Which component of blood is responsible for transporting oxygen to tissues?

A. Antidiuretic hormone (ADH):ADH (vasopressin) promotes water reabsorption in the kidneys; deficiency reduces water reabsorption, producing excessive urine output (polyuria) and compensatory thirst (polydipsia), and head trauma can damage the hypothalamic–posterior pituitary axis causing this deficiency.
B. Aldosterone:Aldosterone increases sodium reabsorption and water retention in the distal nephron; deficiency can cause salt wasting and volume depletion but is less directly associated with the classic polyuria/polydipsia pattern seen after head trauma.
C. Oxytocin:Oxytocin primarily affects uterine contraction and milk ejection; deficiency does not typically produce polyuria and polydipsia.
D. Cortisol:Cortisol influences metabolism and stress responses and, in excess, can cause polyuria via osmotic diuresis from hyperglycemia, but isolated cortisol deficiency or excess is a less direct explanation for sudden polyuria and polydipsia following head trauma compared with ADH loss.

A. It directly releases cortisol into the bloodstream.:The hypothalamus does not release cortisol; cortisol is secreted by the adrenal cortex under pituitary control.
B. It secretes antidiuretic hormone (ADH) to control fluid balance.:ADH is synthesized in the hypothalamus but is stored and released from the posterior pituitary; secretion of ADH is one hypothalamic function but not the primary role in the HPA axis.
C. It inhibits the release of aldosterone from the adrenal cortex.:Aldosterone regulation is mainly via the renin–angiotensin system and potassium levels; the hypothalamus does not primarily inhibit aldosterone.
D. It secretes corticotropin-releasing hormone (CRH) to stimulate ACTH release.:The hypothalamus releases CRH, which stimulates the anterior pituitary to secrete ACTH, initiating the HPA axis cascade that leads to cortisol production.