1st Evals 2018 - Cell Physiology & Electrophysiology Flashcards
The “milieu interieur” to which the cell is exposed to in a multicellular organism is the
Interstitial fluid
In a homeostatic control system, the component that triggers the response is
stimulus
In a homeostatic control system, it is the “detectable change”
stimulus
In a homeostatic control system, it relays information about the nature of the change via afferent pathway
sensor
In a homeostatic control system, it maintains conditions at baseline values and relays signal via efferent pathway
integrating center (feedback controller)
In a homeostatic control system, it causes the response to the change in biologic system
effector
When exposed to cold, which of the mechanisms triggered to maintain body temperature actively PRODUCES BODY HEAT
involuntary contraction of skeletal muscles (shivering)
When exposed to cold, which of the mechanisms triggered to maintain body temperature DECREASE HEAT LOSS from the body
- constriction of blood vessels
- curling up to decrease exposure
sickle cell anemia
- adaptive response
- hereditary
- inhibits oxygen binding
- RBC resistance to malaria
characteristics of homeostatic control systems
- NOT ALL VARIABLE CAN BE MAINTAINED RELATIVELY CONSTANT
- Correction is within a narrow range of normal in response to a disturbance
- There is a “resetting” of baseline values following a disturbance
- Redundancy of control is ensured by involvement of than one mechanism
characteristics of homeostatic control systems
- NOT ALL VARIABLE CAN BE MAINTAINED RELATIVELY CONSTANT
- Correction is within a narrow range of normal in response to a disturbance
- There is a “resetting” of baseline values following a disturbance
- Redundancy of control is ensured by involvement of than one mechanism
- balancing of inputs and outputs/simultaneous activation of counter-regulatory mechanisms
The most common response to disturbance in control systems in the body
Negative Feedback
Stimulus elicits a response that results in an effect opposite of the initiating stimulus
Tendency is to revert to baseline
Negative Feedback
The response tends to amplify the change that can initiating a “vicious cycle” that can be fatal
Positive Feedback
The recruitment of activated platelets to form a plug to control bleeding is an example
Positive Feedback
Stimulus elicits a response that increases or amplifies the original effect
Positive Feedback
anticipatory effect/ Resetting of biologic variables occur in anticipation of the change in the system
Feedforward
“a learned response”
Feedforward
Fluid compartment where K+ is higher. ICF or ECF?
ICF
Plasma is part of this fluid compartment. ICF or ECF?
ECF
Osmolality is 300 mOsm/L. ICF or ECF?
both
Fluid compartment where GLUCOSE concentration is UNDETERMINED. ICF or ECF?
ICF
[Cl-] is higher in this compartment. ICF or ECF?
ECF
Fluid compartment where Na+ is higher. ICF or ECF?
ECF
composition of ECF and percentage
ECF is 20% of total body weight
blood/plasma = 5% of BW
interstitial fluid = 15% of BW
The selective permeability of the cell membrane is a function of which structural component:
Lipids
Presence of phospholipids determine which substances will be allowed to cross the membrane (lipid soluble substances)
The type of substances to which the cell membrane is permeable are:
Non-polar, lipid-soluble substances
The transport of substances into the cell to which the membrane is not permeable occurs through:
Integral proteins
protein embedded through the thickness of the membrane
integral protein
protein located either at the inner or outer surface
peripheral protein
Which of the following transport mechanisms can occur across a semipermeable membrane: A. Simple Diffusion B. Facilitated Diffusion C. Active Transport D. All of the above
All of the above :)
The determinants of the direction of net flux of solute in simple diffusion is/are:
concentration, and
charge of the solute.
