9th Grade - Biology - Unit 10: Homeostasis
Describe homeostasis.
Homeostasis describes the property of a system that maintains a stable internal environment despite a widely fluctuating external environment. In addition to body-temperature regulation, many other properties of our internal environment are kept within specific limits so that our bodies can function properly. This particular feature is called homeostasis. Other properties that are regulated include levels of fluids, salts, gases, and nutrients.
Explain homeostasis.
Homeostasis is the body's way of regulating and stabilizing processes of the body (maintaining balance among body systems). The body systems work to react to an external condition in order to regulate the amount of glucose, temperature, etc. For example, one of the body's natural reactions to an external condition is how a human may begin shivering when temperature is cold (muscle contractions keep the body warm).
Define homeostasis.
Homeostasis is the natural process of equilibrium and stable levels of sugar, temperature, etc. within the body of an organism.
What are some examples of homeostasis in the human body?
Homeostasis regulates many properties including levels of fluids, salts, gases, and nutrients. Many systems are involved in homeostasis. For example, the respiratory and urinary systems act together to maintain blood pH at 7.3, the value critical for life. As the external and internal environments change, homeostatic mechanisms act to return the body to optimal operating conditions.
What does a thermostat do if it gets too cool?
If it gets too cold, the thermostat will shut off the air conditioning to warm up the building as a way of regulating temperature.
What does a thermostat do if it gets too hot?
If it gets too hot, the thermostat will turn on the air conditioning to warm up the building as a way of regulating temperature.
What can result if homeostasis is not maintained in the body?
If the negative feedback system is impaired, homeostasis is not maintained. In the case of blood sugar levels, this can lad to serious diseases such as diabetes, chronic high blood pressure, or kidney disease. Homeostatic imbalance eventually will lead to organ failure and death.
If blood glucose levels are too high, what hormone will this organ secrete?
Insulin
Adrenal Gland
On top of the kidneys are the adrenal glands. The adrenal glands are made up of two layers. The outer layer produces hormones called corticosteroids. Corticosteroids help the body to keep the right balance between salt and water. This balance is necessary to control how the immune system fights infections, how metabolism burns calories, how a person's reproductive organs develop, and how the body handles stress. The inner layer of the adrenal glands produce adrenaline. Like endorphins, adrenaline helps to regulate and control your reaction to situations, especially stress. Adrenaline helps keep blood pressure where it should be and the heart rate to stay normal. It also helps a person decide how to react in a situation that you find scary or threatening. It is responsible for what is known as the fight or flight response.
What are the levels of organization in a living organism?
Our bodies are made up of cells. When similar cells work together, they are called tissue. Tissues that are together and work for one purpose are called organs. When a group of organs function together to do a job, they are a system. Every body system has a specific task that keeps you alive. A single system can't do it alone. They all work together.
How do our bodies sometimes act like a thermostat?
Our bodies work similarly to thermostats, as our bodies regulate body temperature through involuntary body processes and reactions. For example, our bodies excrete sweat as a way of releasing excessive heat and keeping one's body cool. On the other hand, shivering is a natural body reaction that occurs through muscle friction/tension that allows the body temperature to stay warm and stable.
What organ detects above or below normal blood glucose concentrations?
Pancreas
Blood Sugar Example: Reaction
Pancreas secretes the hormone insulin causing liver cells to take up glucose and store it as glycogen Most body cells also take up more glucose
What is the difference between positive and negative feedback?
Positive feedback = more and more responses (escalating effect) to achieve the body's goal. Negative feedback = counteracting responses to a variable to maintain homeostasis
Reproductive System
Produces gametes, produces offspring
Endocrine System
Produces hormones that regulate the body
Immune System
Protects the body from microorganisms (i.e. bacteria)
Integumentary System
Regulates body temperature, protects the body, retains fluid
Excretory System
Removes waste from the body
Blood Sugar Example: What is the stimulus?
Rising blood glucose level
Nervous System
Senses, interprets, and responds to stimuli
Pancreas
The pancreas is an essential part of the endocrine system, although it also has an important role in the digestive system. The pancreas produces two main hormones, insulin and glucagon. They work together to make sure that a person's blood always has the right amount of sugar. Insulin helps a person's cells absorb glucose. Leftover glucose gets stored in the liver. Later, if a person's blood sugar gets too low, the pancreas sends another hormone, glucagon to the liver. Glucagon causes the liver to release the stored sugar into the person's blood to be used by their cells. This feedback loop keeps a person's energy steady all day long. When the pancreas does not produce enough insulin, a person can become diabetic. Left untreated, diabetes can lead to nerve damage, blindness, and heart disease.
