Item 1 Flashcards
The body’s _ are the smallest living units independently capable of carrying out its own basic life processes
cells
The brain contains four groups or _ or cells according to their differences
morphologies
All _ or _ cells transmit information in the form of electrical signals from one body location to another
neurons; nerve cells
Oxygen is carried in the bloodstream by cells called _cytes
erythrocytes
Erythrocytes, cells that carry oxygen in the bloodstream, are manufactured by _ _
bone marrow
The synthesis of erythrocytes, cells manufactured by the bone marrow and that carry oxygen in the bloodstream, is regulated by _poietin
erythropoeitin
Erythropoietin, a hormone that synthesizes erythrocyte/oxygen-carrying cells through the bloodstream, is secreted by the _
kidneys
The heart must pump a sufficient volume of blood every minute, and for this reason the rate and force of its contractions are regulated by the _ system
nervous system
The Purkinje cell looks like a _
tree
Cells are grouped together to form _
tissues
Tissues are grouped together to form _
organs
Organs are grouped together to form _ _
organ systems
There are _ major classes of cells in the body
four
The four major classes of cells in the body include: neurons, muscle cells, connective tissue cells, and _ cells
epithelial
Neurons relay signals to muscles, _ and other organs, enabling the control of movement, hormone secretion, and other bodily functions
glands
Muscle cells are also called muscle _
fibres
Muscle fibres that move body parts voluntarily are called _ muscle
skeletal
Muscle of the heart is called _ muscle
cardiac
Blood vessel muscle fibres is called _ muscle
smooth
_ cells consist of a continuous, sheetlike layer of cells in combo with a thin underlying layer of noncellular material, or basement membrane
epithelial
Epithelial cells consist of a continuous, sheetlike layer of cells in combo with a thin underlying layer of noncellular material, or _ membrane
basement
The body’s ability to maintain a normal internal environment
homeostasis
the study of the functions of organisms, comes in many forms
physiology
Some organs/tissues occur in this system: Hypothalamus, pituitary gland, adrenal gland, thyroid gland, parathyroid glands, thymus, pancreas
endocrine
Some organs/tissues occur in this system: Brain, spinal cord, peripheral nerves
nervous
Some organs/tissues occur in this system: Skeletal muscle, bones, tendons, ligaments
musculoskeletal
Some organs/tissues occur in this system: Heart, blood vessels, blood
cardiovascular
Some organs/tissues occur in this system: lungs, pharynx, trachea, bronchi
respiratory
Some organs/tissues occur in this system: kidneys, ureters, bladder, urethra
urinary
Some organs/tissues occur in this system: mouth, esophagus, stomach, small intestine, large intestine, liver, pancreas, gallbladder
gastrointestinal
Some organs/tissues occur in this system: gonads, reproductive tracts and glands
reproductive
Some organs/tissues occur in this system: white blood cells, thymus, lymph nodes, spleen, tonsils, adenoids
immune
Some organs/tissues occur in this system: skin
integumentary
The integumentary system includes this vital organ/tissue:
skin
Extracellular fluid is the immediate part of most of the body’s cells, also applies to the fluid in the bloodstream that surrounds blood cells: _ environment
internal
exo- refers to exterior, whereas _- refers to interior/within
endo-
Dichotomoies: absorption vs…
secretion
Dichotomies: oxygen vs…
carbon dioxide
Oxygen enters the bloodstream from the air that is breathed in during _
inspiration
Carbon dioxide exits the bloodstream and is expelled in the air that is breathed out during _
expiration
In the gastrointestinal tract, the water, inorganic salts and nutrients obtained from digested food are transported from the _ to the bloodstream
lumen
Absorption can refer to the gastrointestinal tract obtaining water, nutrients and inorganic _ from digested food from the lumen to the bloodstream
salts
Unabsorbed materials plus bacteria and cellular _ remain in the gastrointestinal tract and are ultimately eliminated from the body as feces
debris
The creation of feces from the gastrointestinal tract uses the process called _
excretion
The digestion of food in the gastrointestinal tract uses the process called _
secretion
Fluid from the bloodstream first enters tubules via a mechanism known as _ in the kidneys
filtration
When fluid travels back into the bloodstream as selected nutrients, inorganic salts, etc are taken back into the bloodstream is called _
reabsorption
The fluid that eventually reaches the ends of the tubules from the kidneys is called _
urine
_serves as a solvent for a number of solutes using small and large molecules
water
Total body water (TBW) includes water in all cells, whether interstitial, ECF, intracellular and _
plasma
Interstitial fluid does not include _ because it is a liquid, NONcellular part of blood
plasma
The _ _ is outside the blood and bathes most of the cells in the body
interstitial fluid
_ fluid is synonymous with the internal environment because it isn’t within a cell itself, but rather the area surrounding cells (although this can be confusing when considering the name of fluid inside a cell!)
