Homeostasis
52 flashcards covering Homeostasis for the MCAT Biology & Biochemistry section.
Homeostasis is the body's way of keeping internal conditions stable despite changes in the external environment. For example, it helps maintain your body temperature around 98.6 degrees Fahrenheit, even if you're in a hot room or cold weather. This process involves sensors that detect imbalances, like rising temperature, and responses that correct them, such as sweating to cool down. Essentially, homeostasis ensures organs and systems function properly, making it crucial for survival and overall health.
On the MCAT, homeostasis appears in biology and biochemistry questions that test your understanding of regulatory mechanisms, feedback loops, and their role in systems like the endocrine or nervous systems. Expect multiple-choice questions on examples such as blood sugar regulation or pH balance, with common traps like confusing negative feedback (which restores balance) with positive feedback (which amplifies changes). Focus on applying concepts to real-world scenarios and identifying disruptions that lead to disorders.
A concrete tip: Practice drawing feedback loop diagrams to solidify your grasp.
Terms (52)
- 01
Homeostasis
Homeostasis is the process by which living organisms maintain a stable internal environment despite changes in external conditions.
- 02
Negative Feedback
Negative feedback is a regulatory mechanism that reverses a deviation from the set point, helping to maintain homeostasis by counteracting changes.
- 03
Positive Feedback
Positive feedback amplifies a deviation from the set point, which can lead to rapid changes and is less common in maintaining homeostasis but useful in specific processes.
- 04
Set Point
The set point is the optimal level or range for a physiological variable, such as body temperature, that the body works to maintain through homeostatic mechanisms.
- 05
Receptor in Feedback Loops
In homeostatic feedback loops, a receptor detects changes in the internal environment and sends signals to the control center to initiate a response.
- 06
Control Center
The control center in a homeostatic system, often in the brain, compares input from receptors to the set point and determines the appropriate response.
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Effector
Effectors are organs or tissues that carry out the response directed by the control center to restore balance in a homeostatic system.
- 08
Thermoregulation
Thermoregulation is the homeostatic process of maintaining body temperature within a narrow range, primarily through mechanisms like sweating and shivering.
- 09
Osmoregulation
Osmoregulation is the homeostatic maintenance of solute concentrations and water balance in the body, often involving the kidneys and hormones.
- 10
Blood Glucose Regulation
Blood glucose regulation is a homeostatic process where insulin and glucagon work to keep blood sugar levels stable by promoting uptake or release of glucose.
- 11
Blood pH Regulation
Blood pH regulation maintains the body's acid-base balance around 7.4 through buffers, the respiratory system, and kidneys to prevent cellular damage.
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Blood Pressure Regulation
Blood pressure regulation is a homeostatic mechanism involving baroreceptors, the heart, and blood vessels to ensure adequate perfusion of tissues.
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Hypothalamus Role
The hypothalamus plays a key role in homeostasis by monitoring internal conditions and coordinating responses through hormone release and neural signals.
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Pituitary Gland
The pituitary gland helps maintain homeostasis by secreting hormones that regulate other endocrine glands and bodily functions like water balance.
- 15
Insulin
Insulin is a hormone that lowers blood glucose levels by promoting glucose uptake into cells, thus contributing to homeostatic balance.
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Glucagon
Glucagon is a hormone that raises blood glucose levels by stimulating glycogen breakdown in the liver, aiding in homeostatic regulation.
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Vasoconstriction
Vasoconstriction is a homeostatic response that narrows blood vessels to reduce heat loss and maintain body temperature in cold environments.
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Vasodilation
Vasodilation is a homeostatic mechanism that widens blood vessels to increase blood flow and release heat, helping to cool the body.
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Sweating
Sweating is a homeostatic process that cools the body by evaporating water from the skin, triggered when body temperature rises.
- 20
Shivering
Shivering is a homeostatic response that generates heat through rapid muscle contractions when body temperature drops below the set point.
- 21
Antidiuretic Hormone (ADH)
Antidiuretic hormone regulates water balance in homeostasis by promoting water reabsorption in the kidneys to prevent dehydration.
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Renin-Angiotensin-Aldosterone System
The renin-angiotensin-aldosterone system is a homeostatic pathway that maintains blood pressure and fluid balance by regulating sodium and water retention.
- 23
Baroreceptors
Baroreceptors are sensors in blood vessels that detect changes in pressure and initiate homeostatic responses to adjust heart rate and vessel diameter.
