Understanding Homeostasis

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Questions and Answers

The average human body temperature is maintained within a narrow range. What is the MOST likely consequence if the body temperature consistently exceeds this range?

  • Denaturation of cellular proteins, impairing essential metabolic functions. (correct)
  • Increased enzyme activity, leading to more efficient cellular processes.
  • Heightened cellular sensitivity to regulatory signals, improving homeostatic control.
  • Enhanced cellular membrane stability, protecting cells from external stressors.

Which statement BEST describes the function of negative feedback in maintaining homeostasis?

  • It amplifies the initial stimulus to accelerate the response.
  • It reverses the direction of the initial stimulus, bringing the body back towards its set point. (correct)
  • It enhances the effects of the original stimulus, pushing the body further away from its set point.
  • It creates a continuous cycle, amplifying the initial stimulus until an external intervention occurs.

How would you BEST describe 'allostasis'?

  • The maintenance of the range of normal values in the body.
  • The ability of the body to maintain a fixed internal environment, or set point.
  • The adaptive way in which the body changes its set point in response to changes in life or the environment. (correct)
  • The processes that aim to maintain a single consistent internal parameter regardless of external factors.

Imagine a scenario where a previously healthy individual begins to experience erratic blood glucose levels, fluctuating widely despite consistent dietary habits. Which component of the homeostatic control system is MOST likely malfunctioning?

<p>The integrating center, responsible for determining the appropriate response. (A)</p> Signup and view all the answers

During prolonged exercise in a hot environment, the body temperature rises. Which of the following mechanisms does NOT contribute to the body's attempt to maintain homeostasis?

<p>Shivering to generate heat. (D)</p> Signup and view all the answers

Which BEST describes a scenario exemplifying positive feedback?

<p>The release of oxytocin during childbirth causes stronger uterine contractions, leading to more oxytocin release. (B)</p> Signup and view all the answers

An individual moves from sea level to a high-altitude environment. Initially, they experience increased heart rate and breathing. Over time, their body adjusts, and these symptoms subside. WHICH process is MOST responsible for this adaptation?

<p>Acclimatization. (C)</p> Signup and view all the answers

How does feed-forward regulation MOST improve homeostatic control?

<p>By anticipating changes and initiating responses before the regulated variable is significantly affected. (D)</p> Signup and view all the answers

Predict what would happen if the body could NOT maintain homeostasis.

<p>The body's internal environment would become unstable and incompatible with life. (B)</p> Signup and view all the answers

Which process is LEAST likely to be regulated by homeostasis?

<p>Hair color. (D)</p> Signup and view all the answers

What determines the degree of correction applied in a negative feedback control system?

<p>Magnitude of the error signal. (D)</p> Signup and view all the answers

Which of the following is NOT a limitation of negative feedback?

<p>Destabilization of controlled variable. (A)</p> Signup and view all the answers

When would you MOST expect acclimatization to occur?

<p>Seasonal changes. (B)</p> Signup and view all the answers

How is balance in homeostasis of chemical substances achieved?

<p>Balancing inputs and outputs. (C)</p> Signup and view all the answers

What two main systems are responsible for initiating internal communication?

<p>Endocrine and Nervous. (C)</p> Signup and view all the answers

Which of the following BEST describes the role of an 'integrator' within a homeostatic control system?

<p>Comparing sensory data to a set point and activating a response. (B)</p> Signup and view all the answers

Which component of a reflex arc is responsible for detecting a stimulus?

<p>The receptor. (A)</p> Signup and view all the answers

How is intercellular communication achieved?

<p>All of the above. (D)</p> Signup and view all the answers

What happens when homeostasis can no longer be maintained?

<p>It results in a homeostatic imbalance. (C)</p> Signup and view all the answers

Which statement BEST captures the relationship between homeostasis and enzymatic activity within the human body?

<p>Homeostasis maintains a stable internal environment, providing optimal conditions for enzymes to function efficiently. (C)</p> Signup and view all the answers

What role does the hypothalamus play in thermoregulation?

