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149 Cards in this Set
- Front
- Back
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What are the presynaptic components of a chemical synapse?
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Quantal transmitter release
Synaptic vesicle exocytosis Voltage gated Ca++ |
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During chemical synaptic transmission, what will produce excitation of the postsynaptic neuron?
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Decreased conductance of potassium ions (if open would flow out)
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Synaptic delay at chemical synaptic junctions is primarily a function of
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The time for neurotransmitter to diffuse across the synaptic cleft
(as opposed to latent period - Ca++ diffusing from lateral cisterna to A band) |
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Characteristics of electrical synapse.
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Bidirectional
Pre- and postsynaptic ion currents |
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Which type of junctions are characteristic of the electrical type synapse?
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gap junctions
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What is a property of electronic potentials along an axon?
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Has graded amplitude (not all or none)
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What are some characteristics of electrical type synapses?
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gap junctions
bilateral no delay presynaptic and postsynaptic currents |
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examples of bioelectrical signal
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inhibitory postsynaptic potentials
end plate potentials receptor potentials |
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What are some characteristics of muscle end plate?
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End plate potential is partially determined by the passive properties of the muscle
The reversal potential for the EPP is about 0mV Curare will block the ACh binding sites on the end plate The end plate potential is due mainly to the influx of Na An EPP is normally suprathreshold |
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What are some characteristics of miniature end plate potentials (MEPP)?
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Have fixed quantized potentials
Can occur spontaneously Are less than 1mV Summate to form EPP |
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At the neuromuscular junction, the voltage gating of which ions contribute to the post synaptic action potential?
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K
Na (**not Ca - presynaptic) |
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Where are multiunit smooth muscles found?
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piloerector muscles
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Smooth muscle cells that contract without any change in Vm utilize what?
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Binding to receptor activates G protein
Intracellular IP3 genterated Ca released form sarcoplasmic reticulum |
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What is the principal Ca binding protein in skeletal muscle?
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Calsequestrin
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Describe the mechanism by which muscle length influences tension.
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Degree of actin to myosin filament overlap
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What is a property of slow twitch?
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High mitochondria content
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Name properties of excitation coupling in skeletal muscle.
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Activation of L-type Ca channels
Depolarization of T-tubule membrane L-type Ca and Ca release channel coupling |
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What regulates strength of cardiac muscle contraction?
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Ca influx via L-type Ca channels
Norepinephrine increase in cAMP Altering Ca sensitivity of regulatory proteins |
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Describe initiation of cross-bridge cycling.
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Phosphorylation of myosis light chain
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Which motor unit type plays an important role in maintaining upright posture?
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slow motor
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Slow motor units produce (less/more) overall force than other motor units.
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less
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Norepinephrine is removed mainly from the terminals of adrenergic nerve fibers by:
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destruction of catechol-o-methyl transferase
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The slowest response of vascular smooth muscle contraction when stimulated by postganglionic sympathetic stimulation is controlled by which neurotransmitters?
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Norepinephrine
Neuropeptide Y (**not ACh) |
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What produces the "fastest phase" of vascular smooth muscle contraction when stimulated by postganglionic sympathetic neurons?
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ATP release
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Contractions in which the length of the muscle is unchanged is...
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isometric contraction
possible because the series elastic components allow sarcomere shortening without change in overall muscle length. (**not isotonic contraction) |
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Smooth muscle contraction may result from and interaction of calmodulin-4Ca what?
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ATP-kinase in the myosin heads
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Which muscles contract as syncytium?
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smooth muscle, cardiac muscle
(**not multiunit smooth muscle or skeletal muscle) |
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The level of contraction of muscle bundle to increase work output can be achieved by:
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temporal summation
spatial summation preloading the muscle |
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During contraction ____ band remains the same length, and others can shorten and lengthen.
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A
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The monosynaptic reflex DOES NOT require:
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Golgi tendon organs
(**does require Group Ia muscle afferents, primary endings on muscle spindles, alpha motor neurons, Ach) |
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What neurotransmitter is released from nerve terminals of alpha motor neurons?
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ACh
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What is the walk along theory?
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Movement of actin is powered by ATP release
Binding of ATP releases myosin from actin |
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Order for skeletal muscle contraction...
