Flashcards in Skin Deck (148):
What are the three components of all connective tissues?
Cells, fibers, ground substance
Connective tissue is derived from....
Create and repair ECM
Produce hyaluronan: space filling, lubrication, water homeostasis, creation of matrix that facilitates migration of cells through ECM
Special CT cell that has contractile properties
1.) Long spindle shaped cells
2.) round or spindle shaped nuclei (round = active, spindle = inactive); 3.) pale cytoplasm
4.) contain rER and Golgi
Store energy as TGs and produce leptin
Cells that migrate into CT and stay
Macrophages, mast cells, and plasma cells
Cells that wander in and out of CT; B and T lymphocytes, eosinophils, neutrophils, monocytes
1.) Derived from monocytes found in circulating blood (leave circulation and develop into macrophages)
3.) named differently based on location in which they're found (Kupffer, osteoclasts, microglial cells, Langerhans)
Mast cell characteristics
1.) derived from bone marrow
2.) inflammatory response
3.) oval/round cells with large basophilic granules in cytoplasm
4.) granules contain: heparin, histamines, chemotatic mediators
Plasma cell characteristics
1.) Derived from B lymphocytes
2.) produce and release antigen specific antibodies
3.) eccentric nucleus, clock face chromatin, basophilic cytoplasm (rER), Golgi
Fibers, ground substance, and extracellular fluid
Type I collagen fibers...
3 collagen polypeptide alpha chains>>collagen molecules>>fibrils>>fibers (parallel fibrils)
Collagen precursor proteins (called _______) are created in fibroblast _______ and assembled in _______
Tropocollagen; cytoplasm; EC space
I: most common
IV: basal lamina of epithelial cells
VII: anchors basement membrane of epithelial cells
Elastic fibers 1.) made by, 2.) composed of, 3.) function in
1.) fibroblasts, chondrocytes, and smooth muscle cells)
2.) elastin and fibrillin
3.) stretch and recoil
Fibrillin serve as _____ for longer ______ molecules
How do elastic fibers provide so much elasticity?
Fibrillin and elastin molecules branch three-dimensionally and surround nearby collagen fibers to provide a greater degree of elasticity; ligaments have high density to allow them to snap back
Reticular fibers 1.) made by and 2.) function to
1.) fibroblasts, Schwann cells, smooth muscle cells
2.) create frame meshwork of dense organs to support functional cells within (type I collagen takes up a lot of space; reticular fibers organize cells and take up less space)
CT cells and some epithelial cells release these to break fibers into smaller chunks that can then be phagocytosed by macrophages, degraded by lysosomal enzymes, and removed
Ground substance allows diffusion of _______ but not ________
water soluble molecules; large macromolecules and bacteria
In ground substance, _______ release charged substances into the ______ to create a ________ environment. This promotes ______ to and from cells.
Fibroblasts; ECM; hydrophilic; diffusion
Glycoproteins in ground substance help to...
Anchor cells to ECM
Glycosaminoglycans (GAGs) in ground substance are.....
The most plentiful and are negatively charged, attracting water
Proteoglycans are 1.) created by... 2.) and provide
1.) arranging GAGs like bristles stemming from a core protein
2.) Stability to the extracellular space while allowing diffusion to occur
Structural tissues of organs (scaffolding)
Functional parts of an organ
Types of CT
1.) Embryonic (mesenchymal, mucous)
2.) CT Proper (dense reg and irreg, loose)
3.) specialized (adipose, supporting, blood, lymph)
Composition of mesenchymal CT
Ground substance (semi-fluid, gelatinous)>>cells (mesenchymal)>fibers (type III); allows for rapid growth without constricting the fetus
Location of mesenchymal CT
Embryo and fetus
Location of mucous CT
Umbilical cord (Wharton Jelly), subdermal CT of fetus, dental pulp of developing teeth
Composition of mucous CT
Ground substance (semi-fluid, gelatinous)>>cells (stellate fibroblasts)>fibers (few type I)
Location of dense regular CT
Collagenous: tendons, ligaments, and aponeuroses
Elastic: some vertebral ligaments and suspensory ligaments of penis
Composition of dense regular connective tissue
Fibers (mostly type I or elastic - fibers in one direction)>>>cells (fibroblasts)>ground substance (very little)
Locations of dense irregular CT
Dermis, submucosa of organs, scars, and organ capsules
Composition of dense irregular CT
Fibers (mostly type I with some elastic and reticular)>>cells (mostly fibroblasts with some macrophages and mast cells)>ground substance (very little)
Location of reticular tissue
Dense organs (liver, kidney, spleen, bone marrow, lymph nodes)
Composition of reticular tissue
Fibers (type III)>cells (reticulocytes, fibroblasts)>ground substance (very little)
Location of oose (areolar) CT
Lamina propria: GI and Resp
Superficial fascia and invests in neurovascular bundles and around glands
Composition of loose CT
Ground substance (watery tissue)>>cells (fibroblasts with many transient immune cells)>fibers (very few)
Composition of loose CT allows for _______ __________ of nutrients and other substances. Because these regions are in close contact with _________ environment, there are many ________ cells that move into the area to interact with _______ ________.
