There are no comments, be the first and leave one below:
Hormones:
are chemical regulators that are conveyed from one organ to another via the blood stream
act only on target cells
all of the above
may be secreted by endocrine glands
may be secreted by nerve cells
For an action potential to occur
The cell membrane must be out of the relative refractory period
Cl- influx must exceed K+ efflux
The cell membrane must be in absolutely refractory period
K+ influx must exceed Na+ efflux
the stimulus must reach or exceed threshold
During the rising phase of the action potential
voltage-gated Cl- channels apex
voltage-gated Na+ channels open
voltage-gated Na+ channels close
voltage-gated K+ channels close
voltage-gated K+ channels open
The concept of homeostasis
refers only to the regulation of body temperature
refers to maintaining a stable external environment
refers to maintaining physiological functions in a stable condition
refers to the unwavering control of a physiological set point
refers to the 'all-or-one' law
The plasma membrane
may contain proteins, which confer iron permeability
may burst in hypotonic extracellular solutions
can generate action potentials in excitable cells
is permeable to lipophilic molecules
Overcooling the nerve will cause
increase of the excitability
increased release of neurotransmitters
increase of the liability
increase of the threshold
decrease of the threshold
The properties of local response:
excitability is decreased
summation
without energy consumption
transmission with energy consumption
'all-or-none’ law
A “less negative" membrane potential means:
slight depolarization
the resting membrane potential is closer to the sodium equilibrium
it is closer to zero mV
it is “more positive” than the resting potential
The membrane of a typical resting neuron is largely impermeable to
Cl-
K+
Ca2+
Na+
none of the above
The ion with the lowest intracellular concentration is:
HCO3
Mg2+
The most common intracellular cation is:
phosphorus
magnesium
potassium
sodium
calcium
What is the normal pH value of body fluid?
7.35-7.45
6.5-7.5
7.55-7.65
7.00-7.35
7.15-7.25
Which of the following requires energy?
Osmosis
Active transport
Facilitated diffusion
Filtration
Diffusion
Which of the following is not found in the cell membrane?
Proteins
Galactose
Phospholipids
Cholestrol
Nucleic acids
The local response is:
A potential that is generated as a result of the action of a superthreshold stimulus and could be registered only at the site of irritation
A potential that is generated on the postsynaptic membrane as a result of the action of a mediator
A potential that is generated as a result of the action of a subthreshold stimulus and could be registered only at the site of irritation
A potential that is generated as a result of the action of a subthreshold stimulus and propagated along the nerve cell membrane
A potential that is generated as a result of the action of a superthreshold stimulus and propagated along the nerve cell membrane
The oculocardiac reflex is an example of:
soma-visceral reflex
viscera-visceral reflex
viscera-somatic reflex
soma-somatic reflex
integrated conditioned reflex
Norepinephrine is a neurotransmitter with the highest affinity to:
β-adrenergic receptors
α- and β-adrenergic receptors
M-choline receptors
α-adrenergic receptors
N-choline receptors
The parasympathetic post-ganglionic neurons of the ANS secrete
L-DOPA
Epinephrine (80%) and nor-epinephrine (20%)
Nor-epinephrine (98%) and epinephrine (2%)
Nor-epinephrine (2%) and epinephrine (98%)
Acetylcholine
The critical (firing) level of depolarization is
a degree of depolarization of the excitable membrane at which its intensity does not depend on irritant action
a level of AP at which depolarization goes into repolarisation
a degree of depolarization of the nerve cell membrane at which its sources of energy are completely exhausted
a degree of depolarization of the postsynaptic membrane at which further action of the neurotransmitter is abolished
a level of AP at which repolarization goes into depolarization
A structure that permits a neuron to pass an electrical or chemical signal to another cell (neural or otherwise) with excitatory or inhibitory effects is called:
Golgi apparatus
juxtaglomerular apparatus
synapse
modulator
intercalated disc
H1 receptors are situated an the smooth muscle cell membrane of the:
bronchi
blood vessels
gastrointestinal tract
uterus
urinary tract
The adrenergic effect an the cardiac conduction system and working myocardium is exercised by affecting:
α2 receptors
α1 receptors
β2 receptors
β1 receptors
The parasympathetic spinal centers, regulating the reservoir functions, are situated in the following
Th1-Th8
Th10-L2
S2-S4
L2-L4
C8-Th1
Facilitated diffusion is a mechanism:
For transporting lipid soluble substances through the membrane
That works with the help of a carrier in the membrane
Connected with loss of energy
Connected with membrane polarity
For transporting substances against their concentration gradient
A distinguishing feature of the membrane potential at rest is:
the small difference between the equilibrium potentials for Na+ and K+ ions
low permeability for Na+ and high for K+ ions
low permeability for Na+
low permeability for Cl- ions
high permeability for K+ ions
Acetylcholine is a neurotransmitter which has:
always an inhibitory effect on the postsynaptic membrane
always an excitatory effect on the postsynaptic membrane
no effect on the postsynaptic membrane
excitatory or inhibitory effect on the postsynaptic membrane depending on the type of receptors
excitatory or inhibitory effect depending on the amount released
The common expression of excitation is:
nerve cell conduction and excitation
membrane transport
glandular cell secretion
the action potential
muscle cell contraction
Curare is a substance that blocks
N-choline receptors in neuromuscular synapses
all types of cholinoreceptors
An example of a ligand dependent membrane is
the nodes of Ranvier
the skeletal muscle cell membrane
the axon membrane
the postsynaptic membrane
the axon hillock
Throughout the relative refractory period:
the excitability is equal to that at rest
