Physiology Ch.7
The sympathetic nervous system is part of the __________ nervous system.
autonomic
Cardiac muscle, smooth muscle, most exocrine glands, some endocrine glands, and adipose tissue are innervated by the ____.
autonomic nervous system
What chemical agent causes an explosive release of ACh?
black widow spider venom
Most visceral organs are innervated by _______________ nerve fibers.
both parasympathetic and sympathetic
Propagation of an action potential to the axon terminal triggers the opening of what kind of voltage-gated channels?
calcium
agonist
causes same response as neurotransmitter
__________ blocks the action of acetylcholine at the acetylcholine receptor on the motor end-plate.
curare
The __________ contains acetylcholinesterase, acetylcholine receptors and cation channel proteins.
motor end-plate
The specialized portion of the muscle cell membrane immediately under the terminal button is known as the_________.
motor end-plate
ALS (Lou Gehrig's disease) is characterized by degeneration and eventual death of____________ .
motor neurons
Skeletal muscle cells are innervated by _______________.
motor neurons
A single muscle cell is called a(n) _________.
muscle fiber
One disease known as ____________is characterized by extreme muscular weakness.
myasthenia
As the axon approaches a muscle, it divides into many terminal branches and loses its myelin sheath. Each of these axon terminals forms a special junction called _______ ____________.
neuromuscular junction
As the axon approaches a muscle, it divides into many terminal branches and loses its myelin sheath. Each of these axon terminals forms a special junction called _____________.
neuromuscular junction
The ________ is the junction between a motor neuron and a skeletal muscle fiber.
neuromuscular junction
cotransmitters
secreted along with neurotransmitter
In the ___________ nervous system, there is a single neuron from the origin in the CNS to the effector organ.
somatic
Stimulation of the _________ division of the autonomic nervous system causes an increased heart rate.
sympathetic
The __________ nervous system promotes responses that prepare the body for strenuous physical activity.
sympathetic
Smooth muscle cells are innervated by ___________.
sympathetic nerve fibers
The axon terminal is enlarged into a knoblike structure called a(n) _______.
terminal button
What kind of receptor responds to acetylcholine released by all autonomic preganglionic fibers?
nicotinic cholinergic receptors
What neurotransmitter is released from the parasympathetic postganglionic fiber?
norepinephrine
Acetylcholinesterase is located ____.
on the motor end-plate membrane
What do chemoreceptors monitor?
protein or fat content of ingested food
What is the most harmful result of prolonged depolarization at cholinergic sites?
respiratory failure
What kind of muscles are respiratory muscles?
skeletal
How is most of the motor activity in the somatic nervous system coordinated?
subconsciously
Each autonomic nerve pathway (from the CNS to an innervated organ) consists of how many nerves?
two
Where are the cell bodies of almost all motor neurons situated within the spinal cord?
ventral horn
What are some examples of autonomic cotransmitters?
ATP, dopamine, and neuropeptide Y
Efferent neurons carry instructions from the CNS to the effector organs.
True
Most visceral (internal) organs are innervated by both sympathetic and parasympathetic nerve fibers.
True
Motor neurons innervate skeletal muscle and trigger voluntary movement.
True
Organophosphates (example: sarin gas) irreversibly block acetylcholinesterase (AChE), resulting in respiratory failure.
True
The neurotransmitter released at the neuromuscular junction is acetylcholine (ACh).
True
________ released from the motor neuron diffuses across the cleft and binds with specific receptor sites.
Acetylcholine
What response is triggered when the sympathetic system is dominant?
fight or flight response
What is the shape of a muscle cell or fiber?
long and cylindrical
What are the two types of cholinergic receptors?
nicotinic and muscarinic
Afferent neurons terminate at interneurons.
True
What cranial nerve directly impacts heart rate by decreasing it?
. X (vagus)
__________ exerts its lethal blow by blocking the release of ACh from the terminal button in response to an action potential in the motor neuron.
Botulinum toxin
A neuromuscular junction is a link between two motor neurons.
False
Acetylcholinesterase (AChE) is an enzyme that keeps the muscle cell's electrical response turned on.
False
Adrenergic fibers release acetylcholine.
False
Botulinum toxin acts by triggering explosive release of ACh from storage vesicles at all cholinergic sites.
False
Preganglionic fibers release neurotransmitter onto effector organs in the autonomic nervous system pathway.
False
The autonomic nervous system is subject to voluntary control.
False
The somatic nervous system can both stimulate and inhibit effector organs.
False
The somatic nervous system originates in the lateral horn of the thoracic spinal cord.
False
_____________ receptors are found on the cell membrane of cardiac muscle, smooth muscle and glands.
Muscarinic
_______________ receptors respond to acetylcholine released from both sympathetic and parasympathetic preganglionic fibers.
Nicotinic
____________ postganglionic fibers are short, terminating on the effector organs.
Parasympathetic
dominance is concerned with general "housekeeping" activities.
Parasympathetic
__________ dominance promotes the "fight or flight" response.
Sympathetic
__________nerve fibers originate in the thoracic and lumbar regions of the spinal cord.
Sympathetic
Where do the sympathetic nerve fibers originate?
The lateral horn of the thoracic and lumbar regions of the spinal cord
Acetylcholine can bind to nicotinic receptors in the autonomic nervous system.
True
The chemical neurotransmitter at the neuromuscular junction is__________.
acetylcholine
The venom of black widow spiders exerts its deadly effect by causing an explosive release of ___________ from the storage vesicles.
acetylcholine
___________ is an enzyme in the motor end plate membrane that inactivates acetylcholine.
acetylcholinesterase
A(n) _________ binds with the receptor and causes the same response as the neurotransmitter would.
agonist
A(n) ________ binds with the receptor and prevents the neurotransmitter from causing a response.
antagonist
The parasympathetic and sympathetic nerve fibers innervate most visceral organs, a phenomenon called __________ .
dual innervation
motor neuron
efferent somatic fiber
Acetylcholinesterase is classified as a(n) ____.
enzyme
Acetylcholinesterase
inactivates acetylcholine
Each muscle cell connects to how many neuromuscular junctions?
one
__________ are a group of chemicals that modify neuromuscular junction activity.
organophosphates
The __________ division of the autonomic nervous system stimulates contraction of the bladder wall.
parasympathetic
The ____________ nervous system dominates in quiet, relaxed situations.
parasympathetic
________ system promotes "rest and digest" bodily functions.
parasympathetic
norepinephrine, epinephrine fight or flight acetylcholine muscarinic receptor rest and digest
parasympathetic sympathetic both parasympathetic parasympathetic
antagonist
prevents neurotransmitter from acting
What response is triggered when the parasympathetic system is dominant?
rest and digest response
autonomic
two-neuron chain
The somatic system is considered to be under ___________ control.
voluntary
What type of control exists in the somatic nervous system?
voluntary
Botulinum toxin exerts its lethal blow by blocking the release of what chemical compound?
ACh
What chemical compound do motor-neuron axon terminals release?
acetylcholine
What neurotransmitter is released from the sympathetic preganglionic fiber?
acetylcholine
What is a compound called that mimics a neurotransmitter's response?
agonist
Curare blocks the action of ACh at receptor-channels. Therefore, it is considered a(n) ____.
antagonist
The poliovirus selectively destroys what part of the somatic nervous system?
cell bodies of motor neurons
Parasympathetic preganglionic fibers arise from the ____.
cranial and sacral areas of the CNS
Innervation of a single organ by both branches of the autonomic nervous system is known as ____.
dual innervation
