Item 8 Flashcards
REad page 238 (pupillary light reflex), 304-19, 326-334, 336-37
ok
27
The autonomic nervous system is responsible for the dual _, and maintenance of homeostasis for smooth muscle
innervation
T or F: nearly all organs are impacted by the ANS
true
ANS are fast/slow
fast, to minimize homeostatic errors
The _ and _ activities are the dual innervation systems (impacting most organs, regulating them to maintain homeostasis) which oppose each other
parasympathetic;
sympathetic
Two types of neurons from cns TO EFFECTOR ORGANS: _ganglionic and _ganglionic
pre;
post
_ ganglia communicate from pre- to post-ganglionic neurons
autonomic (cardiac, gland, smooth, even adipose tissue)
The _ganglionic neurons are in the CNS, either the brain stem or spinal cord
pre-
Two neurotransmitters of the ANS is _ and norepinephrine (although the most common is the first)
acetylcholine
The signal transduction mechanisms for the different classes of adrenergic receptors are all - receptors that either activate or innervate second messenger systems
G-protein
The NTs used by the preganglionic neurons for the para- and sympathetic systems are ACETYLCHOLINE/NOREPINEPHRINE as well as for the parasympathetic postganglionic neurons. However, the sympathetic postganglionic neurons use ACETYLCHOLINE/NOREPINEPHRINE
acetylcholine;
norepinephrine
The para- and sympathetic nervous systems innervate and are opposing forces on _ _
effector organs
The sympathetic nervous system uses ADRENERGIC/CHOLINERGIC preganglionic neurons with MUSCARINIC/NICOTINIC cholinergic receptors, and then ADRENERGIC/CHOLINERGIC postganglionic neurons with adrenergic receptors that innervate effector organs
cholinergic;
nicotinic;
adrenergic
The PARAsympathetic nervous system uses ADRENERGIC/CHOLINERGIC preganglionic neurons with MUSCARINIC/NICOTINIC cholinergic receptors, and then ADRENERGIC/CHOLINERGIC postganglionic neurons with MUSCARINIC/NICOTINIC cholinergic receptors that innervate effector organs
cholinergic;
nicotinic;
cholinergic;
muscarinic
Nicotinic receptors are ionotropic, causing cation channels to _, resulting in _polarization
open;
depolarization
_ cholinergic receptors are metabotropic, G-protein-coupled, with effect depending on the effector organ
Muscarinic
It is the NEUROTRANSMITTER/RECEPTOR that determines the effect, and not the NEUROTRANSMITTER/RECEPTOR, such as the case of muscarinic cholinergic receptors’ effect depending on the effector organ’s NEUROTRANSMITTERS/RECEPTORS
receptor;
neurotransmitter;
receptors
In the _ nervous system, the preganglionic cholinergic neuron releases acetylcholine to the nicotinic cholinergic receptor of the postganglionic adrenergic neuron, which then releases _ to an adrenergic receptor of an effector organ
norepinephrine
Adrenaline is he same as _
epinephrine
Nearly all organs are innervated by the _ system/s
para- and sympathetic NS
In the _ NS, preganglionic neurons are located in the thoracic and upper lumbar regions of the spinal cord
sympathetic
The autonomic ganglia of the _ NS are linked together in the _ chain
sympathetic;
sympathetic
The sympathetic chain is located close to the spinal cord, meaning the _ganglionic neurons of the sympathetic NS have a relatively short axon, as compared to the long _ganglionic axons of the parasympathetic NS neurons
pre;
pre
Most preganglionic neurons originate from the brain stem in the _ NS, and the sacral portion of the spinal cord (i.e., there isn’t a ‘chain’ near the spinal cord)
parasympathetic
We have a _ axon for the preganglionic neuron of the PNS and _ axons for the postganglionic neuron (which synapse in autonomic neuron)
long;
short (they’re close to the effector organ)
Neuroeffector junctions are between the postganglionic neuron and the _
effector organ
Neurotransmitters are synthesized and stored in axon swellings of _ and are released in response to action potentials in postganglionic neurons
varicosities
The mechanism for neurotransmitter release is similar to an ordinary axon terminal apart for the diffusion of…
neurotransitters from the varicosities over a greater area
With an action potential, the polarizing quotient will open Ca2+ gated channels, triggering exocytosis of neurotransmitters, which bind to a muscarinic cholinergic receptor (if accepting acetylcholine as part of the _ NS), which the effector organ responds and the NTs are degraded, diffused away or taken up
parasympathetic
