deck_705737 Flashcards
• Clathrin coating
– regulated secretion or signal mediated intracellular transport
• COP 1
– recycling or retrograde movement
• COP 2
– constitutive secretion or anterograde movement
Intermediate filaments
- Toughest of 3 types, great tensile strengtho Associated with desmosomes and hemidesmosomesnuclear lamina - underlie and strengthen the nuclear envelope
Microtubules
- Responsible for organizing cell interior and determining polarity- Motor proteins (MAP’s)o Kinesins – movement and transport to + endo Dynein – movement and transport to – end- prefers addition at + end (Beta tubulin end) and disassembly at – end - MT’s form cilia and flagellao Core is MT bundles called Axonemes (“9+2”)
Microfilaments
(actin filaments)-Unstable and continually assemble and disassembleo Assembly can occur at either end, but preferred and faster at + endo Assembly requires ATP most abundant - cell cortexMotors:o Myosin I: o Myosin II: forms a filament – in muscle cells particularlyo Myosin motors always walk toward + end (membrane)
CNS
brain and spinal cord- Nuclei: collection of cell bodies- Tracts: collection of axons- White Matter: larger tracts that are myelinated- Grey Matter: smaller tracts that are unmyelinated- Neurons: functional unit- Supporting cells: neuroglia (glia)
PNS:
- Ganglia: collection of nerve cell bodies- Nerves: collection of axons - Specialized motor and sensory nerve endings- Neurons: schwann cells- Supporting cells: satellite cells (around ganglion cell bodies)
Nissl bodies
- in Cell BodyRER – divided by neurofilaments into clumps Nissl Bodies extend into proximal part of dendrites
- Dendrites
receives input and stimuli -afferent process of Neurono unmyelinated Structure maintained by ACTINo Many per cell
- Axons
impulse conduction/sendingo Efferent process of neuronHillock = no organelles, just microtubules1/cell
- Supporting Cells Of CNS
Neuroglia (glia): 3 types• Astrocytes – largest and most numerous o Provide physical and metabolic support for neurons of CNS Feet provide coverings for cell bodiesOligodendrocytes – produce CNS myelinMicroglia – phagocytes of the CNS
Supporting Cells of PNS
Schwann Cells – provide myelinated covering over axons Satellite Cells – surround ganglion cell bodies
Node Ranvier
small unmyelinated areas b/w schwann cells or oligodendrocytes • Allow salutatory conduction to occur… internodal segments- faster conduction
acetylcholine neurotransmitter for…
myoneural junction, presynaptic symp, pre and post synaptic parasymp.
Nissl bodies
granular, basophilic bodies composed of polysomes and RER… in neuron cell body
zonula occludens
tight junctiondiffusion barrier, at apical pole Maintains PM domains, prevents leakage of molecules b/n cells Does NOT mean held together tightly, means water tight junction
zonula adherens
mechanical stability Interacts w/ actin (a MF) in cytoskeleton of adjacent cells Signal transduction, cell-to-cell recognition in differentiatio
o Desmosome
joins IFs (keratin)binds cell-to-cell on lateral domain, cadherins bind keratin
gap junctions
chemical & electrical coupling
o Hemidesmosome
= static link, binds cell to ECM (basal lamina) on basal domain Integrin binds to collagen IV & keratin
o Focal adhesions
= dynamic link b/n cytoskeleton & ECM on basal domain Integrin binds to fibronectin & actin = MFs (IC), in migrating epithelial cells
o Skeletal Muscle
Multiple peripheral nuclei
Sarcoplasmic reticulum
• Stores Ca in skeletal
skeletal Thin filaments
actin from Z disk 2 chains of F-actin + tropomyosin + Troponin
skeletal Thick filaments
myosin II that interdigitates with thin filamentso 2 heavy chains and 2 light chainso Titan – anchors myosin to z disk
skeletal muscle Contraction
Width of I band and H band reduceA band is unchangedAll or None Strength of contractions = # of fibers contractedImpulses at sarcolemma transmitted via T tubules – transferred to Terminal cisternae of SR – Ca is released to cytosol – Ca is bound by TnC – troponin conformational change (exposing myosin binding site of actin) – ATP on S1 of myosin is hydrolyzed to ADP + Pi – S1 myosin binds actin (when Pi released bind is stronger) – as ADP is released… powerstroke
smooth muscle contraction
Ca enters cell via caveolae from extracellular space Ca binds calmodulin Ca-calmodulin activates myosin light chain kinase Phosphorylates and changes conformation of myosin light chain… exposes actin binding site Actin binds mysosin… contraction Decreased Ca levels stops contraction
Cap Z & -actinin
prevent polymerization @(+) end
Tropomodulin
prevents F-actin depolymerization @(-) end
Nebulin
surrounds actin, helps anchor to Z disc & hold in arrays
• Collagen I –
CT of skin, tendon, bone, dentin
Collagen II
cartilage, vitreous humor
Collagen III –
loose CT, smooth muscle, blood vessels
Collagen IV
– basal lamina
Ground substance of CT
non fibrous components of ECMGlycosaminoglycans (GAGs; mucopolysaccharides) – unbranched polysaccharides w/ repeating disaccharide unit• Negatively ChargedGlycoprotein – any protein w/ a glycosaminoglycan linked to it• Adhesive (laminin, fibronectin) – connect cells to fibrous ECM
• Fibroblast/fibrocytes
in CT - resident cell– responsible for synthesis of all extracellular components
Hyaline Cartilage
-most abundant, found on articular surfaces of joints and in costal, thyroid and nasal cartilages- semi –transparent opalescent blue color• Aggrecan – main PG in hyaline cartilage
• Perichondrium:
dense irregular CT tissue surrounding hyaline cartilageSource of cells IN growing cartilage 1. Outer Layer – Fibroblasts and Conventional CT 2. Inner Layer – Chondroblasts (differentiating cells that release cartilage matrix)
Interstitial growth
chondrocytes w/in tissue divide and lay down new matrix from w/in
Appositional growth
stem cells in perichondrium give rise to chondroblasts, which lay down new matrix on the surface
Elastic Cartilage
mostly in ear, epiglottis etc• Usually has a higher density of cells• Looks like Hyaline cartilage, but has more elastic tissue
Fibrocartilage
In anulos fibrosus of spine, pubic symphosis, knee joint• Usually b/w 2 pieces of hyaline cartilage running into bone• b/w areas subject to force
• Vessel Tissue Layers
Tunica Intima = endothelium - Fibroblasts, Collagen I fibersTunica Media = circularly arranged SMCsTunica Adventitia = elastic & Collagen I fibers- Reticular (Collagen III)
• Artery Types
- Elastic (conducting) = high P, aorta, pulmonary aa.Intima = relatively thick Media = bulk of wall Adventitia = thin- Muscular (distributing) = downstream of elastic aaIntima = relatively thinMedia = very thickmostly SMAdventitia = 1/3-2/3 media thickness- Arteriolesw/in organs or tissuesIntima = very thin Adventitia = very thinMedia = 1-5 layers SM