extracellular fluid / ECF
_CF refers to the internal environment
extracellular fluid/ECF
ICF contains many _ and is relatively rich in potassium
proteins
ECF has few proteins and is relatively rich in _
sodium
Extracellular fluid can include plasma, whereas _ fluid does not
interstitial fluid does not contain plasma
An example of eustress or a ‘good’ stress for the body is _
exercise
The _ releases glucose into the bloodstream during exercise
liver
Adipose tissue releases _ _ so that exercising muscles can use these substances for energy
fatty acids
Increased muscle and nerve activity causes _cellular levels of potassium to increase
extracellular levels of potassium to increase
The levels increase outside the cell, which the cells are more compelled to bring them in
Type 2 _ mellitus is help prevented with exercise
diabetes
Hemorrhage is the loss of whole blood, which consists of approx 55 - 60% _
plasma
Heat exhaustion requires a significant reduction in _ volume in order to produce massive quantities of sweat
blood
Heat exhaustion requires a significant reduction in blood volume and blood pressure, due to diverting blood from other areas of the body to the _ to cool off the body
skin
A consequence of reduced blood volume and pressure due to heat exhaustion is…
dizziness, fainting, and even loss of consciousness
Heat _ is a more serious condition than heat _, because of a failure of thermoregulation
heat stroke is more serious than heat exhaustion
Heat stroke is defined by skin that is flushed and _, whereas heat exhaustion shows flushed skin and _ skin
heat stroke confuses the brain which prevents sweating, therefore heat stroke is shown as flushed and with DRY skin, whereas heat exhaustion is flushed and SWEATY skin
Immersing the body in ice water could save the life of one who has heat _, provided there is not permanent damage to the brain’s thermoregulatory systems
heat stroke can be helped by dunking in ice water
Body temperature is not free to vary, therefore it is considered a _ variable
regulated
Homeostatic _ mechanisms of organ systems are considered regulated variables
homeostatic regulated mechanisms
A car’s cruise control is considered a _ feedback loop
negative feedback loop
Negative feedback loops detect a difference between the actual value of the regulated variable and the normal “desired” value, a.k.a. _ _
set point
The difference between the actual value and the set point of a negative feedback loop is called a/n _ signal
error signal
The actions of _ detect the regulated variable
sensors
_receptors are sensitive to concentrations of oxygen and carbon dioxide in the blood, and are considered blood vessel’s homeostatic sensors
chemoreceptors
Sensors relay signals to an integrating centre, a process called _
input
The integrating centre of a homeostatic regulatory mechanism relays signals, called _, to the cells, tissues, or organs that bring about a final response
output
E_ are the cells, tissues or organs that bring about a final response of the homeostatic regulatory mechanism
effectors
Beta cells detect blood glucose levels in the _
pancreas
A negative feedback loop is called that because the response of the system (e.g., a fall in blood glucose) is _ in direction to the change that set it in motion (i.e., a rise in blood glucose)
opposite direction to the change that set it in motion
Positive feedback is the response of a homeostatic regulatory mechanism that goes in the _ direction as the change that sets it in motion
same direction
The secretion of luteinizing hormone (LH) from the pituitary gland to the ovaries to secrete estrogens each can trigger an increase in the other, causing _ feedback
positive feedback (increase in one means an increase in the other, to a certain extent)
Which of the following best illustrates the concept of positive feedback?