Events at the _ junction:
1. action potential arrives at varicosity
neuroeffector
Events at the neuroeffector junction:
1. action potential arrives at varicosity
2. voltage-gated _channels open
Ca2+
Events at the neuroeffector junction:
1. action potential arrives at varicosity
2. voltage-gated Ca2+ channels open
3. Ca2+ triggers _ of NT
exocytosis
Events at the neuroeffector junction:
1. action potential arrives at varicosity
2. voltage-gated Ca2+ channels open
3. Ca2+ triggers exocytosis of NT
4. NT binds with receptors on _ _
effector organ
Events at the neuroeffector junction:
1. action potential arrives at varicosity
2. voltage-gated Ca2+ channels open
3. Ca2+ triggers exocytosis of NT
4. NT binds with receptors on effector organ
5. Response in effector organ occurs
6. NT is degraded and diffuses away, or _ occurs
reuptake
With an action potential, the polarizing quotient will open Ca2+ gated channels, triggering exocytosis of neurotransmitters, which bind to a nicotinic adrenergic receptor (if accepting norepinephrine as part of the _ NS), which the effector organ responds and the NTs are degraded, diffused away or taken up
sympathetic
_ activity is found with:
quiet, relaxed states
active in “rest and digest”
increases gastrointestinal activities
decrease in blood pressure and heart rate
parasympathetic
Sympathetic activity is assoc with:
fight-or-flight response
prepares for emergency, stress and exercise
increases heart rate and blood pressure
mobilizes energy stores
_ _
decreases gastrointestinal and urinary functions
releases epinephrine/adrenaline
dilates pupils
Release of _ in the sympathetic NS is from the adrenal medulla
epinephrine/adrenaline
What is monoamine oxidase inhibitors?
a powerful antidepressant, increasing the amount of norepinephrine by decreasing their degradation at CNS synapses of sympathetic NS
Why aren’t monoamine oxidase inhibitors commonly prescribed?
it also acts in the peripheral NS, with levels at areas of the autonomic NS may also be increased, such as blood pressure, kidney dilation, decreasing gastrointestinal functions and constipation
Sympathetic and parasympathetic NS are opposing in their innervation, although the _ NS dominates, resulting in decreased heart rate, blood pressure, etc.
parasympathetic
upset stomach, blushing, sweating is suggestive of the _ NS dominating
sympathetic
It is often the … of autonomic system innervation that cause dominating NS problems, whether an overactive bladder or an upset stomach
mishap between parasympathetic and sympathetic nervous systems
The ANS _ is liked to the sensory system to produce functional reflexes
autonomic efferent
Autonomic reflexes are good examples of _ feedback loop. E.g., is having to go to the bathroom but not being able to go because of impact of the sympathetic nervous system (called shy bladder). Its overall goal is…
negative;
to maintain homeostasis
Pupillary light reflex uses OFF/ON and OFF/ON afferents to luminance and darkness detectors, respectively
on;
off
If a pupillary light reflex show something is too BRIGHT/DARK, parasympathetic reflex to ciliary ganglion and circular iris muscles, causing pupil CONSTRICTION/DILATION
bright;
constriction
“on” afferent
If a pupillary light reflex shows something is too BRIGHT/DARK, sympathetic reflex to radial muscles causing pupil CONSTRICTION/DILATION
dark;
dilation
“off” afferent
Orthostatic hypotension is postural hypotension, i.e., a ‘head rush’, a form of hypotension in which a person’s blood pressure suddenly falls when standing up or stretching. This normally doesn’t happen due to the _, allowing us to adjust blood pressure depending on posture
baroreflex
The _ _ found in the ventrolateral medulla is the center of the baroreflex mechanism
cardiovascular center
The muscle PARA-/SYMPATHETIC effects are of the baroreflex system
sympathetic
The baroreflex’ major influence is noradrenergic vaso-CONSTRICTION/DILATION to maintain blood pressure
constriction
The baroreflex’ muscle sympathetic effects are extremely important for regulation of _ _
blood pressure
The baroreflex system works most of the time, but when you go in a fighter jet, a G-suit puts pressure on your limbs so that…
your chest cavity retains blood in its normal position, preventing you from passing out
Areas of the brain that regulate autonomic function are the:
hypothalamus
pons
_ _
medulla oblongata
Can the autonomic NS be regulated by the CNS?