Rapid diffusion; external; transient; invading pathogens
Unilocular (white) adipose
Distributed throughout body but mostly around neurovascular bundles, mesenteries, and hypodermis
Storage of fat, thermal insulation, shock absoption
Composition of adipose
cells>fibers>ground substance (very very little)
Multilocular (brown) adipose
Found in neonate (and upper back of adults who endure low temps over prolonged periods); many droplets of TGs in cell cytoplasm vs single droplet in white fat; heat-generating (high content of mitochondria that release ATP)
Function of epithelial tissue
Movement of material along surface
Protection from mechanical abrasion, chemicals, and pathogens
Reception of sensory signals
Reduction of friction
Secreting enzymes, hormones, lubricants, and other products
Synthesis of proteins, enzymes, mucins, hormones, and other substances
What characteristics make epithelium different from other tissues?
Polarity, cell arrangement, avascular, and basement membrane
Basement membrane is a thin ______ on the basal surface that binds ________ ______ to underlying tissues. It does not contain ______ or ______.
ECM; epithelial cells; cells; blood supply
Layers of basement membrane from top to bottom...
Lamina lucida>>lamina densa>>lamina reticularis
Basal lamina is made up of what 2 layers? What produces the basal lamina? What type of collagen is it?
Lamina lucida and lamina densa; epithelial cells; type IV
Lamina reticularis is type ____ collagen and comes from ______ cells
Anchoring fibrils within the lamina reticularis are type ______ collagen
Metaplasia is a response to ________ ________ or _______.
chronic irritation; damage
Increase surface area for absorption and secretion
Facilitate absorption in male genital ducts, sensory mechanoreceptors in ear
Motile cilia function
Transport substances along epithelial surface
Primary cilia function
Generate and transmit signals from outside to inside the cell
Nodal cilia function
Development of left and right asymmetry or internal organs
Pseudostratified columnar epithelium located in....
Transitional epithelium located in....
Bladder and ureters
Keratinization is a process by which ________ _____ produce the protein _______. It provides ________ and _______. It is found in _______, _______, and ______.
epithelial cells; keratin; waterproofing; protection; skin; hair; nails
Goblet cells are ________ glands that produce ______.
Endothelium are classified as _______ ________ epithelium. They are found lining the inside or _________ and _________.
simple squamous; blood vessels; heart
Mesothelium is classified as ______ _______ epithelium. It is found lining ______ ________.
simple squamous; body cavities
Glandular epithelium characteristics
Secretory cells that arise as ingrowths of the epithelium; typically in single layers or clusters; cuboid or columnar
Function and location of simple squamous epithelium
Diffusion, filtration; capillaries, alveoli, glomerulus
Function and location of simple cuboidal
Secretion, absorption; ovaries, nephrons, renal tubules
Function and location of simple columnar
Secretion, absorption; GI, repro, resp
Function and location of stratified squamous
Protection; tongue, hard palate, esophagus, anus
Function and location of stratified cuboidal
Secretion, absorption; glands
Function and location of stratified columnar
Protection; conjuctiva, resp
Function and location of pseudostratified columnar
Movement; trachea and upper resp
Function and location of transitional epithelium
Stretch; bladder and ureters
1.) Structural function?
3.) Energy for polymerization
5.) actin, myosin
1.) Structural function?
3.) Energy for polymerization
1.) Structural function?
3.) Energy for polymerization
5.) Keratins, nuclear lamins, etc
Cytoskeletal classes have both ________ and _______ function. __________ _________ do not have ________ function.
