HUMAN ANATOMY & PHYSIOLOGY
(BIOL 235) ACTUAL ASSIGNMENT 2
QUESTIONS AND ANSWERS,100%
VERIFIED WITH GUARANTEED
SUCCESS ATHABASCA UNIVERSITY..
, BIOL235 Assignment 2
Question1. 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.
When observing lever systems, we will see three key components of the system: the fulcrum
(Fixed point), the effort (cause of movement), and the load (resistance). The way these three
components are arranged allows for either mechanical advantage or mechanical disadvantage.
In order for a lever system to operate with a mechanical advantage, the load must be close to
the fulcrum and the effort farther from the fulcrum. The opposite is true for a lever system to
operate at a mechanical disadvantage. If the load is farther from the fulcrum, and effort is
applied closer to the fulcrum, it will require more effort to create movement. (Page 346)
5/5
Question2. Name and describe the locations and actions of the muscles typically used in
breathing.
The muscles of the thorax are typically the muscles used in breathing. The muscles of the
thorax change the size of the thoracic cavity, allowing breathing to occur. The major muscle
used for breathing is the diaphragm. The diaphragm is positioned as the floor of the thoracic
cavity and the roof of the abdominal cavity. It originates of the xiphoid process of the sternum,
costal cartilages of ribs 7-12, lumbar vertebrae and their corresponding intervertebral discs. It
inserts on the central tendon, which is near the centre of the muscle and is fused with the
inferior surface of the pericardium and pleurae. Contraction of the diaphragm causes it to
flatten and increase vertical surface area of the thoracic cavity, resulting in inhalation.
Relaxation of the diaphragm causes it to return to its original position (decreases surface area
of thoracic cavity), resulting in exhalation.
Another pair of muscles that help aid in breathing is the intercostal muscles. There are two
layers to the intercostal muscles, the external layer, and the internal layer. Each layer consists
of 11 pairs. The external intercostals occupy the superficial layer, and the fibres run in an
oblique direction. They originate on the inferior border of the rib above and insert on the
superior border of the rib below. They function to elevate the ribs during inhalation and help to
expand the thoracic cavity. The internal intercostals occupy the intermediate layer of the
intercostal spaces, and the fibres run in an oblique direction as well. They originate on the
superior border of the rib below and insert on the inferior border of the rib above. The internal
intercostals function to draw ribs together during forces exhalation to decrease the size of the
thoracic cavity. (Page 369).
(BIOL 235) ACTUAL ASSIGNMENT 2
QUESTIONS AND ANSWERS,100%
VERIFIED WITH GUARANTEED
SUCCESS ATHABASCA UNIVERSITY..
, BIOL235 Assignment 2
Question1. 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.
When observing lever systems, we will see three key components of the system: the fulcrum
(Fixed point), the effort (cause of movement), and the load (resistance). The way these three
components are arranged allows for either mechanical advantage or mechanical disadvantage.
In order for a lever system to operate with a mechanical advantage, the load must be close to
the fulcrum and the effort farther from the fulcrum. The opposite is true for a lever system to
operate at a mechanical disadvantage. If the load is farther from the fulcrum, and effort is
applied closer to the fulcrum, it will require more effort to create movement. (Page 346)
5/5
Question2. Name and describe the locations and actions of the muscles typically used in
breathing.
The muscles of the thorax are typically the muscles used in breathing. The muscles of the
thorax change the size of the thoracic cavity, allowing breathing to occur. The major muscle
used for breathing is the diaphragm. The diaphragm is positioned as the floor of the thoracic
cavity and the roof of the abdominal cavity. It originates of the xiphoid process of the sternum,
costal cartilages of ribs 7-12, lumbar vertebrae and their corresponding intervertebral discs. It
inserts on the central tendon, which is near the centre of the muscle and is fused with the
inferior surface of the pericardium and pleurae. Contraction of the diaphragm causes it to
flatten and increase vertical surface area of the thoracic cavity, resulting in inhalation.
Relaxation of the diaphragm causes it to return to its original position (decreases surface area
of thoracic cavity), resulting in exhalation.
Another pair of muscles that help aid in breathing is the intercostal muscles. There are two
layers to the intercostal muscles, the external layer, and the internal layer. Each layer consists
of 11 pairs. The external intercostals occupy the superficial layer, and the fibres run in an
oblique direction. They originate on the inferior border of the rib above and insert on the
superior border of the rib below. They function to elevate the ribs during inhalation and help to
expand the thoracic cavity. The internal intercostals occupy the intermediate layer of the
intercostal spaces, and the fibres run in an oblique direction as well. They originate on the
superior border of the rib below and insert on the inferior border of the rib above. The internal
intercostals function to draw ribs together during forces exhalation to decrease the size of the
thoracic cavity. (Page 369).