a) The secretion of acid by cells in the stom- ach lining is suppressed when the acidity of the stomach contents increases.
b) A rise in blood pressure stimulates the elimination of water in the urine, which reduces the blood pressure.
c) An increase in the concentration of
in blood causes an increase in excretion in urine.
d) An increase in the carbon dioxide concentration of the blood stimulates breathing, which increases the rate at which carbon dioxide is eliminated from the body.
e) Contractions of the uterus push the fetus against the cervix, which triggers release of oxytocin into the blood- stream; oxytocin then stimulates stronger contractions of the uterus.
e) Contractions of the uterus push the fetus against the cervix, which triggers release of oxytocin into the blood- stream; oxytocin then stimulates stronger contractions of the uterus.
The hormone aldosterone stimulates the reabsorption of sodium ions from the lumen of a kidney tubule. Based on your knowledge of the body’s cell types, you can surmise that this hormone acts on
a) Neurons.
b) Muscle cells.
c) Epithelial cells.
d) Connective tissue cells
c) Epithelial cells
Hormones are secreted
a) Into the blood.
b) From exocrine glands.
c) From endocrine glands.
d) Both a and b are true.
e) Both a and c are true
e) Both a and c are true:
Into the blood.
From endocrine glands.
Which cell type is specialized for contraction and generation of force?
a) Muscle
b) Epithelial
c) Connective tissue
d) Nerve
a) Muscle
Normal blood glucose level is
a) 50mg/dL.
b) lOOmg/dL.
c) 50mg/mL.
d) lOOmg/mL.
e) 50mg/L
b) lOOmg/dL.
Maintenance of constant conditions in the internal environment is known as
homeostasis
Plasma is extracellular fluid, (true/false)
True
In homeostasis, all physiological variables are regulated to stay constant, (true/false)
False
The protein elastin is found in (epithelial/ connective) tissue.
Connective
Plasma and interstitial fluid are identical in composition, (true/false)
False
A hormone that causes movement of glucose from plasma to cells is
insulin
Examples of homeostatic control:
plasma glucose
body temperature
blood pH, oxygen and carbon dioxide levels
blood pressure and volume
plasma _
plasma concentrations of potassium, calcium and glucose
plasma osmolarity
the measure of the different solutes in plasma (not tonicity, which refers to its comparisons with other liquid)
The example of homeostasis shown was…
regulating glucose in the blood
When excessive glucose is in the body (blood stream), what happens first?
Glucose enters beta cells of the pancreas, considered the integrating centre, sending signals through the blood, some of which goes to the liver
Once the liver received the signals from the beta cells from blood that is high in glucose, the liver cells…
bind to the signals from the beta cells, which release the hormone insulin into the bloodstream
Once insulin is found in the blood, it binds to liver cells, causing the liver cells to…
take in more glucose, which is converted into glycogen, a storage molecule
Examples of physiological flow down gradients:
passive transport of ions and molecules into and out of cells
movement of _ into and out of the _
flow of blood in the cardiovascular system
movement of air into and out of the lungs
Factors that regulate flow down gradients are energy gradients (whether electrical, chemical or electrochemical/net flux) or…
resistance to flow
The direction of the electrical driving force is based on…
the perspective that you’re looking at
e.g., Sodium inside a cell with a negative charge membrane potential would have an electrical driving force going out of the cell, whereas Potassium outside that same cell would have an electrical driving force going inside the cell
Hydrophobic and water molecules can cross the _bilayer, through passive transport
phospholipid bilayer
Hydrophilic molecules (e.g., ions, glucose, amino acids and water as well) travel across the plasma membrane for passive transport by…
membrane proteins
Does water only travel by simple diffusion across cells?
