Physiology Exam 3

juliaterese's version from 2015-04-16 17:15

Section 1

Question Answer
what is the basic energy dilemma?food intake is intermittent, glucose requirement (esp. for nervous system) is continuous
how is the basic energy dilemma solved?the body has a way to store and mobilize glucose to keep blood sugar stable
when glycogen stores can be used upafter a few hours of fasting
the process where new glucose molecules are synthesized from proteins and fatsgluconeogenesis
where gluconeogenesis is carried outliver
how is the body able to run glycolysis in reverse for gluconeogenesisenzymes

Section 2

Question Answer
three things that can happen to biomolecules inside cellsbroken down to release energy, used to synthesize other molecules, converted to energy storage molecules
2 energy storage moleculesglycogen, triglyceride
what is metabolic rate?amount of energy (heat + work) released per unit time
factors that influence metabolic ratemuscular activity, age, gender, body surface area, environmental temperature
examples of body's mechanical workuse of proteins to generate movement (muscles, cilia)
examples of body's chemical workformation of chemical bonds (anabolism)
examples of body's transport workmoving molecules across membranes (active transport, endo/exo cytosis)

Section 3

Question Answer
what is BMR?metabolic rate of someone who is awake, lying down, physically/mentally relaxed, fasted for 12 hours
what BMR is roughly equal torate of oxygen consumption
why oxygen consumption is a good indicator of metabolic rate?oxygen is needed as the final electron acceptor in ATP synthesis
formula for energy storedenergy input-energy output
formula for energy outputwork performed + heat released
positive energy balance 3-4 hours after a meal where energy is storedabsorptive state
negative energy balance between meals where energy is mobilized postabsorptive state
what state is glucose sparing?postabsorptive
what does it mean to be glucose sparing?most cells metabolize fats and proteins, save gluose for CNS

Section 4

Question Answer
normal percent body fat20-30
maximum percent body fat80
percent of total energy reserves that body fat is75-80
number of months you could live off of body fat stores2

Section 5

Question Answer
what regulates transitions between postabsorptive and absorptive states?hormones and endocrine system
main hormonal regulators of postabsorptive and absorptiveinsulin, glucagon, epinephrine
another name for epinephrineadrenaline
what epinephrine has the same function asglucagon

Section 6

Question Answer
hormone that promotes synthesis of energy storage moleculesinsulin
type of hormone insulin isanabolic
when release of insulin is increasedabsorptive state when blood glucose is high
when release of insulin is decreasedpostabsorptive state when blood glucose is low
where insulin is producedbeta cells in pancreatic islets of Langerhans
how insulin functionspromotes cellular uptake to lower blood sugar
how insulin functions in most tissuesincreased glucose uptake (except brain, liver, exercising muscle), increases AA uptake, increases protein synthesis, decreases protein breakdown
how insulin functions in adipose tissueincreases FA and triglyceride synthesis, decreases lypolysis
how insulin functions in the muscleincreases glycogen synthesis, decreases glycogenolysis
4 ways insulin functions in the liverincreases glycogen synthesis, decreases glycogenolysis, increases FA/triglyceride synthesis, decreases glyconeogenesis

Section 7

Question Answer
insulin sensitive glucose transport proteinGLUT4
effect of insulin on GLUT 4increases membrane expression and synthesis of the protein
antagonist to insulinglucagon
when glucagon is decreasedabsorptive state (glucose levels high)
when glucagon is increasedpost absorptive state (glucose levels are low)
where glucagon is producedalpha cells in pancreatic islets of Langerhan
6 actions of glucagon in liverincrease glycogenolysis, decrease glycogen synthesis, increase gluconeogenesis, increase ketone synthesis, increase protein breakdown, decrease protein synthesis
actions of glucogon in adipose tissueincrease lypolysis, decrease triglyceride synthesis

Section 8

Question Answer
fasting blood glucose that indicates hyperglycemia/DM>140mg/dL
fasting blood glucose that indicates hypoglycemia<60mg/dL
how epinephrine is madeas a product of the sympathetic nervous system
effect of epinephrine on other hormonessuppresses insulin, stimulates glucagon
processes promoted by epinephrinepost absorptive
function epinephrine is very important forfight/flight (adrenaline rush provides energy for running away)

