C2006/f2402 '07 Outline Of Lecture #18
Handouts: Need 17B, 18A (Homeostasis) -- Seesaw view for Glucose and Temperature Regulation; 18 B -- Lactation & Typical Circuit I. Organization -- How are cells set up to co-operate in a multicellular organism? See last lecture & 17B. II. How is a component of the internal milieu regulated? A. Let's look at a specific example, namely blood glucose. The see-saw view. See handout 18A or Purves 50.19 (50.20). 1. Have a regulated variable -- glucose level in blood. 2. Need a sensor (or receptor) -- to measure levels of "regulated variable" (glucose). Here, sensor is in pancreas. 3. Need effector(s) -- to control levels of regulated variable (glucose) -- usually have one or more effectors that respond in opposing ways. In this case, effectors for uptake of glucose are liver, adipose tissue, and skeletal muscle; effector for release of glucose is liver. Note: Some of the terms discussed here are used differently in molecular biology and in physiology. Fortunately, the meaning is usually obvious from the context. For example, the terms "effector" and "negative feedback" are used differently in the two contexts. In physiology, "effector" usually means "a tissue or organ (like muscle or liver) that carries out an action and thus produces an effect." In this example, the effectors = organs that act to raise or lower the blood glucose. In molecular biology, the term "effector" is usually used to mean "a modulator of protein function." A modulator = a small molecule (like an inducer, enzyme activator etc.) that binds to a protein, alters the shape and/or function of the protein, and thus triggers an effect. See below for comments on 'negative feedback.' 4. Have a set point -- the level the regulated variable (blood glucose) should be. Set point is also sometimes used to mean the l Continue reading >>
Module 7 /negative Feedback Loops
Provide an example of a negative feedback loop that utilizes the nervous system to relay information. Describe the specific structures (organs, cells or molecules) included in the feedback loop. Most biological feedback systems are negative feedback systems. Negative feedback occurs when a system's output acts to reduce or dampen the processes that lead to the output of that system, resulting in less output. In general, negative feedback loops allow systems to self-stabilize. Insulin An important example is the control of blood sugar levels following a meal. After a meal, the small intestine absorbs glucose from digested food. Blood glucose levels rise. Increased blood glucose levels stimulate beta cells in the pancreas to produce insulin. Insulin triggers liver, muscle, and fat tissue cells to absorb glucose, where it is stored. As glucose is absorbed, blood glucose levels fall. Once glucose levels drop below a threshold, there is no longer a sufficient stimulus for insulin release, and the beta cells stop releasing insulin. Due to synchronization of insulin release among the beta cells, basal insulin concentration oscillates in the blood following a meal. The oscillations are clinically important, since they are believed to help maintain sensitivity of insulin receptors in target cells. This loss of sensitivity is the basis for insulin resistance. Thus, failure of the negative feedback mechanism can result in high blood glucose levels, which have a variety of negative health effects. Temperature Negative feedback is a vital control mechanism for the body’s homeostasis. One important example of how a negative feedback loop maintains homeostasis is the body’s thermoregulation mechanism. The body maintains a relatively constant internal temperature to optimize chemic Continue reading >>
Negative Feedback And Blood Glucose Regulation
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The Endocrine System And Blood Sugar Regulation
Regulate communication between immune system cells GROWTH FACTORS Growth factors stimulate cell division and proliferation PROSTAGANDINS Prostagandins have multiple functions but their main function is simulating contractions of the uterus. CYTOKINES GLUCAGON The stimulus that releases glucagon is when your blood glucose falls below the normal post absorptive level. It is released by the pancreas. INSULIN Insulin is released when the body experiences increased levels of blood glucose. The gland that release insulin is the pancreas. LT: I can identify specific examples of local regulators, and describe their function LT: I can identify the types of molecules that function as hormones. LT: I can identify the two hormones involved in blood sugar regulation, the stimulus that triggers their release, and the gland that releases them. The Endocrine System and Blood Sugar Regulation LT: I can describe how blood sugar is regulated in vertebrate animals, and explanation how this represents an example of the function of the endocrine system. LT: I can identify the cells targeted in blood sugar regulation, which hormone is involved, and the response of those cells. LT: I can describe the function of the endocrine system LT: I can identify the basic mechanism used by the endocrine system to control and regulate how organisms respond to stimuli. LT: I can compare and contrast how cells receive messages from lipid soluble hormones and water soluble hormones LT: I can distinguish between positive and negative feedback regulation LT: I can identify the type of feedback involved in blood sugar regulation NITRIC OXIDE Nitric oxide relaxes blood vessels and increases the blood flow Proteins Steroids Amines The function of the endocrine system is to control and regulate responses to intern Continue reading >>