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a. Depolarization of presynaptic terminal
b. End plate potential c. Muscle action potential in T-tubule d. Depolarization of cisternae of sarcoplasmic reticulum e. Calcium released from sarcoplasmic reticulum |
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During skeletal muscle contraction, the total isometric stress is:
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greater than the passive stress at any length
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Angiotensin and epinephrine cause smooth muscle ____.
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contraction
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Single unit type smooth muscle is joined by what kind of junction?
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gap junction
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In smooth muscle cells, what is the source of calcium ions which activate the cross bridge cycle?
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sarcoplasmic reticulum, extracellular fluid
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Relaxed skeletal muscle has ____ elastic component.
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one
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Which shortens a far greater percent of length during contraction, smooth muscle or skeletal muscle?
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smooth
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In skeletal muscle the ATPase activity is located on what molecule?
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Heavy chain of myosin molecule.
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Smooth muscle relaxation requires...
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myosin phosphatase
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What causes smooth cell relaxation?
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Excessive CO2
(nor)Epinephrine Angiotensin Hypoxia |
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What is shared by both multiunit and visceral type smooth muscle?
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Dense bodies
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What disease causes Na channel mutation?
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Generalized epilepsy with febrile seizures
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What disease is caused by Ca channel mutation?
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Familial hemiplegic migrane
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What drug selectively blocks K current in nerve membranes?
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Tetraethylammonium
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What drug selectively blocks Na current in nerve membranes?
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Tetrodotoxin
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What ion is released from cells following tissue damage?
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K
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Stimulation of which brain regions can produce analgesia?
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Periaqueductal gray mater
Rostral medulla |
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Cause of Parkinson's Disease...
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Dopaminergic neurons degenerate
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Parkinson's symptoms
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tremor at rest
bradykinesia |
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Huntington's Disease
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Thalamic excitation
Reduced inhibitory outflow from basal ganglia hyperkinetic |
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Characteristics of cerebellar lesions?
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degeneration of anterior cerebellar cortex
damage effects lower limbs (**not hypokinesia or rapid jerky movements) |
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Slowing adaptive receptors provide ____ information.
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predictive
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Ionotropic GABA receptors
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usually inhibitory
associated with Cl ion channels Binding sites of barbiturates and steroids |
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NMDA Glutamate receptors
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Allow entry of Ca as well as Na/K
Requires presence of co-agonist (glycine) Blocked by M2 at hyperpolarized voltages |
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Light photon absorption cause pigment conversion to all ____ ____.
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trans retinal
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What is typically active at the skin temperature of 20 degrees C?
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Cold (24-48)
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Maximum firing rate for cold receptors in the skin occurs at what skin temperature?
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27 degrees C
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Which fiber innervates the annulospiral nerve endings in the spindle receptors?
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Ia
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B-alpha fibers are the most susceptible to ____.
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hypoxia (most myelinated)
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Which fibers are the least susceptible to hypoxia?
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C
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Which fibers conduct pain sensation?
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C and A-delta
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Which peripheral nerve fiber has the highest threshold?
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C-Type motor neurons
(**note, large myelinated = low threshold, small unmyelinated = high threshold) |
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What is the response of the Ia afferent during the contraction of skeletal muscle if its gamma motor nerves are damaged?
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decreased impulse activity
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Which receptor is efficient in mainly detecting low frequency vibrations?
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Meissner's corpuscles
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Which receptor is slowly adapting?
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Golgi Tendon Organ
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Golgi Tendon Organs are innervated by type ____.
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Ib
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Concerning Golgi Tendon Organs, afferent firing increases during ____ muscle stretch.
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passive
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Which sensory receptor is responsible for stimulating feedback inhibition on skeletal muscle contraction?
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Golgi tendon reflex (tension)
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Activation of the Golgi Tendon Organ produces inhibition of what?
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The alpha motor neurons innervating the same muscle.
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Which somatic sensory receptor has a high threshold of activation?
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free nerve endings (hardest to stimulate)
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Where are receptors for detecting rotational acceleration of the body?
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ampullae
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Where are receptors for angular acceleration of the body?
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ampullae
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What are some characteristics of cholinergic neurons?
