Endocrine Disorders: Hormonal and Metabolic Regulation

Exam-recognition practice flashcards covering endocrine regulation, stress adaptation stages, and major endocrine disorders including Acromegaly, SIADH, Diabetes Insipidus, Graves Disease, Hypothyroidism, Cushing Syndrome, Addison Disease, and Hypoparathyroidism.

What is the primary role of the hypothalamic–pituitary axis?

The hypothalamus and pituitary coordinate hormone release to regulate other endocrine glands.

How does negative feedback maintain hormonal balance?

When a hormone reaches an adequate level, it signals the body to reduce further release, suppressing upstream stimulation to help restore balance.

What characterizes a positive feedback loop in endocrine regulation?

A hormonal response amplifies or increases its original stimulus until a specific event ends the cycle.

What is the difference between paracrine and autocrine cell-to-cell communication?

Paracrine communication involves a cell signaling nearby cells (such as histamine affecting nearby capillaries during inflammation), whereas autocrine communication occurs when a cell signals itself (such as immune-cell cytokines regulating that same cell).

How do endocrine and neuroendocrine communication differ?

In endocrine communication, hormones travel through blood to distant targets (such as pituitary TSH stimulating the thyroid), while in neuroendocrine communication, neurons release hormones into the blood (such as hypothalamic ADH and oxytocin released via the posterior pituitary).

Which neurological structures help recognize and respond to stress during the neurologic stress response?

The autonomic system, cerebral cortex, limbic system, thalamus, hypothalamus, and reticular activating system.

What sequence of hormonal signaling occurs in response to stress involving CRH and ACTH?

Corticotropin-releasing hormone (CRH) from the hypothalamus stimulates pituitary ACTH release, which then stimulates the adrenal cortex to release cortisol.

What occurs during the alarm stage of the General Adaptation Syndrome?

Initial stress activates fight-or-flight with adrenaline and cortisol, raising heart rate, blood pressure, and available energy.

What occurs during the resistance stage of the General Adaptation Syndrome?

During continued stress, cortisol remains elevated to sustain energy and alertness while the body attempts to cope and stabilize.

What clinical consequences characterize the exhaustion stage of the General Adaptation Syndrome?

Prolonged stress drains resources and may cause fatigue, burnout, reduced immunity, and illness.

What is impaired cellular response in altered hormone function?

Target cells resist a hormone despite adequate hormone levels, such as seen in insulin resistance.

What is ectopic hormone production?

A tissue outside the normal hormone-producing gland releases that hormone.

What causes acromegaly and why does it not increase height in adults?

It is caused by excess growth hormone in adulthood, usually from a benign pituitary tumor; it thickens bones and soft tissues rather than increasing height because the epiphyseal plates have already closed.

What are frontal bossing and macroglossia in acromegaly?

Frontal bossing is an unusually prominent forehead due to bony enlargement, and macroglossia is an enlarged tongue.

What cellular mechanism contributes to acromegaly-related tissue enlargement?

Hyperplasia, which is an increase in cell number.

What is Syndrome of Inappropriate Antidiuretic Hormone (SIADH)?

A disorder involving excess ADH secretion, which causes water retention and dilutional hypotonic hyponatremia.

What malignancy is identified as an ectopic source of ADH in SIADH?

Small-cell lung cancer.

Why does cellular swelling occur in SIADH and which organ is particularly vulnerable?

Excess retained water creates low plasma tonicity, allowing water to enter cells and disrupt function, particularly in the brain.

How do clinical cues progress across mild-to-moderate, moderate-to-severe, and critical SIADH?

Mild-to-moderate hyponatremia causes anorexia, nausea, vomiting, and headache; moderate-to-severe causes irritability, disorientation, muscle cramps, and weakness; critical hyponatremia causes psychosis, gait disturbance, seizures, or coma.

What is diabetes insipidus (DI)?

Insufficient ADH activity that prevents the kidneys from concentrating urine, causing excessive dilute urine and water loss.