YES
If you activate the _ nervous system, is causing an increase in heart rate, conduction velocity and dilation of pupils, etc.
sympathetic
If you activate the _ nervous system, it can cause sweating, contraction of the bladder wall and relaxation of the anal sphincter
parasympathetic
A PARA-/SYMPATH-ectomy of the first cervical neurons of the sweat glands in the hands would block the transmission of PARA-SYMPATHETIC impact to the hands, done on individuals with hyperhydrosis (sweating of the palms of the hands)
sympathectomy;
sympathetic
There are 1/2 set of neurons in the somatic nervous system
1 - just the motor neurons going to the effector organ skeletal muscle
_ neurons control muscles, which synapse in the muscle fiber
motor
The … is the synapse where motor neuron axons and muscle fibers meet
neuromuscular junction
The axon terminal of the neuromuscular junction is the _ _
terminal bouton (terminal button)
All motor neurons release ACETYLCHOLINE/EPINEPHRINE
acetylcholine (cholinergic)
All synapses in the neuromuscular junction are EXCITATORY/INHIBITORY
excitatory
The terminal bouton meets the _ _ _ at the neuromuscular junction
motor end plate
Activation of motor neuron depends on summation of _s/_s, which occur at the axon hillock
EPSPs/IPSPs
this is not contradictory to all motor neurons being cholinergic; it’s merely what starts it from happening then if it does create an action potential then it has to be excitatory
Communication at the neuromuscular junction
1. action potential arrives at the _ _
terminal bouton
Communication at the neuromuscular junction
1. action potential arrives at the terminal bouton
2. voltage-gated _ channels open
Ca2+
Communication at the neuromuscular junction
1. action potential arrives at the terminal bouton
2. voltage-gated Ca2+ channels open
3. Calcium enters cell triggering release of _
Ach; aceylcholine
Communication at the neuromuscular junction
1. action potential arrives at the terminal bouton
2. voltage-gated Ca2+ channels open
3. Calcium enters cell triggering release of ACh
4. ACh diffuses across cleft and binds to _ receptors on motor end plate/muscle fibre (the receiving end of the muscle fibre)
nicotinic
Communication at the neuromuscular junction
1. action potential arrives at the terminal bouton
2. voltage-gated Ca2+ channels open
3. Calcium enters cell triggering release of ACh
4. ACh diffuses across cleft and binds to nicotinic receptors on motor end plate/muscle fibre (the receiving end of the muscle fibre)
5. ACh triggers opening of channels for small cations of _ and _
sodium and potassium
Communication at the neuromuscular junction
1. action potential arrives at the terminal bouton
2. voltage-gated Ca2+ channels open
3. Calcium enters cell triggering release of ACh
4. ACh diffuses across cleft and binds to nicotinic receptors on motor end plate/muscle fibre (the receiving end of the muscle fibre)
5. ACh triggers opening of channels for small cations of Na+ and K+
6. Net movement causes a NEGATIVE/POSITIVE change, triggering a _polarization
positive;
depolarization
Communication at the neuromuscular junction
1. action potential arrives at the terminal bouton
2. voltage-gated Ca2+ channels open
3. Calcium enters cell triggering release of ACh
4. ACh diffuses across cleft and binds to nicotinic receptors (containing acetylcholinesterase for potential clean-up) on motor end plate/muscle fibre (the receiving end of the muscle fibre)
5. ACh triggers opening of channels for small cations of Na+ and K+
6. Net movement causes a positive change, triggering a depolarization
7. Causes action potential in muscle cell
8. _ _ spreads through muscle causing contraction
action potential
The mechanism of force generation in muscle is the _ cycle
crossbridge, much like using an oar to row a boat
The two contractile proteins for the crossbridge cycle are _ and _
actin and myosin
_ makes up the general structure of the thin filament, a long filamentous polymer composed of several _ [same] molecules
actin
ACTIN/MYOSIN makes up the thick filament and contains numerous crossbridges, the elements responsible for attaching to ACTIN/MYOSIN
myosin;
actin
The ACTIN/MYOSIN head undergoes conformational changes swiveling back-and-forth
myosin
it is the oar of a canoe, with the actin which is like the water
In myosin’s high-energy form, it has a HIGH/LOW affinity for actin, whereas the low-energy form has a HIGH/LOW affinity for actin
high;
low
it’s the same - high energy means it’s going to touch it
Filaments run PARALLEL/PERPENDICULAR to the long axis
parallel
Thick filaments are made of myosin molecular, which is composed of _ molecules bound at their tail ends
two
The _ binding site an the nucleotide binding site of ATP are on the two heads, with ATPase that uses the energy
