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66 Cards in this Set

  • Front
  • Back
What are muscle cells used for?
-generation of mechanical force and movement
What are nerve cells used for?
-rapid communication
What are connecting/supporting cells used for?
-structural integrity
What are epithelial cells used for?
-protection, selecticve secretion and absorption
How is tissue integrity maintained?
-by interconnection b/t ind. cells
-through gap juntions or tight junctions
What are gap junctions?
-pores within cell membrane that allow chemical movement between cells
What are tight junctions?
-area in cell membrane that seals off specific chemical movement b/t cells
Why are different fluid compartments kept separate within the body?
-b/c of physical barriers and at the expense of enegy
What is a phospholipid bilayer made of?
-hydrophilic head and a hydrophobic tail
-contains cholesterol anjd imbedded proteins (integral and peripheral)
What are the integral proteins in a cell membrane?
-(transmembrane) receptors,pores, ion channels, etc.
What are peripheral proteins in a cell membrane?
-enzymatic activities
What is the nucleus used for?
-to hold DNA, heredity
What is within the cytoplasm?
-cytosol and filaments
-membrane-bound organelles
-endoplasmic reticulum (smooth and rough)
-golgi apparatus
What is RNA interferance? How does is work? Clinical significance?
-silencing of mRNA
-RNA gets cleaved by an enzyme into siRNAs
-siRNA sep.s into single strands
-strands bind to mRNA to block translation
-can block production of single proteins related to specific diseases
How is energy used in cells?
-by catabolic processes such as oxidative phopsorylation and glycolysis
What is ATP?
-molcule that transfers energy for cell work
What is necrosis?
-a type of cell death related to cell injury
-necrotic cells swell, organelles deteriorate
-leads to cell rupture
-cell contents release digestive enzymes that damage nearby cells that result in an inflammation response
What is apoptosis?
-programmed cell death isuially related to tissue remodeling
-intestinal epithelium is relaced every 2-5 days
-cell shrinks and pulls away from nearby cells and generally does not induce an inflammation response
What is homeostasis?
-phsyiological system striving to maintain a constant internal environment
What does homeostasis involve?
-involves the maintenance of reasonable stable values for specific physiologic parameters over time
What is the set point of homeostasis?
is the value of a specific parameter that is physiologically controlled
-if the system is perturbed and the parameter changes, control mechanisms work to bring the value of the parameter back to a set point
What is negative feedback?
-homeostatic control systems that utilize negative feedback to maintain constant conditions
-act to negate change
What is positive feedback?
-initiating stimulus that produces more of the same
What is the pathway for reflexes wihin a homestatic control system?
-stimulus-> receptor (skin cells)-> integrating center (brain)-> effector (whatever does changes)
What is feedback gain?
-degree of effectivness of a system in maintaining constant conditions

GAIN= value with- value without (feedback)/ value with-control (set pt) value
What is diffusion?
-movement of molecules from one location to another as a consequence of their random thermal motion
What is passive diffusion?
-diffusion with no additional energy input
-movement from high to low concentration
What is diffusion equilibrium?
-movement is same in all directions, no further net movement
How is the rate of diffusion affected?
-increasing temp.
-decreasing molecular weight
-increasing concentration difference
-increasing pressure difference
-increasing electrical potential difference
What does diffusion time depend on?
-depends on diffusion rate and diffusion distance
What is simple diffusion?
-direct lipid solubility, movement through pores or open protein channels
What is faciliated diffusion?
-association with an integral protein, or carrier protein, that mediates or faciliates transfer across the lipid membrane
How is permeability affected within a cell during diffusion?
-thicker membrane= lower perm
-more soluible lipid= higher perm.
-more channels= higher perm.
-higher MW= lower perm
-greater resistance= lower perm
How do you calculate the permeability of a cell's membrane?
[(# of channels / unit area) x temp.)]/ (resistance x square root of MW)
How does the rate of diffusion increase within a cell?
- increase in concentration gradient
-increase in electrical potential difference
-increase in pressure (partial pressure=concentration)
What is the electrochemical gradient?
-concentration gradient+ electrical gradient
-may oppose each other or enhance each other
What is active transport?
-transport of chemicals in and out of cell with the required use of ATP to create energy for the mechanism to occur
What does ATPases or pumps do?
-primary transport process that directly hydrolyse ATP in the reaction that moves a substance across the membrane
-ex. Na+/K+ ATPase/pump
What do co-transporters or symports do?
-secondary transport process that moves 2 substances in the same direction
- energy is stored in concentration gradient that was established by a primary transport process
-ex. Na+-glucose transporter
What do counter-transporters/antiports do?
-secondary active process that moves 2 substances at the same time in opposite directions
-ex. Na+/H+ antiport transporter
What is primary active transport?
-ATP breakdown directly to drive movement
What type of transport is the sodium-potassium pump?
What type of transport is Ca2- ATPase?
What type of transport is the proton pump?
What type of pump is the H+-K+ ATPase?
What are the functions of the NA+-K+ pump?
-osmotic stability
-gradient for co-transport
How do you calculate the energy required against a concetration gradient?
-Energy= 1400log C1/C2
What is the secondary active transport?
-energy derived from energy stored in ionic concentration differences created by primary active transport
What si the order of rates for inter-membrane tranports of molecules?
-diffusion> faciliated diffusion< primary active transport< secondary active transport
What uses diffusion in the cell's membrane?
-leak (pores)
-gated channels
What uses faciliated diffusion in the cell's membrane?
-carrier proteins
What uses primary transports in cell membrane?
What uses secondary active transports in the cell's membrane?
What is phagocytosis?
-cell engulfs bacterium or other particle into phagosome
What is endocytosis?
-membrane surface indents and forms vesicles
-active process which can be nonselective (pinocytosis) or high selective
-receptor-mediated uses clarthrin-coated pits
What is exocytosis?
-fusion of vescile with cell membrane to release contents to extracellular side
What are leak channels?
-pores that allow specific ions to move across membrane
-not gated
-diffusion occurs
What is a ligand gated channel?
-binding of specific chem. (ligand) to membrane protein
-changes conformation transiently
-uses faciliated transport
ex. nicotinic receptors
What are voltage gated channels?
-change in charge changes confromation transiently to openj
-conducts muscle contraction
What are examples of stretch or pressure gated channels?
-ex. sensory receptors
What are examples of phopsylation-gated channels?
-ex. protein kinase A
-ex. calcium channels
What is a Na+ channel?
-.3 X.5 in diameter
-neg. charged
-allows Na to move down gradient (extra to intra)
-opposed by outward pump of K
-"voltage activated" (fast Na+ channel)
-has dual gates
What is a fast gate?
-closed when mem. is polarized, opens when depolarized
What is a slow gate?
-closed when mem is polarized, opens when depolarized
What are K+ channels?
-pores that leak K+ to move down gradient (intra to extra
-oppossed by action of Na+-K+ pump
-K+ ion more permeable, less hydrated, passes pores more easily
-single gate (rleative slow opening and closing)
-closed when polarized
What are calcium ion channels?
-"voltage gated" (slow Ca++-Na+ channel)
-found on plasma membrane of smooth and cardiac muscle
-permeable to Na+ ions
-slower act. than fast Na+ channel
-Ca++ and Na+ move down gradient into cell