BIO 203 UNIT 2 - UNIT 2 PDF

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UNIT 2
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Introspect What work have you done so far for Unit 2 of BIO203? Write a paragraph describing what you did, when, and for how long. Include the amount of time you spent watching lectures 2 and 3, reviewing them, finishing the activities, practicing test questions, reading, studying with a group or alone, or any other work you did for these two lectures. I first began my work for Unit 2 of BIO 203 on Sunday, August 30th which is when I watched Lectures 2 and 3. I spent two hours watching lecture 2 while taking notes on the slides and extra things that the professor said. After taking notes on lecture 2, I took an hour to write additional notes on Body Temperature that was mentioned in the textbook. On the same day, I started watching lecture 3 and took notes on the slides and what the professor mentioned about the topic. I looked back at the textbook and wrote additional notes on Water and Ion Balance as well as Temperature Regulation, altogether this took me two and a half hours. On Monday, I decided to review and read the material I took notes on the day prior, alone for an hour. Afterwards, My study group decided to video chat and discuss any problem areas we had and any confusion we ran into while watching the lecture or reading the textbook. We were on call for two hours. On Tuesday, I completed my Learn activity which took 20 minutes. On Wednesday, my study group video chatted again to go over test questions on Lectures 2 and 3, for an hour. After our call, I decided to take notes on the questions I got wrong during the review session. On Thursday, I completed my Verify and Evaluate assignments which took me two hours. Afterwards, I completed my Introspect assignment which took 10 minutes. Verify 1. For the following question, select the correct answer and explain why your answer is correct. A hyperosmotic solution is a) Hypertonic b) Hypotonic c) Isotonic d) Not enough information to determine the tonicity There is not enough information to determine the tonicity of the hyperosmotic solution. Tonicity is defined as the effect a solution has on a cell. In order to determine the tonicity of a solution, osmolarity must also be considered because they are interrelated but still different. Osmolarity is defined as the index of water concentration which requires a frame of reference and refers to the animal or organ as a whole instead of just on a cellular level, like in tonicity. In simpler terms, the greater the concentration of a dissolved solute in the water, the less concentrated the water would be. This is measured in the number of osmoles of solute per liter of solution. The terms to describe tonicity are hypertonic, hypotonic, and isotonic and explain the effect a solution has on the cell. Where in hypotonic solutions there is a net water influx into cells, isotonic solutions have no net movement of water into cells, and hypertonic solutions have a net water flux out of the cells. The terms hyperosmotic, hypoosmotic, and isomosic refer to the total amount of solutes in a solution and like the terms for tonicity is relative to another compartment. For example, if compartment A is 300 mOsm and compartment B is 100 mOsm, compartment A would be considered hyperosmotic or to have a greater amount of solutes relative to compartment B. If there was a third compartment called compartment C that has a solution with 200 mOsm, it would be considered hyperosmotic to compartment B but hypoosmotic to compartment A. For a solution to be considered isosmotic it must have no net water flow and the same concentration of solutes relative to another solution. A net flow of water is present in these examples since water moves from a region of low osmolarity to one of high osmolarity. This shows that the net movement of water cannot be determined without a frame of reference, and this would mean that tonicity is inconclusive without more information.

In order to do so, each compartment should be specified with its osmolarity to determine the movement of water and a clear indication of frame of reference must be included or the tonicity of the solution will not be able to be determined. There is not enough information to determine the tonicity of the solution. To begin, Osmolarity is defined as an index of water concentration. In that sense, the greater the concentration a dissolved solute is in the water, the less concentrated the water would be. It should also be noted that osmolarity typically refers to a whole animal or organ level and calls for a frame of reference. A frame of reference is needed as a given solution can be described as hyperosmotic relative to one solution and hyperosmotic to another. Take, for example, a solution that is 300 mOsm. This solution would be considered hyperosmotic relative to a solution with 200 mOsm by hypoosmotic relative to a solution with 1000 mOsm. A net flux of water is present in these examples as water will move from a region of low osmolarity to one of high osmolarity. Additionally, the 200 mOsm solution would be considered isosmotic relative to a solution with the same concentration as there would be no net movement of water. The main point is that the net movement of water becomes inconclusive without a frame of reference, and this would mean that tonicity cannot be determined without more information. Ideally, each compartment should be specified with its osmolarity to determine the movement of water. With tonicity, this term is used to describe the effect a solution has on the cell. Therefore, tonicity is more focused on a cellular level while osmolarity is more commonly used for the organ or animal level. Additionally, it should be noted that tonicity can be used to describe three types of solutions. This includes hypotonic solutions, where there is a net water influx into cells, isotonic solutions where there is no net movement of water into cells, and hypertonic solutions where there is a water efflux from the cells. Generally, water tends to go into the cell when osmolarity of a solution is lower than that of the cell, which indicates a hypotonic solution. This also applies in vice-versa, where water leaves the cells when the osmolarity of the solution is higher than that of the cell, which is a hypertonic solution. To reiterate, without the osmolarity of the solutions and a clear indication of frame of reference, the tonicity of the solution cannot be determined. 2. Beginning with the introduction of bacteria into a human, describe the sequence of events that produce fever, Include each of the 10 terms below at least once. ○ Pyrogen - fever producing substances i. Raises the set point in the hypothalamic thermoregulatory center ii. Exogenous pyrogens raise the body temperature by acting directly on hypothalamic thermoregulatory centers and indirectly by stimulating the release of endogenous pyrogens 1. Exogenous pyrogens a. Produced by gram negative bacteria b. potent 2. Endogenous pyrogens a. Heat-labile proteins produced by own leukocytes (white blood cells) b. Released in response to circulating exogenous pyrogens ○ Vasoconstriction ○ Shivering ○ Set Point ○ Body Temp (Tb) ○ Hypothalamus i. Mammal’s Thermostat ○ Endogenous Heat ○ Effectors

