A & P ch. 11 & 12
sequence of autonomic pathway:
1. preganglionic neuron2. autonomic ganglion3. postganglionic neurontakes a message from the CNS to a target tissue through an autonomic ganglion middle-man
The motor end plate is _____.
A folded area of muscle cell membrane with nicotinic ACh receptors clustered at the top of each fold
A motor unit consists of ____.
A motor neuron and all of the myofibers innervated by it
Postganglionic neuron from the parasympathetic nervous system (ACh or NE)
ACh
Preganglionic neuron from the parasympathetic nervous system(ACh or NE)
ACh
Preganglionic neuron from the sympathetic nervous system.(ACh or NE)
ACh
Somatic motor neuron (ACh or NE)
ACh
Muscle relaxation requires __________.
ATP
Thick filaments have __________.
ATPase activity and actin binding sites
what do parasympathetic postganglionic neurons release and onto what receptors?
AcH onto muscarinic receptors
What is a similarity between the somatic motor and autonomic pathways?
Acetylcholine is secreted from the neuron that originates in the CNS.
What are the parts of the autonomic nervous system?
Adrenal sympathetic pathways, parasympathetic pathways, sympathetic pathways
In contrast to autonomic synapses, the synapses between neurons and skeletal muscle (neuromuscular junctions) ______.
Almost always produce muscle contractions when the synapse is active, are always excitatory, produce end-plate potentials that almost bring the postsynaptic muscle cell to threshold
The disease known as myasthenia gravis produces an unusually rapid onset of fatigue and weakness in certain muscle groups due to ____.
Autoimmune destruction of the ACh receptors and motor neurons
What best describes the direction and function of efferent signals?
Away from the CNS, cause motor effects in glands or muscles
If a person has a genetic disorder that causes him or her to not produce norepinephrine, which of the following would be affected the LEAST?
Bronchioles since they have a higher affinity for epinephrine than norepinephrine
Why is Buproprion used to help people who have chosen to quit smoking?
Buproprion mimics the effects of nicotine by keeping dopamine around the synapses
Both alpha-bungarotoxin and curare are chemical agents that bind to the same neurotransmitter receptor, but only curare binds reversibly. Which of the locations listed would not be a location for this receptor?
Cardiac muscle, smooth muscle, and glands
When an action potential travels along the sarcolemma of a muscle cell __________.
DHP receptors in the T-tubule undergo a conformational change and Ca2+ flows down its concentration gradient through the ryanodine receptors
The disease myasthenia gravis is caused by ____.
Destruction of acetylcholine receptors
Which of the following statements about muscle contraction is(are) true?
Each myosin head completes about five crossbridge cycles per second, but each thick filament has hundreds of myosin heads.
A toxin that prevents the release of acetylcholine at the neuromuscular junction would cause ____.
Flaccid paralysis of skeletal muscles
A location outside of the central nervous system where autonomic signals can synapse
Ganglion
With an up-regulation of receptors, how would you predict that a person would need to change the amount of nicotine consumed to get the same effects as they did in the beginning?
Increase use, because there are more receptors available for the chemical to bind to
With paralytic chemical agents or drugs, such as curare, what factor must be taken into consideration to keep the patient alive?
Interference at the muscular junction can cause paralysis of the respiratory muscles
The adrenal medulla is important to the sympathetic branch of the autonomic nervous system because it _____.
Is a source of catecholamines
The somatic nervous system differs from that parasympathetic nervous system in that ____.
It is mostly under voluntary control and the efferent pathway consists of only a single motor neuron
As the load on a muscle increases, which of the following also increase(s)?
Latent period
Somatic motor neurons in the spinal cord control all of the following muscles, except those that __________.
Move the face
A toxin that inhibits acetylcholinesterase at the neuromuscular junction would cause _____.
Muscle spasms and respiratory failure
The functional unit within a muscle fiber is called a sarcomere. Which of the following does not make up part of the sarcomere?
Myofibril
How do the effects of chronic nicotine on nAChR expression differ from the predicted effects of a typical receptor agonist?
Nicotine causes up-regulation of nAChR
What kind of receptors do skeletal muscle fibers have ?
Nicotinic
Both alpha-bungarotoxin and curare are chemical agents that bind to the same neurotransmitter receptor, but only curare reversibly. Which receptor is involved?
Nicotinic acetylcholine receptor
Curare procedures skeletal muscle paralysis because it is a(n) _____.
Nicotinic cholinergic antagonist
The somatic nervous system and the parasympathetic nervous system both release acetylcholine (ACh) onto their target tissues. Do you predict that this would indicate that these two pathways carry out the same effects? Why or why not?
No, because the receptors found on the target tissue for each pathway are different.
