General Physiology Practice Questions

Q: All are examples of negative feedback except

Coagulation of the blood. ***Coagulation of the blood*** - **Blood coagulation** is a classic example of **positive feedback**, where the initial clotting process amplifies itself until bleeding stops - Platelets aggregate and release factors that promote further platelet aggregation and activation of the clotting cascade, thereby **accelerating the response** rather than diminishing it - This is the exception among the options, as it represents positive feedback while all others are negative feedback *Regulation of blood CO2 level* - The regulation of **blood CO2 levels** is a vital example of **negative feedback**, where an increase in CO2 stimulates breathing to expel excess CO2 - This mechanism works to return the blood CO2 concentration to its homeostatic set point, thus **counteracting the initial stimulus** - Central and peripheral chemoreceptors detect elevated CO2 and trigger increased ventilation *Regulation of pituitary hormones* - The regulation of **pituitary hormones** involves **negative feedback loops**, where high levels of target gland hormones inhibit the release of stimulating hormones from the pituitary and hypothalamus - For example, high thyroid hormone levels inhibit TSH release from the pituitary and TRH from the hypothalamus - This effectively **reduces the initial stimulus** and maintains hormonal balance *Regulation of blood pressure* - The regulation of **blood pressure** is primarily controlled by **negative feedback mechanisms** involving baroreceptors, which detect changes in pressure - If blood pressure rises, baroreceptors in the carotid sinus and aortic arch signal the medulla to reduce heart rate and dilate blood vessels - This response **lowers the pressure back to the set point**, maintaining cardiovascular homeostasis

Q: BMR is increased in all except:

Hypothyroidism. ***Hypothyroidism*** - **Hypothyroidism** leads to a **decreased metabolic rate** due to insufficient thyroid hormone production, thus **reducing BMR**. - Symptoms like **weight gain**, **fatigue**, and **cold intolerance** are consistent with a lower metabolic rate. *Fever* - **Fever** causes an **increase in body temperature**, which directly elevates the **metabolic rate** as the body expends more energy to combat infection. - Each degree Celsius rise in body temperature increases BMR by approximately **13%**. *Exercise* - **Chronic exercise training** leads to an **increase in muscle mass**, which is metabolically more active than fat tissue. - This increased muscle mass contributes to a **higher resting metabolic rate (BMR)** over time, even when at rest. - The adaptive response to regular physical activity permanently elevates baseline energy expenditure. *Hyperthyroidism* - **Hyperthyroidism** results in an **overproduction of thyroid hormones**, significantly **increasing the metabolic rate**. - This leads to symptoms such as **weight loss**, **heat intolerance**, and **tachycardia**, all indicative of an elevated BMR.

Q: Increased BMR is associated with -

Increased glycolysis. ***Increased glycolysis*** - An increased **basal metabolic rate (BMR)** signifies higher energy expenditure at rest, which reflects increased cellular metabolic activity and ATP consumption. - Among the given options, **increased glycolysis** is most consistent with increased BMR, as glycolysis is the primary pathway for ATP generation from glucose, and cells with higher metabolic rates require increased energy production. - Conditions that increase BMR (such as hyperthyroidism, fever, and increased muscle mass) are typically accompanied by **increased glycolytic activity** to meet higher energy demands. *Incorrect: Increased body fat store* - **Increased body fat** is generally associated with a *lower* BMR per unit of body weight, as adipose tissue is metabolically less active than lean tissue (especially muscle). - Higher body fat percentage reflects **energy storage**, not increased energy expenditure, and does not contribute to elevated BMR. *Incorrect: Increased lipogenesis* - **Lipogenesis** (synthesis of fatty acids and triglycerides) is an anabolic process that occurs during states of **energy surplus** for fat storage. - This process represents energy **storage** rather than energy **expenditure**, and is inversely related to BMR - it increases when energy intake exceeds expenditure. *Incorrect: Increased gluconeogenesis* - **Gluconeogenesis** (synthesis of glucose from non-carbohydrate sources) is primarily active during **fasting, starvation, or prolonged exercise** when glucose availability is low. - While gluconeogenesis is energy-consuming, it is characteristic of catabolic states with low energy availability, not the increased metabolic activity associated with elevated BMR. - In conditions that increase BMR (like hyperthyroidism), glucose is typically utilized via glycolysis rather than synthesized via gluconeogenesis.