○ ○

Metabolic Rate (MR) Heat loss

This statement is incorrect. Although a person who is starting to get a fever may feel cold and have the chills, or shiver, these responses are due to an increase in the temperature set point of the body, not a decrease. In fever, the temperature set point value is elevated due to the activity of pyrogens. A normal body temperature is less than this new, elevated, set point. The body's hypothalamic thermoregulatory system increases the activity of effector processes that generate heat in response to this difference measured by its integrating center. "Feeling" cold may lead to behavioral thermoregulatory actions to minimize heat loss to the environment, such as staying in bed or putting on warm clothing, and shivering generates endogenous heat. Both of these processes lead to an increase in body temperature until it reaches the new, higher, set point value When a bacteria is introduced into the human body, a fever may be produced. This fever first proceeds through having exogenous pyrogens enter the bloodstream. Exogenous pyrogens are defined as polysaccharides that are produced by gram negative bacteria and are known as being very potent. After this the leukocytes, also known as white blood cells, which are from the human who has the fever detects the circulating exogenous pyrogens. This will trigger a response to produce and release the endogenous pyrogens. These endogenous pyrogens are assigned as heat-labile proteins. During this process, since the hypothalamic thermoregulatory center is very sensitive to any type of pyrogens and all temperaturerelated information, it will raise the set point. This is done by the exogenous pyrogens who act directly upon the hypothalamic thermoregulatory center. Set point is defined as a reference or target value, that means that if the body temperature becomes too high and goes past the set point, increasing it, the body will use d ifferent methods to reach the set point again. The next step is done through endogenous heat production which allows for heat to be generated internally through chemical processes, such as metabolism. Metabolism attempts to maintain body temperature by increasing the metabolic rate which will allow heat to be produced. Since the body deviated from the set point by increasing it, effectors will be activated in order to provide negative feedback that is critical for maintaining homeostasis. For example, one effector would be shivering thermogenesis which is defined as the process where muscle contraction is utilized to produce heat. Although this method can help the body reach back to the set point it is not efficient because it uses a lot of energy. However, another example of a more effective effector would be vasoconstriction. Vasoconstriction is the process where the vessels in the human body become smaller in order to decrease its length and therefore lower heat transfer. Due to the decreased heat transfer, heat dissipation to the environment is minimized and heat loss is reduced. All of these events and responses are due to the orchestration of the hypothalamus which assesses all of the temperature-related information and constructs a systemic response. Evaluate The following statements are similar to those you might see on exams:1. Write a paragraph of 3-5 sentences describing 1) whether the statement is correct or incorrect and 2) the reasoning for your answer. Your answer should demonstrate your understanding of the physiological concepts underlying the statement and be written professionally. The transport of both hydrophilic and hydrophobic substances through the cell membrane

requires the presence of transmembrane integral proteins in the membrane.

This statement is incorrect. The transport of hydrophobic substances through the cell membrane does not require the presence of transmembrane integral proteins in the membrane. Unlike hydrophilic substances which are blocked by the hydrophobic core of the lipid bilayer, hydrophobic substances easily pass directly through the lipid bilayer without the help of transmembrane integral proteins, no matter what kind of transport. Due to the blockage by the hydrophobic core of the lipid bilayer, hydrophilic substances require transmembrane integral proteins in the membrane for both active and passive transport. Transmembrane protein passes through the lipid bilayer and is essential for movement of molecules from one side of the membrane to the other. There are two different types of transmembrane proteins that aid in different types of transport. The transmembrane channel, also known as an aqueous pore, aids in facilitating passive transport of hydrophilic substances by creating a pathway for substances to cross the membrane. Facilitated diffusion takes place with the assistance of carrier proteins which will move the hydrophilic substance against the concentration gradient. 2. Write a paragraph of 3-5 sentences describing 1) whether the statement is correct or incorrect and 2) the reasoning for your answer. Your answer should demonstrate your understanding of the physiological concepts underlying the statement and be written professionally. In the case of a seagull standing on ice, counter-current exchange in the legs minimizes heat loss by reducing the ease of movement of heat transfer to the environment through conduction. This is an incorrect statement. Countercurrent exchange does not minimize the heat lost to the environment by reducing the ease of movement through conduction. In this case, the ease of movement is higher because the thermal conductivity is high due to the small distance between the ice and the skin of the seagull’s foot and the contact between the seagull’s foot and the ice being a very large surface area. In order for the seagull to effectively minimize heat loss to the environment it can decrease driving force by utilizing the countercurrent heat exchange mechanism in its limbs. This would be done between the veins and arteries of the seagull’s legs, lowering the temperature of the blood to the feet. This mechanism is done with the close contact of the arteries, in the legs, taking blood to the feet and the veins, in the legs, returning blood to the body. Heat will then transfer by conduction from the warmer arterial blood to the cooler venous blood. These will counter each other with heat moving across the vessels. Allowing for the venous blood to increase in temperature from the arteries before returning to the body and the arteries being cooled before reaching the seagull’s feet. This countercurrent exchange mechanism in the seagull’s legs decreases the driving force allowing for minimal heat loss....