actin
Thin filament is made up of polymerase of _ molecules wound together, with mosin-binding sites. They are only binded when they get _
calcium, which starts the contraction process (binds the myosin head and actin for contraction)
During a power stroke…
1. the myosin head moves propelling _ filament towards the centre of the muscle (like movement of an oar propelling a boat)
thin (contains the actin)
During a power stroke…
1. the myosin head moves propelling thin filament towards the centre of the muscle (like movement of an oar propelling a boat)
2. …filaments detach (oar breaks contact with water)
thick and thin
During a power stroke…
1. the myosin head moves propelling thin filament towards the centre of the muscle (like movement of an oar propelling a boat)
2. thick and thin filaments detach (oar breaks contact with water)
3. _ _ returns to initial position (oar moved to new position, cycle starts again)
myosin head
Crossbridge cycle involves:
1. binding of myosin to actin, with _ release
inorganic phosphate (Pi) released
imagine the myosin head is cocked, with Pi and ADP connected on the myosin head, but nothing is happening, until Pi’s release)
Crossbridge cycle involves:
1. binding of myosin to actin, with Pi release
2. _ _
power stroke
(imagine ADP is still connected to the myosin head, while actin propels thin filament towards the centre of the muscle)
Crossbridge cycle involves:
1. binding of myosin to actin, with Pi release
2. power stroke
3. rigor (myosin in _-energy form) - actin gets pulled towards middle of sarcomere, and ADP is released
low
energy isn’t released for the oar going into the water, rather what needs the energy is breaking the oar from the water and pulling it out
(ADP is released from the myosin head, but nothing has happened yet)
Crossbridge cycle involves:
1. binding of myosin to actin, with Pi release
2. power stroke
3. rigor (myosin in _-energy form) - actin gets pulled towards middle of sarcomere, and ADP is release
4. unbinding of myosin and actin - new ATP binds to myosin head, and then once contraction occurs myosin and _ are released
ATP (energy is used at the myosin head site, with movement having taken place, and then myosin head is released)
Crossbridge cycle involves:
1. binding of myosin to actin, with Pi release
2. power stroke
3. rigor (myosin in _-energy form) - actin gets pulled towards middle of sarcomere, and ADP is release
4. unbinding of myosin and actin - new ATP binds to myosin head, and then once contraction occurs myosin and ATP are released
5. _ is hydrolyzed, and cocking of the myosin head occurs (myosin being in _-energy form)
ATP;
high-energy
(myosin head and muscle fibre are separated and regrouping, with ‘cocking’ referring to the myosin having moved flush/parallel to the thick filament (the rest of the time the myosin head is perpendicular to it!)
_ _ involves a body’s muscles becoming fully contracted once one dies, no longer generating any more energy. If it was energized, the muscles would release, but it remains stiff and the crossbridge is still detached…only changes when body breaks down in death
rigor mortis
- coupling involves an action potential in the sarcolemma which causes contraction
excitation-contraction
Excitation-contraction coupling is dependent on neural input from a motor neuron and requires _ release
calcium
Termination of contraction involves _ leaving the binding sites, or a _ ATPase
calcium (both!)
Ca2+ ATPase actively transports calcium into the _ _ from the cytosol, using calcium pumps for later use, terminating a contraction
sarcoplasmic reticulum
_ contraction is ANY contraction produced in a muscle fibre in response to a single action potential
twitch
Twitches are considered … events for a given muscle fibre at rest because they produce a response to an action potential
all-or-nothing
T or F: twitch can be defined for a a muscle fibre
false - a muscle fibre or the whole muscle level
There are three phases of a muscle twitch:
1. _
2. contraction
3. relaxation
latent
The latent period of a muscle twitch follows a stimulus from the _ _, but no contractile force has developed.
motor neuron
The latent period of a muscle twitch follows a stimulus from the motor neuron, but no contractile force has developed. … is occurring, with action potentials travelling down the muscle (through the T-tubules)
Excitation-coupling
The latent period of a muscle twitch follows a stimulus from the motor neuron, but no contractile force has developed. Excitation-coupling is occurring, with action potentials travelling down the muscle (through the T-tubules), and the calcium is being released by the _ _ to initiate the cross-bridge cycle
sarcoplasmic reticulum
Does contraction occur during the latent period of a muscle twitch?