Parathyroid Gland
The parathyroid glands are located at the back of the thyroid. They make sure that the body has the right amount of calcium in its blood. Without enough calcium, nerves can't carry their messages properly and well. Muscles don't work well, and bones become much weaker. When the calcium level is too low, The parathyroids produce hormones that get bones to release stored calcium, signal the small intestine to absorb more calcium from food, and stop the kidneys from releasing so much calcium in urine. The parathyroid makes sure that calcium stays at the right level. It maintains homeostasis.
Testes/Ovaries
The reproductive organs, the ovaries on women and testes on men, are often considered part of the endocrine system. The testes and ovaries produce testosterone and estrogen respectively. These organs are also part of the reproductive system. The pituitary makes hormones that start puberty. When babies are born, they have all the body parts necessary to be able to reproduce, but it isn't until puberty that humans are actually able to reproduce. Puberty is the term used to describe the time when all of these changes are happening in one's body. Puberty begins when the pituitary gland produces a hormone that signals the ovaries in girls to make a hormone called estrogen and the testes in boys to start making a hormone called testosterone.
A person with diabetes is unable to regulate blood sugar. How does this occur and relate to negative feedback of homeostasis?
Long-term disruption in homeostasis can lead to chronic diseases, such as diabetes. Under normal conditions, blood glucose is taken up by the cells to fuel their metabolism. However, this process is inhibited in diabetes patients because of a breakdown in the hormonal response that normally maintains blood glucose levels. Specialized cells in the pancreas, known as beta cells, release the hormone insulin. Insulin is secreted when blood glucose levels are elevated. The insulin will then induce cells to take up glucose, lowering the level circulating in the blood. However, diabetes patients either produce too little insulin (this is called type I diabetes) or their cells somehow fail to respond to insulin (type II diabetes). For those with diabetes, it is crucial to monitor blood glucose levels regularly and adjust their diet, activity, and treatment to keep glucose levels within the safe range. Many people with diabetes must inject insulin daily in order to maintain appropriate blood glucose levels.
Muscular System
Moves the body and generates heat (muscle contractions = shivering)
Why is negative feedback often associated with maintaining homeostasis?
Negative feedback is associated with the counteraction of body systems, responding to variables that may affect the body's homeostasis in the long run.
Homeostasis can require the control of many different variables in organisms. Homeostasis regarding internal body temperature is very important for many organisms. How is this different among ectotherms and endotherms?
Ectotherms are cold-blooded organisms, meaning that their body systems do not regulate their body temperature (rely on eternal sources). Endotherms are warm-blooded organisms, meaning that our bodies can naturally maintain body temperature at a stable state.
If blood glucose levels are too low, what hormone will this organ secrete?
Glucagon
Blood Sugar Example: Detection
High blood glucose level is detected by insulin-secreting cells of pancreas
Reasoning
unites a scientific claim with the evidence used to support the claim, use reasoning to justify how or why the data provide evidence to support your claim
How does the factor of exercising affect body temperature?
increase
How does the factor of increased air temperature affect body temperature?
increase
How does the factor of shivering affect body temperature?
increase
Claim
one-sentence statement summarizing the results of an experiment or observation
Ectothermic
regulation of body temperature depends almost entirely upon external sources, such as the temperature of the water surrounding the organism
Evidence
scientific data to support the claim
Negative Feedback Mechanisms
self-correcting actions that stabilize a body system, returning internal conditions to a steady state after a disturbance is detected
Glucose
the molecule measured in "blood-sugar" levels
Epinephrine
(also known as adrenaline) is a chemical signal released by the adrenal glands in the body, strong emotions such as fear stimulate the release of epinephrine into the bloodstream, which brings about an increase in heart rate, blood pressure, and metabolism.
What is a feedback mechanism?
- A feedback mechanism operates to keep body conditions at a level needed for normal functioning. It involves constant communication by various parts of the body. - There are 2 types of feedback mechanisms: negative + positive - Ex. Endocrine system: hormones
Describe two processes that will most likely occur in her body to maintain homeostasis.