Fick’s equation:
J = -DA (change in c/change in x),
where: J = rate of diffusion or FLUX D = diffusion coefficient A = area of membrane change in x = membrane thickness change in c = concentration difference
Accdg Fick’s equation, which is INVERSELY proportional to the rate of diffusion or FLUX
membrane thickness, x
Transport across the cell membrane is by simple diffusion for which of the following: A. Non-polar molecules B. Small, uncharged polar molecules C. Large, uncharged polar molecules D. Ions
A
The cell membrane is most permeable to
hydrophobic, nonpolar molecules (respiratory gases, )2, CO2, N2, Benzene)
The cell membrane is impermeable to
ions (charged, water-soluble molecules)
e.g. H+, Na+, HCO3-, K+, Ca++, Cl-, Mg++
In the body, the main limit to distribution of nutrients from the capillary by diffusion is:
diffusion distance
formula: time = square of distance
The different forms of stimuli that can activate a membrane transport mechanism include:
- Hormone/neurotransmitter
- Intracellular depolarization
- Mechanical stimuli
PROTEIN MEDIATED transport mechanism
all, except simple diffusion
memorize table, slide 61
transport mechanism that DEPEND ON Na+ GRADIENT
secondary active transport (co-transport and counter-transport)
(memorize table, slide 61)
Transport is against the concentration gradient for the solute
secondary active transport (co-transport and counter-transport)
(memorize table, slide 61)
Transport is along the solute’s concentration gradient
simple diffusion,
facilitated diffusion,
(memorize table, slide 61)
ATP is utilized in which transport mechanism
directly in primary active transport and
indirectly in secondary active transport
- True of protein-mediated transport:
A. The transport protein is unique for each solute
B. There is conformational change in the transport protein
C. Transport protein-solute interaction results in a chemical bond
D. All of the above
D. All of the above
The difference of secondary active transport from primary active transport is that: In secondary active transport,
A. Transport of the solute is against its concentration gradient
B. It involves the transport of a second solute
C. The ATP is used by another transport protein
D. All of the above
C. The ATP is used by another transport protein
The transport protein involved does not directly utilize ATP; it is utilized by another transport protein
The driving force for osmosis across a semipermeable membrane is the difference in the:
total solute concentration
Osmosis is the movement of water through a partially permeable membrane down a concentration gradient from a dilute solution (where there is a high concentration of water) to a concentrated solution (where there is a relatively low concentration of water)
The initial condition that determines the distribution of solutes following the Donnan effect is the increased A. [Cations] in the ICF B. [Anions] in the ECF C. [Proteins] in the ICF D. [Glucose] in the ECF
C. [Proteins] in the ICF
Negative charge inside the cell is relative to outside
Due to limitation of protein molecules on one side of the membrane
The characteristic distribution of substances in the ICF according to Gibbs-Donnan equilibrium, include: A. Increased [cations] B. Less [anions] C. increased water volume D. All of the above
D. All of the above
saka din:
more diffusible ionice particles
The fastest route of cell communication occurring via synapse
Neural communication
The route for SELF-regulation of cell function
Autocrine
secretion of chemical into interstitial fluid AFFECTING THE SAME CELL
Autocrine
Cells influencing the activity of NEARBY cells
PARAcrine
secretion of chemical into interstitial fluid; acts on NEARBY cells
PARAcrine
Chemical messengers carried by BLOOD to target cells
ENDOcrine
release of hormone into BLOOD/LYMPH affecting distance target cells
ENDOcrine
mediated by chemical messengers to initiate response
ALL - neural communication, endocrine, paracrine, autocrine
Receptor molecules involved in cell communication are
Proteins
Receptors are protein molecules to which a chemical messenger can bind in order to stimulate a cell response
In general receptors for water-soluble substances are located on/in the:
Cell membrane
The direct exchange of material between cells that mediates the rapid propagation electrical occur through:
Gap junctions
Direct cell-to-cell communication
The interaction of receptors with the appropriate ligand can result in:
A. Change in cell membrane permeability to a specific ion
B. Change in activity of enzymes
C. Alteration in gene expression
D. All of the above
D. All of the above
The acetylcholine-gated Na+ channel is which type of receptor:
Ion channel linked receptor
Change in ion permeability of membrane
For G-protein coupled receptor
It is a seven-helix receptor protein molecule
Also known as serpentine receptors
Traverses the whole enzyme membrane 7x
G-protein
Collectively known as trimeric protein (α,β and γ subunits)
α and γ subunits are attached to the membrane facing intracellularly
Activation of the G-protein coupled receptor occurs with the presence of
GTP
G-protein dislodges the GDP to GTP and is enhanced by GEF (guanosine exchange factors)
GTP = active; GDP = inactive
which G-protein subunits are associated with the membrane
alpha and gamme
which G-protein subunit separate from the 2 other subunits
alpha subunit ang humihiwalay sa beta at gamma
attachment site for GDP upon inactivation
alpha subunit
The inherent catalytic activity that leads to inactivity of the G-protein resides in the:
alpha subunit
The second messenger cAMP is produced by the activation of which enzyme system in G-protein coupled receptor response
Adenylyl cyclase
Activation of adenylyl cyclase produces more cAMP
what happens upon activation of adenylyl cyclase
ATP is converted to cAMP
An increase in intracellular cAMP results in:
Activation of protein kinase A, PKA
activation of cAMP will lead to
Activation of protein kinase A, PKA
It catalyzes phosphorylation of proteins which affects the synthesis or inhibition of enzymes
The increase in intracellular [Ca++] in G-protein coupled receptor response is the immediate effect of:
Inositol triphosphate
Influences mobilization of intracellular calcium
activation of Protein Kinase C, PKC, in G-protein coupled receptor is the immediate effect of
DAG, Diacylglycerol
catalyze phosphorylation of proteins and phosphorylates creb in nucleus
immediate effect of
Protein Kinase A, PKA
The insulin receptor increases activates enzyme systems by phosphorylation of which amino acid residues:
Tyrosine
Involved in the synthesis of glucose transporter proteins (GLUT4)
Also involved in epidermal & nerve growth factor
what happens with activation of phosphodiesterase?
