Question 1

Which hormone is primarily responsible for stimulating the release of cortisol from the adrenal cortex, and what is the main physiological effect of elevated cortisol levels during prolonged stress?

Accepted Answer

Adrenocorticotropic hormone (ACTH); increased gluconeogenesis leading to elevated blood glucose

Question 2

A patient presents with symptoms of muscle weakness, fatigue, and low blood pressure. Laboratory tests reveal low levels of cortisol and aldosterone. Which endocrine disorder is most likely responsible, and which part of the adrenal gland is affected?

Accepted Answer

Addison's disease; adrenal cortex

Question 3

Which equation best represents the Nernst potential for potassium ions ($$K^+) $$across a neuronal membrane?

Accepted Answer

$$E_K = \frac{RT}{zF} \ln \left( \frac{[K^+]_{out}}{[K^+]_{in}} \right)$$

Question 4

Which of the following best describes the difference between a graded potential and an action potential in a neuron?

Accepted Answer

Graded potentials vary in amplitude and can summate, while action potentials are all-or-none and propagate without decrement

Question 5

Which hormone is essential for bone growth and maintenance, and what is its primary target tissue?

Accepted Answer

Parathyroid hormone (PTH); bone tissue

Question 6

A patient with hyperthyroidism is likely to exhibit which of the following symptoms due to increased thyroid hormone levels?

Accepted Answer

Elevated heart rate and increased metabolic rate

Question 7

Which of the following best explains why myelinated axons conduct action potentials faster than unmyelinated axons?

Accepted Answer

Saltatory conduction allows action potentials to jump between nodes of Ranvier, reducing membrane capacitance and increasing conduction velocity

Question 8

Which part of the brain is NOT covered by the blood-brain barrier, and what is the physiological significance of this exception?

Accepted Answer

The hypothalamus; allows for direct monitoring of blood composition for homeostatic regulation

Question 9

Which neurotransmitter is released at the neuromuscular junction to stimulate skeletal muscle contraction, and what is the effect of its binding to the postsynaptic membrane?

Accepted Answer

Acetylcholine; opens ligand-gated sodium channels causing depolarization

Question 10

Which of the following best describes the role of the sarcoplasmic reticulum in skeletal muscle contraction?

Accepted Answer

Stores and releases calcium ions ($$Ca^{2+}) to $$initiate contraction

Question 11

Which equation describes the relationship between membrane potential ($$V_m$$), equilibrium potentials, and ion conductances according to the Goldman-Hodgkin-Katz equation?

Accepted Answer

$$V_m = \frac{RT}{F} \ln \left( \frac{P_{K^+}[K^+]_{out} + P_{Na^+}[Na^+]_{out} + P_{Cl^-}[Cl^-]_{in}}{P_{K^+}[K^+]_{in} + P_{Na^+}[Na^+]_{in} + P_{Cl^-}[Cl^-]_{out}} \right)$$

Question 12

Which of the following is a primary function of the T-tubules in skeletal muscle fibers?

Accepted Answer

Transmit action potentials deep into the muscle fiber to trigger calcium release

Question 13

Which hormone is secreted by the anterior pituitary and stimulates growth in nearly all tissues, and what is its effect on protein synthesis?

Accepted Answer

Growth hormone (GH); increases protein synthesis

Question 14

Which of the following best explains the difference between an electrical synapse and a chemical synapse?

Accepted Answer

Electrical synapses transmit signals via gap junctions for rapid communication; chemical synapses use neurotransmitters for slower, modifiable transmission

Question 15

A patient is experiencing excessive thirst and urination. Laboratory results show low levels of antidiuretic hormone (ADH). Which condition is most likely present, and what is the primary function of ADH?

Accepted Answer

Diabetes insipidus; promotes water reabsorption in the kidneys

Question 16

Which of the following best describes the role of the trigger zone in the generation of an action potential?

Accepted Answer

It is the site where graded potentials summate to reach threshold, initiating an action potential

Question 17

Which of the following is true regarding the absolute refractory period of a neuron?

Accepted Answer

No new action potential can be generated regardless of stimulus strength

Question 18

Which hormone is primarily responsible for increasing blood calcium levels, and what is its mechanism of action?

Accepted Answer

Parathyroid hormone (PTH); stimulates osteoclast activity and increases renal calcium reabsorption

Question 19

Which of the following best describes the difference between hyperpolarization and depolarization in a neuron?

Accepted Answer

Hyperpolarization makes the membrane potential more negative, while depolarization makes it less negative

Anatomy & Physiology Study Guide: Endocrine, Nervous, and Muscular Systems

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