Q: Which equation best represents the law of mass balance in physiology?

$$\text{Total amount} = \text{Existing amount} + \text{Input} - \text{Output}$$

Question 1

Which of the following best describes the concept of homeostasis in human physiology?

Accepted Answer

The process by which the body maintains a dynamic steady state, compensating for changes to keep regulated variables near a set point.

Question 2

A patient consumes 1200 mg of sodium chloride (NaCl) and excretes 1000 mg in urine. According to the law of mass balance, what happens to the remaining 200 mg?

Accepted Answer

It is stored in the body, potentially increasing extracellular fluid osmolarity.

Question 3

Which of the following is an example of a negative feedback loop in human physiology?

Accepted Answer

Regulation of blood pressure by baroreceptors adjusting heart rate and vessel diameter.

Question 4

Which statement correctly distinguishes between 'function' and 'process' in physiology?

Accepted Answer

Function explains 'why' a physiological event occurs (teleological), while process describes 'how' it happens (mechanistic).

Question 5

Which of the following is NOT a central theme in physiology?

Accepted Answer

Behavioural adaptations drive physiological changes.

Question 6

Which equation best represents the law of mass balance in physiology?

Accepted Answer

$$	ext{Total amount} = 	ext{Existing amount} + 	ext{Input} - 	ext{Output}$$

Question 7

Which of the following best describes the role of proteins in ligand binding?

Accepted Answer

Proteins bind ligands at specific binding sites using noncovalent interactions, often following the induced-fit model.

Question 8

Which of the following is a consequence of failure to compensate for loss of homeostasis?

Accepted Answer

Disease develops due to inability to maintain internal stability.

Question 9

Which of the following is an example of compartmentalisation in human physiology?

Accepted Answer

The separation of intracellular and extracellular fluids by the cell membrane.

Question 10

Which of the following is a correct sequence for a simple reflex control system?

Accepted Answer

Stimulus → Sensor → Input signal → Integrating center → Output signal → Target → Response

Question 11

Which of the following best explains why homeostasis is not the same as equilibrium?

Accepted Answer

Homeostasis maintains a dynamic steady state, where variables are kept within a range but not necessarily equal across compartments.

Question 12

Which of the following is a plausible effect of an ageing population on physiology and healthcare?

Accepted Answer

Increased demand for management of chronic diseases and age-related physiological changes.

Question 13

Which of the following is a correct example of feedforward control in physiology?

Accepted Answer

Increase in salivation when food is seen or smelled before ingestion.

Question 14

Which of the following best describes the induced-fit model of protein-ligand binding?

Accepted Answer

The protein changes shape slightly to accommodate the ligand, increasing binding affinity.

Question 15

Which of the following is a function of the cell membrane?

Accepted Answer

Physical isolation, regulation of exchange, communication, and structural support.

Question 16

Which of the following best describes the role of the cytoskeleton in cells?

Accepted Answer

It provides cell shape, internal organization, intracellular transport, assembly of cells into tissues, and movement.

Question 17

Which of the following is a correct example of a positive feedback loop?

Accepted Answer

Amplification of uterine contractions during childbirth by oxytocin.

Question 18

Which of the following is a correct description of mass flow in physiology?

Accepted Answer

$$	ext{Mass flow} = 	ext{Concentration} 	imes 	ext{Volume flow}$$

Question 19

Which of the following is a plausible effect of glucose metabolism on mass balance in the body?

Accepted Answer

Glucose is converted to CO$$_2$$ and H$$_2O$$, which are excreted, maintaining mass balance.

Physiology as an Integrated Science: Control Systems and Homeostasis

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