- A process that will most likely occur in her body to maintain homeostasis is the process of sweating. This will allow heat to be released as a way to cool down the girl. Another process that will most likely occur is the dilation of blood vessels in order to cool down the body by allowing an increased amount of oxygen to flow through the blood vessels. - Another possible process is the respiratory system (breathing heavier).
Blood Sugar Example: Stabilization
- As body cells take up blood glucose, glucose levels in the blood decline, and insulin release stops (negative feedback) - Insulin's job: gets cells to take in glucose for ATP - Sugar leaves blood and into cells - Return to homeostatic blood glucose level - Glucagon: response (release stored glucose into blood)
What is an additional reason (other than obesity) that there may be a rise in the number of patients with diabetes?
- Growing rates of obesity, poor diets, and lack of physical activity, among other factors, have contributed to a raise in diagnosed diabetics. - Factors such as income, education, housing, access to healthy food, as well as poorer access to healthcare, have been shown to be strongly linked to an increased risk of developing conditions such as diabetes. - Also, the presence of diabetes in people of childbearing age is an important factor, because maternal diabetes increases the risk of diabetes in children.
Insulin
- Hormone that causes the blood sugar level to decrease - Promotes movement of glucose into certain cells - Stimulates the formation of glycogen from glucose
Glucagon
- Hormone that causes the blood sugar level to increase - Stimulates cells to break down glycogen into glucose
Negative Feedback
- The end product of the series prevents the first step from happening again. - A negative feedback system operates to keep the system within a normal range. - Ex. body temperature (thermoregulation), blood sugar levels, and hormone levels.
What is thermoregulation?
- The process in which a stead temperature is maintained inside the body. - Some responses to temperature, such as sweating and shivering, are involuntary. Other actions, such as exercising or putting on clothes, are called voluntary responses.
Be able to create a line graph.
- X and Y axes - Title - Values on Axes
How does insulin cause the blood glucose level to decrease? How does glucagon cause the blood glucose level to decrease?
- stores glucose or glycogen in the liver
What occurs when the blood glucose level is too low?
1. Pancreas secretes glucagon. 2. Glucagon breaks down glycogen from the liver. 3. Glucose is released into the blood stream.
What occurs when the blood glucose level is too high?
1. Pancreas secretes insulin. 2. Insulin triggers the absorption of glucose into the cells of the body. 3. Blood glucose levels decrease.
What is the set point (normal level) for blood glucose?
70 mg/dl - 100 mg/dl
Describe how the circulatory system maintains homeostasis with blood pressure.
A critical property of the circulatory system that must be maintained is blood pressure. Blood pressure is the pressure of circulating blood on artery walls. Normally, blood pressure is influenced by several factors as the rate at which the heart beats (heart rate), the volume of blood that exits the heart per beat (stroke volume), and the amount of resistance to blood flow within the vessels. Larger vessels have less resistance to flow. These properties of the heart and blood vessels are controlled by the body in order to increase or decrease blood pressure so that it stays within healthy limits. Blood pressure is constantly measured by receptors in the arteries and veins. These receptors then send signals back through nerve fibers to a part of the brain called the medulla. The medulla acts as a processor in the negative feedback loop that controls blood pressure. It either increases the heart rate and stroke volume if the pressure is too low, or decreases both when the pressure is too high. Hormones are also released to signal the blood vessels to increase or decrease resistance in order to maintain blood pressure within an optimum range.
What is a negative feedback loop? Describe using a thermostat as an example.
A negative feedback loop is the most critical mechanism of homeostasis. It is similar to the way in which a thermostat maintains a constant room temperature. The thermostat is set to the desired temperature. If the room is too cold, the equipment reacts by turning on the heat. If the room is too hot, sensors prompt the air conditioner to turn on. The control system requires three parts. These include a sensor that monitors the particular property of interest, a processor that determines how far the measured value deviates from the set value, and an actuator tat can change the particular property. Similar to the thermostat, the human body has sensors, processors, and actuators to maintain optimum levels of pH, blood sugar, body temperature, and more. In addition, these parts must be linked together in order for the negative feedback mechanism to function properly.