<p>It is a integrating center. (D)</p> Signup and view all the answers

Why is temperature regulation so biologically important?

<p>Maintaining body temp is one of the body's biological necessities. (C)</p> Signup and view all the answers

What is 'basal metabolism'?

<p>Energy the body requires while at rest. (B)</p> Signup and view all the answers

How is fever an example of the body resetting its set point?

<p>The body maintains temperature at the new higher value. (C)</p> Signup and view all the answers

In childbirth, how do uterine contractions lead to the release of oxytocin?

<p>Increase strength of uterine contractions. (A)</p> Signup and view all the answers

Can positive feedback be potentially harmful?

<p>Yes, fever is something positive feedback can cause. (A)</p> Signup and view all the answers

What BEST explains the purpose of feed forward regulation?

<p>Works in conjunction with the feed back system. (A)</p> Signup and view all the answers

Imagine a person experiences the failure of their sweat glands. What is the MOST likely and detrimental result?

<p>Body is unable to cool itself. (C)</p> Signup and view all the answers

Which process displaces a variable from the set point?

<p>External environment. (A)</p> Signup and view all the answers

Flashcards

What is Homeostasis?

The term used to describe the constant state of the internal environment.

Homeostasis

The maintenance of a steady state in the body despite changes in the external environment.

Homeostasis in a Dynamic Environment

The body's ability to maintain a stable internal environment in a constantly changing external environment.

Homeostatic Mechanisms

Processes and actions that help maintain homeostasis.

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What the the body's internal environment?

The body's internal environment. An extracellular fluid.

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Homeostasis Indicates

Stable condition of the internal environment resulting from compensatory control system.

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Homeostasis Control

Regulated and integrated activities of cells, tissues, and organs, correcting changes in extracellular fluid.

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Components of a Reflex Arc

Receptors, afferent pathway, integrating center, efferent pathway, effector.

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Homeostasis Involves

Maintaining body conditions within set ranges/limits.

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Thermoregulation

The process of maintaining a steady body temperature under varying conditions.

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Internal Communication

The body's internal communication that maintains homeostasis.

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Components of a Home Heating System

Sensor detects stress, control center receives info, effector produces response.

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Variable in Automatic Control

The characteristic of the internal environment being controlled.

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Sensor (Receptor)

Detects changes in variable and feeds info back to control the center.

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Integrator

Integrates sensor data with 'setpoint' data.

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Effector in Control

Mechanism that has an effect on the variable.

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Set Point

A single value the body strives to maintain.

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Allostasis

Adaptive way body changes set point due to life/environment changes.

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Basal Metabolism

Energy used to maintain a constant body temperature while at rest.

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What is Negative Feedback?

Feedback that reverses the direction of change.

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Cellular Relay Race

Stimulus, receptor, integrating center, effector, response reversing original stimulus.

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Negative Feedback

Feedback (from sensor to integrator) causing a reversal of the direction of change.

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Processes that Reduce Discrepancies

Reduces discrepancies from the set point.

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What is Positive Feedback?

Feedback that enhances or exaggerates the original stimulus.

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What is A Positive Feedback systems

The direction of a stimulus and can accelerate its effect.

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Acclimatization

Ability to respond to environmental stress through prolonged exposure.

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Feed forward regulation

Feed forward system.

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Biological Rhythms

Body's rhythms driven by brain pacemakers, influenced by environmental cues.

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Homeostatic Imbalance

Homeostasis is being disterberd.

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Name two harmful effects of positive feedback.

Fever, atherosclerosis.

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Study Notes

Definition of Homeostasis

  • homeo means "same" and stasis means "standing"
  • Term to describe the constant state of the internal environment.
  • Is a state of balance in the body.
  • Homeostatic mechanisms refer to activities that help to maintain hemostasis.

What is Homeostasis?