No, it can go by simple diffusion across the phospholipid bilayer (even though only other hydroPHOBIC molecules do the same), but also by membrane proteins for transport, much like hydroPHILIC molecules
Facilitated diffusion, the use of carriers or channels to bring molecules DOWN an electrochemical gradient is an example of _ transport
passive!
The _ of two solutes that have movement of solute DOWN a concentration gradient through simple diffusion is:
= constant x area/distance x (‘triangle’ C1 - ‘triangle’ C2)
rate of simple diffusion
For figuring out the rate of simple diffusion, _ permeability is shown as a steep rate, whereas _ permeability is shown as a flatter rate
high; low
For mapping out the rate of permeability of simple diffusion starting at ‘0’, the x-axis is represented by the _ _, whereas the y-axis by the net flux (i.e., electrochemical driving force), with the rate of permeability of simple diffusion being the line
concentration gradient
The rate of simple diffusion is technically the rate of _ of simple diffusion
permeability of simple diffusion (net flux - y-axis, concentration gradient -x-axis)
Low permeability means _ to flow
resistance
T of F: the rate of facilitated diffusion reaches a maximum, whereas the rate of simple diffusion is theoretically infinite
true
there are limited carriers or channels in a cell, so the degree of concentration gradient only impacts diffusion as much as the number of carriers or channels can allow movement
For active transport, _ active transport using pumps that require ATP, whereas _ active transport require carriers (similar to facilitated diffusion)
primary active transport pumps use ATP, secondary active transport carriers do not
Osmolarity is the concentration of _ in 1 L solution
particles
that’s why you would multiple the number of parts of a molecule (e.g., NaCl, or 2 mOsm) to give you a greater osmolarity than something like glucose (1 mOsm). Note in this example that Na+ and Cl- separate as their own particles in water, vs glucose doesn’t which is why glucose is lower than NaCl
Pure water is _ osmolarity or _ M
zero osmolarity or 0 M
Water moves from a _ osmolarity to a _ osmolarity
low to high
water moves from a low concentration gradient to a high concentration gradient solution
In order to terminate a cAMP-mediated response, the enzyme ________ can be activated to degrade cAMP.
a. cAMP decarboxylase
b. cAMP phosphodiesterase
c. cAMP protein kinase
d. Camp HYDROLASE
e. cAMP hydrogenase
b. cAMP phosphodiesterase
When associated with G protein, guanylate cyclase will activate the enzyme ________ .
A) phospholipase C
B) protein kinase
C) phosphodiesterase
D) protein kinase C
E) protein kinase A
B) protein kinase
Which of the following proteins is directly activated by a G protein?
A)
tyrosine kinase
B)
protein kinase G
C)
phospholipase A2
D)
calmodulin
E)
adenylate cyclase
E)
adenylate cyclase
Which of the following is a second messenger?
158)
_____
A)
cAMP, calcium, and inositol triphosphate
B)
inositol triphosphate only
C)
both cAMP and inositol triphosphate
D)
calcium only
E)
cAMP only
cAMP, calcium, and inositol triphosphate
Oxytocin is synthesized in the ________ nucleus located within the _____
A)
paraventricular : hypothalamus
B)
paraventricular : posterior pituitary
C)
supraoptic : posterior pituitary
D)
paraventricular : anterior pituitary
E)
supraoptic : hypothalamus
supraoptic : hypothalamus
The release of ________ from the pineal gland is important for establishing ________.
173)
_____
A)
prolactin : breast milk production
B)
melatonin : circadian rhythm
C)
prolactin : circadian rhythm
D)
melatonin : thirst
E)
melanin : thirst
B)
melatonin : circadian rhythm
The neural input for circadian rhythmicity of hypothalamic tropic hormones originates from the ________.