Section 9

Question Answer
% americans who are diabetic8 (24M people)
number of people with prediabetes57M
percent of the world that is diabetic 7
ethnicities with highest rates of diabeteshispanics, african americans, native americans, alaskan natives
type of disease type I diabetes isautoimmune
what happens in type I diabetesimmune system destroys beta cells of pancreas --> loss of insulin secretion
causes of type I diabetespossibly genetic, maybe triggered by virus insertion into genes of insulin production
which has a larger genetic factor, type 1 or type 2?type 2

Section 10

Question Answer
3 acute effects of diabetesketoacidosis, hyperosmolar non-ketotic coma, hypoglycemic coma
decrease in blood pH due to buildup of acidic ketonesketoacidosis
how does decreased insulin lead to ketoacidosis?decreased insulin --> increased blood glucose --> ketones
why hyperglycemia causes increased urine outputblood sugar is filtered by kidneys, enters urine and draws water in (leads to dehydration)
how a hyperosmolar non-ketotic coma occursincreased urination and dehydration (usually elderly) --> decreased blood volume --> increased blood osmolarity --> coma and/or increased clotting
why a hyperosmolar non-ketotic coma predominates among the elderlythey don't monitor their glucose closely enough
accidental insulin overdose as part of diabetes treatmenthypoglycemic coma

Section 11

Question Answer
afferent informationinput information (to the brain)
somatic movementsvoluntary
autonomic movementsnon-voluntary
signal away from the brainefferents
efferent somatic transmissionmotor neurons to skeletal muscle
efferent autonomic transmissionneurons to cardiac muscle, smooth muscle, glands (sympathetic) / neurons to GI tract (parasympathetic/enteric)
somatic sensesskin, muscles, joints (pain) (afferent)
special senses hearing, vision, equilibrium, smell, taste (afferent)
visceral sensesstomach fullness, blood pressure, pH (afferent)

Section 12

Question Answer
close to dendrites/cell body of neighboring neuronaxon terminal
neurons that send signals to the brainafferent
neurons that send signals away from the brainefferent
neurons between efferent and afferent neuronsinterneurons
where cell bodies of the CNS are groupednuclei
where axons of the CNS are groupedbundles or commissures
where cell bodies are grouped in the PNSganglia
where axons are grouped in the PNSnerves

Section 13

Question Answer
non-neuronal nervous system cellsglial cells
glial cells whose function is maintenance of the extracellular environmentastrocytes
glial cells that line ventriclesependymal
glial cells responsible for immunitymicroglia
glial cells in myelin for CNSoligodendrocytes
glial cells in myelin for PNSSchwann cells
holes in the brainventricles
narrowing of capillaries to prevent entry of certain substances into the brainblood-brain barrier

Section 14

Question Answer
what does it mean to be excitable?have ion channels and can modify their membrane potentials
resistance and conductance of extra- and intra-cellular fluid (bc it is mostly water)low resistance, high conductance
resistance and conductance of membrane (bc it is lipid)high resistance, low conductance
what determines ion permeability across a membraneion channels present and whether they are open
2 factors that affect resting membrane potentialconcentration gradients of ions, relative permeability of ions
concentration of K+ in ICF v ECF140/4 mM
concentration of Na+ in ICF v ECF15/145 (mM)
ions that are permeable at restNa and K
of K and Na, which is more permeable?K
why a resting cell is permeable to K and Naleak channels
how many more times is K permeable than Na25
maintains concentration gradients and prevents leaking channels from leading to equilibriumNa+/K+ ATPase

Section 15

Question Answer
ionic currentthe actual movement of ions across the membrane
formula for ionic currentI ion = g ion (Vm-E ion) [ current=conductance x driving force]
formula for driving forcemembrane potential (Vm) - equilibrium potential (Eion)
cells that can change their Vmneurons
how neurons change their Vmgated ion channels