the excitability is lower than that at rest
the excitability is higher than that at rest
the excitability becomes equal to zero
accommodation occurs
Na/K pump is called electrogenic, because:
exports equal amount of Na+ and K+
imports equal amount of Na+ and K+
exchanges equal amount of Na+ and K+
the exchanged amount of Na+, and K+ is not equal
The conditioned reflexes are:
formed on the basis of unconditioned reflexes
inborn
typical of the species
permanent
Which of the statements is not true:
when there is continuous excitation at a synapse, fatigue occurs
the velocity of transmission of excitation is higher at the chemical synapses than at the electrical ones
at most of the electrical synapses transmission is two-way
the velocity of transmission of excitation is greater at the electrical synapses than at the chemical ones
at the chemical synapse transmission of excitation is one way
Which is the basic inhibitory neurotransmitter in CNS:
Substance P
GABA
Glutamate
Nitric Oxide
Neuropeptide 4
The basic factor for the ion asymmetry on both sides of the excitable membrane is
Na+ pump and the low permeability for Na+
Iodine pump
Ca++ pump and the low permeability for Na+
K+ pump and the high permeability for Na+
Na+/K+ pump and the low permeability for Na+
The velocity of AP propagation along the axon membrane depends on:
the direction of its propagation
the duration of irritation
the cross sectional area of the axon
the threshold
the strength of irritation
The sympathetic postganglionic neurons secrete:
acetylcholine
epinephrine (20%) and norepinephrine (80%)
norepinephrine (98%) and epinephrine (2%)
norepinephrine (2%) and epinephrine (98%)
The result of activated α1-adrenergic receptors is:
constriction of the vessels smooth muscle
relaxation of the gastrointestinal tract smooth muscles and contraction of the sphincters
dilation of the vessels smooth muscle and relaxation of the uterus
increased heart rate
The result of activated α2-adrenergic receptors is:
Protein synthesis occurs at the
lysosomes
within the nucleus
ribosomes
vacuoles
mitochondria
During repolarization of the cell membrane:
Na+ move inside of the cell
Cl- move outside of the cell
Na+ move outside of the cell
K+ move outside of the cell
K+ move inside of the cell
In a cell, movement of molecules from an area of low concentration to an area of high concentration:
uses facilitated diffusion
requires cellular energy
requires both cellular energy and facilitated diffusion
uses its concentration gradient to move
is passive transport
Movement of solvent and dissolved substances across a cell membrane by hydrostatic pressure is:
simple diffusion
filtration
facilitated diffusion
active transport
osmosis
The substance acetylcholine (ACh) is released from synaptic vesicles by the process of:
passive transport
phagocytosis
endocytosis
exocytosis
Cell membranes
are formed entirely by protein molecules
are not changed throughout life
are permeable to water soluble substances
are impermeable to fat soluble substances
in some tissues permit transport of glucose at a greater rate in the presence of insulin
Proteins that are secreted by cells are generally:
synthesized in the lysosomes
synthesized in the mitochondria
packed in the Golgi apparatus
not synthesized on ribosomes that are bound to endoplasmic reticulum
across the cell membrane by endocytosis
The unique feature in mitochondria is:
myosin
DNA
haemoglobin
prothrombin
actin
The resting membrane potential of a cell:
is equal to the equilibrium potential of Cl-
is equal to the equilibrium potential for K+
is equal to the equilibrium potential of Na+
falls to zero if Na+/K+ ATPase in the membrane is inhibited
is dependent on the permeability of the cell membrane to K+ being greater to Na+
Many substances are removed from the cell to the outside by:
chemotaxis
pinocytosis
An example of co-transport is:
Ca++ pump
Na+ glucose transport
Na+-K+ pump
Na/Ca pump
Na+-H+ pump
Mitochondria:
are the chief site for protein synthesis
are absent near the membranes of actively secreting cells
are the chief sites for generation of ATP
are more numerous in white than in brown fat cells
are the Chief site for lipid synthesis
The endoplasmic reticulum:
has a membrane structure similar to the cell membrane
is a complex system of intracellular tubules
is associated with ribonucleoprotein
is well developed in secretory cells
The mammalian cell membrane:
consists mainly of protein
contains the receptors for steroid hormones
contains enzymes DNA
is more permeable to fat- than to water-soluble particles
is seen as an optically dense line using light microscopy
Membrane ion channels:
remain open as long as the activating signal is present
have a specific structure for each ion species
consist mainly of lipids
for sodium may be blocked by tetrodotoxin
consist mainly of carbohydrates and lipids
The speed of conduction of a nerve impulse can be determined by which of the following factors? 1. temperature 2. diameter of axon 3. stimulus frequency 4. myelin sheath; 5. stimulus strength
3 and 1
1, 2 and 3
1,3, 5 and 4
3 and 2
4, 2 and 1
The junction between one neuron and the next, or between a neuron and an effector is called:
a ventricle
a dendrite
a neurotransmitter
a synapse
Which of the following blocks acetylcholine receptor sites causing muscle relaxation?
nicotine
novocain
nerve gases
curare
carbon monoxide
Transmission across a synapse is dependent on the release of?
neurons
neurotransmitters
receptor proteins
synaptic vesicle
hormones
Saltatory conduction:
is faster than non-saltatory conduction in nerve fibres with diameters around 10 μm
all of them
transmits impulses with a velocity proportional to fibre diameter
has a slower velocity in cold than in warm conditions
occurs only in myelinated fibres
An action potential in a nerve fibre:
is associated with a transient decrease in membrane permeability to potassium
has an amplitude which varies directly with the strength of stimulus
induces local response
is associated with a transient increase in membrane permeability to sodium
occurs when its membrane potential is hyperpolarized to a critical level