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Chemoreceptors
Chemoreceptors detect changes in chemical levels, such as CO2 or pH in the blood, and trigger homeostatic adjustments in breathing or kidney function.
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Acclimatization
Acclimatization is the homeostatic adaptation to environmental changes over days or weeks, such as increased red blood cell production at high altitudes.
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Allostasis
Allostasis is an advanced homeostatic concept where the body anticipates and adjusts to stressors by changing set points, rather than maintaining a fixed state.
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Homeostatic Imbalance
Homeostatic imbalance occurs when the body's regulatory mechanisms fail, leading to conditions like disease, where variables deviate from normal ranges.
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Diabetes Mellitus
Diabetes mellitus is a disorder of homeostasis characterized by impaired blood glucose regulation due to insufficient insulin or cellular resistance.
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Fever
Fever involves a temporary upward shift in the body's temperature set point as a homeostatic response to infection, mediated by the hypothalamus.
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Childbirth
Childbirth exemplifies positive feedback in homeostasis, where uterine contractions intensify until delivery occurs.
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Blood Clotting
Blood clotting uses positive feedback to rapidly form a clot at an injury site, preventing excessive blood loss.
- 32
Osmotic Pressure
Osmotic pressure is a key factor in homeostasis, driving water movement across membranes to maintain cell volume and fluid balance.
- 33
Tonicity
Tonicity describes the effect of solute concentration on cell volume in a solution, which homeostasis regulates to prevent cell swelling or shrinking.
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Hypertonic Solution
A hypertonic solution has a higher solute concentration than body fluids, causing water to leave cells in homeostatic responses like osmoregulation.
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Hypotonic Solution
A hypotonic solution has a lower solute concentration than body fluids, potentially causing cells to swell, which homeostasis counters through kidney function.
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Isotonic Solution
An isotonic solution has the same solute concentration as body fluids, maintaining cell stability without disrupting homeostasis.
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Countercurrent Multiplier
The countercurrent multiplier in the kidneys creates a concentration gradient to conserve water, essential for homeostatic fluid balance.
- 38
Respiratory Acidosis
Respiratory acidosis is a homeostatic imbalance where CO2 buildup lowers blood pH, often due to impaired breathing, and the body attempts to compensate.
- 39
Metabolic Alkalosis
Metabolic alkalosis is a disruption in acid-base homeostasis caused by excess base or loss of acid, leading to elevated blood pH.
- 40
Buffer Systems
Buffer systems in the blood maintain pH homeostasis by quickly neutralizing acids or bases to prevent drastic changes.
- 41
Bicarbonate Buffer
The bicarbonate buffer system helps maintain blood pH homeostasis by converting excess acids or bases into neutral compounds.
- 42
Homeostatic Range
The homeostatic range is the acceptable variation around a set point for physiological variables, allowing flexibility while maintaining stability.
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Steady State
In homeostasis, a steady state is achieved when inputs and outputs of a substance balance out, keeping levels constant over time.
- 44
Feedforward Regulation
Feedforward regulation anticipates changes and adjusts homeostatic responses proactively, such as salivating before eating to prepare for digestion.
- 45
Hormonal Control
Hormonal control in homeostasis involves chemical messengers that regulate processes like metabolism and growth to maintain internal balance.
- 46
Neural Control
Neural control uses the nervous system to rapidly adjust homeostatic functions, such as heart rate changes in response to exercise.
- 47
Autoregulation
Autoregulation is a local homeostatic mechanism where tissues adjust their own blood flow based on metabolic needs, independent of central control.
- 48
Endocrine Disruptors
Endocrine disruptors interfere with hormonal homeostasis by mimicking or blocking hormones, potentially causing imbalances in the body.
- 49
Acclimation vs. Adaptation
Acclimation is short-term homeostatic adjustment to environmental changes, while adaptation refers to long-term evolutionary changes.
- 50
Thermoneutral Zone
The thermoneutral zone is the range of environmental temperatures where the body maintains homeostasis without extra energy expenditure for thermoregulation.
- 51
Basal Metabolic Rate
Basal metabolic rate is the energy used at rest to maintain homeostatic functions like breathing and circulation, influenced by factors like thyroid hormones.
- 52
Calorie Intake Regulation
Calorie intake regulation is a homeostatic process involving hunger and satiety signals to balance energy input with expenditure and maintain body weight.