  • Body cells function optimally in the correct environment.
  • Correct temperature
  • Correct water levels
  • Correct glucose concentration
  • The body is equipped with mechanisms designed to keep cells in a constant environment.

Homeostasis Characteristics

  • Ability to maintain a relatively stable internal environment in a dynamic external environment
  • Internal environment of the body is always in a dynamic state of equilibrium.
  • Chemical, thermal, and neural factors work together to maintain.
  • Homeostatic system maintains its structure and functions by dynamic equilibria strictly regulated by interdependent regulation mechanisms
  • The system reacts to environmental changes through modifications of equal size and opposite direction to those that created the change

Summary of Homeostasis

  • Body’s internal environment comprises extracellular fluid.
  • Organ systems' job is to maintain a stable internal environment.
  • Numerous variables require homeostatic maintenance within the body
  • Loss of homeostasis for just one variable may trigger changes in others
  • Example: a consideration is the swing in blood glucose level over the course of day

General Characteristics of Homeostatic Control Systems

  • Denotes the stable condition of the internal environment.
  • Stability results from operation of compensatory homeostatic control systems.

Homeostasis Control System Components

  • Reflexes
  • Local homeostatic responses
  • Intercellular chemical messengers

Reflex Arc Components

  • A reflex arc pathway may be neural or hormonal and consists of a receptor, afferent pathway, integrating center, efferent pathway, and effector.

Intercellular Communication

  • Essential to reflexes and local response as well as is achieved by neurotransmitters, hormones, paracrine and autocrine agents
  • Intercellular communication through either gap junctions or cell-bound messengers is less common

Homeostasis and Body Conditions

  • Conditions in the body must remain within a narrow range.
  • This involves keeping the internal environment within set ranges/limits.

Mechanism of Homeostasis

  • Thermoregulation maintains a steady body temperature under a variety of conditions.
  • Systems involved include:
    • Muscular
    • Integument (skin)
    • Respiratory
    • Circulatory
    • Nervous (hypothalamus in brain)
    • Endocrine (hormones, feedback)

Body Temperature

  • The living processes in the cells depend on the activity of enzymes
  • Enzymes function in specific conditions, such as those of temperature and pH
  • Changing conditions affects the function of the enzymes
  • Change may lead to the death of the cells or, ultimately, the whole organism
  • Internal environment requires regulation and kept constant regulated and kept constant.
  • Human body temperature varies between 36.1 – 37.8 °C with average 36.8°C.

Internal Communication

  • Body requires good internal communication for it to be maintained with the aid of the endocrine and nervous systems
  • Feedback inhibition will limit the actuation of a system and shut it down when a certain substance is too high such as water, glucose, salt, heat and CO2
  • When there is too little of this product, the system will "turn back on."

Home Heating System

  • Homeostatic mechanisms reestablish homeostasis when there is an imbalance.
  • In a home heating system:
    • When the temperature of a room decreases below a set point, the thermostat electrically starts the furnace.
    • As the temperature of the room rises to the set point, the thermostat shuts down the furnace.
    • As the room cools, step one is repeated.
  • System Components
    • The Sensor detects the stress.
    • Control Center receives information from the sensor and sends a message to the Effector.
    • The Effector receives the message from the control center and produces the response, which reestablishes homeostasis.

Homeostatic Control Mechanisms

  • Variable produces a change in the body
  • Three interdependent components of control mechanisms
    • Receptor monitors the environments and responds to changes (stimuli)
    • Control center determines the set point at which the variable is maintained
    • Effector provides the means to respond to the stimulus

Thermostatic heating system Components

  • Variable is the characteristic of the internal environment controlled by a mechanism like internal temperature
  • Sensor detects the change in the variable, feeds this information to the Integrator in the control center like a thermometer
  • Integrator puts together and records the data to create the setpoint
  • Effector is the mechanism that has the effect of this variable, such as a furnace