Q: Sweat glands of palm can be differentiated from others by the following:

Secretion stimulated by emotional stimuli. ***Secretion stimulated by emotional stimuli*** - Sweat glands in the palms (and soles) are primarily regulated by the **sympathetic nervous system** and are uniquely responsive to **emotional or psychological stress**, leading to emotional sweating. - This response is mediated via **cholinergic postganglionic sympathetic fibers**, despite being part of the sympathetic system. *High chloride content* - While sweat does contain chloride, the overall **concentration of electrolytes** like sodium and chloride can vary, and a specifically "high" chloride content is not a unique distinguishing feature of palm sweat compared to other eccrine sweat. - **Cystic Fibrosis** is characterized by abnormally high sweat chloride due to a defect in the CFTR channel, but this represents a pathological condition, not a normal physiological differentiator of palm sweat. *Chemical mediators control the secretion.* - All sweat gland secretion, including that of the palms, is controlled by **neurotransmitters (chemical mediators)**, primarily acetylcholine acting on muscarinic receptors (M3) on eccrine sweat glands. This is not a differentiating factor. - The specific mediator (acetylcholine) is common to eccrine glands throughout the body and does not distinguish palm sweat. *Controlled by sympathetic adrenergic fibers* - Most eccrine sweat glands are innervated by **sympathetic cholinergic fibers** (they release acetylcholine), not adrenergic fibers (which release norepinephrine). - While sympathetic, their neurotransmitter **acetylcholine** is the primary mediator for thermoregulatory sweating, which also applies to palm sweat glands in their response to emotional stimuli.

Q: Endogenous electric signal that is also seen in bone that is not stressed:

Streaming Potential. ***Streaming Potential*** - This is the **correct answer** - streaming potentials are endogenous electrical signals present in bone even without mechanical stress - Generated by the **flow of interstitial fluid** through the charged porous structure of bone (canalicular system) - Exists continuously due to **normal physiological processes** like blood pressure fluctuations, osmotic gradients, and metabolic activity - Increases with mechanical loading but is **always present as a baseline signal** in living bone - Plays an important role in bone remodeling and mechano-transduction *Bioelectric Potential* - This is a **generic term** that encompasses all electrical potentials in biological tissues - Too broad and non-specific - it could refer to action potentials, membrane potentials, or any bioelectric phenomenon - Not a specific, well-defined electrical signal characteristic of bone tissue - While technically present in bone, it's not the specific answer for endogenous bone electrical signals *Capillary potential* - This term relates to **capillary action** and surface tension phenomena in porous materials - More relevant to fluid mechanics in soil science and plant physiology - Not a recognized term for endogenous electrical signals in bone physiology *None of the options* - Incorrect because **Streaming Potential** is the accurate description of endogenous electrical signals in unstressed bone

Q: Two solutions with equal osmotic pressures are called:

Isotonic solution. ***Isotonic solution*** - **Isotonic solutions** have the same solute concentration, and therefore the same **osmotic pressure**, as another solution. - In biological systems, an isotonic solution has the same osmotic pressure as the **cytosol** inside cells, preventing net water movement. *Normal solution* - "Normal solution" is a general term often referring to a solution at standard conditions or a commonly used concentration, but it does not specifically mean equal osmotic pressure. - While **normal saline** (0.9% NaCl) is isotonic to human plasma, the term "normal solution" itself is not a direct definition of equal osmotic pressure. *Hypertonic solution* - A **hypertonic solution** has a higher solute concentration and thus a higher **osmotic pressure** compared to another solution. - When a cell is placed in a hypertonic solution, water moves out of the cell, causing it to **crenate** or shrink. *Hypotonic solution* - A **hypotonic solution** has a lower solute concentration and thus a lower **osmotic pressure** compared to another solution. - When a cell is placed in a hypotonic solution, water moves into the cell, causing it to **swell** and potentially lyse.

Q: Which among the following results in a combination of elastic and viscous behavior, where only the elastic component is recovered when the stress is removed?

Viscoelastic deformation. ***Viscoelastic deformation*** - This type of deformation involves both **elastic** and **viscous** components, meaning that biological materials exhibit characteristics of both solids (elastic) and fluids (viscous). - Upon removal of the applied stress, only the **elastic strain** is recovered immediately, while the **viscous component** results in time-dependent behavior such as stress relaxation and creep. - This is the characteristic behavior of biological tissues, cell membranes, and cytoplasm, which demonstrate **viscoelastic properties** essential for physiological function. *Elastic deformation* - Involves only **elastic strain**, meaning the material fully recovers its original shape instantaneously once the applied stress is removed. - There is no time-dependent behavior or permanent deformation, as observed in materials within their elastic limit. *Plastic deformation* - Occurs when a material is stressed beyond its **yield point**, resulting in a permanent change in shape even after the stress is removed. - This is primarily due to **irreversible structural rearrangements** and does not involve time-dependent viscous flow. - This is not characteristic of normal physiological tissue behavior. *None of the options* - This option is incorrect because **viscoelastic deformation** accurately describes the phenomenon where biological materials exhibit a combination of elastic and viscous behavior, with only the elastic component being immediately recoverable.

Q: Energy expenditure in the resting state mainly depends on which of the following parameters?