187)
_____
A)
paraventricular nucleus
B)
cerebrum
C)
supraoptic nucleus
D)
pineal gland
E)
suprachiasmatic nucleus
e. suprachiasmatic nucleus
What is the structural classification of a neuron composed of a single axon and a number of dendritic projections from the nerve cell body?
A)
multipolar
B)
polar
C)
pseudo-unipolar
D)
unipolar
E)
bipolar
A)
multipolar
Which of the following is a functional classification of neurons that, for the most part, are bipolar in structure and carry information from the peripheral axon to the central axon?
A)
efferent neurons
B)
interneurons
C)
multipolar cells
D)
afferent neurons
E)
bipolar cells
D)
afferent neurons
Which of the following cells is NOT classified as a glial cell?
A)
Schwann cell
B)
oligodendrocyte
C)
ventricular cell
D)
ependymal cell
E)
astrocyte
C)
ventricular cell
The resistance to an ion’s movement across a membrane is determined by ________.
A)
the ions present on either side of the membrane
B)
receptors on the cell membrane
C)
enzymes on the surface of the cell membrane
D)
ion channels within the membrane
E)
the resting membrane potential
D)
ion channels within the membrane
Which of the following statements about sodium is FALSE?
A)
There is a chemical force driving sodium ions into the cell.
B)
At the resting membrane potential, there is an electrical force driving sodium ions into the cell.
C)
At the potassium equilibrium potential, there is an electrical force driving sodium ions out of the cell.
D)
At the sodium equilibrium potential, the electrochemical force for sodium movement across the plasma membrane is zero.
E)
At the sodium equilibrium potential, there is an electrical force driving sodium ions out of the cell.
C)
At the potassium equilibrium potential, there is an electrical force driving sodium ions out of the cell.
Which of the following best describes the electrochemical forces acting on sodium and potassium ions at the resting membrane potential?
A)
Forces on both sodium and potassium ions are to move out of the cell.
B)
The force on sodium ions is to move into the cell, and the force on potassium ions is to move out of the cell.
C)
The force on sodium ions is to move out of the cell, and the force on potassium ions is to move into the cell.
D)
There is no force on either ion to move.
E)
Forces on both sodium and potassium ions are to move into the cell
B)
The force on sodium ions is to move into the cell, and the force on potassium ions is to move out of the cell.
Given a cation with an equilibrium potential of -55 mV. If the plasma membrane of the cell is permeable only to this ion, then which of the following best describes the resting membrane potential?
A)
-70 mV
B)
-55 mV
C)
+55 mV
D)
More negative than -55 mV
E)
More positive than -55 mV
B) -55 mV
if a cell is only permeable to one ion and it is already at its equilibrium potential, then its resting potential will be the same (not opposite)!
At the resting membrane potential, the membrane is most permeable to ________, which moves ________ the cell due to its electrochemical gradient.
A)
chloride : into
B)
sodium : into
C)
potassium : out of
D)
potassium : into
E)
sodium : out of
C)
potassium : out of
remember, there are more potassium leak channels than sodium, so even though the electrochemical gradient for sodium to enter the membrane is high, ultimately the greater number of potassium leak channels will win out, with exiting potassium from the cell (after-hyperpolarization
The electrochemical gradient for sodium across the membrane is such that the net flux of sodium will be ________, thereby causing the cell’s membrane potential to become more ________.
A)
outward : negative
B)
inward : negative
C)
outward : positive
D)
inward : positive
E)
at equilibrium : positive
D)
inward : positive
bc the resting membrane potential is -70 mV, it is closer to the potassium equilibrium potential which makes sodium want to go inwards. If an action potential starts, the membrane potential becomes more positive, becoming closer to the sodium equilibrium potential
The membrane potential at which there is no net flux of an ion across the membrane is called that ion’s ________.
A)
potential difference
B)
equilibrium potential
C)
resting membrane potential
D)
graded potential
E)
action potential
B)
equilibrium potential
The presence of the ________ prevents the dissipation of the concentration gradient for Na+.
