New Cell physio Flashcards
What is a molar solution ?
when 1 mole of a solute is dissolved in 1L of solvent
What is a molal solution ?
concnetration of a substance based on the mass of the substance in a mass of solvent
What are the constituents of the ECF ?
25% plasma
75% ISF
What is ion movement influenced by ?
electrochemical gradients
made by active transport
What affects membrane permeability ?
composition of the bilayer
lipophobic/hydrophobic
size and shape of the molecules
What is secondary active transport ?
uses the concentration gradient of another molecule to push molecules against the concentration gradient - Sodium/glucose co transporter
What is antiport?
2 different molecules being transported
in different directions
Describe receptor mediated endocytosis ?
binding of a ligand to a receptor
migration of the ligand receptor complex to the clathrin coated pits
invagination in the membrane
enters endosome- goes to a lysosome
What is the resting membrane potential of excitbable cells ?
-60 to -70 mV
What is hyperpolarisation due to ?
increased activity of K channels
When does depolarisation take place ?
vm < -50
When does hyperpolarisation take place ?
Vm> -70
What are anchoring junctions between
cell to cell
cell to ECM - use integrin
What do adherens attach to ?
actin
What do desmosomes attach to ?
intermediate filaments
Is smooth muscle striated ?
no
What do T-tubules allow for ?
action potentials to bypass the cytosol
move rapidly from the cell surface to the interior
What is the A-band ?
full length of the thick filament
What is the H-zone ?
central region of the A-band- lighter as no overlap
What is not present in smooth muscle ?
troponin
What is the pattern of myosin head movement ?
myosin head binds to actin - ADP and Pi on surface powerstroke ADP and Pi Dissociate ATP binds head detaches hydrolysis- recocking binds
What is the mechanism of cardiac muscle contraction ?
Sodium ions enter Alters the DHP receptor activates RyR receptor calcium enters from SERCA stimualtion of contractile apparatus
What is the mechanism of cardiac muscle relaxation ?
calcium uptake into SERCA Na/Ca exchanger Na/K ATPase activation of potassium channels calcium no longer binds to troponin- tropomyosin recovers binding site
Smooth muscle contraction ?
calcium binds to calmodulin
calcium-calmodulin complex activates MLCK
Phosphorylate myosin head
cross bridges
