All MCQs

Water-soluble peptide hormones typically bind cell-surface receptors. Second messengers carry the signal inside the cell to produce a response.

Endocrine hormones are commonly transported through blood, so blood levels provide useful information about endocrine function and feedback status.

Fish generally have single circulation: heart to gills to body and back to heart. The heart contains one atrium and one ventricle.

Antidiuretic hormone increases water reabsorption in kidney collecting ducts, helping maintain body water balance and osmotic homeostasis.

Steroid hormone-receptor complexes often bind DNA or influence transcription. This can lead to slower but longer-lasting physiological changes.

Exocrine glands release secretions through ducts to surfaces or cavities. Endocrine glands release hormones directly into internal fluids without ducts.

Amphibians have two atria and one ventricle, allowing partial separation of blood streams. It is an intermediate condition between fish and birds/mammals.

The hypothalamus links nervous and endocrine systems. It releases factors that regulate the pituitary and receives feedback from circulating hormones.

Exocrine glands use ducts to deliver secretions to body surfaces or cavities. Endocrine glands are ductless and release hormones internally.

High thyroid hormone feeds back to reduce hypothalamic and pituitary stimulation, including TSH. This prevents excessive thyroid activity.

Four-chambered hearts fully separate oxygenated and deoxygenated blood. This supports efficient oxygen delivery and high metabolism.

Thyroid-stimulating hormone from the anterior pituitary stimulates thyroid hormone production. It is part of the hypothalamic-pituitary-thyroid axis.