BIOL235: Assignment 1 (2020): Athabasca University
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BIOL 235
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BIOL 235
BIOL235: Assignment 1 (2020): Athabasca University
Biology 235: Human Anatomy and Physiology (Latest): Athabasca University 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 functio...
Student ID: 3369857
Assignment 1
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 dynamic condition of equilibrium in the body’s internal environment due to the constant interaction of the body's many regulatory processes . A feedback system is a cycle of events in which the status of a body condition is monitored, evaluated, changed, re-monitored, reevaluated and so on. The three basic components of a feedback system are the receptor, control center and effector. A receptor is a body structure that monitors changes in a controlled condition and sends input to a control center through the afferent pathway. A control center is the body sets the range of values within which a controlled condition should be maintained, evaluates the input it receives from the receptor and generates output commands to effectors through the efferent pathway. An effector is a body structure that receives output from the control center and produces a response or effect that changes the controlled condition. A negative
feedback system reverses a change in a controlled condition. Usually, the blood plasma level of calcium ion is regulated at a certain concentration. In the scenario, a person’s calcium level in blood will rise suddenly if he or she swallowed 100 calcium compound tablets. The person might experience hypercalcemia. High calcium concentration acts as a stimulus and it disrupts calcium homeostasis by increasing the controlled blood calcium level (controlled condition). thyroid gland parafollicular cells (the receptor) therefore detect the increased calcium concentration and release calcitonin. calcitonin is a hormone inhibits the activity of osteoclast (effector), speeds blood calcium uptake by bone, and increase calcium deposition into bones. Therefore, calcitonin increase bone formation and decreasing blood Ca 2+ level. (response). At the same time, parathyroid glands will reduce the release of, parathyroid hormone to the blood. Unlike calcitonin, parathyroid hormone increases blood ca 2+ level and increase bone resorption (the breakdown of bone extracellular matrix) by osteoclast. What’s more, the kidney will excrete calcium in blood so excessive calcium can be excreted out of the body through urine. After the calcium blood level lowers down to the optimal range by a negative feedback loop, calcium homeostasis is achieved.
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2. Provide one important example (in the human body) of each of the following:
Assignment 1 :: Biology 235: Human Anatomy and Physiology 1 Student ID: 3369857
What is the function of each of these three molecules you have identified in the human body? Explain why each of these three molecules must have specific types of bonds in order to perform that molecule’s function.
a.a molecule containing ionic bonds
Sodium Chloride (NaCl), which is known as salt, contains ionic bonds. which is the force of attraction that holds together cation and anion. The sodium atom has 11 electrons in total, consists of 2 electrons in the first shell, 8 electrons in the second shell and one valence electron. By donating one electron, the sodium atom becomes a cation, which has a positive charge. A chlorine atom has 17 electrons in total, consists of 2 electrons in the first shell, 8 electrons in the second shell seven valence electrons. By gaining one electron, the chlorine atom becomes anion, which has a negative charge. In order to form a chemically stable arrangement of eight valence electrons according to the octet rule, sodium atom and chlorine atom interact with each other and form the ionic bond. Sodium Chloride can be added to food as seasoning. Sodium ion and chlor ine ion are important in maintaining water balance in our body and they are the most plentiful cation and anion in extracellular fluids. Sodium-potassium pumps are the primary active transport mechanism that maintains a low concentration of sodium iron and a high concentration of potassium in the cytosol, which is important for maintaining normal cell volume and for cells to generate electrical signals. In addition, the energy stored in sodium ion concentration gradient is used for secondary active transport that transport other substances across the membrane against their own concentration gradients. Sodium is required to produce an action potential. 0.9% NaCl isotonic saline is commonly used as an intravenous solution in hospital. 2% NaCl hypertonic solution is used to relieve fluid overload in the body. Ionic compounds can be broken into positive and negative ions in solutions, which become electrolyt e. b.a molecule containing covalent bonds
Covalent bonds are the most common chemical bonds in the body. Two atoms (same or different elements)
that form covalent bond share electrons to have a complete octet of electrons in their outermost shell, instead of donating or accepting them like an ionic bond. Depends on the pair of sharing valence electrons between two atoms, there is a single, double and triple covalent bond. If two atoms share the electrons equally, the covalent bond is nonpolar. However, if the sharing of electrons is unequal between two atoms, a polar covalent bond is formed. The atom that attracts electrons more strongly than the other has greater electronegativity. O2 (oxygen molecule) is one the example that forms a nonpolar covalent bond between two oxygen atoms. Each Oxygen atom has 8 electrons in total, containing 2 electrons in the first shell and 6
in the second shell. Each oxygen atom requires two more electrons to achieve eight valence electrons based on the octet rule. By sharing two pairs of electrons, two oxygen atom is stabilized and form an oxygen molecule. An oxygen molecule (O2) form a double nonpolar covalent bond. Oxygen is the most important major element in the body. oxygen is necessary to generate energy through
aerobic respiration. Oxygen is part of the air and We cannot breathe without oxygen. It is part of water and many organic molecules. Oxygen molecule combines with hydrogen molecule to form water molecules through synthesis reactions.
c.a molecule containing hydrogen bonds
Assignment 1 :: Biology 235: Human Anatomy and Physiology 2
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