Review of Homeostasis

  • Temperature changes are detected by the thermometer
  • This relays the temp back the thermostat
  • The thermostat is then set to an ideal that is signaled to the furnace
  • The furnace then either heats or cools the area back to the ideal set point
  • An example would be shutting down when the temp is recorded above the set temp

Temperature Regulation

  • Set point refers to a single value that the body works to maintain, this includes:
  • Levels of water, carbs, oxygen, acidity etc.
  • Processes that reduce discrepancies from the set point are known as negative feedback.
  • Adaptive way in which the body changes its set point based on current environment

Temperature Regulation as a Biological Priority

  • Body temperature regulation is a key biological priority
  • Takes up about two-thirds of our energy/kilocalories per day
  • Basal metabolism refers to the energy that is required to maintain body temperature while at rest

Homeostatic Regulation of Body Temperature

  • Heat receptors in the skin is the sensors for hyperthermia, in the body.
  • Sends stress signals to the hypothalamus which acts as the control center
  • Effectors such as increased activity of sweat glands and increased blood flow to the skin are activated
  • This causes perspiration and cooling of the skin
  • When a stress is low enough to be considered shut down the mechanism, processes such as sweating are reduced.

Feedback Systems

  • Positive
  • Negative

Cellular Relay Race

  • Cellular relay race for homeostasis
  • Stimulus to receptor to integrating center to effector to response to stimulus

Negative Feedback Control

  • Animals/Humans must have bodily constraints within a tolerable limit to maintain proper function
  • Use of negative feedback control which brings about a reaction from receptors and effectors to make sure that conditions are still favorable
  • The shift within a variable brings about a change that moves the direction against the original one, stabilizing the overall system

Negative Feedback

  • Is an occurrence when feedback from an integrator results in a reversal of the change in direction.
  • Negative feedback tends to stabilise a system by correcting deviations from the set point

Homeostatic Control Mechanisms

  • Input: Information sent along afferent pathway to a control center.
  • Change detected by a receptor (sensor).
  • Stimulus: Produces a change in a variable.
  • Output: Information sent along efferent pathway to an effector.
  • Response of effector feeds back to influence magnitude of stimulus and returns variable to homeostasis.

Negative Feedback

  • Cooling and Heating are components to negative feedback.
  • In cooling vasodilation occurs to release heat.
  • Sweating(Diaphoresis) can also occur to cool down.
  • The cooling is triggered by the hypothalamus when external factors are in play.
  • In heating, shivers are triggered which generate heat.
  • In order to conserve heat vasoconstriction occurs.
  • The hypothalamus is the trigger for this cycle when external actors are in play as well.

Homeostasis and the Environment

  • An example of Homeostasis is humans shivering in response to cooling
  • Homeostasis allows organisms to remain balanced with certain environments
  • Not maintaining these balances can kill the organism

Negative Feedback Systems

  • Systems when in the negative, send signals that shuts off the original stimulus
  • Example is regulation of blood glucose levels

Negative Feedback Loop Requirements

  • Sensor to detect changes needed in certain variable
  • Comparator to be a reference point for the sensor to compare to
  • Effector which determines direction of signal to restore levels

Dueling Hormones

  • What goes up, must come down in insulin and glucagon
  • Insulin is produced by beta-cells of the pancreas to trigger the use of glucose by the body, to lower blood glucose, while glucagon is produced by alpha cells, to increase blood sugar
  • Insulin facilitates the transport of glucose into target cells
  • Signals the liver to break down glycogen into simple glucose to increase the levels

Dueling Mechanisms

  • Thermoregulation is one of the many dueling mechanisms in the body.
  • It is where sweating assists the body in cooling vs. shivering which assists with warming processes.
  • Blood pressure uses a dueling mechanism of Vasoconstriction vs. vasodilation.
  • Osmoregulation uses Hypotonic vs. hypertonic dueling mechanisms.