Lean body mass. ***Lean body mass*** - **Lean body mass** (muscle, organs, bone) is metabolically active and requires significant energy, making it a primary determinant of Basal Metabolic Rate (BMR) or **resting energy expenditure**. - Tissues like **muscle** have a higher metabolic rate even at rest compared to adipose tissue. *Exercise* - **Exercise** accounts for the most variable component of daily energy expenditure, but it does not determine the energy expenditure in the **resting state**. - While physical activity consumes significant energy, that is separate from the baseline energy required to sustain life at rest. *Resting heart rate* - **Resting heart rate** is an indicator of cardiovascular fitness and sympathetic nervous system activity, but it is not a direct measure or primary determinant of total resting energy expenditure. - While a higher heart rate often correlates with a slightly elevated metabolic rate, the **amount of metabolically active tissue** is a more fundamental driver. *Adipose tissue* - **Adipose tissue** (fat) is metabolically less active than lean body mass, contributing minimally to resting energy expenditure compared to muscle or organ mass. - Although it does have some metabolic activity, its contribution is minor relative to the **energy demands of essential organs and muscle tissue**.

Q: Gibbs-Donnan effect is seen on the distribution of:

Diffusible ions. ***Diffusible ions*** - The **Gibbs-Donnan effect** describes the unequal distribution of **diffusible ions** across a semi-permeable membrane in the presence of a non-diffusible charged macromolecule. - This effect is crucial for maintaining **osmotic balance** and electrical neutrality, as the diffusible ions adjust their concentrations to balance the charge imbalance caused by the non-diffusible species. *Only proteins* - While **proteins** are often the **non-diffusible macromolecules** that cause the Gibbs-Donnan effect, the effect itself is observed in the distribution of the *diffusible* ions. - Proteins themselves do not *distribute* in response to the effect; they *cause* the effect on other ions. *Non-diffusible ions* - **Non-diffusible ions** (like large protein anions) are the *cause* of the Gibbs-Donnan effect, by creating an **osmotic and electrical gradient**. - The effect is not seen *on* their distribution because they cannot cross the membrane in the first place. *Diffusible + Non-diffusible ions* - The Gibbs-Donnan effect specifically concerns the **unequal distribution of *diffusible* ions**. - Non-diffusible ions do not distribute across the membrane, so their distribution is not influenced by this effect.

Q: Why do eyebrows not grow beyond a certain length?

Anagen phase. **Anagen phase** - The **anagen phase**, or growing phase, is significantly shorter for eyebrow hairs (typically 30-45 days) compared to scalp hair (2-7 years), which limits their maximum length. - The duration of this active growth phase **determines the ultimate length** hair can reach before it transitions to resting and shedding. *Telogen phase* - The **telogen phase** is a **resting phase** where the hair follicle is completely inactive; it does not contribute to the hair's growth or final length. - During this phase, the old hair is shed to make way for new hair growth, but it is not the phase that dictates the maximum length. *Catagen phase* - The **catagen phase** is a **transitional phase** lasting about 2-3 weeks, during which hair growth stops and the hair follicle shrinks. - This phase prepares the hair for resting and shedding but does not directly limit how long the hair grows. *Exogen phase* - The **exogen phase** is when a hair is **shed from the follicle**, often aided by activities like washing or brushing. - This phase is responsible for hair shedding, not for limiting the maximum length hair can attain.

Question 1

All are examples of negative feedback except

Accepted Answer

Coagulation of the blood

Answer

Regulation of blood CO2 level

Answer

Regulation of pituitary hormones

Answer

Regulation of blood pressure

Question 2

BMR is increased in all except:

Accepted Answer

Hypothyroidism

Answer

Fever

Answer

Exercise

Answer

Hyperthyroidism

Question 3

Increased BMR is associated with -

Accepted Answer

Increased glycolysis

Answer

Increased body fat store

Answer

Increased lipogenesis

Answer

Increased gluconeogenesis

Question 4

Sweat glands of palm can be differentiated from others by the following:

Accepted Answer

Secretion stimulated by emotional stimuli

Answer

High chloride content

Answer

Chemical mediators control the secretion.

Answer

Controlled by sympathetic adrenergic fibers

Question 5

Endogenous electric signal that is also seen in bone that is not stressed:

Accepted Answer

Streaming Potential

Answer

Bioelectric Potential

Answer

Capillary potential

Answer

None of the options

Question 6

Two solutions with equal osmotic pressures are called:

Accepted Answer

Isotonic solution

Answer

Normal solution

Answer

Hypertonic solution

Answer

Hypotonic solution

Question 7

Which among the following results in a combination of elastic and viscous behavior, where only the elastic component is recovered when the stress is removed?

Accepted Answer

Viscoelastic deformation

Answer

Elastic deformation

Answer

Plastic deformation

Answer

None of the options

Question 8

Energy expenditure in the resting state mainly depends on which of the following parameters?

Accepted Answer

Lean body mass

Answer

Exercise

Answer

Resting heart rate

Answer

Adipose tissue

Question 9

Gibbs-Donnan effect is seen on the distribution of:

Accepted Answer

Diffusible ions

Answer

Only proteins

Answer

Non-diffusible ions

Answer

Diffusible + Non-diffusible ions

Question 10

Why do eyebrows not grow beyond a certain length?

Accepted Answer

Anagen phase

Answer

Telogen phase

Answer

Catagen phase

Answer

Exogen phase

General Physiology — MCQs

General Physiology — MCQs

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