A)
equilibrium potential
B)
Na+/H+ antiporter
C)
Na+/Ca2+ exchanger
D)
action potential
E)
Na+/K+ pump
E)
Na+/K+ pump
The Na+/K+ pump is called an electrogenic pump because the imbalance between ________.
A)
Na+ out to K+ in leaves the inside of the cell with a net negative charge
B)
ATP utilization inside the cell relative to the outside
C)
Na+ out to K+ in leaves the inside of the cell with a net positive charge
D)
Na+ in to K+ out leaves the inside of the cell with a net negative charge
E)
Na+ in to K+ out leaves the inside of the cell with a net positive charge
A)
Na+ out to K+ in leaves the inside of the cell with a net negative charge
The electrical potential of a membrane at rest is closest to potassium’s equilibrium potential because ________.
A)
more sodium channels are open, allowing more sodium to move into the cell
B)
more potassium channels are open, allowing more potassium to move into the cell
C)
more sodium channels are open, allowing more sodium to move out of the cell
D)
more potassium channels are open, allowing more potassium to move out of the cell
E)
all potassium channels are open
D)
more potassium channels are open, allowing more potassium to move out of the cell
remember, more sodium exists outside the cell and potassium inside, therefore there is more of a drive for the potassium to leave than the sodium to move in (what is it like with the resting potential becoming an action potential, and the moves it makes to get there?)
If, under resting conditions, the membrane is much more permeable to sodium than potassium, resting membrane potential would ________.
A)
be altered very little
B)
approach potassium’s equilibrium potential
C)
become more negative
D)
approach sodium’s equilibrium potential
E)
approach chloride’s equilibrium potential
D)
approach sodium’s equilibrium potential
As a membrane’s permeability to a particular ion increases, membrane potential will move ________ that ion’s ________.
A)
away from : electrochemical gradient
B)
away from : electrical gradient
C)
closer to : equilibrium potential
D)
closer to : electrochemical gradient
E)
away from : equilibrium potential
C)
closer to : equilibrium potential
Membrane permeability is altered in the short term (seconds) by changes in the ________ of ion channels.
A)
formation
B)
cleavage
C)
degradation
D)
gating
E)
production
D)
gating
Closure of an ion channel will increase a cell membrane’s ________, whereas ________ will decrease.
A)
permeability : conductance
B)
permeability : resistance
C)
conductance : resistance
D)
electrical current : permeability
E)
resistance : conductance
E)
resistance : conductance
closer means it is met with more resistance, whereas it being open allows more movement or conductance
The fact that a cell has an electrical potential difference across its membrane makes that cell ________.
A)
polarized
B)
polar
C)
hyperpolarized
D)
repolarized
E)
depolarized
A)
polarized
The direction of change in membrane potential, in response to a stimulus that initiates a graded potential, is dependent upon ________.
A)
that membrane’s threshold potential
B)
the ion channels that are opened or closed
C)
the gating of sodium channels only
D)
the changes in ion concentration across the membrane
E)
the gating of potassium channels only
B)
the ion channels that are opened or closed
pay attention to the question - it’s asking for the DIRECTION OF CHANGE, not what helps a graded potential in general
Which of the following does NOT produce graded potentials?
A)
the release of a neurotransmitter onto a cell body
B)
light impinging on a photoreceptor
C)
arrival of a suprathreshold stimulus at the axon hillock
D)
touching a sensory receptor
E)
the release of a neurotransmitter onto a dendrite
C)
arrival of a suprathreshold stimulus at the axon hillock
this is actually an action potential!
Which of the following statements is FALSE?
A)
Graded potentials and action potentials are caused by ions moving through channels.
B)
Graded potentials and action potentials are all-or-none.
C)
Graded potentials and action potentials can change the membrane potential of adjacent areas of the membrane through electrotonic conduction.
