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physio 1 premidterm
Terms in this set (80)
what are the functional units of the cell membrane?
phospholipids, sphingolipids, and cholesterol
what is the role of cholesterol in the cell membrane?
stabilization and stiffening
how do neighboring cells connect to each other?
by attachment between membrane proteins
what can easily pass through the cell membrane?
water, CO2, and small molecules
why are there no strong chemical bonds between phospholipids?
maintains fluidity of membrane and allows for spontaneous repair
why is permeability selective? give an example
it is crucial to the function of the cell because it controls what enters and prevent valuable substances from leaving
what is the main difference between active and passive transport?
active: requires energy - moves against gradient
passive: does not require energy - moves towards the gradient
what affects the diffusion rate?
area, diffusion coefficient, thickness of membrane
what is the diffusion coefficient?
how permeable the membrane is for a specific molecule
can osmosis be stopped?
yes, by applying pressure (osmotic pressure)
how does filtration occur?
by exceeding osmotic pressure
why does the membrane potential exist?
the charge on the inside is opposite of the charge on the outside
compare and contrast facilitated diffusion
pro: faster in moving ion across membrane
con: membrane carrier protein can become saturated
at resting membrane potential, where is sodium the highest?
outside of the cell
at resting membrane potential, where is potassium the highest?
inside of the cell
what creates the electrical gradient?
the difference between the negatively charged inner membrane and the positively charged outer membrane
which ion channel maintains electrical potential during resting conditions?
how are ions actively transported?
through an ATP pump
what is the best example of active transport?
Na K ATPase pump
what gradient does the secondary active transport use?
the sodium gradient created by the Na K ATPase pump
what is resting membrane potential?
what is the electroneutrality principle?
the number of positive and negative charges in the ICF and ECF are equal
why is the sodium/potassium pump considered electrogenic?
its leaves the inside of the cell less positively charged than the outside of the cell - creates the membrane potential
which ion has a voltage closest to resting membrane potential and contributes the most to maintaining the gradient?
what structures aid the neuron in receiving and sending messages?
dendrites = receiving
axons = sending
what are the three different types of neurons?
what is responsible for converting mechanical events into electrical events?
what are the types of sensory receptors?
why are encapsulated nerve endings able to respond to a lower stimulus?
they have increased sensitivity to pressure
how does myelin affect the speed of conductivity?
more myelin = faster conductivity
why is saltatory conduction faster than continuous conduction?
because the current jumps from a depolarized node of ranvier to the next node of ranvier that has not yet been depolarized and skips over the membrane that is insulated by a schwann cell
if the diameter of the axon is large, is the current fast or slow?
if the resistance is low, is current faster or slower?
if the diameter of the axon is smaller, what happens to the resistance and current?
the resistance would be higher and the current would be slower
what are the two types of synapses and what are the differences?
electrical = no neurotransmitters and using gap junctions
chemical = uses a neurotransmitter
what ions are moving through channels and what happens to the cell during an inhibitory stimulus?
potassium leaves and chloride enters
cell hyperpolarizes therefore there is no AP
how is the nervous system divided?
CNS and PNS
how is the PNS divided?
sensory and motor
how is the motor nervous system divided?
somatic and autonomic nervous system
what does the somatic and autonomic nervous systems control?
somatic = movement of skeletal muscles
ANS = glands, heart, and smooth musculature
how is the ANS divided?
parasympathetic and sympathetic
what do the parasympathetic and sympathetic nervous systems control?
parasympathetic = rest and digest
sympathetic = fight of flight
what are ganglia?
bodies of sensory neurons
which part of the ANS has longer preganglionic fiber?
how are the parasympathetic and sympathetic nervous systems complementary?
they balance each other and work towards reaching homeostasis
where is the origin of the sympathetic ganglia?
thoracolumbar intermediolateral neurons
where is the origin of the parasympathetic ganglia?
craniosacral (brain stem)
true or false: in the parasympathetic division, pre and post ganglionic neurons are cholinergic because they release acetylcholine
what are the receptors found at the parasympathetic ganglion and effector ganglion?
ganglion synapse = nicotinic
effector synapse = muscarinic
in the sympathetic division what are the receptors in the ganglion synapse and the effector synapse?
ganglin synapse = cholinergic
effector synapse = adrenergic
what type of receptor does noreprinephrine bind to?
it binds better to an alpha receptor (of the adrenergic receptor)
what type of receptor does epinephrine bind to?
it binds better to a beta receptor (of the adrenergic receptor)
what is a reflex?
an involuntary sequential process as the result of an adequate stimulus to an effector organ
what is a monosynaptic reflex?
the simplest reflex that only contains two neurons
what is a polysynaptic reflex?
a reflex that involves more than two neurons
what is a proprioceptive reflex?
aka idioreflex - the source organ and the target organ are identical
what is an extrinsic reflex?
the source organ and the target organ usually differ, but may be identical in some cases; it is always a polysynaptic reflex
how is a monosynaptic reflex conducted?
a sensory receptor is stimulated in the muscle -> AP are conducted afferently to the CNS -> AP is transmitted by alpha motor neuron and efferently to the same muscle
what is the smallest functional unit of contraction in a muscle?
which ion is the key factor to develop contraction?
where is calcium stored in the skeletal muscle?
what are t-tubules?
extensions of the cell membrane that help with excitability
what are the different bands of the sarcomere and what do they contains?
I band = thin (actin) filaments
A band = thin and thick filaments
H zone = thick (myosin) filaments
under resting conditions in the skeletal muscle, why can't actin and myosin interact?
tropomyosin is blocking the active site for myosin to bind to actin
what contributes to the longer/wider AP in cardiac muscle?
influx of calcium from ECF
why is there a delay between the excitation and the mechanical contraction in skeletal muscle?
there is an influx of calcium into the cell and it takes some time
what is the difference between calcium release in cardiac muscle vs skeletal muscle?
cardiac muscle = calcium induced calcium release
skeletal muscle = T-tubule stimulates L-system release of calcium
what is the motor end plate?
synapse connecting motor neuron and skeletal muscle fiber
why is the heart a functional syncytium?
because all muscle cells are electrically connected to their neighboring muscle cells and acts a single unit = one AP depolarizes the entire the syncytium
how are smooth muscles contracted?
triggered by influx of calcium from ECF and the dense body organizes the arrangement of thin filaments
what is isometric contraction?
length = constant
tension = changes
what is isotonic contraction?
length = changes
tension = constant
what is auxotonic contraction?
both length and tension change
what is active tension?
determined by the number of actin and myosin cross bridges
what is passive tension?
developed when the muscle is stretched in the resting state and determined by the elastic component
what is summation of twitches in the skeletal muscle?
there is not enough time for the muscle fiber to relax because the other AP arrives already and there is a further shortening of the muscle fiber
what is a tetanus of the skeletal muscle?
twitches fuse and cause maximal contraction because the frequency of AP is so high
what kind of response does the skeletal muscle has to an increase strength of stimulus?
it is a graded response
why can't the myocardium develop a tetanus?
because the absolutely refractory period is very long
what is the relationship between duration cardiac muscle contraction and duration of action potential?
they are equal because contraction begins when AP begins and ends when AP ends
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