Postganglionic neuron from the sympathetic nervous system.(ACh or NE)
Norepinephrine (NE)
Which division of the autonomic nervous system contains adrenergic neurons?
Only the sympathetic division
What are the components of the efferent nervous system?
Parasympathetic neurons Sympathetic neurons Somatic motor neurons
Bill contracts a viral disease that destroys cells in the anterior gray horns in his spinal cord. As a result, which of the following could you expect to happen to Bill?
Possible problems with moving his arms and problems with moving his legs
A neuron that delivers an action potential from the central nervous system to another neuron in the peripheral nervous system
Preganglionic autonomic neuron
High capillary density, high myoglobin content, and high resistance to fatigue describe which of the following skeletal muscle types?
Red, slow oxidative muscle fibers
What initiates muscle contraction ?
Release of ach onto nictonic receptors of skeletal muscle fibers
Effector tissue of the somatic motor division is _____.
Skeletal muscle
If a person has a genetic disorder that caused him/her to not produce norepinephrine, which type of tissue would be affected the least?
Skeletal muscle
What are the targets of the efferent nervous system?
Smooth muscle Glands Skeletal muscle Cardiac muscle
A single neuron is stimulated at the central nervous system; this signal travels all the way to the target tissue, where the neurotransmitter acetylcholine is released onto the target tissue. The acetylcholine binds to a nicotinic receptor to induce skeletal muscle contraction. These steps describe the function of which branch of the efferent nervous system?
Somatic
A neuron that delivers an action potential from the central nervous system to a skeletal muscle
Somatic motor neuron
Why are some substances like nicotine difficult for users to stop using?
The nicotine in cigarettes enhances the reward pathways in the brain and the social aspects associated with smoking become pleasurable
If a somatic motor neuron fires an action potential, then ____.
The response is always excitatory
Which of the following statements about muscle contractions is(are) true?
The sarcomeres shorten during isometric and isotonic contractions.
Aliens on Planet X have a hormone that has a structure similar to epinephrine. Scientists are calling it X-epinephrine and would like to see if it has the same effects as epinephrine does in humans. Upon administration to humans, which of the following results would best demonstrate that X-epinephrine is an epinephrine agonist?
The subjects' heart rates increase; epinephrine acting of beta 1 receptors causes increased heart rate
The two divisions of the autonomic division of the nervous system are _____.
The sympathetic and the parasympathetic divisions
Compare and contrast the voltage-gated sodium and potassium channels. What type of change in the cell is produced by ion movement through each type of channel?
The voltage-gated sodium channel opens in response to threshold voltage and allows sodium to enter the cell, thereby depolarizing the membrane potential and the potassium channel is also opened by threshold voltage and allows potassium to exit the cell, repolarizing or hyperpolarizing the membrane potential
End-plate potentials at the neuromuscular junction are similar to excitatory postsynaptic potentials in which of the following way(s)?
They are depolarizing
Which of the following is(are) true about small motor units?
They tend to be recruited first during a contraction and they generate less tension than large motor units.
Motion sickness if probably caused by miscommunication between which of the following systems?
Vestibular, proprioceptive, autonomic
To perform surgery with a minimum of pain for the patient and hassle for the surgeon, a patient may be administered a general anesthetic to prevent sensation and consciousness, as well as a paralytic agent to prevent reflexive muscle spasms. From what you have learned of motor control, which of the mechanisms below describes how a paralytic can prevent muscle contraction?
Virtually any drug that interferes with motor neuron activity at the neuromuscular activity junction could accomplish this
The motor end plate is ____.
a folded area of muscle cell membrane with nicotinic ACh receptors clustered at the top of each fold
The neurotransmitter that signals the contraction of skeletal muscle fibers is __________.
acetylcholine
Which neurosecretory endocrine gland is closely allied to the sympathetic branch?
adrenal medulla
adrenergic receptor subtypes:
alpha 1, alpha 2, beta 1, beta 2, beta 3
Norepinephrine receptors
alpha 1, beta 1, beta 3
The A band contains __________.
an area of partial overlap between thick and thin filaments
what reflexes are important for homeostasis?
autonomic
what system works closely with the endocrine system to maintain homeostasis?
autonomic system
Put the events of the crossbridge cycle in the correct order, starting with the binding of myosin to actin:
b. release of Pi d. Power stroke c. Release of ADP a. Binding of ATP
Epinephrine receptors
beta 1 and beta 2
When myosin is bound to actin during the crossbridge cycle __________.
calcium is bound to the troponin complex and myosin is in its high-energy form
Muscarine, a chemical produced by certain mushrooms, binds to muscarinic receptors mimicking the effect of acetylcholine. How do you think administering this chemical would change body function? The drug would _____________.
