BIO 235 Assignment 2 Exam
Questions and Answers 100% Pass
With regards to effort and load, describe the main difference between a
lever operating with a mechanical advantage versus a lever operating at a
mechanical disadvantage. - ✔✔a. Mechanical advantage- If the load is
closer to the fulcrum and the effort farther from the fulcrum, then only a
relatively small effort is required to move a large load over a small
distance.Mechanical disadvantage- If the load is farther from the fulcrum
and the effort is applied closer to the fulcrum then a relatively large effort
is required to move a small load.
Name and describe the locations and actions of the muscles typically used
in breathing. - ✔✔a. The diaphragm forms the floor of the thoracic cavity. It
flattens during inspiration to increase the size of the thoracic cavity. The
external intercostals between the ribs increase the lateral and
1
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,anteroposterior dimensions of the thorax. Internal intercostals between ribs
pull ribs together in the opposite movement during expiration to decrease
the size of the thoracic cavity. The diaphragm relaxes during expiration to
form a dome and decrease the size of the thoracic cavity. The anterior
scalenes and the pectoralis minor may assist during forced inspirations.
Describe how K+ permeability and Na+/K+ pump activity contribute to
the unequal distribution of ions and charges, thereby establishing a resting
membrane potential. - ✔✔a. K+ permeability - Because the plasma
membrane has more K+ leak channels than Na+ leak channels, more K+
leaves the cell than Na+, causing the inner membrane to become more
negative and the outside membrane to become more positive.
b. Activity of the Na+/K+ Pump - this pumps out 3 Na+ ions for every 2
K+ ions imported. The Na+/K+ ATPase is electrogenic and helps generate
the inside-negative resting membrane potential by removing more positive
charges from the cell than it puts into it.
Describe the difference between spatial and temporal summation in a
postsynaptic neuron. - ✔✔a. In temporal summation, the action potentials
2
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, of the presynaptic and the elicited postsynaptic neuron summate with each
other. However, in spatial summation, the action potential within a neuron
is a result of several action potentials of presynaptic cells. A presynaptic
neuron is the one that fires the neurotransmitter to the postsynaptic neuron
(receives neurotransmitter that triggers the action potential.
Describe the gross external and cross-sectional anatomy of the spinal cord.
- ✔✔a. The spinal cord begins as a continuation of the medulla oblongata
and terminates at about the second lumbar vertebrae in an adult.
It contains cervical and lumbar enlargements that serve as points of origin
for nerves and extremities.
The tapered portion of the spinal cord is the conus medullaris from which
arise the filum terminale and cauda equina from; 'Horsetail'.
The spinal cord is partially divided into right and left sides by the anterior
median fissure and posterior sulcus.
Paired spinal nerves arise from a spinal segment spinal nerves and paths of
communication between S.C. and body. Roots=2 parts of attachment that
connect each spinal nerve to spinal cord 1) Posterior(Dorsal) Root=sensory
3
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Questions and Answers 100% Pass
With regards to effort and load, describe the main difference between a
lever operating with a mechanical advantage versus a lever operating at a
mechanical disadvantage. - ✔✔a. Mechanical advantage- If the load is
closer to the fulcrum and the effort farther from the fulcrum, then only a
relatively small effort is required to move a large load over a small
distance.Mechanical disadvantage- If the load is farther from the fulcrum
and the effort is applied closer to the fulcrum then a relatively large effort
is required to move a small load.
Name and describe the locations and actions of the muscles typically used
in breathing. - ✔✔a. The diaphragm forms the floor of the thoracic cavity. It
flattens during inspiration to increase the size of the thoracic cavity. The
external intercostals between the ribs increase the lateral and
1
100% Pass Guarantee Katelyn Whitman, All Rights
,anteroposterior dimensions of the thorax. Internal intercostals between ribs
pull ribs together in the opposite movement during expiration to decrease
the size of the thoracic cavity. The diaphragm relaxes during expiration to
form a dome and decrease the size of the thoracic cavity. The anterior
scalenes and the pectoralis minor may assist during forced inspirations.
Describe how K+ permeability and Na+/K+ pump activity contribute to
the unequal distribution of ions and charges, thereby establishing a resting
membrane potential. - ✔✔a. K+ permeability - Because the plasma
membrane has more K+ leak channels than Na+ leak channels, more K+
leaves the cell than Na+, causing the inner membrane to become more
negative and the outside membrane to become more positive.
b. Activity of the Na+/K+ Pump - this pumps out 3 Na+ ions for every 2
K+ ions imported. The Na+/K+ ATPase is electrogenic and helps generate
the inside-negative resting membrane potential by removing more positive
charges from the cell than it puts into it.
Describe the difference between spatial and temporal summation in a
postsynaptic neuron. - ✔✔a. In temporal summation, the action potentials
2
100% Pass Guarantee Katelyn Whitman, All Rights
, of the presynaptic and the elicited postsynaptic neuron summate with each
other. However, in spatial summation, the action potential within a neuron
is a result of several action potentials of presynaptic cells. A presynaptic
neuron is the one that fires the neurotransmitter to the postsynaptic neuron
(receives neurotransmitter that triggers the action potential.
Describe the gross external and cross-sectional anatomy of the spinal cord.
- ✔✔a. The spinal cord begins as a continuation of the medulla oblongata
and terminates at about the second lumbar vertebrae in an adult.
It contains cervical and lumbar enlargements that serve as points of origin
for nerves and extremities.
The tapered portion of the spinal cord is the conus medullaris from which
arise the filum terminale and cauda equina from; 'Horsetail'.
The spinal cord is partially divided into right and left sides by the anterior
median fissure and posterior sulcus.
Paired spinal nerves arise from a spinal segment spinal nerves and paths of
communication between S.C. and body. Roots=2 parts of attachment that
connect each spinal nerve to spinal cord 1) Posterior(Dorsal) Root=sensory
3
100% Pass Guarantee Katelyn Whitman, All Rights