D)
Graded potentials do not have refractory periods, but action potentials do.
E)
Graded potentials can sum over time but action potentials cannot.
B)
Graded potentials and action potentials are all-or-none.
The ________ in graded potential that occurs as current spreads along the membrane happens as a consequence of the ________ of current across the membrane.
A)
decrement : leakage
B)
elevation : blockade
C)
decrement : blockade
D)
elevation : leakage
E)
elevation : generation
A)
decrement : leakage
Which of the following is an example of spatial summation?
A)
A neuron sends out information through collaterals to several target cells.
B)
An action potential occurs at the same time as a graded potential, and they sum.
C)
Two action potentials occur at the same time and sum.
D)
Two stimuli from two sources produce graded potentials on the same neuron at the same time such that the two potentials sum.
E)
Two rapid stimuli from the same source produce graded potentials on the neuron that sum.
D)
Two stimuli from two sources produce graded potentials on the same neuron at the same time such that the two potentials sum.
Which of the following changes in membrane potential is considered excitatory?
A)
depolarization only
B)
both hyperpolarization and depolarization
C)
repolarization only
D)
hyperpolarization only
E)
both hyperpolarization and repolarization
A)
depolarization only
The spread of voltage by passive charge movement is called ________.
A)
diffusion
B)
integration
C)
propagation
D)
saltatory conduction
E)
electrotonic conduction
E)
electrotonic conduction
DEFN: the passive flow of a change in electric potential along a nerve or muscle membrane. It occurs in response to stimulation that is inadequate to trigger an actively propagated action potential (i.e., subthreshold stimulation) but instead generates depolarization in a small area of membrane.
perhaps diffusion is more spread of chemicals than voltage
he patterns of change in ion channel permeability that occur during an action potential are due to ________ gating of voltage-sensitive potassium and sodium channels.
A)
mechanically-induced
B)
time-dependent
C)
temperature-induced
D)
light-sensitive
E)
ligand-driven
B)
time-dependent
hich of the structures below lacks voltage-gated ion channels responsible for the production of action potentials?
A)
axon hillock
B)
muscle cell membrane
C)
nodes of Ranvier
D)
axon
E)
epithelial cell membrane
E)
epithelial cell membrane
Which of the following events is fastest?
A)
opening sodium activation gates
B)
closing sodium activation gates
C)
closing voltage-gated potassium channels
D)
closing sodium inactivation gates
E)
opening voltage-gated potassium channels
A)
opening sodium activation gates`
Stimuli A and B are both suprathreshold stimuli that last for one second, but stimulus A is stronger. Which of the following statements is TRUE?
A)
The action potential produced by stimulus A will be larger than that produced by stimulus B.
B)
Stimulus A will cause a higher frequency of action potentials.
C)
Only stimulus A can produce an action potential.
D)
The action potential produced by stimulus A will be of longer duration than that produced by stimulus B.
E)
A single action potential will be produced by both stimulus A and stimulus B. The action potentials produced from each stimulus will be identical in size and duration
B)
Stimulus A will cause a higher frequency of action potentials.
The repolarization phase of action potentials in neurons is due primarily to ________.
A)
sodium flow into the cell
B)
sodium flow out of the cell
C)
potassium flow out of the cell
D)
increased activity of the Na+/K+ pump
E)
potassium flow into the cell
C)
potassium flow out of the cell
The regenerative nature of a sodium channel’s activation gate refers to the situation where an activation gate’s opening, and the resulting depolarization, ________.
A)
stimulates the opening of a potassium channel
B)
stimulates the inactivation gate of the same sodium channel to open
C)
stimulates the opening of another sodium channel’s activation gate
D)
stimulates the opening of another sodium channel’s inactivation gate
E)
stimulates the closure of other sodium channels’ activation gates
C)
stimulates the opening of another sodium channel’s activation gate
The positive feedback loop that is involved in the generation of an action potential is terminated by the ________.
