TEST 4
Preganglionic fibers of parasympathetic neurons are present in all of the following cranial nerves except
XIII
A nerve is
a bundle of axons
The electrochemical gradient for potassium ions when the transmembrane potential is at the resting potential (-70 mV) is caused by what?
a chemical gradient going out of the cell and an electrical gradient going into the cell
In which of the following would the delay between stimulus and response be greater?
a polysynaptic contralateral reflex
Of the spinal meninges, the middle one is the ________ mater.
arachnoid
Where are action potentials regenerated as they propagate along an unmyelinated axon?
at every segment of the axon
Where in the neuron is an action potential initially generated?
axon hillock
Which of the following would lead to increased heart rate?
both increased sympathetic input and decreased parasympathetic input
The posterior root ganglia mainly contain
cell bodies of sensory neurons
The ________ plexus supplies innervation to the diaphragm.
cervical
Splanchnic nerves
consist of axons that synapse in collateral ganglia
The ________ is a strand of fibrous tissue that provides longitudinal support as a component of the coccygeal ligament.
film terminale
Which brain area is considered to be the headquarters of the ANS?
hypothalamus
A viral disease that destroys the neuronal cell bodies of the anterior gray horn will
lead to muscle weakness or paralysis.
Reflexes, controlled by the spinal cord, act by
motor output over spinal nerves to effectors.
Which kind of neural circuit processes information in a stepwise fashion, one neuron to another? (Module 12.11B)
serial processing
What brain structure relays somatosensory information? (Module 14.11B)
thalamus
What is the value for the resting membrane potential for most neurons?
-70 mV
In a typical neuron, what is the equilibrium potential for potassium?
-90 mV
What is the magnitude (amplitude) of an action potential?
100mV
Sensory input from interoceptors of the body walls and limbs is carried to the spinal nerve via the
anterior rami
What is the typical duration of a nerve action potential?
2ms
A typical spinal cord has how many pairs of spinal nerves, and where does the spinal cord end? (Module 12.2A)
31 pairs; lumbar vertebra 1 or 2
The spinal cord continues to elongate until about age
4 years
What is a reflex? (Module 12.1B)
A reflex is a rapid, automatic response triggered by specific stimuli.
What are common characteristics of reflexes? (Module 12.12A)
All reflexes are rapid, unconscious patterned responses to stimuli that restore or maintain homeostasis.
Describe an intramural ganglion. (Module 14.3B)
An intramural ganglion is a group of neurons embedded in the tissues of the target organ.
What is the significance of the cauda equina?
It is made up of extensions of the posterior and anterior roots of spinal segments L2 to S5. It forms as the vertebral column continues to elongate after growth of the spinal cord ceases at about age 4.
What ion causes repolarization of the neuron during an action potential?
K+ (potassium)
The membranes of neurons at rest are very permeable to _____ but only slightly permeable to _____.
K+; Na+
The concentrations of which two ions are highest outside the cell.
Na+ and Cl-
The Na+-K+ pump actively transports both sodium and potassium ions across the membrane to compensate for their constant leakage. In which direction is each ion pumped?
Na+ is pumped out of the cell and K+ is pumped into the cell.
Differentiate between sensory nuclei and motor nuclei. (Module 12.4A)
Sensory nuclei receive and relay sensory information from peripheral receptors; motor nuclei issue motor commands to peripheral receptors.
The sodium-potassium exchange pump transports potassium and sodium ions in which direction(s)?
Sodium ions are transported out of the cell. Potassium ions are transported into the cell.
Describe the ENS. (Module 14.2C)
The ENS is a division of the nervous system consisting of a network of neurons and nerve networks in the walls of the digestive tract that primarily operates locally, without instructions from the CNS.
Compare the SNS with the ANS. (Module 14.1A)
The SNS provides conscious and subconscious control over skeletal muscles. The ANS controls the visceral effectors: smooth muscle, glands, cardiac muscle, and adipocytes.
Describe the brachial plexus. (Module 12.9A)
The brachial plexus is a network of nerves formed by branches of spinal nerve segments C5-T1.
In the patellar reflex, how does stimulation of the muscle spindle by gamma motor neurons affect sensitivity and reaction time? (Module 12.13C)
The muscle spindles become more sensitive and the reflex response occurs more quickly.
Describe the solitary nuclei. (Module 14.9C)
They are large masses of gray matter on each side of the medulla oblongata that serve as processing sorting centers for visceral sensory information.
Describe the role of preganglionic neurons. (Module 14.1B)
They are part of visceral reflex arcs, and most of their activity is a direct reflex response, rather than responses to commands from the hypothalamus.
What neurotransmitter is released by all parasympathetic neurons? (Module 14.5B)
acetylcholine
An inhaler used to treat airway constriction in asthma or allergy might contain a drug that
activates β2 adrenergic receptors or blocks muscarinic cholinergic receptors.
Neurons that use norepinephrine as a transmitter are called
adrenergic
Suppose that you feel something brushing against your abdomen. The sensory information would be carried to the spinal cord over a ________ ramus.
anterior
A decrease in the autonomic tone of the smooth muscle in a blood vessel would result in
both an increase in vessel diameter and an increase in blood flow through the vessel.
The adrenal medullae secrete
both epinephrine and norepinephrine.