no, during the contraction phase
The contraction phase of a muscle twitch involves the EXTRA/INTRAcellular calcium levels are HIGH/LOW, and the crossbridge cycle occurs, producing force.
intra;
high;
The contraction phase of a muscle twitch involves the intracellular calcium levels are high, and the crossbridge cycle occurs, producing force. In the graph of phases of a muscle twitch, this cycle is shown as…
the steep incline (not just the top) from the flat initial stimulus
The relaxation phase of a muscle twitch is the decline of force from the peak, in which calcium is being pumped back _ the sarcoplasmic reticulum, and the intracellular calcium levels _, therefore the force drops back to zero
into;
fall
Muscle twitches increase the tension through _
summation
As action potentials become more and more stimulated on the x-axis (over time), the tension generated (y-axis) goes DOWN/UP
UP
Eventually, when action potentials are delivered in very close succession, their fusing of contractions will end up with _, shown as a plateaued hill on a graph of muscle twitches, considered the maximum force reached
tetanus
Does tetanus occur in all muscle cells?
no, it doesn’t occur in cardiac muscles
The pupillary light reflex is an example of _ cranial reflex
autonomic
The photoreceptors in a pupillary light reflex activate _erent neurons that transmit signals to areas in the midbrain of the brainsteam that function as the integration centre
afferent
The photoreceptors in a pupillary light reflex activate afferent neurons that transmit signals to areas in the midbrain of the brainsteam that function as the integration centre.
These midbrain areas then activate, through a polysnaptic pathway, autonomic _s that innervate the smooth muscle surrounding the pupils of both eyes
efferents
The photoreceptors in a pupillary light reflex activate afferent neurons that transmit signals to areas in the midbrain of the brainsteam that function as the integration centre.
These midbrain areas then activate, through a polysnaptic pathway, autonomic efferents that innervate the smooth muscle surrounding the pupils of both eyes.
The response is pupillary CONSTRICTION/DILATION in both eyes
constriction
Autonomic is another term for _
subconscious or involuntary
When we say sympathetic activity increases, what do we mean?
the frequency of action potentials in sympathetic neurons increases
T or F: a single preganglionic neuron generally synapses with several postganglionic neurons
true
The preganglionic neurons original in _ matter, called the lateral horn/intermediolateral cell column
grey
Which part of the autonomic NS - sympathetic or parasympathetic - produces the more diffuse response? Why?
parasympathetic, bc often the sympathetic requires more discrete actions, whereas parasympathetic can be slow and emit during rest and digest stages
The autonomic nervous system innervates all the following effector organs and tissues EXCEPT
a. skeletal muscles
b. cardiac muscles
c. endocrine glands
d. smooth muscle
a. skeletal muscles
Which of the following physiological responses is associated with elevated sympathetic nervous system activity?
a. increased contractile force of the heart
b. decreased heart rate
c. enhanced absorption of nutrients
d. enhanced digestion
a. increased contractile force of the heart
What is the correct order for the steps of synaptic transmission at the motor end plate?
Acetylcholine binds to postsynaptic receptors. Acetylcholine is released by exocytosis. A graded depolarization is produced. An action potential is produced on the muscle cell membrane. Channels that primarily allow diffusion of sodium are opened. Voltage-dependent calcium channels on the plasma membrane open. An action potential arrives at the axon terminal.
a. 7 6 2 1 5 3 4
b. 7 5 2 1 3 4 6
c. 6 7 2 1 3 5 4
d. 7 6 2 1 3 4 6
a. 7 6 2 1 5 3 4
What is the function of T tubules?
a. they conduct action potentials from the sarcolemma to the interior of the muscle cell
b. they hold the thick filaments to the Z line
c. they provide elasticity to the muscle
d. they store calcium
a. they conduct action potentials from the sarcolemma to the interior of the muscle cell
The binding of calcium to troponin will directly allow which of the following?
a. the movement of tropomyosin, thereby exposing the myosin-binding site on the actin molecule
b. the hydrolysis of ATP
c. the further release of calcium into the cytoplasm
a. the movement of tropomyosin, thereby exposing the myosin-binding site on the actin molecule
Which of the following endocrine glands is innervated by sympathetic preganglionic neurons?
a. adrenal medulla
b. pancreas
c. anterior pituitary
d. adrenal cortex
a. adrenal medulla
In addition to sympathetic postganglionic axons, which types of axons travel in a spinal nerve?
axons of afferent neurons and motor neurons
Sympathetic postganglionic neurons that innervate the _ _ release acetylcholine
sweat glands
