Introduction to Physio Flashcards
homeostasis
constant internal environment through system cooperation
- regulated by body systems
- constant ph, electrolytes, wastes, termperature
- each cell experiences little variation
dynamic steady state
matter and energy flow in and out of system while the system itself stays constant
- open state
- NOT equilibrium
flow of negative feedback loop
variable-sensor-afferent pathway-integrator (compares actual value to set value)-set point-efferent pathway-effector
tonic control
control more or less of one effector (car accelerator)
antagonistic control
controls opposites (hot+cold, etc). accelerator+ brake
sensitivity
how good is sensor for feedback
gain
how good is the effector
lag time
time to complete feedback loop
-slower if part of cycle is defective
feed forward
brain-stomach-brain=hungry
- see food, get hungry
- food goes down, systems prepare for food
positive feedback
continues same action
-heightened response, goes to some sort of endpoint
proteins in negative feedback loop
action molecules
- part that does action
- binds to something to do action on
ligand
binds to protein
ligand concentration
determines how often a ligand will go in and bind to a binding site on a protein
affinity
determine how long the ligand occupies the binding site, or when it will come out
3 things that affect the # of full binding sites
- number of binding sites
- concentration of ligand
- affinity
4 ways to cause molecular movement
- diffusion
- pressure
- voltage
- motor proteins
diffusion
molecules move from high concentration to low
-“unidirectional flux”
net flow
add the two vectors of diffusion (water and glucose for example) and if =0 then at equilibrium
entropy
diffusion is caused by a force, know because have to work against it
-equilibrium in diffusion represents a higher entropy state than a concentration gradient
osmosis
diffusion of water from higher [] to lower []
hydrostatic pressure
compartments with higher solute concentration have higher HP because water diffuses in
two forces that make water move
hydrostatic pressure
diffusion
-equilibrium can be achieved where hydrostatic pressure is equal and opposite diffusion force
how to determine diffusion force
measure hydrostatic pressure difference, diffusion is opposite
osmotic pressure
diffusional force, measured in pressure units, but not really pressure
-represents force of diffusion reported in units of pressure
higher osmotic pressure?
higher solute concentration, even tho lower h20
osmotic strength
- proportional to osmotic pressure
- dtermined by counting number of dissolved solute particles per liter of solution
- also known as OSMOLARITY
osmolarity
number of moles of solute per liter of solution
similar osmotic strength
100mM CaCl2 (breaks into 3x mM) and 300 mM glucose
isotonic
cell mOSM is equal to solution mOSM
hypertonic
cell has less osmolarity than solution (less particles)
-cell shrivels
hypotonic
higher osmolarity than solution
-cell bursts
facilitated diffusion
molecules need a special transport proetin to pass membrane
facilitated diffusion controlled by
- number of transporters
- concentration of solute
- affinity
channel vs carrier
passive diffusion
-channel, NA+ goes through, carrier for glucose
active transport (primary)
needs energy (ATP)
- pumps against gradient
- Na+ K+
active transport (secondary)
uses energy of molecules diffusing into cell to transport against gradient
-requires active transport to transport diffusing molecules out
epithelial transport
-ex small intestine
-sodium pumped to basal lateral side, through cells
-lumen side has a negative charge while the blood has a positive charge
-sodium (+) diffuses in, chloride follows because its negative
-blood becomes hypertonic, h20 naturally follows
only energy is in sodium potassium pump
-glucose pumped into cell, diffuses into blood
transcellular
-transport through both membranes
paracellular
transport through tight junctions
-“leaky epithelia”
intrinsic cell protein control
-control system based on intracellular conditions and/or concentrations of intracellular chemicals
extrinsic cell protein control
control system based on messages received from other cells
2 ways to control cell protein
- control number of each type of protein
2. control activity of existing proteins
central dogma of controlling type and number of proteins present
DNA-> transcription-> mRNA-> translation->protein-> degradation-> amino acids
-focus on control of transcription, but can use translation and degradation to control as well
transcription controlled by
activator
-repressor
-promotor
RNA polymerase
RNA polymerase
- binds to promotor, starts transcription
- change # polymerases, affinity for promotor
repressor
protein binds to repressor, inhibits transcription
-inducer can bind to it and stop repression
activator
causses more transcription of protein
inducer
allosteric modulator
- binds to repressor, reduces affinity for DNA, causes increased transcription
- binds to activator, increases affinity for DNA, increases transcription
covalent modification
- i.e. phosphorylation
- influences repressors and activators affinity for DNA binding
positive allosteric modulator
-activity increases when modulator binds
negative allosteric modulator
activity decreases when modulator binds
allosteric control
- ligand causes protein shape change
- modulator binds somewhere other than active site, changes activity of protein
phosphorylation
kinase
protein phosphatase
protein kinase
an enzyme that transfers a phosphate group to or from ATP. Protein kinase uses ATP to phosphorylate proteins
protein phosphatase
an enzyme that removes a phosphate group from a molecule. it DEphosphorylates proteins
cleavage
cutting the peptide chain activates some enzymes
zymogen
an inactive enzyme, awaiting activation by cleavage
negative regulation
controlling transcription
- increase modulator, no transcription
- decrease modulator, transcription
positive regulation
increase modulator, transcription
-decrease modulator, no transcription