cGMP is converted to GMP
In cholera, the toxin causes the uncontrolled transport of which ion in intestinal epithelial cells:
Chloride
–e laging sumasama sa Cl- yung Na+. ayun! Na+ laging kasama H2O. Ayan. kaya may massive diarrhea. :’(
Sildenafil (Viagra) causes sustained vasodilation by potentiating the effect of:
Nitric oxide
Sildenafil prolongs the vasodilator effects of NO by inhibiting cGMP-phosphodiesterase
Factors that create conditions for ions to move across the cell membrane
- voltage gradient
- chemical or concentration gradients
- metabolic pump (e.g. Na+-K+ pump)
- symport & antiport systems
The Na+-K+-ATPase system (also known as the sodium-potassium pump) of nerves and muscles is partly responsible for the:
A. “resting” distribution of ions across the cell membrane
B. Immediate repolarization of the cell membrane during the downstroke phase
C. upstroke phase of the action potential
D. undershoot
A. “resting” distribution of ions across the cell membrane
?
The electrical gradient, created by the outflow of more positive sodium ions than the inflow of positive potassium ions, resulting in a relatively negatively charged cytoplasm,is used in neurons and muscles to create the action potentials responsible for nervous system function and muscular contraction
In most excitable cells, the negative value of the resting membrane potential is primarily due to: A. Leaky Ca++ channels; Ca++ influx B. Leaky Na+ channels; Na+ influx C. Leaky Cl- channels; Cl- influx D. Leaky K+ channels; K+ efflux
D. Leaky K+ channels; K+ efflux
?
The cell membrane at rest is more permeable to potassium than to sodium, thereby leaking out more readily than sodium can leak in
This mathematical model computes for the membrane potential caused by movement of multiple ions, provided their respective concentrations in the ICF and ECF are known, with known values for their membrane permeabilities:
Goldman-Hodgkin-Katz equation
This could be said of the cell membrane of nerves or muscles during their “resting state”
polarized
The axon hillock, or initial segment of the axon of central or motor axons, (or 1st node of Ranvier of sensory neurons) are normally the regions where _______ are produced in neurons when threshold is reached.
Action potentials
What contributes to the upstroke phase of the nerve and skeletal muscle action potentials in typical cases?
A. Activation of voltage-gated Na+ channels
B. Ca++ influx
C. blockade of Cl- influx
D. K+ influx
A. Activation of voltage-gated Na+ channels
?-When the membrane is depolarized to threshold, a positive process produces an all-or- none upstroke of the action potential
?-The M-gates of the sodium channels open in response to initial depolarization, producing further sodium influx and greater depolarization (overshoot)
63. The peak voltage of a nerve action potential is closer to the equilibrium potential for: A. Na+ ions B. K+ ions C. Cl- ions D. none of the above
A
Example(s) of ligand-gated ion channels :
A. Ionotropic receptors
B. Ion channels which are activated by intracellular activation sites via metabotropic receptors
C. Nicotinic acetylcholine receptor
D. All of A, B and C
D
The plateau phase of the action potentials of certain cardiac muscle cells are due to:
A. Voltage-gated calcium channels and Ca++ influx
B. Leaky, non-gated Na+ channels with high permeabilities
C. Voltage-gated K+ channels and K+ efflux
D. Both A and C
D
Your dentist uses local anesthetics , like procaine, to block ________________ ion channels, thus preventing the conduction of action potentials along nerve fibers.