change the functionality of the heart change the functionality of certain exocrine and endocrine glands change the functionality of the smooth muscles within the digestive system
Neurons that secrete acetylcholine are described as __________ neurons, whereas those that secrete norepinephrine are called either __________ or ____________ neurons
cholinergic; adrenergic or nonadrenergic
During complete tetanus __________.
cytosolic calcium levels are high enough to saturate all the troponin molecules, action potential frequency is higher than the fused muscle twitch frequency, and action potential frequency is higher than the fused muscle twitch frequency
The latent period is due to the time it takes for __________.
excitation-contraction coupling
Somatic pathways are always ___.
excitatory
During a prolonged bout of continuous exercise (longer than 30 minutes), ATP stores are replenished by __________.
fatty acids in the bloodstream
The force generated by a muscle depends directly or indirectly on the __________.
force generated by individual muscle fibers, number of muscle fibers contracting, and number of active crossbridges formed
alpha-2 adrenergic (isomer) receptor
found in GI tract and pancreas; higher affinity for NE
beta-3 adrenergic (isomer) receptor
found in adipose tissue; higher affinity for NE
beta-2 adrenergic (isomer) receptor
found in certain blood vessels and smooth muscle of some organs; higher affinity for E than NE
beta-1 adrenergic (isomer) receptor
found in heart muscle and kidney; equal affinity for NE and E
alpha-1 adrengeric (isomer) receptor
found in most sympathetic target tissues; higher affinity for NE
Muscle fibers can obtain energy from __________ when the oxygen supply for catabolism is too slow to meet the ATP demands of heavy exercise.
glucose that is metabolized to lactic acid
Increased parasympathetic stimulation ______.
increases insulin secretion
Aliens on Planet X have a hormone that has a structure similar to epinephrine. Scientists are calling it X-epinephrine and would like to see if it has the same effects as epinephrine does in humans. If the scientists find that X-epinephrine causes pupil dilation, localized sweating, increased blood pressure, and high blood glucose levels in the subjects, what might they conclude about the nature of X-epinephrine?
it behaves like catecholamines and acts on adrenergic receptors
how can the limbic system affect homeostasis
it can influence the pons, medulla and hypothalamus, which regulate the autonomic, behavioral and endocrine systems
The synapse between a postganglionic autonomic neuron and its target cell is called the ___________ ___________.
neuroeffector junction (recall that targets are also called effectors).
The synapse between a postganglionic autonomic neuron and its target cell is called a __________. Autonomic postganglionic axons end with a series of swollen areas called __________.
neuroeffector junction; varicosities
Acetylcholine receptors
nicotinic and muscarinic
What kind of receptor is found on the postsynaptic cell in a neuromuscular junction?
nicotinic cholinergic
what do sympathetic postganglionic neurons release and onto what receptors?
norepinephrine onto adrenergic receptors
A neuron that receives an action potential from another neuron and then delivers that action potential to a smooth muscle
postganglionic autonomic neuron
autonomic pathways are made up of 2 neurons:
preganglionic neuron & postgnanglionic neuron
Molecules that are more likely to be found in higher concentrations in a fast glycolytic fiber include __________.
pyruvate and lactic acid
Skeletal muscles with the most endurance (resistance to fatigue) are __________ in color.
red
Autonomic pathways consist of two neurons in __________. The first is called the __________, and it originates __________.
series; preganglionic neuron; in the CNS
What's the target of somatic motor neurons?
skeletal muscle
what is the neuroeffector junction?think of what effectors are..
synapse between postganglionic neuron and target (so the 2nd neuron in the 2 series and its target)note: targets are also called effectors...
If a somatic motor neuron fires an action potential, then ____.
the response is always excitatory
When the arrival of an action potential at the muscle cell membrane triggers the release of calcium from the sarcoplasmic reticulum, this process does not go on indefinitely because __________.
the rising concentration of cytosolic calcium triggers the closure of calcium channels in the sarcoplasmic reticulum
Muscle tension decreases at short muscle lengths because __________.
the thin filaments at opposite ends of the sarcomere overlap and the Z lines come into contact with the thick filaments
After the myosin ATPase hydrolyzes ATP into ADP + Pi, __________.
the two products stay attached to the myosin head, the myosin head is cocked and binds to a different G-actin molecule, ready for the power stroke
Most sympathetic pathways originate in the __________ of the spinal cord, whereas most parasympathetic pathways originate in the __________.
thoracic and lumbar regions; sacral region and brain stem
The troponin complex in thin filaments can bind __________.
tropomyosin, calcium, and actin
what are autonomic synapses called?
varicosity
