ASU BIO 201: EXAM 3 EXPECTED QUESTIONS WITH
VERIFIED ANSWERS
Question 1.
steps of regeneration of PNS nerve fiber
ANSWER
Question 2.
structure of
a chemical synapse
ANSWER
Question 3.
action potential
ANSWER
quick up and down voltage shift from -RMP to a positive value, and back to the negative value
again
-RMP= stable voltage seen in a waiting muscle or nerve cell
-seen in an active stimulated cell
-one action potential at one point on a plasma membrane causes another to happen,
triggering a chain rxn
,Question 4.
isometric muscle contraction
ANSWER
Isometric: muscle is producing internal tension while an external resistance causes it to stay
the same length or become longer, can be a prelude to movement when tension is absorbed
by elastic component of muscle, important in postural muscle function and antagonistic
muscle joint stabilization
Question 5.
major differences between smooth, cardiac, and skeletal muscle
ANSWER
Smooth: one nucleus, no striations, dense bodies instead of Z discs, no T tubules, capable of
mitosis and hyperplasia, involuntary
Cardiac: striated, intercalated discs, damaged cells repair by fibrosis, larger T tubules,
involuntary
Skeletal: striated, voluntary,
Question 6.
characteristics of muscle
ANSWER
Responsiveness (excitability): to chemical signals, stretch and electrical changes across plasma
membrane
Conductivity: local electrical change triggers a wave of excitation that travels along the muscle
fiber
Contractility: shortens when stimulated
Extensibility: capable of being stretched between contractions
Elasticity: returns to its original resting length after being stretched
Question 7.
3 fundamental types of neurons and their functions
ANSWER
Sensory (afferent) neurons: detect changes in environment called stimuli, transmit info to
brain or spinal cord
Interneurons (association neurons): between sensory and motor pathways in
CNS, 90% of our neurons are interneruons, they process, store, and retrieve info
Motor (efferent) neuron: send signals to muscle and gland cells, organs that carry out
responses called effectors
,Question 8.
steps of an action potential
ANSWER
-Local potential arrives at axon hillock
-voltage reaches threshold potential
-Voltage-gated Na+ channels open (Na+ enters for depolarization)
-Passes 0 mV and Na+ channels close (peaks @+35)
-K+ gates fully open (K+ leaves) and produce repolarization
-Negative overshoot produces hyperpolarization
Question 9.
somatic motor neuron and location of their cell bodies
ANSWER
stimulate skeletal muscle
-cell bodies located in brainstem and spinal cord
Question 10.
flexor withdrawal and crossed-extensor reflexes
ANSWER
Question 11.
2 main pathways of ATP synthesis
ANSWER
Anaerobic fermentation: cells make little ATP w/out oxygen, produces lactic acid
(a major part in muscle fatigue)
Aerobic respiration: produces more ATP, less toxic end products (CO2 and water), requires
constant supply of O2
Question 12.
origin and insertion definition
ANSWER
i. Origin: bony attachment at stationary end of muscle
ii. Insertion: bony attachment to mobile end of muscle
, Question 13.
Isotonic muscle contraction
ANSWER
i. muscle changes in length with no change in tension
ii. concentric and eccentric contraction
Question 14.
how the diameter of a nerve fiber and myelin affect speed of signal transmission
ANSWER
large fibers have more surface area for signals, and the presence of myelin makes signal
transmission faster
Question 15.
components of neuromuscular junction
ANSWER
Synaptic knob: swollen end of nerve fiber (synaptic vesicles undergo exocytosis and release
ACh into synaptic cleft)
Synaptic cleft: tiny gap between synaptic knob and muscle sarcolemma
Schwann cell: envelops and isolates all of the NMJ from surrounding tissue fluid
50 mil ACh receptors - junctional folds of sarcolemma
Basal lamina: thin layer of collagen and glycoprotein separates Schwann cell and entire muscle
cell from surround tissues (contains AChE)
Question 16.
ionic vs adrenergic synaptic transmission
ANSWER
Cholinergic synapse produces an ionotropic effect
-nerve signal opens voltage-gated Ca channels
-triggers release of ACh which crosses synapse
-ACh receptors trigger opening of Na+ channels producing local potential
-when reaches -55mV, triggers action potential
Adrenergic synapse: employs the neurotransmitter norepinephrine (NE), also called
noradrenaline
-Receptor is not an ion gate, but a transmembrane protein associated with a G protein
-Slower to respond than cholinergic and GABA-ergic synapses
-Has advantage of enzyme amplification-single molecule of NE can produce vast numbers of
product molecules in the cell
VERIFIED ANSWERS
Question 1.