Voltage-gated sodium
Demyelination slows down or blocks nerve conduction velocity as:
it results in loss of saltatory conduction of action potentials
68. The formula for the length constant for a nerve tells us about influence of the following on nerve conduction velocity: A. Effect of membrane resistance (rm) B. Effect of axoplasmic resistance (ri ) C. Effect of membrane capacitance (Cm) D. Both A and B E. Both A and C
D
- What can immediately trigger muscle action potentials during normal, voluntary movements ?
A. End-plate potentials (EPPs)
B. Miniature endplate potentials (MEPPs) of about 0.3-0.5 mv
C. Excitatory post-synaptic potentials (EPSPs) in dendrites
D. Fibrillation potentials
A. End-plate potentials (EPPs)
- Activation of motor neuron causes a large, suprathreshold depolarization (EPPs) bringing the muscle fiber to an action potential threshold
?- Leads to excitation-contraction coupling and muscle contraction
- During the absolute refractory period, a nerve exhibits the following behavior:
A. Effect of membrane resistance (rm)
B. Effect of axoplasmic resistance (ri )
A. An action potential can be elicited with temporal stimulation.
B. A supranormal stimulus intensity can elicit another action potential.
C. A supranormal stimulus intensity cannot elicit another action potential.
D. An action potential can be elicited with spatial stimulation.
C. A supranormal stimulus intensity cannot elicit another action potential.
?-An action potential cannot occur because the sodium channels are inactivated by the h (inactivation) gates
- Why a new action potential cannot be produced during the absolute refractory period:
A. voltage-gated chloride channels have opened up
B. voltage-gated sodium channels have been inactivated by the h-gates
C. voltage-gated K+ channels are slowly opening up
D. Both A and C
B
- Not true of myelin’s contribution to the properties of the nerve membrane
A. increases membrane resistance
B. decreases membrane resistance
C. increases length constant (rm/ ri)
D. Increases conduction velocity via saltatory conduction
B. decreases membrane resistance
?-Myelin increases the membrane resistance and decreases the membrane capacitance
73. The neuro-muscular junction in skeletal muscles is an example of a/an: A. Excitatory synapse B. Electrical synapse C. Chemical synapse D. Both A and C E. Both A and B
D
- An irreversible acetylcholinesterase inhibitor may cause the following effect(s) on the neuro- muscular junction:
A. Rapid degradation of acetylcholine
B. A reduction in acetylcholine released into the synaptic cleft
C. Muscle twitching and/or paralysis
D. Block conduction of nerve action potentials
C. Muscle twitching and/or paralysis
?-If acetylcholinesterase is unable to breakdown or remove acetylcholine, the muscle can continue to move uncontrollably.Electrical impulses can fire away continuously unless the number of messages being sent through the synapse is limited by the action of cholinesterase
- Blocking K+ channels in the presynaptic motor nerve terminals innervating skeletal muscles will result in:
A. prolongation of duration of action potential, enhancing transmitter release
B. Rapid termination of the action potential
C. Shortening of duration of action potential (AP)
D. Hyperpolarization of neuronal membrane
A
76. Large metabolites, like cyclic AMP, and small ions can pass through: A. Chemical synapse B. Gap junction channels C. ion channels D. phospholipid bilayer
B. Gap junction channels
?-Allow substances to pass freely between cells without entering the ECF
- Electrical synapses, unlike chemical synapses :