Hire-Wire Artist Model

  • Model of homeostasis
  • Demonstrates body's responses to maintain a position of equilibrium.
  • Variable: position of body
  • Setpoint: directly over the wire
  • Sensors: nerve receptors (eyes, inner ears, muscle stretch receptors, etc.)
  • Integrator: brain
  • Effectors: skeletal muscles
  • High-wire artist uses negative feedback to maintain relatively constant position on wire.

Positive Feedback

  • Ability to maintain the direction of a stimulus and can accelerate its effect
  • Accelerates a process leading to explosive effects
  • Involves no means of stopping

Positive Feedback Mechanisms

  • Homeostatic systems that exhibit two primary Characteristics:
  • Time Limitation - Processes in the body are completed within a constrained time frame.
  • Intensification of stress – The initial imbalance or stress is intensified rather than reduced Typical Process
  • Stress -Sensor - Control Center - Effector

Positive Feedback Control Details

  • Is a Biochemical control in which the accumulation of a substance will trigger the accumulation of an enzyme, further increasing the accumulation of the substance
  • The trigger works in information that further accelerates the stimulus of the response from increasing levels of a trigger

Blood Clotting and Positive Feedback

  • An example of homeostasis related to blood clotting is a break or tear in a blood vessel
  • This tear triggers the feedback cycle which entails the release of chemicals that attract more platelets to that site
  • The resulting process seals the wound in a positive feedback loop until the cycle ends

Hyperthermia

  • Causes a positive feedback within homeostasis because it pushes the body temperature continually higher
  • If the temperature reaches 45 degrees centigrade (113 degrees Fahrenheit), cellular proteins denature bringing metabolism to a stop, and leads to death

Chronic Hypertension

  • Favors the process of atherosclerosis
  • Process can narrow blood vessels
  • Intensifies the hypertension, which causes even more damage to the walls of blood vessels

Feedback Control Comparison

  • Negative feedback: promotes stability
  • Feed-forward: anticipates change, and prepares for them
  • Positive feedback: promotes a change in one direction that in many instances can cause distress or death to subject

Feed Forward Regulation

  • Anticipates changes in regulated variable
  • Improves the speed of the body's homeostatic responses
  • Minimizes fluctuations in the level of the variable being regulated
  • Works in conjunction with feedback system

Temperature Sensitive Nerve Cells Example

  • A temperature shift can trigger a negative loop in order to accommodate the change in the body
  • Addition of additional nerve cells, such as in the skin, may take an effect.
  • Other bodily effects are the measure of a change, such as an opened door in order to automatically turn on the heater

Limitations of Negative Feedback

  • Feedback control must occur after a variable is disturbed
  • The correction will be incomplete without a measurement being applied to the magnitude fo error
  • Overcorrection can cause oscillations
  • These disadvantages will be overriden by proper regulatory measures
  • Insulin regulation
  • Release of insulin causes glucose levels to decrease

Advantages of Homeostasis

  • Has benefits of survival due to the animal's adapting to changing environment, such differences stepping outside.
  • Body maintains a norm that attempts to stay at an even level
  • Can only work with extreme situations by disabling negative feedback; treatment must ensue

Acclimatization

  • Refers to how and organism can adapt to certain events or changes
  • The improvement happens, given the exposure without any changes in genetic features, it may be irreversible

Biological Rhythms

  • Provides a feed forward component to control systems for homeostasis .
  • Rhythms are internally driven by pacesetters within the brain that get adjusted by cues, such as light.
  • Without these adjustments, the body will free run.

Resetting of Set Point Details

  • External environment changes can displace variable from set point
  • Set points can adjust within the body through new values such as a response to high body temperature
  • The elevated temperature is maintained and adaptive so infection stops because elevated temperature inhibits pathogens to proliferate.

Balance of Chemical Substances Balance

  • Chemical body homeostasis will be achieved through matching inputs and outputs
  • Overall balance will shift through negative or positive states

Homeostatic Imbalance

  • Disturbance/Destruction in overall equilibrium
    • Results in over-correction of of negative feedback

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