(in regards to where they are found in symp/para systems) |
All sympathetic preganglionic neurons are cholinergic.
All parasympathetic preganglionic neurons are cholinergic. (**not true? Not all sympathetic postganglionic are cholinergic) |
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Postganglionic parasympathetic neurons release neurotransmitter that binds to which receptor type?
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Muscarinic cholinergic receptors.
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Where are Beta-2 adrenergic receptors found?
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bladder wall muscle, vascular smooth muscle
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The dilation of coronary arteries is stimulated by which receptors on the vascular smooth muscle?
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Beta 2
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Isoproterenol excites mainly ____ receptors.
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beta
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Indirect pathway through basal ganglia.
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Projects to external segment of the globus pallidus
Modulates the disinhibitory actions of the direct pathway Acts as a break on the direct pathway |
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Which is part of the direct pathway in the motor loop that passes through the basal ganglia?
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caudate putamen
globus pallidus internal segment VA/VL complex of thalamus |
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What provides the main output from the basal ganglia complex?
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Globus palidus
Substantia nigra pars reticulate (**not supthalmic nucleus) |
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What is characteristic of stage 4 sleep?
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EEG with delta waves
deepest stage of sleep (**not sleep spindles, drowsiness) |
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Which neurotransmitters are active in brainstem neurons during wakefulness?
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ACh
Norepinephrine Orexin |
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What frequency characterizes delta rhythm in the EEG?
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.5-2 Hz
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In humans, what modulates the brainstem circuits that govern sleep-wake cycles?
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Pineal gland
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Which brainstem neurons are responsible for activating the state of nonREM sleep?
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Raphe nuclei
Locus coeruleus Pons-midbrain junction cholinergic nuclei |
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Transmitter substance histamine has its action by which signal transduction pathway?
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Arachidonic acid cascade
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Muscarinic neurotransmission
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Release stored Ca
Stimulates IP3 production Causes dissociation of G protein |
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Horizontal gaze center is located where?
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Paramedian pontine reticular formation
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What plays a major role in error correction of complex voluntary movements?
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cerevrocerebellum
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Glucose molecules are transported across membranes by
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secondary active transport
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An accident resulting in hemisected spinal cord on the left side can result in...
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Reduced two-point discrimination on the left side
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What is the predicted effect of sudden increased concentration of extracellular potassium surrounding an axon?
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nerve cell depolarization
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Characteristics of presynaptic inhibition
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Occurs at axo-axonic synapse
Inhibitory effect can last for at least seconds Produces a decreased calcium ion current into the presynaptic terminal |
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Properties of peptide class neurotransmitters
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transmitter synthesized in inactive form
transmitter released into synaptic cleft |
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Which transmitter brainstem nuclei systems are responsible for REM sleep "on" stage?
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Raphe nuclei releasing serotonin
Cholinergic nuclei of pons-midbrain junction releacing acetylcholine |
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The paralysis of large muscles during REM stage sleep is due to increased activity of ____ ____ in the reticular formation.
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GABAnergic neruons
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Sleep spindles occur in the EEG of which stage?
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Stage 2
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What kind of movement is saccades eye movement?
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balistic movment
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Contraction of the ciliary muscle in the eye does what to lens thickness?
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increases lens thickness
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How is intraocular fluid produced?
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produced by ion transport and ultrafiltration
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What is the effect of cold water irrigation of the left ear?
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?Afferent fibers from the left horizontal duct show decreased firing
Afferent fibers from the right horizontal duct show increased firing (**no nystagmus) |
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What is the effect of warm water irrigation of the right ear?
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Afferent fibers rom the right horizontal duct show increased firing.
Eye movements consist of a slow movement away form the warm irrigated ear Eye movements consist of a fast movement toward the warm irrigated ear |
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Describe the vestibular nerve activity when the head is upright in static position.
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steady at moderate firing rate
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Name three movements of the eye
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saccade
vergence smooth pursuit |
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What occurs when light energy is absorbed by rhodopsin in the outer segment of the retinal rods?
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closing of membrane sodium channels
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The cochlear apex is tuned for ____ frequencies
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low
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The most direct route of info flow from photoreceptor to optic nerve includes which cell type?
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bipolar
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In the retina, the off-center bipolar cells habe receptors for which neurotransmitter?