A. allow bi-directional flow of signals .
B. have very fast signal transmission
C. have gap junctions
D. all of the above
D
78. Slow synaptic potentials are produced when neurotransmitters directly bind to: A. Ionotropic receptors B. G-protein coupled receptors C. nicotinic receptors D. Both A and C
B. G-protein coupled receptors
?-Activates or inactivates membrane-associated enzymes or channels
79. What is a common feature of inhibitory post-synaptic potentials and excitatory post-synaptic potentials ? A. Local graded responses B. depolarizations C. Hyperpolarizations D. “All-or-none” event
A - both
yung B at D, epsp yun
yung C, ipsp yun
80. Theoretically, EPSPs in neurons of the central nervous system will not be produced by: A. Increased Na+ conductance B. Decreased K+ conductance C. Increased Chloride conductance D. Increased Ca++ influx
C. Increased Chloride conductance
?-It only involves sodium, potassium and calcium conductance
81. True of acetylcholine in the neuro-muscular junction: A. produces slow synaptic potentials B. Activate non-gated ion channels C. activates an ionotropic receptor D. Mediate fast synaptic potentials E. Both C and D
E
- Neurotransmitter action can be terminated by the following, with the EXCEPTION of:
A. Enzymatic degradation
B. Diffusion away from synaptic cleft
C. Neurotransmitter absorption by post-synaptic cell to inactivate it
D. Neurotransmitter re-uptake mechanisms by pre-synaptic cell or glial cells
E. uptake of neurotransmitters by non-neuron cells in CNS - i.e. astrocytes
C
- The following is /are characteristic(s) of acetylcholine receptor activation in the specialized post- junctional membrane of the motor endplate region of skeletal muscle cells:
A. Allows for Na+ influx
B. Coupled to a G-protein
C. G-protein alpha- subunit activates adenylyl cyclase
D. Cyclic AMP, through a kinase, mediates phosphorylation of cation channel.
E. All of B, C and D
A. Allows for Na+ influx
?A high concentration of voltage-sensitive sodium channels is located in the sarcolemma of the junctional folds near the nicotinic receptor ion channels, making them sensitive to endplate depolarization
4. The neurotransmitter GABA (gamma-Aminobutyric acid)) can produce hyperpolarizing effects on the post-synaptic neuron by activating specialized membrane receptors which: A. Paralyze the sodium-potassium pump B. Increase K+ conductance C. Increase Cl- conductance D. Either A or B E. Either B or C
E
85. In Lambert-Eaton Myasthenic syndrome, an auto-immune disease, the following membrane channel proteins in the presynaptic nerve terminals are attacked by antibodies, impairing their function: A. Voltage-gated Cl- channels B. voltage-gated Na+ channels C. leaky, non-gated K+ channels D. voltage-gated Ca++ channels
D. voltage-gated Ca++ channels
? LEMS disrupts the normally reliable neurotransmission at the neuromuscular junction (NMJ). This disruption is thought to result from an autoantibody-mediated removal of a subset of the P/Q-type Ca2+ channels involved with neurotransmitter release.
86. Localized depolarization(s) along the sarcolemma (muscle cell membrane) arising from binding of acetylcholine molecules to the muscle nicotinic receptors: A. End plate potential B. Miniature endplate potential C. receptor potential D. Both A and B
D
87. This is a calcium sensor in the membrane of synaptic vesicles in pre-synaptic nerve terminals, which detects intracellular Ca++ increase that triggers exocytosis of neurotransmitters : A. Syntaxin B. synaptotagmin C. Snap-25 D. synaptobrevin
B. synaptotagmin
? Synaptotagmin is localized to synaptic vesicles and is the trigger for their calcium- induced exocytosis. The two C2 domains of synaptotagmin insert into the membrane upon calcium binding
- Nicotinic acetylcholine receptors in skeletal muscle cells are impaired under this condition:
A. Lambert-Eaton disease
B. Myasthenia gravis
C. Demyelinating disease
D. Exposure to procaine, lidocaine and local anesthetics
B. Myasthenia gravis
? In myasthenia gravis, antibodies block, alter, or destroy the receptors for acetylcholine at the neuromuscular junction, which prevents the muscle contraction from occurring
- Denervated skeletal muscles develop:
A. Fibrillation potentials
B. Fetal nicotinic acetylcholine receptors
C. Hyper-reflexia; Increased muscle tone,
D. Both A and B
E. Both B and C
D
90. In skeletal muscle tissue, the voltage-gated ion channels are in the sarcolemma in the vicinity of the motor endplate post-junctional nicotinic receptors, making it possible for these voltage-gated ion channels to open up to produce: A. Endplate potentials B. Action potentials C. Miniature endplate potentials D. Inhibitory post-synaptic potentials
B. Action potentials
? A high concentration of voltage-sensitive sodium channels is located in the sarcolemma of the junctional folds near the nicotinic receptor ion channels, making them sensitive to endplate depolarization