Structural; motile; intermediate filaments; motile
Bind filaments together
Filaments cross-linked into 3D, criss-crossed meshworks (resist stretching and compression)
Filaments cross-linked in parallel to form fibers that resist stretching
Anchoring by junctions serve to anchor the __________, attach cells to the ________ ________ or to _____ _______, or allow cells to interact with _________.
cytoskeleton; basal lamina; each other; ECM
Motility mechanisms include the use of _______ ______ an example of which is ________ _______ in muscle contraction and ____________________ an example of which is segregation of chromatids during anaphase.
motor proteins; sliding filaments (microfilaments); polymerization-depolymerization (microtubules)
G actin subunits polymerizing into F actin filaments is driven by __________.
Actin is ________ because the plus sides of G actin subunits point to one end and the minus to the other end of the F actin filaments
___________ and _______ bind F actin and interact with ______ heads to mediate _______ _________ _________.
Troponin; tropomyosin; myosin; sliding filament contraction
Actin cross-linking protein that forms networks in erythrocytes
Cross-linking protein that forms striated muscle network
Duchenne muscular dystrophy is a mutation of the X linked _________ gene
________ are finger-like projections of the plasma membrane that increase surface area for _________ and are supported by internal ______ bundles. They are present in ____ cells but most abundant on the brush border of ________ epithelium.
Microvilli; absorption; actin; all; intestinal
These microfilaments serve as motor proteins for actin and some serve a structural role
Myosin heavy chains are composed of two _______ and two globular ________. The _____ coil around each other to form dimers which requires ___ __________.
tails; heads; tails; ATP hydrolysis
Myosin light chains bind the _______ of each head. They serve as regulatory factors controlling __________ of the globular heads.
The myosin tetramers associate with the ______ extending into the periphery, and the ______ pointing inward making the myosin microfilament _______. The heads provide the _______ force.
heads; tails; polar; motor
Sliding filament model
ATP hydrolysis activates a conformational change of the myosin heads. These contractions cause myosin to crawl along actin. Hence, microfilaments slide past each other to induce contraction.
Examples of microfilament mediated motility
Intracellular membrane trafficking (directed along actomyosin or microtubule filaments), muscle (actomyosin organized into sarcomeres), contractile ring of cytokinesis (actomyosin ring that pinches the cell in two), amoeboid motion (pseudopodia), stress fibers (long bundles of microfilaments that lie along the basal surface of fibroblast that provide tension across a surface
Chemicals that interfere with __________ assembly preferentially attack ________ cells because these rapidly dividing cells require microtubules for cell cycle progression. This occurs drugs during ___________ treatment.
microtubular; tumor; chemotherapy
microtubular associated protein (crosslinking protein that forms networks)
__________ is a motor protein that moves ________, cilia, ________, and mitotic chromosomes associating with the mitotic ______. It also moves ______, ________, and ________ ______ up and down an axon.
Dynein; flagella; cytosolic vesicles; spindle; vesicles; organelles; cytoskeletal fragments
______ is a motor protein that moves _______ _______ and ______ _______ associating with the mitotic spindle.
Kinesin; cytosolic vesicles; mitotic chromosomes
Examples of microtubular mediated motility
Intracellular membrane trafficking, mitotic apparatus, and axonal transport (factors depleted by signal transduction have to be replenished)
Intermediate filament _______ are used to identify the origin of tumor cells. Antibodies target the _______ and ______ of IFs due to their uniqueness. If the ______ were tagged, every IF would be bound to antibody.
Antibodies; heads; tails; core
Speicific IFAP that anchors desmin to the plasma membrane as well as spectrin to the band 3 anion transporter of erythrocytes
Meshwork of intermediate filaments on the nucleoplasmic face of the nuclear envelope
Anchored to the inner membrane of the nucleus by an isoprenyl side group
All 3 forms of lamins consist of _______ ________ and alpha helical ______ and _____.
globular heads; cores; tails
During prophase, nuclear lamins are _________ by MPF. This causes them to _______, inducing nuclear membrane _______. During ________ the nucleus reforms because the lamins are _______, allowing their crisscrossed network to associate.
phosphorylated; depolymerize; breakdown; telophase; dephosphorylated
Lamins A and C are released into the _______, while Lamin B remains bound to _____.
_________ force collagen alpha chains into left-handed helices due to ________ of the backbone, while _______ residues (every third amino acid) allows the helix to be left-handed due to its small _____ ______ (larger side chains would produce _____ _______).
Prolines; contortion; glycine; side chains; stearic hindrance
_______ groups are bound to numerous prolines and lysines. They increase the ___-________ ________ of the collagen helices.
Hydroxyl; non-covalent stability
Why does dietary deficiency of vitamin C result in scurvy?