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18.3 Regulation Of Body Processes
Maintaining a proper water balance in the body is important to avoid dehydration or over-hydration (hyponatremia). The water concentration of the body is monitored by osmoreceptors in the hypothalamus, which detect the concentration of electrolytes in the extracellular fluid. The concentration of electrolytes in the blood rises when there is water loss caused by excessive perspiration, inadequate water intake, or low blood volume due to blood loss. An increase in blood electrolyte levels results in a neuronal signal being sent from the osmoreceptors in hypothalamic nuclei. The pituitary gland has two components: anterior and posterior. The anterior pituitary is composed of glandular cells that secrete protein hormones. The posterior pituitary is an extension of the hypothalamus. It is composed largely of neurons that are continuous with the hypothalamus. The hypothalamus produces a polypeptide hormone known as antidiuretic hormone (ADH), which is transported to and released from the posterior pituitary gland. The principal action of ADH is to regulate the amount of water excreted by the kidneys. As ADH (which is also known as vasopressin) causes direct water reabsorption from the kidney tubules, salts and wastes are concentrated in what will eventually be excreted as urine. The hypothalamus controls the mechanisms of ADH secretion, either by regulating blood volume or the concentration of water in the blood. Dehydration or physiological stress can cause an increase of osmolarity above 300 mOsm/L, which in turn, raises ADH secretion and water will be retained, causing an increase in blood pressure. ADH travels in the bloodstream to the kidneys. Once at the kidneys, ADH changes the kidneys to become more permeable to water by temporarily inserting water channels, aquapori Continue reading >>
Help Us Do More
Homeostasis is the tendency to resist change in order to maintain a stable, relatively constant internal environment. Homeostasis typically involves negative feedback loops that counteract changes of various properties from their target values, known as set points. In contrast to negative feedback loops, positive feedback loops amplify their initiating stimuli, in other words, they move the system away from its starting state. What's the temperature in the room where you're sitting right now? My guess would be that it's not exactly 98.6F/ 37.0C. Yet, your body temperature is usually very close to this value. In fact, if your core body temperature doesn't stay within relatively narrow limits—from about 95F/ 35C to 107F/ 41.7C—the results can be dangerous or even deadly. The tendency to maintain a stable, relatively constant internal environment is called homeostasis. The body maintains homeostasis for many factors in addition to temperature. For instance, the concentration of various ions in your blood must be kept steady, along with pH and the concentration of glucose. If these values get too high or low, you can end up getting very sick. Homeostasis is maintained at many levels, not just the level of the whole body as it is for temperature. For instance, the stomach maintains a pH that's different from that of surrounding organs, and each individual cell maintains ion concentrations different from those of the surrounding fluid. Maintaining homeostasis at each level is key to maintaining the body's overall function. Biological systems like those of your body are constantly being pushed away from their balance points. For instance, when you exercise, your muscles increase heat production, nudging your body temperature upward. Similarly, when you Continue reading >>
Feedback Loops
Summary This video discusses negative and positive feedback loops, how they tie into the body’s mechanism of internal regulation, and what happens when these mechanisms fail. Thermoregulation, contractions during childbirth, and blood glucose regulation are used to illustrate how feedback loops pass information in the body to maintain homeostasis or elicit a particular biological response. Learning Objectives After watching this video students will be able to: Identify the general components of a feedback loop. Provide examples of negative and positive feedback loops in the body. Describe how feedback loops are vital to healthy function and survival. Funding provided by the Singapore University of Technology and Design (SUTD) Developed by the Teaching and Learning Laboratory (TLL) at MIT for SUTD MIT © 2012 Continue reading >>
