Objectives 1-11 Flashcards
changes in the variable result in responses that change the variable in the opposite direction
negative feedback
how do you calculate osmolarity?
of solute particles formed by solute molecule * molarity (M)
changes in the variable result in more responses in the same direction: increase leads to increase
positive feedback
what are examples of nonpolar, lipid-soluble molecules?
oxygen, carbon dioxide, steroid hormones
what is another name for secondary active transport?
coupled transport
what is the osmolarity inside a human cell?
0.3 Osmoles or 300 mOsmoles
what provides energy for the coupled transport of many molecules?
NA/K pump
molecules dissolved in water
solute
what do ions need in order to diffuse?
transport protein
what are the channels in the membrane called that help water pass through?
aquaporins
what do osmoreceptors trigger?
thirst and decreased urine excretion
difference in solute concentration on either side of the membrane
osmotic pressure
what can open a transport channel?
chemical, neurotransmitter, voltage
what does the calcium pump create?
a concentration gradient for movement of calcium back into the cell
what is the tonicity of a penetrating solution?
it doesn’t have tonicity–it must be non-penetrating to have tonicity
where are osmoreceptors in the body?
hypothalamus
what is the universal solvent?
water
what does the NA/K pump create?
resting membrane potential
In what direction does the calcium flow with the calcium pump, initially?
outside of the cell
how is secondary active transport fueled?
resting membrane potential produced by NA/K pump: moving sodium back into the cell
what is the flow of ions in the NA/K pump?
3 NA out, 2 K in
why would water move across the membrane (rather than the solute)?
the solute can’t pass through (it’s non-penetrating)
what body functions does the calcium pump help with?
neurotransmitter release and muscle contraction
what is the process that initiates the transport protein functioning in primary active transport?
hydrolysis
what does the sodium/potassium pump maintain?
osmolarity
the total concentration of solutes in a liter of solution
osmolarity
how is the pump activated in primary active transport?
phosphorylation: removing P from ATP phosphate binds to the pump
what kind of molecules pass easily through the plasma membrane?
nonpolar, lipid-soluble
with this type of coupled transport, the other molecule is moved with sodium
cotransport
with this type of coupled transport, the other molecule is moved in the opposite direction of sodium
countertransport
which part of the nervous system innervates skeletal muscle?
somatic (sensory and motor)
which neurons are involved with the autonomic nervous system?
motor only
what are the divisions of the motor nervous system?
somatic and autonomic
chemical messengers used to communicate with other cells
neurotransmitters
assist neuron functioning, but do not communicate
neuroglia
where is the nucleus located in a neuron?
cell body/soma
what are the gaps in myelin on an axon called?
nodes of Ranvier
which neurons are located in the CNS and are responsible for processing nervous system information?
association/interneurons
what form myelin sheaths around peripheral axons?
Schwann cells
all axons in the PNS are surrounded by a sheath of Schwann cells called the _________
neurilemma
________ matter is cell bodies and axons
gray
__________ matter is myelinated
white
what forms the tube for a regenerating neuron?
schwann cells
what has to be intact in order for a neuron to be able to regenerate?
cell body
what is the resting membrane potential (RMP) of a neuron?
-70mV
why does the cell need RMP?
needs it to communicate
why is the neuron negative inside?
- uses ATP for energy
- K+ leak channels
- Na+/K+ pump
why does using ATP for energy make the neuron negative inside?
ATP > ADP + Pi
leads to many negatively charged Pi (phosphates) being in the cell
why do K+ leak channels lead to the neuron being negative inside?
K+ ions leak out of the cell at rest
why does the Na+/K+ pump lead to the neuron being negative on the inside?
lose 3 Na+, gain 2 K+
this type of channel opens in response to a chemical (neurotransmitter)
ligand gated channel
this type of channel opens when a specific threshold level occurs
voltage gated channel
what is the threshold voltage level for an action potential?
-55mV
what makes the inside of the cell go from -70mV to -55mV (allowing it to reach threshold)?
entrance of Na+
what are the 2 types of channels that allow K+ passage?
leak and voltage gated
____ ions are 75X more permeable than ____ ions at RMP
K+; Na+
what are the 2 types of channels that allow passage of Na+?
ligand and voltage gated
during an action potential, voltage gated channels will be deactivated at what voltage?
+30mV
at what point during action potential are Na+ ions entering ligand gated channels?
-70mV to -55mV
which part of the action potential is the depolarizing phase?
when Na+ is entering the cell
what happens during action potential when the cell reaches threshold (-55mV)?
Na+ begin entering via voltage gated channels
what is the repolarizing phase of the action potential?
when the K+ are leaving the cell, making it more negative again
what happens during action potential at +30mV?
K+ voltage gated channels open finally, allowing K+ to leave the cell
what is hyperpolarization?
K+ channels are slow to close, so cell becomes more negative than RMP
what restores RMP from hyperpolarization?
Na+/K+ pump
what does the all or none law mean?
size of stimulus doesn’t affect size or duration of action potential
how do local anesthetics work?
block voltage gated Na+ channels, preventing them from opening
when is the absolute refractory period for action potential?
during the action potential
when is the relative refractory period?
when K+ channels are still open
this disease involves the loss of myelin at one or several places in the nervous system
MS
in resting state, which ion is dominant in the extracellular fluid?
Na+
in resting state, which ion is dominant in the intracellular fluid?
K+
which part of the phospholipid bilayer is hydrophobic? which is hydrophilic?
tails are phobic; heads are philic