What differentiates central (neurogenic) DI from nephrogenic DI?

Central (neurogenic) DI results from injury, tumor, or surgery involving the hypothalamus or pituitary that reduces ADH production or release, whereas nephrogenic DI occurs when the kidneys fail to respond normally to ADH (e.g., from genetic disorders or lithium toxicity).

What are the key clinical cues of diabetes insipidus?

Polyuria (abnormally large, watery urine output), excessive thirst, dehydration, and potentially shock or death if fluid loss is untreated.

What is the underlying pathophysiology of Graves disease?

It is an autoimmune form of hyperthyroidism in which IgG antibodies stimulate TSH receptors on thyroid cells (thyrocytes), imitating TSH and overstimulating the gland.

What are the common clinical cues of Graves disease?

Goiter, weight loss, restlessness and agitation, heat intolerance, sweating, diarrhea, tachycardia, palpitations, tremors, fine hair, oily skin, irregular menstruation, muscle weakness, and exophthalmos.

What does exophthalmos mean in the context of Graves disease?

Exophthalmos means protruding eyes and serves as an important visual recognition clue for Graves disease.

What is Hashimoto thyroiditis?

An autoimmune condition that damages the thyroid gland and can cause hypothyroidism.

What are the primary clinical cues of hypothyroidism?

Fatigue, weakness, lethargy, weight gain, cold intolerance, constipation, dry skin, coarse hair, reproductive impairment, memory impairment, goiter, and myxedema.

What is myxedema?

Tissue swelling associated with severe hypothyroidism.

What hormones are produced by the adrenal cortex versus the adrenal medulla?

The adrenal cortex produces glucocorticoids, mineralocorticoids, and adrenal androgens, whereas the adrenal medulla produces catecholamines involved in the stress response.

What is the function of aldosterone produced by the adrenal cortex?

Aldosterone promotes sodium and water retention while supporting potassium excretion by the kidneys.

What distinguishes Cushing disease from Cushing syndrome?

Cushing syndrome is the broad condition resulting from excess glucocorticoid activity (including exogenous prednisone or adrenal tumors), whereas Cushing disease specifically refers to the pituitary-tumor cause of excess ACTH and cortisol.

What are the classic physical and laboratory cues of Cushing syndrome?

Truncal obesity, buffalo hump, moon face, hirsutism, abdominal striae, hyperglycemia, hypokalemia, immune suppression, and mood changes.

What is Addison disease and what are its hormone levels?

Autoimmune destruction of the adrenal cortex (primary adrenal insufficiency) that reduces glucocorticoids, mineralocorticoids, and androgens while causing ACTH levels to rise.

Why does hyperpigmentation occur in Addison disease?

High ACTH levels stimulate darker skin pigmentation as the pituitary attempts to stimulate the failing adrenal cortex.

What clinical cues result from mineralocorticoid deficiency in Addison disease?

Dehydration, hyponatremia, hyperkalemia, hypotension, weakness, fatigue, and shock due to loss of sodium and water retention.

What are common acquired and congenital causes of hypoparathyroidism?

Thyroid surgery (damage to parathyroid glands), thyroid radiation, autoimmune damage, and congenital disorders.

What neuromuscular symptoms are caused by hypocalcemia in hypoparathyroidism?

Neuromuscular irritability (increased nerve and muscle excitability), paresthesia (tingling, often in extremities), painful muscle cramps, and seizures.

How do SIADH and Diabetes Insipidus contrast in terms of fluid and sodium regulation?

SIADH causes excessive water retention and dilutes sodium (dilutional hypotonic hyponatremia), whereas DI causes excessive water loss through dilute urine, leading to dehydration.

How do Cushing syndrome and Addison disease contrast in adrenal hormone production and potassium balance?

Cushing syndrome involves excess cortisol activity and can cause hypokalemia, whereas Addison disease involves inadequate adrenal cortex hormones and causes hyperkalemia.