Feedback Loops and Homeostatic Regulation (3A) - Bio & Biochem
- Identify the classic human positive feedback example involving uterine contractions.
- Oxytocin-driven labor (parturition). Oxytocin release amplifies contractions, creating a positive loop that progresses labor to delivery.
- Which option best describes a regulated variable in homeostasis?
- A measurable condition maintained within a narrow range. Regulated variables are essential parameters like blood pressure that homeostasis keeps stable for optimal function.
- What is a positive feedback loop in physiological regulation?
- A response that amplifies the initial change. Positive feedback intensifies a process to completion, like oxytocin enhancing uterine contractions during childbirth.
- What is the response in a physiological feedback loop?
- Effector action that changes the regulated variable. The response corrects the deviation detected by the sensor, bringing the system back toward the set point.
- Identify the three core components of a homeostatic control loop.
- Sensor, integrator (control center), effector. These components form the basic structure of feedback systems, detecting changes, processing information, and enacting responses.
- Which option best defines an antagonist effector pair in homeostasis?
- Two effectors that produce opposing effects on a variable. Antagonist pairs allow precise control by balancing increases and decreases in the regulated variable.
- What is the primary stimulus for insulin secretion by pancreatic cells?
- Increased blood glucose. Elevated glucose levels prompt insulin release to promote uptake and storage, restoring normoglycemia.
- Which effectors primarily conserve or generate heat during hypothermia?
- Shivering and cutaneous vasoconstriction. These responses reduce heat loss and increase heat production to restore normal body temperature.
- Identify the classic positive feedback example involving blood vessel repair.
- Platelet aggregation during blood clotting. Initial platelet activation releases factors that recruit more platelets, accelerating clot formation.
- Which option best defines feedforward control in physiology?
- Anticipatory response that occurs before a variable changes. Feedforward mechanisms preemptively adjust physiology, like salivation before eating to aid digestion.
- What is the set point in a homeostatic control system?
- Target value or range for a regulated variable. The set point represents the ideal physiological value that feedback mechanisms aim to restore when deviations occur.
- What is the function of an effector in a homeostatic control system?
- Carries out the response to adjust the variable. Effectors execute commands from the control center to restore the regulated variable to its set point.
- What is homeostasis in physiology?
- Maintenance of internal conditions near a set point. Homeostasis ensures physiological stability by regulating variables like temperature and pH around optimal levels despite external changes.
- Identify the term for stable oscillations around a set point in homeostasis.
- Dynamic equilibrium. Dynamic equilibrium describes the steady state where variables fluctuate minimally around the set point.
- Which effectors primarily increase heat loss during hyperthermia?
- Sweating and cutaneous vasodilation. These mechanisms enhance evaporative cooling and heat radiation to counteract elevated body temperature.
- What is the primary stimulus for glucagon secretion by pancreatic cells?
- Decreased blood glucose. Low glucose triggers glucagon to mobilize stores and raise levels, preventing hypoglycemia.
- What is a negative feedback loop in homeostatic regulation?
- A response that counteracts the initial change. Negative feedback restores equilibrium by opposing deviations, such as insulin lowering high blood glucose.
- What is the thermoregulatory control center in humans?
- Hypothalamus. The hypothalamus integrates thermal signals and coordinates responses to maintain core body temperature.
- What is the function of an integrator (control center) in homeostasis?
- Compares to set point and generates an output signal. The integrator evaluates sensor input against the set point to initiate appropriate corrective actions via effectors.
- What is the function of a sensor (receptor) in a feedback loop?
- Detects a change in a regulated variable (stimulus). Sensors monitor environmental or internal changes and relay information to maintain homeostasis.
- What is the stimulus in a physiological feedback loop?
- Deviation of a regulated variable from its set point. The stimulus triggers the feedback loop by signaling a need for adjustment to maintain homeostasis.
- What is the net effect of glucagon on blood glucose?
- Increases blood glucose. Glucagon stimulates glycogenolysis and gluconeogenesis to elevate blood sugar during fasting states.
- What is the net effect of insulin on blood glucose?
- Decreases blood glucose. Insulin facilitates glucose uptake by cells and inhibits gluconeogenesis, normalizing high blood sugar.
- Choose the phrase that best defines allostasis in regulation.
- Stability through change by adjusting the set point. Allostasis achieves stability by adapting set points to chronic stressors, differing from fixed homeostasis.