Endocrine System: Adrenal and Thyroid Glands

The outermost layer of the adrenal cortex, the zona glomerulosa (ZG), secretes _____, which promotes Na⁺ retention and K⁺ excretion.

The middle layer of the adrenal cortex, the zona fasciculata (ZF), secretes _____, a glucocorticoid released during stress.

Cortisol acts to raise blood levels of glucose, amino acids, and _____ during the stress response.

In addition to metabolic regulation, cortisol exerts significant _____ and immunosuppressive effects.

The innermost layer of the adrenal cortex, the zona reticularis (ZR), secretes some male _____.

The adrenal medulla secretes epinephrine and _____, which prepare the body for fight-or-flight by increasing energy stores.

Adrenal insufficiency characterized by reduced glucocorticoid production is known as _____ disease.

Hypercortisolism resulting from abnormally elevated levels of glucocorticoids is known as _____ syndrome.

Thyroid follicles synthesize thyroxine (T₄) and triiodothyronine (T₃) from the precursor protein _____.

In peripheral tissues, T₄ is converted into _____, which is the biologically more active thyroid hormone.

The numbers in T₄ and T₃ signify the total number of _____ atoms contained in each hormone molecule.

Thyroid hormones are essential for stimulating baseline metabolism and promoting normal development of the _____ system.

Deficient secretion of T₄ in adults results in _____, whereas excess production leads to hyperthyroidism.

A severe T₄ deficiency during early embryonic and childhood development causes a condition known as _____.

When low thyroid hormone feedback causes sustained elevated secretion of _____, the thyroid gland enlarges to form a goiter.

Calcitonin (CT) is produced by _____ cells located outside the thyroid follicles.

Calcitonin acts to lower blood Ca²⁺ levels by promoting bone deposition and increasing Ca²⁺ excretion by the _____.

Embedded on the posterior surface of the thyroid are four _____ glands that secrete parathyroid hormone (PTH).

Parathyroid hormone (PTH) raises blood Ca²⁺ concentration by promoting bone breakdown, reducing renal Ca²⁺ excretion, and stimulating intestinal Ca²⁺ absorption via _____.

The hormone-secreting endocrine cells of the pancreas are arranged in clusters called the _____.

Beta cells in the pancreatic islets produce _____, which lowers blood glucose by promoting cellular glucose uptake, fat synthesis, and protein synthesis.

Alpha cells in the pancreatic islets secrete _____, which mobilizes energy stores and raises blood glucose during fasting.

Type I diabetes mellitus is an autoimmune disorder characterized by the destruction of pancreatic _____ cells.

Type II diabetes mellitus is characterized by insulin resistance due to defective insulin _____ or impaired intracellular signaling.

Due to increased fat metabolism in untreated Type I diabetes, elevated ketone bodies accumulate in the blood, leading to _____.

The presence of glucose in the urine of diabetic patients, known as glucosuria, leads to osmotic diuresis and increased _____.

The pineal gland secretes the amine hormone _____, which is synthesized from the amino acid tryptophan.

Melatonin secretion is stimulated by darkness, produced primarily at night, and directly inhibited by _____.

Biological rhythms and melatonin regulation are governed by the _____ (SCN) of the hypothalamus via sympathetic innervation.

Disruption of melatonin timing due to time-zone travel or night-shift work contributes to the physiological condition known as _____.

Seasonal affective disorder (SAD) is implicated with altered melatonin rhythms and often involves winter depression and _____ craving.

Atrial natriuretic peptide (ANP) is secreted by the atria of the heart in response to increased _____.

ANP promotes cardiovascular homeostasis by increasing renal excretion of water and _____.

In response to hypoxia, anemia, or high altitude, the kidneys secrete _____ to stimulate red blood cell production.

White adipose tissue secretes _____, a metabolic signal to the brain that suppresses appetite and reduces food intake.

Steroid-derived vitamin D precursors formed in the skin are converted by the liver and _____ into the active hormone.

Presence of human _____ gonadotropin (hCG), secreted by the placenta, is used in clinical assays to confirm pregnancy.

Placental lactogen (PL) is secreted during pregnancy to stimulate _____ growth and development for postpartum lactation.