Homeostasis - Ccma

Which organ is the main source of glycogen storage that stabilizes blood glucose between meals?

Liver. It stores glycogen and performs gluconeogenesis to supply glucose during intervals without food intake.
Which part of the brain functions as the main thermoregulatory control center?

Hypothalamus. It integrates thermal signals and coordinates responses like shivering or sweating for temperature homeostasis.
Which organ system provides the fastest compensation for pH imbalance?

Respiratory system (changes ventilation to alter $CO_2$ ). By adjusting breathing rate, it rapidly expels $CO_2$ to influence blood pH via the carbonic acid system.
Which option best describes how the cardiovascular and respiratory systems work together for gas exchange?

Lungs oxygenate blood; heart and vessels deliver $O_2$ and remove $CO_2$ . Their collaboration ensures efficient oxygen supply and carbon dioxide removal to support cellular respiration.
What is the role of an effector in homeostasis?

Carries out the response to restore the regulated condition. Organs or glands like muscles or kidneys execute changes to counteract deviations from the set point.
Identify the direct effect on blood pH when ventilation increases (hyperventilation).

Blood pH increases (respiratory alkalosis tendency) as $CO_2$ decreases. Reduced $CO_2$ shifts the equilibrium away from carbonic acid, raising pH in a negative feedback response.
What is the set point in a homeostatic control system?

The target value or normal range a variable is regulated around. It serves as the reference point for feedback mechanisms to detect and correct deviations in regulated variables.
What is the role of a control center in homeostasis?

Compares input to set point and directs a response. Typically the brain or endocrine glands, it processes sensory information to activate effectors for homeostasis.
Which organ system is the primary short-term regulator of body temperature?

Integumentary system (sweating and skin blood flow changes). Through evaporation and vasodilation, it dissipates heat to prevent hyperthermia in warm environments.
Which hormone increases sodium reabsorption and potassium excretion in the kidneys?

Aldosterone. From the adrenal cortex, it acts on distal tubules to retain sodium and promote potassium secretion for volume control.
Identify the direct effect on blood pH when ventilation decreases (hypoventilation).

Blood pH decreases (respiratory acidosis tendency) as $CO_2$ increases. Accumulated $CO_2$ forms more carbonic acid, lowering pH to signal respiratory adjustments.
What is homeostasis in human physiology?

Maintenance of a stable internal environment despite external change. This dynamic equilibrium allows cells to function optimally by counteracting fluctuations in variables like temperature and pH.
Which system is activated when renal perfusion drops to raise blood pressure?

Renin–angiotensin–aldosterone system (RAAS). Triggered by low blood flow, it leads to vasoconstriction and aldosterone release to restore pressure.
What is the primary role of the kidneys in long-term fluid and electrolyte homeostasis?

Regulate water, sodium, potassium, and acid–base balance via urine. Nephrons filter and adjust urine composition to maintain extracellular fluid volume and osmolarity.
Which organ system provides the slowest but most powerful compensation for pH imbalance?

Renal system (adjusts $H^+$ excretion and $HCO_3^-$ reabsorption). It fine-tunes pH over hours to days by modulating ion handling in nephrons for long-term balance.
Which hormone lowers blood glucose by promoting cellular uptake and storage?

Insulin. Secreted by pancreatic beta cells, it facilitates glucose transport into cells to prevent hyperglycemia.
What is the primary regulated variable that reflects acid–base balance?

Blood pH. Maintained around 7.4, it ensures enzyme function and metabolic processes by balancing acids and bases.
What are the three core components of a homeostatic control loop?

Receptor (sensor), control center, effector. These elements form a feedback loop where detection leads to integration and response to maintain stability.
Which hormone increases water reabsorption in the kidney collecting ducts?

Antidiuretic hormone (ADH, vasopressin). Released from the posterior pituitary, it enhances aquaporin insertion to conserve water during dehydration.
Which type of feedback amplifies a deviation until a specific endpoint occurs?

Positive feedback. It intensifies changes to achieve rapid outcomes, like in blood clotting or childbirth contractions.
Which option best describes the interdependence of skeletal muscle and respiratory systems during exercise?

Muscles increase $O_2$ demand; ventilation rises to meet demand and remove $CO_2$ . Exercise-induced metabolic activity raises $CO_2$ and lowers $O_2$ , prompting hyperpnea for gas exchange balance.
What is the role of a receptor (sensor) in homeostasis?

Detects change in a regulated condition and sends input. It monitors variables like blood glucose and signals the control center to initiate corrective actions.
Which hormone raises blood glucose primarily by stimulating glycogen breakdown?

Glucagon. From pancreatic alpha cells, it mobilizes hepatic glucose release during fasting to avoid hypoglycemia.
Which type of feedback reverses a deviation from the set point?

Negative feedback. This mechanism restores balance by opposing changes, such as in blood pressure or temperature regulation.
Which option best describes how dehydration affects heart rate and kidney output to preserve homeostasis?

Heart rate increases; kidneys conserve water by reducing urine volume. Low volume triggers sympathetic response for tachycardia and ADH/RAAS activation to concentrate urine.

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