Set Point
A term used to describe the normal range of values for a physiological variables such as the resting heart rate of an organism
Distinguish between accuracy and precision.
Accuracy measures how close results are to the true or known value. Precision, on the other hand, measures how close results are to one another.
Pituitary Gland
Although it is very small, the pituitary gland is the most important gland in the endocrine system. Pituitary hormones help control things like hunger, thirst, blood pressure, emotions, and even body temperature. When the hypothalamus gets the message that the body is getting too hot, it sends hormones to the pituitary. The pituitary sends hormones that widen the capillaries near the skin. The blood flowing through them releases body heat through the surface of the skin. Releasing body heat cools the body down. The pituitary gland produces at least 10 hormones, including ones that help you grow. For example, the front or anterior lobe of the pituitary gland secretes a hormone that makes the cells in bones and muscles increase in size and number. Once the body is fully grown, the pituitary sends only enough growth hormones to maintain one's body size and strength. The pituitary glands sends the hormones that enable women to breastfeed their babies. If a person is scared or in pain, the pituitary will release chemicals called endorphins that reduce painful feelings. The pituitary also makes hormones that start puberty. Puberty begins when the pituitary gland produces a hormone that signals the ovaries in girls to make a hormone called estrogen and the testes in boys to start making a hormone called testosterone. Lastly, the pituitary gland also produces hormones that give signals to the thyroid gland and the adrenal glands.
What is necessary for an organism to survive?
An organism must be able to maintain stable internal conditions in a changing environment. This process is called homeostasis.
People who have Type 1 Diabetes do not make enough insulin. What effect would this have on their blood glucose level?
Because there is not enough insulin, diabetics are unable to lower their blood sugar. Their consistently high levels of blood sugar can potentially have extremely negative effects on their bodies. These include kidney failure or a heart attack.
Thymus Gland
Behind the breastbone is one of the most important glands, the thymus. The thymus gland helps fight disease by releasing hormones that allow germ fighting cells in one's blood to increase in number. These special cells are called T cells for thymus. The thymus gland is full-sized by the time a person is in their teens, but as they age, it shrinks. In old age, the ability to fight disease decreases.
Digestive System
Breaks down and absorbs nutrients from food
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Neurotransmitters
Chemical messengers in the body that communicate information between nerve cells, or between nerve cells and other cells in the body
Skeletal System
Supports, protects internal organs, and helps the body move
Respiratory System
Takes in oxygen and removes carbon dioxide
The cell membrane controls what goes in and out of the cell. How could the cell membrane then be important for homeostasis?
The cell membrane's semi-permeability is important to homeostasis in the cell through its regulation of ensuring that the organelles and additional parts of cell do not become too dense, yet allowing beneficial elements to be transported through the cell. Letting water move into the cell through osmosis can regulate the size of the settle.
How is the endocrine system essential in maintaining homeostasis in the body?
The endocrine system controls and regulates many of the body's functions like growing, sleeping, metabolism, puberty, and mood. It is made up of glands and organs that make and store chemicals called hormones. It is these hormones that control body function and maintain homeostasis in the body's other systems. They do this by starting, maintaining, and stopping processes within the body's other organs. Hormones travel through the blood to all parts of the body. The endocrine system is constantly checking the body's condition and releasing hormones when needed to start and stop actions (positive + negative feedback mechanisms). For example, when a person eats, the pancreas releases a hormone called insulin to help the cell use the digested food sugar for energy. As the sugar glucose is transported and used up where it is needed, the release of insulin slows down. This action/reaction cycle is called a feedback loop, which contributes to the internal balance of an organism called homeostasis. Feedback loops are a big part of the endocrine system.
What is the function of the endocrine system?
The endocrine system's function is similar to that of a factory. It makes and stores chemicals the body needs to work right, then releases them at just the right time. The endocrine system is a body system made up of glands, hormones, and target cells that work together to control various functions of the body and help the body maintain balance. The glands are located throughout the body and make chemicals called hormones. Hormones "excite" or cause things to happen in other places in the body. There are over 30 hormones busy regulating when the body feels sleepy, hungry, full, the rate a person grows, how they react to danger, and much more. Hormones can reach every cell in the human body, but they do not affect every cell, just the cells designed to receive them. They are called target cells. When the hormones reach them, they take specific actions.