A)
closure of activation gates on sodium channels
B)
closure of inactivation gates on sodium channels
C)
opening of inactivation gates on sodium channels
D)
closure of potassium channels
E)
opening of activation gates on sodium channels
B)
closure of inactivation gates on sodium channels
The magnitude of an action potential will never reach sodium’s equilibrium potential because ________.
A)
the inward movement of sodium is countered by the outward movement of potassium
B)
the sodium channel only opens for a short time
C)
the outward movement of sodium is countered by the inward movement of potassium
D)
the potassium channel opens slowly
E)
the inactivation gate closes the sodium channel so rapidly
A)
the inward movement of sodium is countered by the outward movement of potassium
In order for a neuron to move from the absolute to the relative refractory period, a majority of that neuron’s sodium channels must have their ________.
A)
inactivation gates closed and activation gates closed
B)
activation gates closed
C)
inactivation gates closed
D)
activation gates opened and inactivation gates closed
E)
inactivation gates open
E)
inactivation gates open
Toward the end of the relative refractory period, the continued decrease in stimulus intensity required to initiate an action potential is caused by ________.
A)
the number of sodium channels whose inactivation gate has not opened
B)
decreased potassium permeability
C)
decreased sodium permeability
D)
closure of the sodium activation gate
E)
increased potassium permeability
B)
decreased potassium permeability
The stimulus intensity required to initiate an action potential is ________ through the course of the relative refractory period.
A)
progressively reduced
B)
unaltered
C)
progressively increased
D)
increased
E)
stable
A)
progressively reduced
Which of the following characteristics of an action potential does NOT result directly from the refractory period?
A)
the peak level of depolarization reached
B)
the all-or-none principle of action potentials
C)
the frequency of action potentials
D)
the unidirectional propagation of action potentials
E)
the lack of summation of action potentials
A)
the peak level of depolarization reached
The time between action potentials is directly determined by the ________ the graded potential at the axon hillock.
A)
frequency of
B)
duration of
C)
distance traveled by
D)
amplitude of
E)
source of
D)
amplitude of
As an action potential is propagated away from the axon hillock, propagation continues in one direction only because ________.
A)
they will travel the path of least resistance
B)
the region just behind the action potential is in the absolute refractory period
C)
the region just in front of the action potential is in the relative refractory period
D)
the region just in front of the action potential is in the absolute refractory period
E)
the region just behind the action potential is in the relative refractory period
B)
the region just behind the action potential is in the absolute refractory period
Why do the distributions of sodium and potassium ions across the plasma membrane of neurons not change appreciably, even following hundreds of action potentials?
A)
The movement of sodium and potassium ions that occurs during an action potential is countered by the passive leak of these ions when a neuron is at rest.
B)
The movement of sodium and potassium ions that occurs during an action potential is countered by the passive movement of these ions during the after-hyperpolarization.
C)
The movement of sodium and potassium ions that occurs during an action potential is countered by counter-transport of potassium with sodium during rest.
D)
The movement of sodium and potassium ions that occurs during an action potential is countered by the active transport of these ions by the Na+/K+ pump.
E)
The movement of sodium and potassium ions that occurs during an action potential is countered by the passive movement of these ions during the repolarization phase
D)
The movement of sodium and potassium ions that occurs during an action potential is countered by the active transport of these ions by the Na+/K+ pump
When solute is actively transported across epithelium, what usually follows?
A)
water movement in the same direction
B)
water movement in the opposite direction
C)
passive transport of solute in the same direction
D)
passive transport of the solute in the opposite direction
E)
active transport of the solute in the opposite direction
A)
water movement in the same direction
The body is able to synthesize the amino acids glutamate, aspartate, and glycine from ________.
A)
essential amino acids
B)
the degradation of glucose in glycolysis and the Krebs cycle
C)
the glycerol in a triglyceride
D)
the degradation of fatty acids
E)
cholesterol
B)
the degradation of glucose in glycolysis and the Krebs cycle