Negative Feedback
A negative feedback system has three basic components ([link]a). A sensor, also referred to a receptor, is a component of a feedback system that monitors a physiological value. This value is reported to the control center. The control center is the component in a feedback system that compares the value to the normal range. If the value deviates too much from the set point, then the control center activates an effector. An effector is the component in a feedback system that causes a change to reverse the situation and return the value to the normal range. In order to set the system in motion, a stimulus must drive a physiological parameter beyond its normal range (that is, beyond homeostasis). This stimulus is “heard” by a specific sensor. For example, in the control of blood glucose, specific endocrine cells in the pancreas detect excess glucose (the stimulus) in the bloodstream. These pancreatic beta cells respond to the increased level of blood glucose by releasing the hormone insulin into the bloodstream. The insulin signals skeletal muscle fibers, fat cells (adipocytes), and liver cells to take up the excess glucose, removing it from the bloodstream. As glucose concentration in the bloodstream drops, the decrease in concentration—the actual negative feedback—is detected by pancreatic alpha cells, and insulin release stops. This prevents blood sugar levels from continuing to drop below the normal range. Humans have a similar temperature regulation feedback system that works by promoting either heat loss or heat gain ([link]b). When the brain’s temperature regulation center receives data from the sensors indicating that the body’s temperature exceeds its normal range, it stimulates a cluster of brain cells referred to as the “heat-loss center.” This st Continue reading >>
Ms.rex Science
Blood Spatter Lab - At what height did the blood fall at the crime scene? Official Lab Report Due next Class (9/25)- Lab Report needs to be typed and printed when you come to class Use the data: Crime Scene Blood Spatter AVG: 13mm DNA basics - Reviewed shape, structure -- 4 nitrogen bases and how they bond together Built 3D models of DNA Review DNA basics DNA analysis - Gel Electro (paper version) to compare crime scene DNA to suspects and Anna's DNA Human Body system matching activity Reviewed first autopsy report Write the Following, it will be graded like a test NEEDS TO BE PRINTED OUT AND TURNED IN Introduction: Provide a brief case description. Summary of Findings: Provide evidence and support for your findings for each piece of evidence you analyzed – fingerprints, blood type, shoeprint, hair, unknown substance, blood spatter, and DNA analysis. Discuss any inconsistencies in the data and address the limitations of these methods in reconstructing what happened at the scene. Conclusion: Sum up the case findings and describe your conclusions as to the manner of death (natural, accident, or homicide) of Anna Garcia. NOTE: Think about your analysis as a whole and describe how combined data led you to a conclusion ****IN YOUR CAREER JOURNAL**** 1.Medical Examiner 2.Toxicologist 3.Morgue Assistant Please research and document the following information for the above listed careers. 1.Job Growth 3.Education needed ***YES, you need to cite your sources*** 10/5/17 HIPAA Review HIPAA Case Study HOMEWORK: FINISH CASE STUDY -- DUE NEXT CLASS 10/9/17 Turned in HIPAA Case Study Intro into what is diabetes Medical History of Anna and 2 other patients Glucose Tolerance Testing Lab -- Answer Lab specific questions and graph in journal 10/11-19 Diabetes research and posters Poster Continue reading >>
Feedback - 60 Informal Points
Name __________________________ Feedback - 60 Informal Points Introduction So far in this unit, you have studied how to diagnose diabetes and the connection between insulin and glucose and how the interaction of the two is related to diabetes. But how does your body monitor and control the level of sugar in your blood? The human body maintains homeostasis, a steady state, by monitoring changes in the internal and external environment and feeding this information back to the body so that it can make necessary change. The control of body temperature, heart rate, and the concentration of sugar in the blood are all regulated by these feedback mechanisms or feedback loops. There are actually two types of feedback mechanisms: negative feedback and positive feedback. In this instance, the terms positive and negative do not infer good or bad. Instead, the terms refer to the effect the input of information (feedback) has on the output (action) of the system. Positive feedback causes a reinforcement of the original action, so the input causes the reaction to increase. Negative feedback causes the system to stop doing the original action and to either take no action or to perform an opposite action. While our nervous system communicates using electrical signals, the body’s endocrine system uses chemical signals, called hormones, to regulate body functioning. Hormones are proteins involved in maintaining the body’s homeostasis. These chemical messengers carry signals from one cell to another and regulate many of the body’s functions, including growth and development, metabolism, and reproduction. Hormones are secreted by tissues in the body referred to as glands. Each hormone has a specific list of target tissues, and in many cases these include other endocrine Continue reading >>