What are the main regulators of homeostasis in humans?
The hypothalamus and pituitary gland are the main regulators of homeostasis in humans. The hypothalamus is found in the brain below the thalamus and above the brain stem. The pituitary gland is a protrusion from the hypothalamus. It is connected by neural fibers.
How do the nervous system and endocrine system work together to maintain homeostasis?
The hypothalamus is part of the autonomic nervous system. It is sensitive to many properties of the internal environment. It stimulates or inhibits that secretion of pituitary hormones into blood circulation. In turn, these pituitary hormones act on different parts of the human body to maintain homeostasis. Together, the hypothalamus and pituitary gland play the role of the main processor for homeostasis. They bridge the nervous system and the endocrine system.
For each process that you describe, identify to organs or organ systems that are involved.
The organ systems that are involved are the circulatory and the excretory/integumentary system.
What factor raises body temperature the most?
exercising
How does the factor of adding clothing affect body temperature?
increase
Thyroid Gland
The thyroid and parathyroid gland are right next to each other, but they do not work together. They have very different jobs. The thyroid is found in front of the neck and is shaped like a butterfly. It releases hormones that control metabolism.
What methods are used to maintain body temperature (voluntary + involuntary) ?
There are several important methods used by humans to maintain body temperatures at a stable state. These include voluntary or involuntary processes and methods. For example, eating or drinking something warm (hot coffee, hot chocolate, iced lemonade, iced water, etc.). This is a voluntary method, as it is a choice made by the human in order to benefit their body's temperature. Another voluntary method includes going inside a building when it is too hot (air conditioning indoors) or too cold (heaters indoors). In addition, another voluntary (possibly involuntary as well) response can be breathing, as this can keep one's body cool during extreme heat. In addition, going near a fire pit in cold temperatures is another way of maintaining body temperature. On the other hand, an example of an involuntary response to temperature is the changes within blood vessels. Warm weather and heat can cause veins to dilate and blood to pool. Cold weather does the opposite and shrinks veins. Smaller veins can contribute to better blood flow to all parts of the body and consequently regulating body temperature by keeping the body warm even in cold temperatures.
What correlation is indicated by the similarity between obesity and diabetes?
There is a correlation because an increase in obesity as a result of an unhealthy lifestyle is an important factor in the increase of diagnosed diabetics. Having obesity makes you more likely to develop diabetes, the condition of having too much glucose (sugar) circulating in your bloodstream. Obesity also causes diabetes to worsen faster.
If their blood glucose level is too high, what two actions could people with diabetes take to maintain homeostasis?
They can monitor what they eat and take insulin regularly.
Hypothalamus
This gland is the main connection between the endocrine system and the nervous system. Deep inside the brain, this gland receives the information about any changes that are needed in the body. The hypothalamus then starts secreting hormones that put the pituitary gland into action.
Pineal Gland
This gland produces only one kind of hormone, melatonin. This hormone helps to regulate when to sleep and when to stay awake. The pineal gland is located deep inside the brain, directly behind the eyes. Scientists have discovered that the amount of light entering your eyes affects how much melatonin your pineal gland secretes. As it gets darker at night, less light enters the eyes and the pineal gland produces more melatonin. As it brightens in the morning, the pineal gland produces less melatonin, and the body wakes up.
Why does exercising raise body temperature?
This process likely raises body temperature the most because the movement or friction between muscles and body structures maintains body heat through increased blood blow in cold weather.
Circulatory System
Transports oxygen and nutrients through the body by blood
Describe the two main mechanisms the body uses to cope with changing temperatures.
Two primary mechanisms are employed to cope with these situations. In a cold environment, the body shivers. The muscle movements require energy that eventually turns into heat. This compensates for the loss of heat in the environment. In hot conditions, sweat is produced by sweat glands in the skin. As sweat turns into water vapor, heat is released during the evaporation process. Sweating is done at the expense of water loss, so prolonged heat exposure can be dangerous as it can lead to dehydration. The hypothalamus is the main processor for body temperature. It stimulates shivering or sweat.
Acetylcholine
a type of neurotransmitter released by glands to help reduce heart rate
Homeostasis
all organisms must maintain a balance in their internal environments
How does the factor of decreased air temperature affect body temperature?
decrease
How does the factor of sweating affect body temperature?
decrease