Each peripheral nerve provides ________ innervation to peripheral structures.
both motor and sensory
Dual innervation refers to an organ receiving
both sympathetic and parasympathetic innervation
During depolarization, which gradient(s) move(s) Na+ into the cell?
both the electrical and chemical gradients
The ventral rami of spinal nerves C4 to T1 contribute fibers to the ________ plexus.
brachial
Name the plexuses innervated by the vagus nerve. (Module 14.4B)
cardiac, celiac, inferior mesenteric and hypogastric plexuses
Which of the following is not true about a positive Babinski reflex?
causes you to close your eyes when you sneeze
Clusters of ganglionic sympathetic neurons lying along either side of the spinal cord are called sympathetic ________ ganglia.
chain
Leak channels allow the movement of potassium and sodium ions by what type of membrane transport?
channel-mediated diffusion
We describe the regeneration of the action potential down the membrane of the axon of the neuron as _______.
conduction or propagation
Reflexes that activate muscles on the opposite side of the body as the stimulus are called
contralateral
The ________ reflex complements the flexor reflex by activating contralateral muscles.
crossed extensor
The parasympathetic nervous system is especially active during which physiological state(s)?
digestion
In a ________ neuronal pool, one neuron synapses on several postsynaptic neurons.
diverging
The outermost connective-tissue covering of nerves is the
epineurium
What type of membrane transport causes the depolarization phase of the action potential in neurons?
facilitated diffusion
The outward projections from the central gray matter of the spinal cord are called
horns
An axon that is more negative than the resting membrane potential is said to be _______.
hyperpolarized
Action potential propagation begins (is first generated at) what region of a neuron?
initial segment
Where do most action potentials originate?
initial segment
In what part of the neuron does the action potential typically initiate?
initial segment of the axon
The celiac ganglia do not innervate the
intestines
The stretch reflex
is important in regulating muscle length.
If an increase in extracellular potassium hyperpolarizes a neuron, which of the following would be correct?
it would change the membrane potential to a more negative value
As the result of an accident, the white rami of spinal nerves T1 and T2 on the left side of Brad's body are severed. What organ(s) would you expect might be affected by this injury?
left pupil and heart
Spinal nerves from the sacral region of the cord innervate the ________ muscles.
leg
The white matter of the spinal cord is mainly
myelinated axons
A molecule that carries information across a synaptic cleft is a
neurotransmitter
Increasing the voltage resulted in which of the following?
no change to the action potential
The anterior rami form four major plexuses, including all of the following except the ________ plexus.
nuchal
Nicotinic receptors
open chemically-gated sodium ion channels
Baroreceptors are not found in the
oral cavity
The nerve crucial for breathing that originates within the cervical plexus is called the ________ nerve.
phrenic
Damage to which nerve of the cervical plexus would interfere with the ability to breathe? (Module 12.8A)
phrenic nerve
The layer of the meninges in direct contact with the spinal cord is the
pia mater
Through which root of a spinal nerve does visceral sensory information arrive? (Module 12.6B)
posterior root
Which of the following visceral reflexes is not coordinated by the medulla oblongata?
pupillary reflex
Each of the following nerves originates in the lumbar plexus except the ________ nerve.
sciatic
Which nerve divides into the tibial nerve and common fibular nerve? (Module 12.10C)
sciatic
The posterior horns of the spinal cord contain mainly
sensory nuclei
In the condition ________, a virus infects posterior root ganglia, causing a painful rash whose distribution corresponds to that of the affected sensory nerves as seen in their dermatomes.
shingles
Visceral reflex arcs can bypass CNS neurons in ________ reflexes.
short
Compared to the vertebral column, the spinal cord is
shorter
Ganglionic neurons innervate as all of the following except
skeletal muscle
Hyper polarization results from
slow closing of voltage-gated K+ channels
Name the two types of motor pathways. (Module 14.7B)
somatic and visceral
The specialized membranes that surround the spinal cord are termed the
spinal meninges
A posterior and anterior root of each spinal segment unite to form a
spinal nerve
Two terms that both refer to internal organs are
splanchnic and viscera.
Preganglionic fibers that innervate the collateral ganglia form the
splanchnic nerves
The myotatic reflex is also known as the ________ reflex.
stretch
Samples of CSF for diagnostic purposes are normally obtained by placing the tip of a needle in the
subarachnoid space
Postganglionic fibers that innervate targets in the body wall or thoracic cavity originate on neurons within
sympathetic chain ganglia
Identify two major divisions of the ANS. (Module 14.2A)
sympathetic division and parasympathetic division
The small space between the sending neuron and the receiving neuron is the
synaptic cleft
The repolarization phase of an action potential results from __________.
the opening of voltage-gated K+ channels
In a neuron, sodium and potassium concentrations are maintained by the sodium-potassium exchange pump such that __________.
the sodium concentration is higher outside the cell than inside the cell and the potassium concentration is higher inside the cell than outside the cell.
What is the electrochemical gradient of an ion?
the sum of the electrical and chemical gradients for that ion
During an action potential of a neuron, what directly causes the different channels to open and close?
the transmembrane potential (voltage)
The sympathetic division of the ANS is also known as which of the following?
thoracolumbar division
The minimum voltage that is required to generate an action potential is called the _______.
threshold voltage
The region on the neuron where action potentials are generated is called the ______.
trigger zone
The statement "It controls the diameter of the pupil" is
true for both the parasympathetic and sympathetic nervous systems
The statement "There is always a synapse in a peripheral ganglion between the CNS and the effector organ" is
true for both the parasympathetic and sympathetic nervous systems.
The statement "It sends its preganglionic fibers to terminal or intramural ganglia" is
true only for the parasympathetic nervous system.
The statement "Its postganglionic axons always use acetylcholine as the neurotransmitter" is
true only for the parasympathetic nervous system.
In this simulation, ___________________ will be used to stimulate the axon.
voltage
The depolarization phase of an action potential results from the opening of which channels?
voltage-gated Na+ channels
What opens first in response to a threshold stimulus?
voltage-gated Na+ channels
All of the following terms refer to ways that reflexes can be classified except
voluntary
Reflexes can be classified according to all of the following except
whether they are sensory or motor