steps of regeneration of PNS nerve fiber
ANSWER
Question 2.
structure of
a chemical synapse
ANSWER
Question 3.
action potential
ANSWER
quick up and down voltage shift from -RMP to a positive value, and back to the negative value
again
-RMP= stable voltage seen in a waiting muscle or nerve cell
-seen in an active stimulated cell
-one action potential at one point on a plasma membrane causes another to happen,
triggering a chain rxn
,Question 4.
isometric muscle contraction
ANSWER
Isometric: muscle is producing internal tension while an external resistance causes it to stay
the same length or become longer, can be a prelude to movement when tension is absorbed
by elastic component of muscle, important in postural muscle function and antagonistic
muscle joint stabilization
Question 5.
major differences between smooth, cardiac, and skeletal muscle
ANSWER
Smooth: one nucleus, no striations, dense bodies instead of Z discs, no T tubules, capable of
mitosis and hyperplasia, involuntary
Cardiac: striated, intercalated discs, damaged cells repair by fibrosis, larger T tubules,
involuntary
Skeletal: striated, voluntary,
Question 6.
characteristics of muscle
ANSWER
Responsiveness (excitability): to chemical signals, stretch and electrical changes across plasma
membrane
Conductivity: local electrical change triggers a wave of excitation that travels along the muscle
fiber
Contractility: shortens when stimulated
Extensibility: capable of being stretched between contractions
Elasticity: returns to its original resting length after being stretched
Question 7.
3 fundamental types of neurons and their functions
ANSWER
Sensory (afferent) neurons: detect changes in environment called stimuli, transmit info to
brain or spinal cord
Interneurons (association neurons): between sensory and motor pathways in
CNS, 90% of our neurons are interneruons, they process, store, and retrieve info
Motor (efferent) neuron: send signals to muscle and gland cells, organs that carry out
responses called effectors
,Question 8.
steps of an action potential
ANSWER
-Local potential arrives at axon hillock
-voltage reaches threshold potential
-Voltage-gated Na+ channels open (Na+ enters for depolarization)
-Passes 0 mV and Na+ channels close (peaks @+35)
-K+ gates fully open (K+ leaves) and produce repolarization
-Negative overshoot produces hyperpolarization
Question 9.
somatic motor neuron and location of their cell bodies
ANSWER
stimulate skeletal muscle
-cell bodies located in brainstem and spinal cord
Question 10.
flexor withdrawal and crossed-extensor reflexes
ANSWER
Question 11.
2 main pathways of ATP synthesis
ANSWER
Anaerobic fermentation: cells make little ATP w/out oxygen, produces lactic acid
(a major part in muscle fatigue)
Aerobic respiration: produces more ATP, less toxic end products (CO2 and water), requires
constant supply of O2
Question 12.
origin and insertion definition
ANSWER
i. Origin: bony attachment at stationary end of muscle
ii. Insertion: bony attachment to mobile end of muscle
, Question 13.
Isotonic muscle contraction
ANSWER
i. muscle changes in length with no change in tension
ii. concentric and eccentric contraction
Question 14.
how the diameter of a nerve fiber and myelin affect speed of signal transmission
ANSWER
large fibers have more surface area for signals, and the presence of myelin makes signal
transmission faster
Question 15.
components of neuromuscular junction
ANSWER
Synaptic knob: swollen end of nerve fiber (synaptic vesicles undergo exocytosis and release
ACh into synaptic cleft)
Synaptic cleft: tiny gap between synaptic knob and muscle sarcolemma
Schwann cell: envelops and isolates all of the NMJ from surrounding tissue fluid
50 mil ACh receptors - junctional folds of sarcolemma
Basal lamina: thin layer of collagen and glycoprotein separates Schwann cell and entire muscle
cell from surround tissues (contains AChE)
Question 16.
ionic vs adrenergic synaptic transmission
ANSWER
Cholinergic synapse produces an ionotropic effect
-nerve signal opens voltage-gated Ca channels
-triggers release of ACh which crosses synapse
-ACh receptors trigger opening of Na+ channels producing local potential
-when reaches -55mV, triggers action potential
Adrenergic synapse: employs the neurotransmitter norepinephrine (NE), also called
noradrenaline
-Receptor is not an ion gate, but a transmembrane protein associated with a G protein
-Slower to respond than cholinergic and GABA-ergic synapses
-Has advantage of enzyme amplification-single molecule of NE can produce vast numbers of
product molecules in the cell