The enzyme that produces hydroxyproline requires vitamin C as a cofactor
Enzyme that drives cross-linking between lysines near tropocollagen termini
Procollagen spontaneously assembles into triple helices>>post-translational modification in ER>>exocytosis and cleaving of terminal regions (now tropocollagen)>>crosslinkage of tropocollagen to form fibrils>>aggregation into collagen fibers
Excessive collagen production
Lack of hydroxyproline residues due to dietary deficiency of vitamin C. Symptoms include weak and malformed bones, teeth, skin, blood vessel walls, and dermal hemorrhaging.
Mutations resulting in underproduction or incomplete processing of different collagens. Symptoms range from loose skin and joints, to neonatal death. Contortionists often have this disorder.
Mutations of type I collagen, which interfere with triple helix assembly (e.g. substitution of glycines residues with bulkier amino acids). The most severe mutations result in lethality in utero or soon after birth. Less severe mutations produce brittle bones. Note, due to the numerous fractures observed in children with this disorder, it can easily be misdiagnosed as child abuse.
Mutation of fibrillin gene
Functions of skin
Protection (barrier and immunologic)
Homeostasis (waterproof and temp regulation)
Metabolic (endocrine and excretion)
Most abundant cell in epidermis; functions: produce keratins (structural protein), form epidermal water barrier; stem cells on basement membrane; differentiate as they migrate to surface
Dendritic cells of the epidermis (originate in bone marrow and travel to CT in dermis and migrate up); Birbeck granules; phagocytize foreign structures in epidermis and present T lymphocytes in regional lymph nodes; not readily visible with H&E (clear cells)
Derived from neural crest; location: basale; produce melanosomes (transferred into keratinocytes)
What mechanisms are involved with natural skin color variation?
Rate at which melanin granules are produced and degraded (impacted by both intrinsic and extrinsic factors)
One melanocyte and its associated keratinocytes
Processes involved with tanning of the skin?
UV light darkens existing melanin AND increases the rate of melanin synthesis
Function as mechanoreceptors; most abundant in areas of high tactile sensitivity
Thick vs thin skin
Thick: palms, soles; 5 layers; lacks hair follicles
Thin: everywhere else; 3 well-defined layers
Single layer of cuboidal/columnar cells; new cells (keratinocytes) undergoing mitosis
Keratinocytes appear prickly (desmosomes); keratins being synthesized by free ribosomes (more superficial gets stained darker due to increased assembly of intermediate filaments)
Intermediate filaments composed of keratin and most visible in spinosum; converge at desmosomes; provide support for areas under constant friction and pressure (thicker spinosum)
1-3 layers of keratinocytes with granular appearance; cytoplasm being filled with dark keratohyalin granules; initiates promotion of keratin filaments into tonofibrils, converting granular cells into cornified cells (keratinization); cells in superficial layers undergoing apoptosis
only present in thick; translucent layer of keratinocytes; nuclei and organelles lost and replaced by densely packed keratin filaments
dead, keratinized cells; protection against abrasion
Keratinocytes produce these lipid-rich membrane coated granules; secreted by exocytosis into spece between granulosum and corneum for water barrier
Cells in dermis
Fibroblasts, macrophages, mast cells, B lymphocytes (skin homeostasis and immunosurveillance)
Layers of dermis
Papillary (loose CT)
Reticular (into hypodermis - dense irregular CT)
Structures in dermis
Meissner (papillae - light touch), Pacinian (reticular and hypodermis; onion; transmit vibration and pressure
Secrete product via exocytosis (form and packaged into Golgi>>plasma membrane fusion)
Products are pinched off, along with apical portion
Products accumulate in cell, which undergoes programmed cell death and discharges material
Eccrine sweat gland
Merocrine secretion; throughout body; watery; clear cells - produce sweat, dark cells - filled with granules with antibacterial properties, myoepithelial cells - contractile located near basal lamina of secretory portion of gland; duct extends to skin surface; thermoregulation
Apocrine sweat gland
Merocrine secretion; axillary, areola, anal; development dependent on sex hormones; ducts open to follicles; lumens much larger than eccrine glands
Produce and excrete sebum (released via holocrine secretion)
Arrector pili muscle, hair follicle, sebaceous gland
Capillary loops in dermal papillae; superficial plexus right underneath (allows blood to come up if you're hot); communicating vessels connecting the plexi; deep plexus (allows blood to move down if you need to warm up)
Merkel - mechanoreceptors in basale
Free nerve endings - terminate in granulosum; most abundant; sense touch and temp
Pacinian - pressure and vibration in dermis and hypodermis
Meissner's - light touch in dermis