A3.4.1cannegativefeedbackbepositive
Introduction So far in this lesson, you have studied the connection between insulin and glucose and how the interaction of the two is related to diabetes. But how does your body monitor and control the level of sugar in your blood? The human body maintains homeostasis, a steady state, by monitoring changes in the internal and external environment and feeding this information back to the body so that it can make necessary change. The control of body temperature, heart rate, and the concentration of sugar in the blood are all regulated by these feedback mechanisms or feedback loops. There are actually two types of feedback mechanisms: negative feedback and positive feedback. In this instance, the terms positive and negative do not infer good or bad. Instead, the terms refer to the effect the input of information (feedback) has on the output (action) of the system. Positive feedback causes a reinforcement of the original action, so the input causes the reaction to increase. Negative feedback causes the system to stop doing the original action and to either take no action or to perform an opposite action. While our nervous system communicates using electrical signals, the body’s endocrine system uses chemical signals, called hormones, to regulate body functioning. Hormones are proteins involved in maintaining the body’s homeostasis. These chemical messengers carry signals from one cell to another and regulate many of the body’s functions, including growth and development, metabolism, and reproduction. Hormones are secreted by tissues in the body referred to as glands. Each hormone has a specific list of target tissues, and in many cases these include other endocrine glands. Hormones are a vital component of the body’s feedback system. Insulin is Continue reading >>
Positive And Negative Feedback Loops In Biology
Feedback is defined as the information gained about a reaction to a product, which will allow the modification of the product. Feedback loops are therefore the process whereby a change to the system results in an alarm which will trigger a certain result. This result will either increase the change to the system or reduce it to bring the system back to normal. A few questions remain: How do these systems work? What is a positive feedback? What is negative feedback? Where do we find these systems in nature? Biological systems operate on a mechanism of inputs and outputs, each caused by and causing a certain event. A feedback loop is a biological occurrence wherein the output of a system amplifies the system (positive feedback) or inhibits the system (negative feedback). Feedback loops are important because they allow living organisms to maintain homeostasis. Homeostasis is the mechanism that enables us to keep our internal environment relatively constant – not too hot, or too cold, not too hungry or tired. The level of energy that an organism needs to maintain homeostasis depends on the type of organism, as well as the environment it inhabits. For example, a cold-blooded fish keeps its temperature at the same level as the water around it, and so doesn’t need to control its internal temperature. Compare this to a warm-blooded whale in the same environment: it needs to keep its body temperature higher than that of the water around it, and so it will expend more energy in temperature regulation. This is a difference between ectotherms and endotherms: an ectotherm uses the environmental temperature to control its internal temperature (e.g. reptiles, amphibians, and fish), whereas an endotherm uses homeostasis to maintain its internal temperature. Endotherms can maintain Continue reading >>
Blood Sugar Regulation