Section 16

Question Answer
small electrical signals that can be different in sizes and are sub-threshholdgraded potentials
when graded potentials get smaller in magnitudewith distance travelled
larger electrical signals (above threshhold) that are all the exact same size action potentials
electrical signals whose magnitude does not get smaller with distance travelledaction potentials
what a hyperpolarizing graded potential looks on a graphdips under
what a depolarizing graded potential looks like on a graph hump
a depolarization that brings the post-synaptic cell closer to thresholdEPSP (Excitatory Post-Synaptic Potential)
a hyperpolarization that pushes the post-synaptic cell further from thresholdIPSP (Inhibitory Post-Synaptic Potential)
potentials that can be summed togethergraded
threshold in most cells-55mV
how an action potential is generated from graded potentialstheir sums exceed threshold

Section 17

Question Answer
when one cell stimulates another cell twice before the first response has a chance to die down, and causes an action potentialtemporal summation
when 2 or more cells send simultaneous sub threshold stimuli to cell that together cause an action potentialspatial summation
occurs when a graded potential reaches thresholdaction potential
membrane potential when an action potential is generatedbriefly positive
duration of an action potentiala few miliseconds
what action in the cell causes an action potential to be generated?changes in permeability of Na and K bc voltage gated ion channels open/close

Section 18

Question Answer
phase 1 action potentialNa channel activation gates opening, more permeable to sodium
phase 2 of action potentialNa channel inactivation gates closing, K+ channel activation gates opening, more permeable to potassium
phase 3 of action potentialK channel activation gates closing, Na inactivation gates opening, Na activation gates closed
what happens in Na "closed but capable of opening" conformation?inactivation gate open, activation gate closed (door that is shut but not locked)
what happens in Na "open" conformation?inactivation and activation gates open (like an open door)
what happens in Na "closed and incapable of opening" conformationinactivation closed, activation open (like a door that is closed and locked)
possible conformations of Na gateclosed but capable of opening, closed and incapable of opening, open
what opens an activation gate?depolarization
which ion's activation gate is slower?K
which ion's inactivation gate is slower?K

Section 19

Question Answer
why aren't action potentials graded?in the rising phase, all channels open. that is maximum permeability.
why can't Vm equal or exceed Ena or Ek?because the cell is always permeable to both ions
period of time following an action potential in which no stimulus of any strength can generate another action potentialabsolute refractory period
what causes absolute refractory periodall Na channels are either in open or inactivated conformation. cells must be completely repolarized for Na inactivation gates to open again.
when in the action potential is the absolute refractory period?begins at threshold and ends at the end of phase 2
describe the gates in the rising and falling stages of the refractory periodphase 1 all Na are open, phase 2 inactivation gate closes on them all
period of time following an action potential in which another action potential can be generated but a much larger stimulus is neededrelative refractory period
when is the relative refractory period?phase 3
why you need a larger stimulus in refractory periodpotassium channels are open (hard to repolarize when the cell is losing so much potassium/positive charge), some sodium channels still inactivated (fewer channels to work with to repolarize the cell)
purpose of refractory periodsallow action potential to finish once it starts

Section 20

Question Answer
how our brain distinguishes weak from strong stimuli when all action potentials are the samefrequency coding (increasing or decreasing the frequency of action potentials)
how do action potentials travel across the cell in an unmyelinated axon?propagation, it gets recreated at each site down the axon (depolarization happens at each new site)
how do action potentials keep moving only forward down the axon?parts of the axon behind are in refractory
stretches of axon not covered by myelinnodes of ranvier
only part of a myelinated axon with ion channelsnodes of ranvier
why aren't there ion channels in the myelin?it is a glial cell and they don't have ion channels
why is a myelenated axon faster?only nodes of ranvier have to be repolarized
term for propagation of action potentials across myelinated axonssaltatory conduction
is gray matter myelinated or unmyelinated?unmyelinated
is white matter myelianted or unmyelinated?myelinated
why larger diameter axons propagate action potentials more quicklyless internal resisitance