Assignment 1 95.7%
Weight: 5%
Minimum Pass Grade: 50%
Each question is worth 10 marks.
1. Maintenance of calcium ion homeostasis is critical to neurological,
cardiac and skeletal muscle function. Consider the roles of two
hormones involved in the regulation of the concentration of calcium
ions in the blood. Parathyroid hormone increases the concentration of
calcium ions in the blood, while calcitonin decreases the concentration.
Based on this information predict the body’s response to restore calcium
balance if a person swallowed 100 antacid tablets made of a calcium
compound in 10 minutes. Include in your answer the definition of
homeostasis, the type of feedback loop involved and all of the
components of a feedback loop.
Homeostasis is the condition of equilibrium in the body's internal
environment due to the constant interaction of the body's many regulatory
responses
1. FYI -homeostasis: as maintenance of body conditions within acceptable
limits as ‘equilibrium’ for a cell is death
.
. Homeostasis is also a dynamic condition, which maintains body
conditions within a narrow range of limits that are compatible with
maintaining life.
After a person has swallowed 100 antacid tablets, made of a calcium
component, the calcium levels in their blood will increase. This increase
in blood calcium is a stimulus that disrupts homeostasis by increasing
Assignment 1 :: Biology 235: Human Anatomy and Physiology 1
, the blood calcium beyond the normal limits set in the controlled
condition. This change in the controlled condition prompts the body to
reverse and negate the original change (increase in blood calcium) by
decreasing the calcium levels in the blood, thereby making this a
negative feedback loop. Receptors, one of the three basic components of
a feedback loop, in the thyroid gland monitor the controlled condition
and recognize that blood calcium levels have surpassed optimum levels.
The thyroid sends input, in the form of nerve impulses, to the control
center. The control center, one of the three basic components of a
feedback loop, is the brain, which sets the range of values that the
controlled condition should be maintained and evaluates the input from
the receptors in the thyroid gland and generates an output to the thyroid
gland’s parafollicular cells to secrete calcitonin. Effectors, one of the
three basic components of a feedback loop, are the osteoclasts that
receive the output from the control center and work to reverse the
change to the controlled condition. Calcitonin inhibits activity of
osteoclasts, which works to speed up blood calcium uptake by bone,
and accelerate calcium deposition into bones. The receptors in the
parathyroid gland cells also detect the increase in blood calcium and
generate an input: decrease production of cyclic adenosine
monophosphate. The control center, the gene for parathyroid hormone
within the nucleus of the parathyroid gland cell, receives the input
which turns off the gene, thereby blocking the release of parathyroid
hormone. Blocking parathyroid hormone works on the effectors,
osteoclasts and kidneys, by decreasing the number and activity of
osteoclasts, and decreasing the ability of the kidneys to retain calcium,
resulting in the loss of calcium in urine. The effectors bring about
changes that cause blood calcium levels to drop, a result that negates the
original stimulus (an increase in blood calcium). The negative feedback
Assignment 1 :: Biology 235: Human Anatomy and Physiology 2
Weight: 5%
Minimum Pass Grade: 50%
Each question is worth 10 marks.
1. Maintenance of calcium ion homeostasis is critical to neurological,
cardiac and skeletal muscle function. Consider the roles of two
hormones involved in the regulation of the concentration of calcium
ions in the blood. Parathyroid hormone increases the concentration of
calcium ions in the blood, while calcitonin decreases the concentration.
Based on this information predict the body’s response to restore calcium
balance if a person swallowed 100 antacid tablets made of a calcium
compound in 10 minutes. Include in your answer the definition of
homeostasis, the type of feedback loop involved and all of the
components of a feedback loop.
Homeostasis is the condition of equilibrium in the body's internal
environment due to the constant interaction of the body's many regulatory
responses
1. FYI -homeostasis: as maintenance of body conditions within acceptable
limits as ‘equilibrium’ for a cell is death
.
. Homeostasis is also a dynamic condition, which maintains body
conditions within a narrow range of limits that are compatible with
maintaining life.
After a person has swallowed 100 antacid tablets, made of a calcium
component, the calcium levels in their blood will increase. This increase
in blood calcium is a stimulus that disrupts homeostasis by increasing
Assignment 1 :: Biology 235: Human Anatomy and Physiology 1
, the blood calcium beyond the normal limits set in the controlled
condition. This change in the controlled condition prompts the body to
reverse and negate the original change (increase in blood calcium) by
decreasing the calcium levels in the blood, thereby making this a
negative feedback loop. Receptors, one of the three basic components of
a feedback loop, in the thyroid gland monitor the controlled condition
and recognize that blood calcium levels have surpassed optimum levels.
The thyroid sends input, in the form of nerve impulses, to the control
center. The control center, one of the three basic components of a
feedback loop, is the brain, which sets the range of values that the
controlled condition should be maintained and evaluates the input from
the receptors in the thyroid gland and generates an output to the thyroid
gland’s parafollicular cells to secrete calcitonin. Effectors, one of the
three basic components of a feedback loop, are the osteoclasts that
receive the output from the control center and work to reverse the
change to the controlled condition. Calcitonin inhibits activity of
osteoclasts, which works to speed up blood calcium uptake by bone,
and accelerate calcium deposition into bones. The receptors in the
parathyroid gland cells also detect the increase in blood calcium and
generate an input: decrease production of cyclic adenosine
monophosphate. The control center, the gene for parathyroid hormone
within the nucleus of the parathyroid gland cell, receives the input
which turns off the gene, thereby blocking the release of parathyroid
hormone. Blocking parathyroid hormone works on the effectors,
osteoclasts and kidneys, by decreasing the number and activity of
osteoclasts, and decreasing the ability of the kidneys to retain calcium,
resulting in the loss of calcium in urine. The effectors bring about
changes that cause blood calcium levels to drop, a result that negates the
original stimulus (an increase in blood calcium). The negative feedback
Assignment 1 :: Biology 235: Human Anatomy and Physiology 2