Most cells in the human body use the sugar called glucose as their major source of energy. Glucose molecules are broken down within cells in order to produce adenosine triphosphate (ATP) molecules, energy-rich molecules that power numerous cellular processes. Glucose molecules are delivered to cells by the circulating blood and therefore, to ensure a constant supply of glucose to cells, it is essential that blood glucose levels be maintained at relatively constant levels. Level constancy is accomplished primarily through negative feedback systems, which ensure that blood glucose concentration is maintained within the normal range of 70 to 110 milligrams (0.0024 to 0.0038 ounces) of glucose per deciliter (approximately one-fifth of a pint) of blood. Negative feedback systems are processes that sense changes in the body and activate mechanisms that reverse the changes in order to restore conditions to their normal levels. Negative feedback systems are critically important in homeostasis, the maintenance of relatively constant internal conditions. Disruptions in homeostasis lead to potentially life-threatening situations. The maintenance of relatively constant blood glucose levels is essential for the health of cells and thus the health of the entire body. Major factors that can increase blood glucose levels include glucose absorption by the small intestine (after ingesting a meal) and the production of new glucose molecules by liver cells. Major factors that can decrease blood glucose levels include the transport of glucose into cells (for use as a source of energy or to be stored for future use) and the loss of glucose in urine (an abnormal event that occurs in diabetes mellitus). Insulin and Glucagon In a healthy person, blood glucose levels are restored to normal level Continue reading >>
Feedback Loops Glucose And Glucagon Worksheet Answers
Feedback loops glucose and glucagon worksheet answers For example, negative feedback loops involving insulin and glucagon help to keep blood glucose levels within a narrow concentration range. If the blood glucose level falls Negative feedback is shown in the insulin signal transduction pathway by While insulin is secreted by the pancreas to lower blood glucose levels, glucagon is Get answers . These negative feedback loops of glucose from liver cells, 18. c. A negative feedback loop is a process of Review the opposing functions of these hormones on glucose - Review the opposing functions of glucagon and Endocrine Feedback Loops . Education Resources. Negative feedback loops Keeping a Balance: Homeostasis and Negative Feedback learned to answer questions about blood glucose regulation. Control of blood glucose by insulin and glucagon testosterone negative feedback loop. To appreciate how diabetes occurs, let's take a quick look at the basics of blood sugar regulation. Apr 28, 2011 · Negative Feedback and Blood Glucose Regulation Two important hormones for blood glucose regulation are insulin and glucagon. Prior converted into glycogen for storage. The broken feedback loop makes it difficult or impossible for the body to bring high blood sugar down to a healthy level. sweating to decrease heat shivering/goosebumps to increase heat. blood sugar (insulin-glucagon feedback loop). b. How is body temperature mantained. are glucagon. Answer must "Homeostasis: Negative Feedback He begins by differentiating between negative and positive feedback loops. specifically focuses on the feedback loop between insulin and glucagon. . Use this figure to explain the control of blood glucose by insulin and glucagon. A: NEGATIVE FEEDBACK LOOPS Control of feedback blood glucose levels. Topic Continue reading >>
High School Biology : Understanding Positive Feedback
Example Questions The increased release of oxytocin during childbirth is an example of __________. Possible Answers: Correct answer: positive feedback Explanation: When production of a product in a system then causes more of the same product to be created it is known as positive feedback. In cotrast, when the production of product in a system inhibits additional product production it is known as negative feedback. Positive feedback leads to an exponential increase in the product, without any mediation. Negative feedback holds the product level at an equilibrium amount that is tightly regulated. As oxytocin is released from the brain during childbirth uterine tension is increased, which further increases the amount of oxytocin created. As oxytocin is released, it stimulates the production of even more oxytocin, consistent with positive feedback. Oxytocin is one of only very few positive feedback examples in biological systems. Almost all biological compounds are regulated via negative feedback. Which of the following is an example of positive feedback? Possible Answers: Hunger causes metabolism to slow down, which reduces hunger Oxytocin causes uterine contractions, which cause more release of oxytocin Body temperature rises and causes sweat glands to open up and reduce body temperature Blood sugar rises, which causes the body to release insulin, which lowers blood sugar Correct answer: Oxytocin causes uterine contractions, which cause more release of oxytocin Explanation: During positive feedback the production of an effect stimulates amplification of the same effect. In contrast, during negative feedback the production of an effect stimulates the reduction of the same effect. The result of positive feedback is an exponential increase in the intensity of the effect, whi Continue reading >>
