merocrine) Gland- Everywhere else in the body, concentrated in palms, soles of the feet
How do the glands release their content?
Holocrine- releases by disintegration the whole cell to release sebum (more lipid based secretion)
Apocrine- release secretion from the apex of the cell, the top of the cell breaks off to release proteins, lipids, and steroids into the hair follicle
Merocrine- Watery sweat secretions released by exocytosis (budding off of cells membrane with contents from inside the cell)
How are the 3 main classifications of glands utilized throughout the body?
Holocrine- slows bacterial growth, lubricates skin
Apocrine- function after puberty, release pheromones, called emotional sweating
Merocrine- Evaporative cooling, eliminate waste products, release lysozymes (will kills bacteria), and antibodies (help tag bacteria that could harm skin)
What are the formal names for pain and temperature sensing?
Pain- Nociception
Temperature- Thermoception
What molecules are found in Keratohyalin Granules?
Profiliggran- Converted to Filiggran which aggregates keratin
Involucrin- Helps form the cell-envelope protecting cells in corneum
Loricrin- cross-linked with Involucrin
What is the location and function of Merkel Cells?
Epidermis (mostly Basale)
Sensation
What is the location and function of Langerhan Cells?
Epidermis (in Spinosum and upwards)
Immune Cell- Antigen Presentation to Phagocytes
What is the location and function of Melanocytes?
Basale layer of Epidermis
Produce melanin within melanosomes, and passes complex out to surrounding cells- forms cap over nucleus protecting from radiation
What is the location and function of Lamellar Granules?
Found in Keratinocytes in Upper Spinosum and Granulosum layer of epidermis, extruding into intercellular space
Release lipids forming water-resistance, aiding in water retention
What is the location and function of Stem cells (in relation to skin)?
Epidermal Basale Layer
Replenish cells within epidermis
What junctions are found in the epidermis?
Hemidesmosomes- between stratum basale and basement membrane, attaching epidermis to dermis
Desmosomes- primarily in stratum spinosum.
Tight Junctions- within the stratum granulosum
What are the 3 types of Cellular Junctions?
Anchoring, GAP/communicating, Tight/Occluding
What are different types of anchoring junctions (include cytoskeleton, transmembrane link, and cellular attachment).
Desmosomes- Intermediate Filament, Cadheren, Cell-Cell
Hemidesmosomes- Intermediate Filament, Integrin, ECM
Adherens- Actin, and Cadherin (cell-cell)
Focal Adhesions- Actin and Integrins (cell-ECM)
What are the different roles of the 3 anchoring junctions within the skin?
Desmosomes- Epidermal integrity between keratinocytes
Hemidesmosomes- Bind stratum basale of epidermis to dermis
Adherens- Cadherens hold epithelial cells to each other
What cells are found in the dermis?
Mostly Fibroblast
Acellular - type 1 collagen, elastin, ground substance molecules.
What forms a GAP/communicating junction?
6 Connexins bind together in cell forming Connexon.
Connexon from one cell binds to connexon of another, forming a tunnel.
How do anchoring junctions attach two cells?
The transmembrane link binds/anchors to the cytoskeleton within the cell, and has an arm which extends to bind another arm of a fellow anchoring junction, creating a bridge.
What forms a tight/occluding junction?
Many different transmembrane proteins (~40) bind to actin within cell, and to corresponding protein on neighbouring cell.
What are the 3 main proteins involved in tight junctions?
Occludin
Claudin
Junction Adhesion Molecules
What are the types of cytoskeleton and what are they composed of?
Microtubule- alpha and beta tubulin dimers
Intermediate Filament- keratin, vimentin, desmin, lamins
Microfilament- actin
What are the motor proteins in actin and microtubules?
Actin - myosin
Microtubules- dynein and kinesin
What do fibroblasts within the dermis do?
Wound healing (collagen type 1, 3) Synthesis (collagen, elastin, ECM components) Growth Factor (FGF-keratinocyte migration)
What do dermal dendritic cells do?
Phagocytosis
Antigen Presentation
What do Mast Cells in the dermis do?
Produce inflammatory mediators (histamine, heparin)
Release chemotactic factors for neutrophils and eosinophils
What are the extra-cellular molecules of the dermis and their function?
Elastin- stretch and coil to allow for movement
Collagen Type 1- provide strength via fibrous proteins
Glycosaminoglycans - Hydration
Proteoglycans- Hydration
In the process of inflammation in wound healing, what is the order of cellular recruitment if the dermal layer is broken?
- Macrophages/Monocytes in area release cytokines (TNF, IL-1,6,8,12) which recruit Neutrophils
- NEUTROPHILS phagocytose bacteria/dead cells
- Neutrophils recruit more MACROPHAGES which recruit FIBROBLASTS
____ stimulates fribroblasts to produce ______ which initially holds wounds together.
Platelet-Derived Growth Factor
Collagen Type 3
Granulation Tissue consists of…?
Fibroblasts, type 3 collagen, immune cells (macrophages/ monocytes/ neutrophils/ lymphocytes (Abs)), ECM
What are the stages of wound healing?
- Haemostasis
- Inflammation
- Proliferation
- Maturation
What are some key cytokines involved in wound healing, as well as their role(s)?
TNF, IL-1,6,8,12- Released by Macrophages, promote inflammation
Platelet-Derived Growth Factor- Released by activated platelets, stimulates fibroblasts to produce collagen 3, promotes matrix formation
Vascular Endothelial Growth Factor- Released by Macrophages, promotes angiogenesis
Epidermal Growth Factor- Promotes keratinocyte proliferation
Fibroblast Growth Factor- Released by fibroblasts, promote keratinocyte/fibroblast proliferation, and keratinocyte migration
What tissue matures into scar tissue?
Granulation tissue
What can slow wound healing?
Diabetes- can impede circulation
Alcohol/Smoking- impact oxidation levels, slowing vascularization
What is a myofibroblast?
A chain of fibroblasts that pull wound ends together.
How is plasminogen utilized in the wound healing process?
It’s converted to active plasmin which breaks down weak fibrin stands within blood clots (fibrinolysis) allowing for stronger support (collagen) to be put in place.
What are the 4 types of tissue, with their function?
Connective- Support and protect
Muscle- Smooth, Cardiac and skeletal
Epithelial- line our surfaces
Nervous- contain neurons/nerves in ECM
How can tissue be categorized?
Stroma- scaffolding and nutrition
parenchyma- working tissue
What are the common terminology used to describe types of epithelial cells?
Simple vs Stratified vs Pseudostratified - 1 vs many layers vs looks like many layers, but only 1 true layer
Squamous- flat
Cuboidal- cube
Columnar- tall