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glutamate
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Describe synaptic inhibition
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Inhibitory synapses ned not produce hyper IPSP3
Depolarizing IPSPs can inhibit postsynaptic membranes Purves pg 114 discusses inhibitory synapses |
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Characteristics of IPSP
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Produced by glycine
Subthreshold potentials Can be summated on postsynaptic membrane |
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What protein is involved with endocytotic budding of vesicles in presynaptic terminals?
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clatherin
(**not syneptobrevin, syntaxin, SNAP-25) |
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Excessive production of what neurotrasmitter can excite neurons to death?
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glutamate
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What has been observed as mechanisms by which neurotransmitter substance can activate the postsynaptic neuron?
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Increased formation of cAMP
Activation of cellular genes Activation of protein kinase |
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In a neuron, as the extracellular concentration is decreased, what happens to the amplitude of the action potential?
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Decreased amplitude of action potential
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The Goldman, Hodgkin-Katz Equation allows one to calculate resting cell membrane potential from what?
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Concentration gradient
Membrane permeability (**not osmotic pressure) |
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Fick's law of diffusion describes the relationship between net rate of diffusion by a substance and ...
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Solute concentration gradient
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In a biological system, the distance that an average molecule can diffuse in time:
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Einstein relationship
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How do amino acids move into most cells?
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sodium co-transport
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Electrogeneisis contributes ____ to resting membrane potential.
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10mV
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What are the effects of anoxia?
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Ion gradients across membrane decreased
Potassium ions accumulate in extracellular spaces Inability to generate action potentials |
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Properties of synaptic potentials
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Due to sequential gating of Na and K
Ion channels opened by depolarization |
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Human sensory system...
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Second order neurons project to the thalamus in the CNS sensory pathway
The somatic senses are served by both the PCML and ALS within the CNS Senses may have several sensory modalities |
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Highes Na conductance is when?
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when you hit threshold
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Highest K conductance is when?
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At the peak of action potential
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Characteristics of Na/K pump.
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Actively contributes to the resting potential for smooth muscle
Transports 3Na out and 2K in Inside of most carrier proteins exhibits ATPase activity |
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What are mechanisms by which a neurotransmitter substance can activate the postsynaptic cell?
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Increase formation of cAMP
Activation of G proteins Activation of protein kinase C |
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Nerve excitation...
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Axonal membranes of initial segment have high density of voltage gated sodium channels
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Increase in gK would ____ an axon membrane
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hyperpolarize
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Increase in gNA would ____ an axon membrane.
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depolarize
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What type of current occurs at the nodal region of myelinated nerves during saltatory conduction?
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Resistive current
Capacitative current |
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What is due to non-gated channels?
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Resting membrane potential (K)
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Postsynaptic inhibition may occur from
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an increase in gK
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Increase in gK would ____ an axon membrane
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hyperpolarize
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Increase in gNa would ____ an axon membrane
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depolarize
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myelinated nerves exhibit ____ length constants
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large
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What can increase neuronal activity by increasing excitability?
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alkalosis
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Caffeine decreases neuronal ____.
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thresholds
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Acidosis decreases neuronal ____.
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activity
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Presynaptic inhibition occurs at what kind of synapse?
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Axo-axonic
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Sexual sensation is conducted to the brain via which system?
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ALS
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What is used by multisegmental reflexes in the spinal cord?
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propriospinal tract
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Cerebellar purkinje cells recieve excitation from ____ ____ and ____ ____.
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climbing fibers and granule cells
(**Purkinje cells do not release ACh and do not excite deep nuclei cells) |
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What can lead to closure of sodium channels in the outer segment of a rod during light stimulation?
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Decrease in cGMP concentration.
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Cable properties of nerve cell membranes...
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electrical conduction, local response, length constant, passive properties
(**not all or none) |
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What best explains the mechanisms by which ion channels in the nerve membrane exhibits selectivity for K ions?
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Potassium ion channels are lined by hydrophilic amino acid residues.
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Chronaxie, postsurgically.
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gradually decreasing chronaxie
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Hyponatremia (decreased Na levels) of the interstitial fluid surrounding nerves should have what effect?
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Decreased peak amplitude of the action potential.
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